1
Q
- located at the mediastinum- extending form the sternum to the vertberal column, the first rib to the diaphragm and btwn the lungs
- heart outward appearance
- apex at tip of left ventricle
- base is posterior surface
- anterior surface deep to sternum and ribs
- infereior surface betwn apex and R border
- right border faces R lung
- pulmonary border faces L lung
A
anatomy of the heart
2
Q
- Membrane surrounding and protecting the heart
- Confines while still allowing free movement
- includes fibrous , serous, and pericardial fluid
A
pericardium
3
Q
- Tough, inelastic, dense irregular connective tissue
- Prevents overstretching, provides protection and anchorage
A
fibrous pericardium
4
Q
- Thinner, more delicate membrane
- Double layer (parietal layer fused to fibrous pericardium, visceral layer also called epicardium)
A
serous pericardium
5
Q
- Secreted into pericardial cavity
- reduces friction
A
pericardial flluid
6
Q
- Visceral layer of serous pericardium
- Smooth, slippery texture to outermost surface
A
epidcardium(external layer)
7
Q
- 95% of heart is cardiac muscle
- middle layer
A
myocardium
8
Q
- (inner layer)
- Smooth lining for chambers of heart, valves and continuous with lining of large blood vessels
A
endocardium
9
Q
- ATRIA are Receiving chambers:Right and left
- Auricles increase capacity
- VENTRICLES:Right and left
- Pumping chambers
- SUCLI:Grooves on the surface of the heart
- Contain coronary blood vessels
- Coronary sulcus
- Anterior interventricular sulcus
A
chambers of the heart
10
Q
- Forms right border of the heart
- _Receives blood from vein_s:Superior vena cava,Inferior vena cava,Coronary sinus
- Interatrial septum:Separates right and left atrium
- Has fossa ovalis Remnant of foramen ovale
- Tricuspid valve:Separates right atrium from right ventricle
A
right atrium
11
Q
- forms anterior surface of heart
- includes trabeculae carneae, tricuspid valve
- blood leaves thru pulmonary valve into pulmonary trunk and then to R and L pulmonary arteries
A
right ventricle
12
Q
- Ridges formed by raised bundles of cardiac muscle fiber
- Part of conduction system of the heart
- located on right ventricle
A
trabeculate carneae
13
Q
- Connected to chordae tendinae connected to papillary muscles
- Interventricular septum
- located on right ventricle
A
tricuspid valve
14
Q
- About the same thickness as right atrium
- Valve
- Left atrioventricular valve
- Bicuspid (mitral)
- Separates left atrium from left ventricle
- Receives blood from the lungs through pulmonary veins
- Passes blood through bicuspid valve into left ventricle
A
Left atrium
15
Q
- thickest chamber of heart
- forms apex
- chordae tendinae attached to paillary muscles
- blood passes thru aortic valve into ascending aorta
- some blood flows into coronary arteries
- during fetal life ductus arteriosus shunts blod from pulmonary trunk to aorta; closes after birth with remnany called ligamentum arteriosum
A
left ventricle
16
Q
right ventricle pump blood to __ lungs; shorter distance, lower pressure and less resistance while the left ventricle pumps blood to __body bc longer distance, high pressure and more resistance
A
lungs, body
17
Q
left ventricle works ___to maintain same rate of blood flow as right ventricle
A
harder
18
Q
- Dense connective tissue that forms a structural foundation, point of insertion for muscle bundles, and electrical insulator between atria and ventricles
A
fibrous skeleton
19
Q
- Tricuspid and bicuspid valves
- When atria contract and ventricles are relaxed AV valves open, cusps project into ventricles
- In ventricles, papillary muscles are relaxed and chordae tendinae are slack
- When atria relax and ventricles contract
- Pressure drives cusps upward until edges meet and close opening
- Papillary muscles contract tightening chordae tendinae
- Prevents regurgitation
A
atrioventricular valves(AV)
20
Q
- Aortic and pulmonary valves
- Valves open when pressure in ventricle exceeds pressure in arteries
- As ventricles relax, some backflow permitted but blood fills valve cusps closing them tightly
- No valves guarding entrance to atria
- As atria contract, they compress and nearly collapse the venous entry points
A
semilunar valves
21
Q
- Left side of heart
- Receives blood from lungs
- Ejects blood into aorta
- Systemic arteries, arterioles
- Gas and nutrient exchange in systemic capillaries
- Systemic venules and veins lead back to right atrium
A
systemic circuit
22
Q
- Right side of heart
- Receives blood from systemic circulation
- Ejects blood into pulmonary trunk then pulmonary arteries
- Gas exchange in pulmonary capillaries
- Pulmonary veins takes blood to left atrium
A
pulmonary circuit
23
Q
- right atrium(deoxygenated blood)
- tricuspid valve to right centricle
- pulmonary valve to pulmonary trunk and pulm arteries
- in pulm capillaries, blood loses CO2 and gains O2
- pulm veins(oxygenated blood)
- left atrium
- bicupsid valve to left ventricle
- aortic valve to aorta and systemic artieries
- in systemic capillaries blood loses O2 and gains CO2
- superior vena cava, inferior vena cava and coronary sinus lead back to the right atrium
A
blood flow diagram
24
Q
- Myocardium has its own network of blood vessels
- Coronary arteries branch from ascending aorta
- [Anastomoses provide alternate routes or collateral circuits/Allows heart muscle to receive sufficient oxygen even if an artery is partially blocked]
- Coronary capillaries
- Coronary veins[Collect in coronary sinus,Empty into right atrium]
A
coronary circulation
25
* Shorter and less circular than skeletal muscle fibers
* Branching gives “stair-step” appearance
* Usually one centrally located nucleus
* Ends of fibers connected by intercalated discs containing desmosomes (hold fibers together) and gap junctions (allow action potential conduction from one fiber to the next)
* Mitochondria are larger and more numerous than in skeletal muscle
* Same arrangement of actin and myosin
histology of cardiac muscle tissue
26
* specialