CP Week 2

Question 1

What marks the T4/T5 intervertebral disc level and the attachment of the 2nd costal cartilage?

Answer 1

The Sternal Angle (of Louis)

Used to count ribs during physical examination.

Question 2

What does the pericardial cavity contain that lubricates surfaces and maintains lung-chest wall contact?

Answer 2

A capillary layer of serous fluid

Lack of fluid can lead to friction or tamponade.

Question 3

Where is the Transverse Pericardial Sinus located?

Answer 3

Posterior to the ascending aorta and pulmonary trunk, anterior to the superior vena cava

It is a critical surgical landmark.

Question 4

How does the structure of the right main bronchus differ from the left?

Answer 4

Wider, shorter, and runs more vertically

This structure leads to a higher likelihood of foreign body aspiration into the right lung.

Question 5

What structures run from anterior to posterior in the superior mediastinum?

Answer 5

• Thymus
• Veins
• Arteries
• Trachea
• Esophagus
• Thoracic Duct

Nerves like Vagus and Phrenic run integrated within layers.

Question 6

Where do the phrenic and vagus nerves run in relation to the root of the lung?

Answer 6

Phrenic nerves run anterior; Vagus nerves run posterior

Important for root of lung dissection.

Question 7

When are coronary arteries perfused?

Answer 7

During ventricular diastole

Aortic recoil pushes blood back into the aortic sinuses.

Question 8

From where do the right and left coronary arteries arise?

Answer 8

• Right coronary artery: right aortic sinus
• Left coronary artery: left aortic sinus
• Posterior sinus: typically noncoronary

Important for coronary angiography.

Question 9

What is the function of the cardiac skeleton?

Answer 9

Supports valves and acts as electrical insulation

Ensures atria and ventricles contract independently.

Question 10

What is the ligamentum arteriosum a remnant of?

Answer 10

The fetal ductus arteriosus

It connects the pulmonary trunk to the arch of the aorta.

Question 11

What effect does sympathetic stimulation have on heart rate and force?

Answer 11

Increases heart rate and force, causing coronary artery dilation

Involves T1-T5/T6 presynaptic fibers.

Question 12

What is the anatomy of the right ventricle characterized by?

Answer 12

Smooth outflow portion (conus arteriosus/infundibulum) leading to pulmonary trunk

Separated from inflow by the supraventricular crest.

Question 13

What principle governs blood flow regulation?

Answer 13

The heart pumps all the blood returned to it (Frank-Starling Law)

Cardiac Output is the sum of all local tissue blood flows controlled by tissue needs.

Question 14

What happens to cardiac muscle with increased venous return?

Answer 14

Stretches cardiac muscle, optimizing actin-myosin interdigitation

This increases force of contraction/stroke volume within physiological limits.

Question 15

What is the normal pressure in the pleural cavity?

Answer 15

Subatmospheric/negative (e.g., -5 cm H2O at rest)

Results from opposing elastic forces of the lung and chest wall.

Question 16

What type of epithelium lines the respiratory tract?

Answer 16

Ciliated pseudostratified columnar epithelium with goblet cells

Lines conducting portion from nasal cavity down to terminal bronchioles.

Question 17

What is the function of cilia in the respiratory epithelium?

Answer 17

Move mucus layer toward the pharynx

Dysfunction can lead to chronic infections and male infertility (e.g., Kartagener Syndrome).

Question 18

What are the histological types of capillaries?

Answer 18

• Continuous
• Fenestrated
• Discontinuous/Sinusoidal

Each type has different permeability characteristics.

Question 19

What are the differences between Type I and Type II alveolar cells?

Answer 19

• Type I: Extremely thin, form blood-air barrier, optimized for gas exchange
• Type II: Cuboidal, secrete pulmonary surfactant

Type II lowers surface tension; important in conditions like Respiratory Distress Syndrome.

Question 20

What is aortic coarctation?

Answer 20

Narrowing of the aorta lumen

Classified into preductal or postductal types.

Question 21

What characterizes obstructive lung disease?

Answer 21

Increased resistance and high lung volumes

Patients seek higher volume to increase airway caliber via radial traction.

Question 22

What is the composition of the blood-air barrier?

Answer 22

Fused basal laminae of capillary endothelium and Type I alveolar cells

Highly attenuated for rapid gas diffusion.

Question 23

What does the ECG T wave represent?

Answer 23

Ventricular repolarization

Important in diagnosing conditions like hyperkalemia or ischemia.

Question 24

What can cause congenital heart defects during embryonic development?

Answer 24

Viral infection during the first trimester (e.g., German measles)

The fetal heart is forming during this period.

Question 25

What is arteriosclerosis?

Answer 25

Hardening and loss of elasticity of arterial walls ## Footnote Atherosclerosis is the primary cause of ischemic heart disease.

Question 26

What are the remnants of fetal circulation?

Answer 26

* Ductus arteriosus: ligamentum arteriosum * Ductus venosus: ligamentum venosum * Foramen ovale: fossa ovalis ## Footnote Important for understanding neonatal circulation.

Question 27

When does cardiovascular development begin?

Answer 27

Around day 18 ## Footnote This marks the initiation of the heart formation in the embryo.

Question 28

What occurs during days 22-26 of cardiovascular development?

Answer 28

Heart looping ## Footnote This process involves the bending of the heart tube to establish the proper orientation of the heart.

Question 29

When are functional valves in the heart complete?

Answer 29

Approximately 7 weeks ## Footnote This is critical for ensuring proper blood flow through the heart.

Question 30

What do bilateral endocardial tubes fuse to form?

Answer 30

A single heart tube ## Footnote This fusion occurs during embryonic folding.

Question 31

What are the five primitive "rooms" of the heart tube? (Mnemonic: Some People Value Bouncing Tennisballs)

Answer 31

**S**inus Venosus **P**rimitive Atrium Primitive **V**entricle **B**ulbus Cordis **T**runcus Arteriosus

Question 32

What does the sinus venosus develop into?

Answer 32

Smooth part of the Right Atrium, SA node, coronary sinus, and the oblique vein of the left atrium ## Footnote These structures are vital for the heart's electrical conduction and blood flow.

Question 33

What is formed from the primitive atrium?

Answer 33

Trabeculated parts of both adult right and left atrium ## Footnote This structure contributes to the overall shape and function of the atria.

Question 34

What does the primitive ventricle give rise to?

Answer 34

Trabeculated parts of both adult left and right ventricles ## Footnote These parts are essential for effective pumping of blood.

Question 35

What does the bulbus cordis develop into?

Answer 35

Smooth outflow tract of the Right Ventricle and smooth part of the Left Ventricle ## Footnote This includes structures like the **conus arteriosus** and **aortic vestibule**.

Question 36

What does the truncus arteriosus form?

Answer 36

Ascending Aorta and Pulmonary Trunk ## Footnote These are major vessels responsible for carrying blood away from the heart.

Question 37

What is dextrocardia?

Answer 37

Improper or reversed cardiac looping ## Footnote This results in the heart being located in the right chest cavity.

Question 38

What is the role of the secondary heart field (SHF)?

Answer 38

SHF -> Right Ventricle (Finishes the right-side pump). SHF -> Outflow Tract (Builds the two great arteries: Aorta and Pulmonary Artery). ## Footnote SHF cells are crucial for the development of these heart structures.

Question 39

What does the proepicardium contribute to?

Answer 39

Formation of the epicardium and cellular precursors for coronary arteries ## Footnote This is essential for heart vascularization.

Question 40

What happens during AV canal septation?

Answer 40

AV cushions fuse to form the AV septum and valves ## Footnote This separates atrial and ventricular canals.

Question 41

What is the function of the septum primum in atrial septation?

Answer 41

Grows down toward the AV cushions, allowing R → L shunt of oxygenated fetal blood ## Footnote This is important for fetal circulation.

Question 42

What does the septum secundum do?

Answer 42

Grows adjacent to the septum primum, forming the Foramen Ovale ## Footnote This allows for continued shunting of blood in fetal life.

Question 43

What is the membranous interventricular septum formed by?

Answer 43

Fusion of the muscular IVS, AV cushions, and conotruncal ridges ## Footnote Failure to fuse leads to common VSD types.

Question 44

What is the aorticopulmonary septum formed by?

Answer 44

Conotruncal ridges that spiral to separate the truncus arteriosus ## Footnote This is crucial for proper division of the aorta and pulmonary trunk.

Question 45

What role do cardiac neural crest cells (CNC) play?

Answer 45

Form the conotruncal ridges essential for spiraling outflow tract septation ## Footnote CNC are vital for normal heart structure.

Question 46

What is persistent truncus arteriosus (PTA)?

Answer 46

Failure of CNC migration leads to a single outflow vessel ## Footnote This is a cyanotic congenital defect.

Question 47

What causes transposition of the great arteries (TGA)?

Answer 47

Failure of the outflow tract spiraling event ## Footnote This condition results in the aorta arising from the RV.

Question 48

What is a classic chest X-ray finding in TGA (Transposition of the Great Arteries)?

Answer 48

Narrow superior mediastinum with an 'egg-on-a-string' appearance ## Footnote This radiographic appearance indicates misaligned great vessels.

Question 49

What does aortic arch 3 form?

Answer 49

Common Carotid Artery and first part of the Internal Carotid Artery ## Footnote These arteries supply blood to the head and neck.

Question 50

What does aortic arch 4 develop into on the left side?

Answer 50

Arch of the Aorta ## Footnote This extends from the left common carotid to the left subclavian artery.

Question 51

What does aortic arch 6 form on the left side?

Answer 51

Left Pulmonary Artery and Ductus Arteriosus ## Footnote These structures are important for fetal circulation.

Question 52

How does the left recurrent laryngeal nerve course change?

Answer 52

Loops under the Ductus Arteriosus ## Footnote This is due to asymmetrical arch development.

Question 53

What do umbilical arteries become postnatally?

Answer 53

Internal iliac and superior vesical arteries, and umbilical ligaments ## Footnote These derivatives are involved in pelvic circulation.

Question 54

What is the SA Node developed from?

Answer 54

Specialized cardiac myocytes in the right wall of the sinus venosus ## Footnote This development occurs during the 5th week.

Question 55

What does the fetal ductus venosus do?

Answer 55

Bypasses the majority of the liver, directing blood to the IVC ## Footnote This helps in oxygenating blood from the placenta.

Question 56

What is the function of the fetal foramen ovale?

Answer 56

Bypasses the right ventricle/pulmonary circulation ## Footnote This allows for effective fetal blood flow.

Question 57

What connects the pulmonary artery to the aorta in the fetus?

Answer 57

Fetal ductus arteriosus ## Footnote This structure bypasses the non-functional fetal lungs.

Question 58

What is the primary physiologic change that initiates the functional closure of the ductus arteriosus after birth?

Answer 58

Increased PO₂, decreased prostaglandin E2, and bradykinin secretion ## Footnote These factors are crucial for the transition to postnatal circulation.

Question 59

What causes the functional closure of the foramen ovale?

Answer 59

Increased Left Atrial Pressure after the first breath ## Footnote This pressure change leads to the septum primum sealing off the foramen.

Question 60

What does the left umbilical vein become after birth?

Answer 60

Ligamentum Teres Hepatis ## Footnote This remnant is a fibrous cord in the liver.

Question 61

What do the anterior cardinal veins form?

Answer 61

Left Brachiocephalic Vein and Right Brachiocephalic Vein ## Footnote These veins are important for draining the upper body into the heart.

Question 62

What do supracardinal veins develop into?

Answer 62

IVC segment (thoracic), azygos, and hemiazygos veins ## Footnote These veins are critical for venous return from the lower body.

Question 63

What is the definition of the Cardiac Cycle?

Answer 63

Sequence of mechanical events (contraction/relaxation) driven by cyclic variations in cardiac electrical activity.

Question 64

What is the duration of Diastole compared to Systole?

Answer 64

Diastole (0.53 sec) is nearly twice as long as Systole (0.27 sec) at a normal heart rate (75 bpm).

Question 65

What condition severely shortens the critical diastolic filling time?

Answer 65

Tachycardia.

Question 66

What is End Diastolic Volume (EDV)?

Answer 66

Maximum blood volume in the ventricle at the end of diastole, just before contraction; represents Preload (approx 135 mL).

Question 67

What does the P wave represent in cardiac physiology?

Answer 67

SA node fire/atrial depolarization; precedes atrial contraction.

Question 68

What does the QRS Complex signify?

Answer 68

Ventricular excitation/depolarization, signaling the onset of ventricular systole.

Question 69

What causes the First Heart Sound (S1)?

Answer 69

Sharp closure of the Atrioventricular (AV) valves when ventricular pressure exceeds atrial pressure.

Question 70

What is Isovolumetric Contraction (IVC)?

Answer 70

Phase where all four valves are closed; ventricular volume is constant while pressure increases.

Question 71

What marks the Aortic Valve Opening?

Answer 71

Occurs when Ventricular Pressure surpasses Aortic Pressure; starts the ejection phase.

Question 72

What does the T wave signify?

Answer 72

Ventricular repolarization, marking the end of systole and onset of ventricular relaxation.

Question 73

What causes the Second Heart Sound (S2)?

Answer 73

Sharp closure of the Semilunar valves when ventricular pressure falls below arterial pressure.

Question 74

What is the Dicrotic Notch?

Answer 74

Brief disturbance on the aortic pressure curve produced by the closure of the aortic valve.

Question 75

What is End Systolic Volume (ESV)?

Answer 75

Minimum volume of blood left in the ventricle at the end of systole (approx 65 mL).

Question 76

What occurs during Isovolumetric Relaxation (IVR)?

Answer 76

All four valves are closed; ventricular volume is constant while pressure drops.

Question 77

What does the Atrial Pressure A wave represent?

Answer 77

Pressure increase in the atrium due to atrial systole (contraction).

Question 78

What does the Atrial Pressure C wave indicate?

Answer 78

Pressure increase due to the AV valve bulging back into the atrium during early isovolumetric contraction.

Question 79

What does the Atrial Pressure V wave signify?

Answer 79

Pressure increase due to the atrium filling with venous blood while the AV valve is closed.

Question 80

What are Jugular Venous Pressure (JVP) Waves associated with?

Answer 80

Physiologically identical to right atrial pressure changes (A, C, V waves).

Question 81

When is the Third Heart Sound (S3) audible?

Answer 81

During rapid ventricular filling (early diastole); caused by blood *sloshing* into a compliant ventricular wall. ## Footnote A sign of a dilated ventricle

Question 82

What does the Fourth Heart Sound (S4) indicate?

Answer 82

Audible during reduced filling/atrial systole; caused by blood *striking* a stiffened ventricular wall. ## Footnote A sign of a hypertrophied ventricle

Question 83

What are the pressure levels in the Right Heart compared to the Left Heart?

Answer 83

Pulmonary pressures (25/8 mmHg) are lower than Aortic pressures (120/80 mmHg).

Question 84

What characterizes the Right Heart Isovolumetric Phases?

Answer 84

Shorter phases of isovolumetric contraction and relaxation compared to the left heart due to lower required pressures.

Question 85

What is the formula for Cardiac Output (CO)?

Answer 85

CO (L/min) equals Stroke Volume (L/beat) times Heart Rate (bpm) ## Footnote This formula is fundamental in understanding hemodynamics.

Question 86

How is Stroke Volume (SV) calculated?

Answer 86

SV is the difference between End-Diastolic Volume (EDV) and End-Systolic Volume (ESV): SV = EDV - ESV ## Footnote This is crucial for assessing ventricular function.

Question 87

What is the Cardiac Index (CI)?

Answer 87

CO normalized to body size (Body Surface Area) for clinical contexts like medication dosing ## Footnote CI allows for more accurate assessment based on individual size.

Question 88

Define Preload.

Answer 88

Degree of passive tension/stretch exerted on myocardial fibers at the end of diastole, estimated by ventricular and EDV/pressure ## Footnote Preload is a key determinant of cardiac performance.

Question 89

What is Afterload?

Answer 89

Pressure or resistance the ventricle must overcome to eject blood during systole; defined by aortic diastolic pressure and outflow resistance ## Footnote Afterload influences cardiac workload.

Question 90

Define Contractility.

Answer 90

Intrinsic ability of the heart muscle to contract and generate force, **independent of changes in preload or afterload** ## Footnote This is often referred to as **inotropy**.

Question 91

What does the Frank-Starling Law of the Heart state?

Answer 91

Output is directly related to filling (Preload); the heart pumps what it receives, balancing RV and LV outputs ## Footnote This principle is vital for understanding ventricular balance.

Question 92

What is the significance of Starling's Law?

Answer 92

Maintains output balance between pulmonary and systemic circulations; a 1% mismatch shifts total blood volume into one circuit, causing catastrophic pulmonary congestion ## Footnote This can lead to conditions like pulmonary edema.

Question 93

What is the molecular basis of Starling's Law?

Answer 93

Increased sarcomere length (due to filling/Preload) increases Ca²⁺ sensitivity of contractile filaments, leading to greater tension/force generation ## Footnote This highlights the biochemical mechanisms involved in cardiac function.

Question 94

What determines Preload?

Answer 94

Central Venous Pressure (CVP) is the major determinant of right atrial pressure (RAP), which determines ventricular filling (preload) ## Footnote CVP reflects the volume status of the patient.

Question 95

What factors affect CVP/Preload?

Answer 95

* Venous smooth muscle tone * Blood volume * Body position (gravity) * Intrathoracic pressure (respiratory pump) * Skeletal muscle pump ## Footnote These factors influence venous return and cardiac filling.

Question 96

What is a pathophysiologic limit to Preload?

Answer 96

Increased pericardial pressure (effusion/tamponade) or decreased ventricular compliance (hypertrophy) limits diastolic filling, reducing EDV ## Footnote This can lead to compromised cardiac output.

Question 97

How does increased Afterload affect Stroke Volume (SV)?

Answer 97

Increased afterload (e.g., high BP) decreases shortening velocity, forcing the heart to spend more time generating pressure during IVC, reducing overall ejection time and SV ## Footnote This relationship is crucial in systemic hypertension.

Question 98

What is Ejection Fraction (EF)?

Answer 98

Index of cardiac performance, calculated as SV/EDV × 100%; normal range is 55-70% ## Footnote EF is a key indicator of heart function.

Question 99

What happens to EF in Dilated Cardiomyopathy?

Answer 99

EF decreases due to reduced SV (weak pump) and increased EDV (chamber dilation), key measure of systolic heart failure severity ## Footnote This condition reflects severe heart dysfunction.

Question 100

What does the End-Systolic Pressure Volume Relation (ESPVR) describe?

Answer 100

Describes maximal pressure ventricle develops at any given volume; the slope is the best, load-independent index of intrinsic contractility (Inotropy) ## Footnote ESPVR is important for assessing contractility.

Question 101

How do pharmacologic inotropes affect ESPVR?

Answer 101

Positive inotropes (Dobutamine) increase contractility, resulting in a steeper ESPVR slope; Negative inotropes (Esmolol) result in a less steep slope ## Footnote This illustrates the pharmacological manipulation of cardiac function.

Question 102

What is the index of contractility: dP/dt_max?

Answer 102

Rate of maximal ventricular pressure rise during isovolumetric contraction; increased dP/dt reflects increased contractility ## Footnote This measurement is critical for evaluating heart function.

Question 103

What does the End Diastolic Pressure-Volume Relation (EDPVR) reflect?

Answer 103

Describes the passive filling curve; its slope reflects ventricular compliance/stretchiness ## Footnote EDPVR is essential for understanding diastolic function.

Question 104

What is the effect of a stiff ventricle (hypertrophy)?

Answer 104

Decreased compliance/stretch leads to higher filling pressure (↑ EDP) at the same volume, limiting diastolic filling and EDV ## Footnote This condition is associated with diastolic dysfunction.

Question 105

How does tachycardia affect Stroke Volume (SV)?

Answer 105

Increased HR severely reduces diastolic time available for ventricular filling, resulting in reduced EDV and decreased SV ## Footnote This highlights the importance of heart rate in cardiac performance.

Question 106

What is the CO/VR equilibrium point?

Answer 106

The intersection of the Cardiac Function Curve (CFC) and Vascular Function Curve (VFC) represents the steady-state CO and RAP ## Footnote This point is crucial for understanding circulatory stability.

Question 107

What is the equation for Venous Return (VR)?

Answer 107

VR is proportional to the pressure gradient driving flow: (Central Venous Pressure - Right Atrial Pressure) / Resistance ## Footnote This equation is fundamental in hemodynamics.

Question 108

What is the Mean Systemic Filling Pressure (MSFP)?

Answer 108

Theoretical pressure if the heart stopped and all vessel pressures equalized; measures the 'fullness' of the circulatory system ## Footnote MSFP provides insight into blood volume status.

Question 109

What is the effect of increased blood volume/venous tone on VFC?

Answer 109

Increased blood volume or sympathetic-induced venous tone (venoconstriction) shifts the VFC upward and to the right, increasing MSFP and VR ## Footnote This is important in the treatment of hypovolemia.

Question 110

What happens to VFC with increased Total Peripheral Resistance (TPR)?

Answer 110

Arteriolar constriction increases TPR causing a counter-clockwise rotation of the VFC (less VR at any given RAP); MSFP remains unchanged ## Footnote Understanding this relationship is key for managing vascular resistance.

Question 111

How does acute cardiac failure affect the PV loop?

Answer 111

Shifts PV loop toward higher ESV (incomplete ejection) and reduced SV; reduced contractility is the primary driver ## Footnote This change is critical for recognizing acute heart failure.

Question 112

What occurs in chronic compensated heart failure?

Answer 112

CO is restored toward normal (5 L/min) via RAAS activation and increased blood volume, but at the expense of significantly increased RAP (preload/congestion) ## Footnote This highlights the compensatory mechanisms in heart failure.

Question 113

What is the thickest layer in all arteries?

Answer 113

Tunica Intima (TI) ## Footnote This layer is crucial for the structural integrity of the artery.

Question 114

What are the key features of the Tunica Media in a Large Elastic Artery?

Answer 114

Many elastic lamellae (elastic sheets) ## Footnote These elastic sheets allow for expansion and recoil of the artery.

Question 115

What characterizes the Tunica Adventitia in a Large Elastic Artery?

Answer 115

Very sparse/thin connective tissue ## Footnote This layer provides structural support but is not as thick as in veins.

Question 116

What is a prominent feature of the Internal Elastic Lamina in a Medium Muscular Artery?

Answer 116

Prominent, wavy border ## Footnote This feature aids in the flexibility and function of the artery.

Question 117

How many concentric layers of smooth muscle can be found in the Tunica Media of a Medium Muscular Artery?

Answer 117

Up to 40 concentric layers ## Footnote This allows for significant regulation of blood flow.

Question 118

What is the characteristic of the Tunica Media in an Arteriole?

Answer 118

Less than 5 layers of smooth muscle cells ## Footnote This limited number of layers allows for fine control of blood flow.

Question 119

What is the appearance of the Endothelium in a Small Muscular Artery/Arteriole?

Answer 119

Scalloped layer/Wavy appearance ## Footnote This structure helps in adapting to changes in blood flow.

Question 120

What is the wall structure of a Capillary?

Answer 120

One or two endothelial cells/basal lamina only ## Footnote This minimal structure facilitates efficient exchange of materials.

Question 121

What is the thickest layer in a Large Vein (Vena Cava)?

Answer 121

Tunica Adventitia (TA) ## Footnote This layer contains longitudinal smooth muscle bundles.

Question 122

How many layers of smooth muscle are typically found in the Tunica Media of a Large Vein (Vena Cava)?

Answer 122

Few layers, small bundles of smooth muscle ## Footnote This reflects the lower pressure in veins compared to arteries.

Question 123

What is the characteristic of the lumen in a Venule?

Answer 123

Irregular, often collapsed lumen ## Footnote This shape helps in the passage of blood under lower pressure.

Question 124

What is the wall structure of a Lymphatic Vessel?

Answer 124

Single layer endothelium; incomplete basal lamina; lacks distinct tunics ## Footnote This structure allows for the absorption of interstitial fluid.

Question 125

What is the Endocardium in the Heart Wall?

Answer 125

Simple squamous endothelium (T. Intima equivalent) ## Footnote This layer lines the heart chambers and is crucial for smooth blood flow.

Question 126

What type of muscle is found in the Myocardium of the Heart Wall?

Answer 126

Cardiac muscle (T. Media equivalent) ## Footnote This muscle type is responsible for the heart's pumping action.

Question 127

What does the Epicardium consist of?

Answer 127

Connective tissue covered by mesothelium (T. Adventitia equivalent) ## Footnote This layer serves as a protective covering for the heart.

Question 128

What is the function of the Sinoatrial (SA) Node in the heart's conduction system?

Answer 128

Natural pacemaker, located right upper atrium ## Footnote It initiates the electrical impulses that regulate heartbeats.

Question 129

What are Purkinje Fibers characterized by?

Answer 129

Large diameter, abundant glycogen, sparse myofibrils (PALE and FAT) ## Footnote These fibers facilitate rapid conduction of electrical impulses.

Question 130

What are the divisions of the Mediastinum?

Answer 130

Superior (T1-T4) and Inferior (T5-T12) divided by the transverse thoracic plane. ## Footnote The transverse thoracic plane is located at the T4/T5 junction and the sternal angle.

Question 131

What contents are found in the Superior Mediastinum?

Answer 131

Aortic Arch/branches, SVC/Brachiocephalic veins, Esophagus/Trachea, Phrenic (C3-C5), Vagus Nerves. ## Footnote Phrenic Nerve provides motor control to the diaphragm.

Question 132

Where is the Anterior Mediastinum located?

Answer 132

Posterior to sternum, anterior to pericardium; contains mostly fat and adult remnants of the Thymus Gland. ## Footnote The thymus is involved in immune function.

Question 133

What are the contents of the Posterior Mediastinum? (DATES)

Answer 133

**D**escending Aorta **A**zygos Vein **T**horacic Duct **E**sophagus **S**ympathetic Trunk ## Footnote Esophagus, Thoracic Aorta, Sympathetic Trunk, Azygos/Hemiazygos system, Intercostal neurovasculature, Thoracic Duct. These structures are important for both vascular and nervous system functions.

Question 134

What is Aortic Coarctation?

Answer 134

Congenital narrowing of the aorta leading to hypertension in upper extremities and weak/absent pulses in lower extremities. ## Footnote This condition can lead to significant cardiovascular issues.

Question 135

What is a clinical trap associated with Aortic Coarctation?

Answer 135

Significant BP discrepancy (Arm higher than Leg) and development of collateral circulation visible on posterior chest wall (rib notching). ## Footnote Rib notching can be seen on chest X-ray (CXR) as a sign of long-standing coarctation.

Question 136

What characterizes Preductal Coarctation?

Answer 136

Occurs proximal to the ductus arteriosus; more severe presentation resulting in critical systemic hypoperfusion early in life. ## Footnote This condition often requires immediate medical intervention.

Question 137

What is the Postductal Coarctation Pitfall?

Answer 137

Occurs distal to the ductus arteriosus; less severe as collateral blood vessels develop, delaying symptom onset. ## Footnote Symptoms may not present until later in life.

Question 138

What is the mechanism of Patent Ductus Arteriosus (PDA)?

Answer 138

Failure of the ductus arteriosus to close within 72 hours of birth. ## Footnote The ductus arteriosus connects the pulmonary trunk and descending aorta in fetal life.

Question 139

What is the shunt direction in Patent Ductus Arteriosus?

Answer 139

Typically Left-to-Right (Aorta to Pulmonary Trunk), causing increased pulmonary flow and volume overload. ## Footnote This can lead to left ventricular hypertrophy.

Question 140

What is a Bronchoesophageal Fistula?

Answer 140

Abnormal connection due to failure of tracheoesophageal septum separation, allowing air/fluids to pass between. ## Footnote This condition can lead to serious complications like aspiration pneumonia.

Question 141

What symptoms are associated with Bronchoesophageal Fistula?

Answer 141

Recurrent respiratory infections, coughing/wheezing, dysphagia, regurgitation, failure to thrive in infants. ## Footnote These symptoms can significantly affect infant growth and health.

Question 142

What is the function of the Greater Thoracic Splanchnic Nerve?

Answer 142

Contains preganglionic sympathetic fibers from T5-T9 that synapse in the Celiac Ganglion, providing sympathetic innervation to the Foregut. ## Footnote This nerve is crucial for regulating digestive processes.

Question 143

What do the Lesser and Least Thoracic Splanchnic Nerves innervate?

Answer 143

Lesser (T10-T11) hits Superior Mesenteric/Aorticorenal ganglia (Midgut); Least (T12) hits Renal ganglion (Kidneys). ## Footnote They play roles in regulating functions of the midgut and kidneys.

Question 144

What are the symptoms of Mediastinal Syndrome?

Answer 144

Chest pain, cough, dysphagia, fatigue resulting from compression, infection, or tumors in the mediastinum. ## Footnote SVC Syndrome is a common presentation of this condition.

Question 145

True or False: Pericardial pain is midline and intensifies with breathing.

Answer 145

True. ## Footnote It can mimic pain associated with myocardial infarction (MI).

Question 146

What type of pain is associated with pathology in the Posterior Mediastinum?

Answer 146

Pain in the upper back between the shoulder blades. ## Footnote This referred pain can indicate underlying mediastinal issues.

Question 147

What is the sensory innervation responsible for pericardial pain referral?

Answer 147

Phrenic (C3, C4, C5) ## Footnote Pain refers to the neck or shoulder due to sharing the C5 root with the brachial plexus.

Question 148

What are the primary blood supplies to the pericardium?

Answer 148

Pericardiophenic and Musculophrenic arteries ## Footnote These are branches of the Internal Thoracic Artery.

Question 149

What is the clinical significance of the oblique pericardial sinus?

Answer 149

Space for fluid/blood accumulation ## Footnote Significant during effusions/tamponade when the patient is supine.

Question 150

What does the anterior interventricular artery (LAD) supply?

Answer 150

R/L ventricles and anterior 2/3 of the interventricular septum ## Footnote Blockage is known as the 'widowmaker.'

Question 151

What does the posterior interventricular artery (PDA) supply?

Answer 151

R/L ventricles and posterior 1/3 of the interventricular septum ## Footnote Derived from RCA in most cases.

Question 152

What structures are formed from the fetal vitelline vein derivatives?

Answer 152

Hepatocardiac portion of IVC, Portal Vein, Superior/Inferior Mesenteric Veins, Splenic Vein ## Footnote The right side persists.

Question 153

What causes post-natal left ventricular hypertrophy?

Answer 153

Increased systemic workload ## Footnote The absence of the placenta forces the Left Ventricle to work harder, leading to wall thickening.

Question 154

What is a potential complication of left atrial enlargement?

Answer 154

Compression of the adjacent esophagus ## Footnote This can cause dysphagia or a sensation of food sticking.

Question 155

What is a sign of aortic coarctation pathophysiology?

Answer 155

Rib Notching ## Footnote Chronic high pressure causes intercostal arteries to enlarge, carving notches in the inferior rib borders.

Question 156

What is the etiology of a bronchoesophageal fistula?

Answer 156

Failure of the tracheoesophageal septum to separate fully ## Footnote Occurs during 4th-8th week development, allowing fluid exchange and causing aspiration pneumonia.

Question 157

Where is the sympathetic trunk located?

Answer 157

Immediately lateral to the thoracic vertebral bodies ## Footnote Often visualized in dissection as the 'pearl necklace' (T1-L2 ganglia).

Question 158

What does the Somatic Nervous System control?

Answer 158

Voluntary actions of skeletal muscle ## Footnote Interacts with the external environment

Question 159

How does the Autonomic Nervous System (ANS) regulate the body?

Answer 159

Uses 2 neurons to regulate involuntary internal environment ## Footnote Targets smooth muscle, cardiac muscle, or glands

Question 160

Where do the preganglionic cell bodies of the Sympathetic Division originate?

Answer 160

Thoracolumbar segments (T1-L2) of the spinal cord ## Footnote Also known as thoracolumbar outflow

Question 161

Where do the preganglionic cell bodies of the Parasympathetic Division originate?

Answer 161

Craniosacral segments (CN III, VII, IX, X, S2-S4) ## Footnote Also known as craniosacral outflow

Question 162

Where are the cell bodies for preganglionic sympathetics located?

Answer 162

Intermediate gray (lateral horn) within T1-L2 ## Footnote Part of the spinal cord anatomy

Question 163

What is the synapse location for short preganglionic sympathetic fibers?

Answer 163

Ganglia near the CNS, either paravertebral or prevertebral ganglia ## Footnote This allows for quick responses

Question 164

What is the synapse location for long preganglionic parasympathetic fibers?

Answer 164

Ganglia located away from the CNS, typically near or in the effector organ ## Footnote This supports localized responses

Question 165

What neurotransmitter is primarily released by sympathetic postganglionic neurons?

Answer 165

Norepinephrine (NE) ## Footnote Supports the 'fright or flight' response

Question 166

What neurotransmitter is released by both pre- and postganglionic parasympathetic neurons?

Answer 166

Acetylcholine (ACh) ## Footnote Indicates cholinergic activity

Question 167

What are the effects of the sympathetic nervous system on the heart and lungs?

Answer 167

Raises heart rate, causes pupillary dilation (mydriasis), and results in bronchial dilation ## Footnote Known as the 'fight or flight' response

Question 168

What are the effects of the parasympathetic nervous system on the heart and eyes?

Answer 168

Lowers heart rate and causes pupillary constriction (miosis) ## Footnote Known as the 'rest and digest' response

Question 169

What is the organization of paravertebral sympathetic ganglia?

Answer 169

Typically 3 cervical, 11-12 thoracic, 4 lumbar, and 4 sacral ## Footnote Located along the sympathetic chain

Question 170

What are examples of prevertebral sympathetic ganglia?

Answer 170

* Celiac * Superior Mesenteric * Inferior Mesenteric * Aorticorenal ## Footnote These ganglia are associated with splanchnic targets

Question 171

What pathways can preganglionic sympathetic fibers take?

Answer 171

Can synapse at the same level, ascend, descend, or leave the chain without synapsing ## Footnote This forms splanchnic nerves

Question 172

What is the function of white communicating rami?

Answer 172

Carries myelinated preganglionic fibers to the sympathetic chain ## Footnote Found only in the T1-L2 segments "White on, Grey off"

Question 173

What is the function of grey communicating rami?

Answer 173

Carries unmyelinated postganglionic fibers from the sympathetic chain to the spinal nerve ## Footnote Found from C1 to S5 "White on, Grey off"

Question 174

What do cardiopulmonary splanchnic nerves innervate?

Answer 174

Heart and lungs ## Footnote Originates from T1-T4 segments

Question 175

Where does the Greater Splanchnic Nerve originate and what does it innervate?

Answer 175

Originates from T5-T9 and innervates Foregut derivatives ## Footnote Synapses in the Celiac ganglion

Question 176

Where does the Lesser Splanchnic Nerve originate and what does it innervate?

Answer 176

Originates from T10-T11 and innervates Midgut derivatives ## Footnote Synapses in the Superior Mesenteric ganglion

Question 177

Where does the Least Splanchnic Nerve originate and what does it supply?

Answer 177

Originates from T12 and supplies kidneys and suprarenal glands ## Footnote Synapses in the Aorticorenal ganglion

Question 178

What do Pelvic Splanchnic Nerves innervate?

Answer 178

Pelvic viscera ## Footnote Parasympathetic fibers from S2-S4

Question 179

What forms the Stellate Ganglion?

Answer 179

Fusion of the Inferior cervical sympathetic ganglion and the first thoracic ganglion ## Footnote Associated with Horner's Syndrome

Question 180

What percentage of preganglionic parasympathetic fibers does the Vagus Nerve (CN X) carry?

Answer 180

Approximately 75% ## Footnote Extends to the abdomen until the splenic flexure

Question 181

What is the function of CN III in the parasympathetic system?

Answer 181

Innervates sphincter pupillae and ciliary muscle ## Footnote Preganglionic fibers synapse in the Ciliary ganglion

Question 182

What is the function of CN VII in the parasympathetic system?

Answer 182

Supplies the lacrimal gland and mucosal glands of the nasal cavity/palate ## Footnote Preganglionic fibers synapse in the Pterygopalatine ganglion

Question 183

What does CN IX innervate in the parasympathetic system?

Answer 183

Innervates the parotid gland ## Footnote Preganglionic fibers synapse in the Otic ganglion

Question 184

What characterizes visceral sensory pain?

Answer 184

Poorly localized, dull, or diffuse discomfort ## Footnote Arises from internal organs/viscera

Question 185

What characterizes somatic sensory pain?

Answer 185

Well localized sensation ## Footnote Arises from skin, connective tissue, and skeletal muscle

Question 186

What does the cardiac plexus receive input from?

Answer 186

Sympathetic input from T1-T4 and parasympathetic input from the Vagus nerve (CN X) ## Footnote Important for heart rate and rhythm regulation

Question 187

What dermatomes are affected by referred pain from heart ischemia?

Answer 187

T1 to T4 ## Footnote Often perceived in the chest and left arm

Question 188

What dermatomes are affected by referred pain from the foregut?

Answer 188

T5 to T9 ## Footnote Pain perceived in the epigastric region

Question 189

What dermatomes are affected by referred pain from the midgut?

Answer 189

T10 to T11 ## Footnote Pain perceived in the periumbilical region

Question 190

What dictates the heart rate in cardiac conduction?

Answer 190

The fastest inherent rate (autorhythmicity) ## Footnote The SA node dominates at approximately 70 bpm. Failure of the SA node can lead to AV node takeover.

Question 191

What is Pacemaker Potential Phase 4 characterized by?

Answer 191

Slow depolarization driven by Funny channels and T-type Ca²+ channels ## Footnote Decreased K+ permeability is also part of this phase; associated with chronotropy modulation.

Question 192

What occurs during Pacemaker Depolarization Phase 0?

Answer 192

Rapid upstroke mediated solely by Long-lasting L-type Ca²+ channels ## Footnote Unlike contractile cells which have rapid Na+ influx; associated with Calcium Channel Blockers (CCBs).

Question 193

What do nodal cells lack during their action potential?

Answer 193

Phase 1 (Early Repolarization) and Phase 2 (Plateau) ## Footnote Nodal cells skip straight to Phase 3 Repolarization.

Question 194

What determines the upstroke velocity in Ventricular AP Depolarization Phase 0?

Answer 194

Opening of fast voltage-gated Na+ channels ## Footnote Associated with Class I Antiarrhythmics.

Question 195

What causes the plateau phase in Ventricular AP Phase 2?

Answer 195

Inward L-type Ca²+ current balancing outward K+ efflux ## Footnote This phase has a longer duration than in atrial cells; associated with L-type CCBs.

Question 196

What is the sympathetic chronotropic effect mediated by?

Answer 196

Noradrenaline acting on β1 receptors ## Footnote Increases cAMP to enhance Funny current (If), speeding up heart rate; associated with tachycardia and β-agonists.

Question 197

What effect does acetylcholine have on AV nodal conduction?

Answer 197

Decreases ICa²+ and increases outward K+ current ## Footnote This slows AV nodal conduction; associated with prolonged PR Interval.

Question 198

What does the ECG P Wave represent?

Answer 198

Electrical activation (depolarization) of the atria ## Footnote Initiated by the SA node firing.

Question 199

What does the ECG PR Interval indicate?

Answer 199

Time from P wave start to QRS complex start ## Footnote Represents conduction time through the AV node and HIS/Bundle branches; associated with heart blocks.

Question 200

What does the ECG QRS Complex represent?

Answer 200

Rapid ventricular depolarization ## Footnote Atrial repolarization occurs simultaneously but is electrically masked.

Question 201

What does the ECG ST Segment represent?

Answer 201

Time from end of ventricular depolarization to beginning of T wave ## Footnote Corresponds to the period where ventricles are contracting and emptying; associated with myocardial ischemia/infarction.

Question 202

What is the Absolute Refractory Period (ARP)?

Answer 202

Period where the cell membrane cannot be re-excited by any external stimulus ## Footnote This occurs regardless of voltage applied at the single cell level; prevents tetanization.

Question 203

What is the Supernormal Period (SNP)?

Answer 203

Short interval following RRP where the cell is more excitable ## Footnote A weaker than normal depolarizing stimulus can trigger a propagated AP; associated with arrhythmia trigger.

Question 204

What is the mechanism of excitation-contraction coupling in cardiac muscle?

Answer 204

Ca²+-induced Ca²+ release (CICR) ## Footnote Small Ca²+ influx via L-type channels triggers massive Ca²+ release from the Sarcoplasmic Reticulum via Ryanodine receptors; associated with heart failure.

Question 205

What prevents sustained, tetanic contraction in cardiac muscle?

Answer 205

The refractory period is almost as long as the entire mechanical contraction period ## Footnote This prevents tetanus, which would be fatal.

Question 206

What is First Degree Heart Block characterized by?

Answer 206

Slightly delayed conduction to the ventricles ## Footnote Results in a prolonged PR interval (greater than 0.2 seconds or 5 small boxes).

Question 207

What indicates a normal ECG axis using the Quadrant Method?

Answer 207

Positive deflection in both Lead I and Lead aVF ## Footnote Mean Electrical Axis is normal (0° to +90°).

Question 208

What characterizes Right Axis Deviation (RAD) using the Quadrant Method?

Answer 208

QRS is negative in Lead I but positive in Lead aVF ## Footnote RAD occurs within the range of +90° to +180°.

Question 209

What happens if an ectopic focus fires faster than the SA node?

Answer 209

It takes over and drives the whole heart ## Footnote This can lead to tachyarrhythmia.

Question 210

What does the mean QRS vector represent?

Answer 210

The average direction of electrical current in the heart ## Footnote Normally flows toward the apex (down and left, approximately 59 degrees).

Question 211

How are visceral afferent fibers related to the DRG and sympathetic nerves?

Answer 211

Their cell bodies are in the DRG, but their fibers travel alongside sympathetic efferent fibers from the viscera.

Question 212

What does the term 'splanchnic' refer to?

Answer 212

'Splanchnic' simply means visceral and is used loosely in contexts like cardiopulmonary splanchnics (pathway T1-T4).

Question 213

What are the targets of the Lesser Splanchnic Nerve?

Answer 213

Origin T10-T11; synapses at Superior Mesenteric Ganglia; innervates: * Jejunum * Ileum * Appendix * Ascending Colon * Proximal 2/3 of the Transverse Colon.

Question 214

What structures does the Lumbar Splanchnic Nerve innervate?

Answer 214

Origin L1-L2; synapses at Inferior Mesenteric Ganglia; innervates: * Distal 1/3 of the Transverse Colon * Descending Colon * Sigmoid Colon * Rectum.

Question 215

What are the symptoms of Horner's Syndrome?

Answer 215

Symptoms include: * Constricted pupil (miosis) * Drooping eyelid (ptosis) * Vasodilation/facial flushing * Anhydrosis (lack of sweating).

Question 216

List the four major checkpoints of the CN VII parasympathetic pathway to the submandibular/sublingual glands (Nerve -> Branch -> Ganglion -> Target).

Answer 216

Facial nerve CN VII -> chorda tympani -> submandibular ganglion -> submandibular and sublingual glands ## Footnote This pathway is separate from the parotid gland's parasympathetic innervation, which is carried by the Glossopharyngeal Nerve (CN IX) and synapses in the otic ganglion.

Question 217

What is the anatomical difference between the right and left Recurrent Laryngeal Nerve?

Answer 217

Right RLN loops under the right subclavian artery; Left RLN loops under the arch of the aorta (or ligamentum arteriosum).

Question 218

What is the clinical significance of foregut referred pain?

Answer 218

Visceral pain from the foregut (T5-T9) is often referred to the chest/epigastric region; ~70% of chest pain presentations are abdominal in origin.

Question 219

Describe the pain pattern in acute appendicitis.

Answer 219

Initial pain is dull/diffuse around the umbilicus (T10 dermatome); if the appendix expands, pain becomes sharp and localized, commonly referring to McBurney's Point.

Question 220

What is the consequence of losing the AV nodal delay?

Answer 220

Loss of the AV nodal delay would lead to simultaneous contraction and potential ventricular failure.

Question 221

What ionic mechanisms underlie the unstable Phase 4 of the nodal action potential?

Answer 221

The unstable Phase 4 slope is due to increased I_f, transient T-type Ca2+ channels, and decreased outward K+ permeability.

Question 222

How does the Purkinje fiber action potential differ from ventricular myocytes?

Answer 222

Purkinje fibers exhibit an unstable Phase 4, while ventricular myocytes have a stable Phase 4 (Resting Potential -80 to -90 mV).

Question 223

What is the primary driver of atrial myocyte depolarization?

Answer 223

Atrial Phase 0 is slower than ventricular Phase 0 and is driven by both Na+ and L-type Ca2+ currents.

Question 224

What is the significance of the I_K,Ach channel in atrial repolarization?

Answer 224

Atrial repolarization (Phase 3) is shorter than ventricular due to the I_K,Ach potassium channel activated by Acetylcholine (ACh).

Question 225

How does ACh affect AV nodal conduction?

Answer 225

ACh slows AV nodal conduction by decreasing inward Ca2+ current and increasing outward K+ current.

Question 226

What are the calibration standards for ECG paper?

Answer 226

1 small box (1mm) = 40 milliseconds (0.04s) horizontally and 0.1 millivolt (0.1mV) vertically; five small boxes = 0.2 seconds.

Question 227

What does the QRS voltage indicate?

Answer 227

The magnitude correlates with the mass of depolarizing myocardium. ## Footnote The Left Ventricle (LV) often dictates the main electrical axis due to its larger muscle mass. → High voltage can be a sign of Ventricular Hypertrophy.

Question 228

What is the primary mechanism of ventricular filling during the cardiac cycle?

Answer 228

Majority of ventricular filling is passive, driven by a 5 mmHg LA-LV pressure gradient. ## Footnote High flow occurs due to open Mitral/Tricuspid valves offering almost zero resistance.

Question 229

How is the cardiac cycle duration broken down at 75 bpm?

Answer 229

Diastole (0.53s), Filling (0.41s: Rapid 0.12s, Reduced 0.19s), Ejection (0.22s: Rapid 0.09s). ## Footnote Filling phase dominates the cardiac cycle.

Question 230

When does the fastest pressure generation occur in the cardiac cycle?

Answer 230

During the Isovolumetric Contraction (IVC) phase. ## Footnote This reflects peak contractility kinetics.

Question 231

What are the key descents observed in atrial pressure during the cardiac cycle?

Answer 231

X descent during rapid ejection and Y descent immediately after AV valve opens. ## Footnote These descents mark important phases in atrial pressure dynamics.

Question 232

What does the Frank-Starling mechanism indicate about the heart's operation? (which part of the curve)

Answer 232

The heart operates on the ascending limb of its length-tension curve. ## Footnote Increasing preload stretches sarcomeres for optimal overlap and maximal force generation.

Question 233

How does increased afterload affect stroke volume?

Answer 233

Increased afterload decreases stroke volume, spending more time generating pressure during IVC. ## Footnote This results in less time available for actual ejection.

Question 234

How does the right heart cycle length compensate during the cardiac cycle?

Answer 234

Right heart systole is longer, with shorter IVC and IVR phases due to lower pulmonary pressures. ## Footnote Total cycle time is equal, but the right heart adapts to maintain function.

Question 235

What happens to atrial systole's contribution to end-diastolic volume during tachycardia?

Answer 235

Atrial systole's contribution rises from ~10% to 20%+ at high heart rates. ## Footnote This prevents severe filling collapse due to reduced diastolic filling time.

Question 236

What is the effect of arterial constriction on the vascular function curve?

Answer 236

Arterial constriction rotates the Vascular Function Curve counter-clockwise. ## Footnote Mean systemic filling pressure (MSFP) remains unchanged despite changes in vascular resistance.

Question 237

What initial effect does acute sympathetic activation have on the cardiac function curve?

Answer 237

It causes arteriolar constriction, temporarily depressing the Cardiac Function Curve before positive effects take over. ## Footnote This results in reduced stroke volume initially.

Question 238

NE_beta1 -> PKA signaling enhances contractility (Inotropy) by phosphorylating what specific Ca2+ channel?

Answer 238

The L-type Ca2+ channels (Dihydropyridine Receptors) on the cell membrane. ## Footnote This increases Ca2+ influx, massively triggering Ca2+-Induced Ca2+ Release (CICR) from the SR, increasing force generation.

Question 239

What three key physiological effects are mediated by PKA phosphorylation during sympathetic activation?

Answer 239

Chronotropy increases HR via I_f current Inotropy increases force via Ca2+ Lusitrophy increases relaxation ## Footnote Clinically, positive lusitropy is essential for maximizing diastolic filling time when HR is jacked up by the sympathetic system.

Question 240

The positive Lusitropic effect involves PKA phosphorylating which critical pump system?

Answer 240

SERCA2a pump (Phosphlamban) complex ## Footnote This speeds up Ca2+ reuptake into the SR post-contraction. Pitfall: Lack of proper Ca2+ reuptake is a mechanism in cardiac failure.

Question 241

PKA shortens the cardiac Action Potential Duration (APD) by acting on which channel?

Answer 241

The slow delayed rectifier K+ channels I_Ks accelerating Phase 3 repolarization. ## Footnote Board Trap: Shortened APD prevents sustained, tetanic contraction, which would be fatal. This shortening is seen on the ECG as a reduced QT interval.

Question 242

What is the pathophysiologic limit of bradycardia?

Answer 242

If HR falls below ~40 bpm, maximum stroke volume can no longer compensate for the slow rhythm, causing Cardiac Output to decrease in direct proportion to the HR. ## Footnote This refers to the relationship between heart rate and cardiac output in bradycardia.

Question 243

What triggers an increase in blood volume or venous tone that shifts the VFC (Venous Function Curve) up/right?

Answer 243

Key activators include: * Sympathetic activation (alpha-1 receptor targeted venoconstriction) * RAAS activation (fluid retention) * Aldosterone/ADH * Exercise * IV Fluids ## Footnote These factors are crucial for understanding changes in venous compliance and flow characteristics.

Question 244

What effect does vasoconstriction have on the VFC rotation?

Answer 244

Vasoconstriction causes a counter-clockwise rotation of the VFC via Angiotensin II, ADH, Endothelin, and increased sympathetic tone. ## Footnote This rotation indicates changes in arteriolar resistance while maintaining MSFP.

Question 245

What are the three components of the sympathetic response in the CO/VR curve sequence?

Answer 245

1. Initial increase in arterial resistance temporarily decreases CO and shifts the CFC downward. 2. Later, increased contractility shifts CFC up. 3. Increased venous tone shifts VFC up/right, restoring CO at a higher RAP. ## Footnote This sequence illustrates the body's compensatory mechanisms during sympathetic activation.

Question 246

Describe the stepwise compensation in CHF progression.

Answer 246

Heart failure compensation follows: * A (Normal) * B (Acute MI: decrease in contractility) * C (Baroreceptor reflex: increase in sympathetic drive) * D (Chronic/Compensated: RAAS activation, volume retention, CO restored at the expense of increased RAP/preload/congestion). ## Footnote This sequence highlights the adaptive responses of the heart to failure.

Question 247

What is the clinical definition of venous congestion?

Answer 247

Abnormal blood accumulation in the venous circulation leading to elevated capillary hydrostatic pressure, causing disproportionate fluid filtration into interstitial spaces, resulting in edema. ## Footnote Examples include pulmonary congestion or peripheral edema.

Question 248

What hemodynamic changes occur in cardiac failure as represented in the PV loop?

Answer 248

Cardiac failure shifts the PV loop towards increased volumes and decreased pressures: * Decreased Stroke Volume (narrower loop width) * Increased End-Diastolic Volume/Pressure * Decreased Aortic/Ventricular/Pulse pressures. ## Footnote These changes indicate the impaired functioning of the heart in failure.

Question 249

What is a significant pitfall regarding stroke volume in chronic compensated CHF?

Answer 249

In chronic compensated heart failure (RAAS activated), the PV loop shifts further right compared to acute failure, indicating reliance on high EDV/EDP to maintain output, with stroke volume decreasing further. ## Footnote This reflects the progressive nature of heart failure and its impact on stroke volume.

Question 250

ID: Manubrium, Sternal Angle, Body, Xiphoid process

Answer 250

## Footnote The Sternal Angle is critical for locating the 2nd rib and the transverse thoracic plane.

Question 251

ID the following muscles (top). ID its attachments, blood supply, and innervations.

Answer 251

Pectoralis minor Clavicle, Sternum, Bicipital groove Pectoral banch of thoracoacromonial trunk Lateral and medial pectoral nerves

Question 252

ID the following muscles (middle). ID its attachments, blood supply, and innervations.

Answer 252

Pectoralis minor Ribs 3-5, Coracoid process Pectoral banch of thoracoacromonial trunk Medial pectoral nerve

Question 253

ID the following muscles (bottom). ID its attachments, blood supply, and innervations.

Answer 253

Serratus anterior Ribs 8-9, medial border of scapula Lateral thoracic artery Long thoracic nerve

Question 254

ID the muscles from superficial to deep and the direction they run

Answer 254

**External** intercostal muscles (run superomedial/inferior direction). **Internal** intercostal muscles (run superolateral/inferior direction). **Innermost** intercostal (run same direction as internal intercostals

Question 255

ID: Intercostal neurovascular bundle

Answer 255

In the **costal groove** (superior to inferior): Intercostal **V**ein Intercostal **A**rtery Intercostal **N**erve

Question 256

Answer 256

Internal intercostal muscle fascicles (1) run between adjacent ribs (2). An intercostal vein (3), artery (4), and nerve (5) run along the caudal border of each rib.

Question 257

ID: yellow pin

Answer 257

Transversus thoracis muscle

Question 258

ID: green arrow

Answer 258

Internal thoracic artery (and vein adjacent to it)

Question 259

Answer 259

Parietal Pleura Identify its regions: Costal, Diaphragmatic, Mediastinal, and Cervical (cupola)

Question 260

ID green region

Answer 260

Costodiaphragmatic recess (the largest recess, important for effusion accumulation)

Question 261

ID (color coded)

Answer 261

Intercostal VAN

Question 262

ID the lung surfaces/features (Apex, Costal surface, Mediastinal surface, Diaphragmatic surface; Cardiac notch and lungula)

Answer 262

Question 263

ID lung fissures

Answer 263

Oblique fissure (both lungs). Horizontal fissure (right lung, delineating the middle lobe).

Question 264

Answer 264

Main (primary) bronchus (Right is wider, shorter, more vertical—aspiration trap!). Secondary (lobar) bronchi. Tertiary (segmental) bronchi. Basic Science: ID bronchi by the presence of cartilage in their walls.

Question 265

Answer 265

Pulmonary arteries, Pulmonary veins, Primary bronchii. Trap Alert: Arteries are thick-walled and usually superior to the thinner-walled veins.

Question 266

Answer 266

Pulmonary arteries, Pulmonary veins, Primary bronchii. Trap Alert: Arteries are thick-walled and usually superior to the thinner-walled veins.

Question 267

ID: the blue structure

Answer 267

Pulmonary ligament ## Footnote Fold of parietal pleura extending inferiorly from the root of the lung

Question 268

Answer 268

## Footnote Phrenic nerve is located anterior to the root of the lung. Innervates the diaphragm (motor and central sensory). Pericardicophrenic artery and vein medial to the root of the lung and adjacent with the phrenic nerve.

Question 269

Answer 269

## Footnote Vagus Nerve (CN X) is located posterior to the root of the lung. Contributes parasympathetic input to the pulmonary plexus. NOTE the fibrous pericardium around the heart inferiorly*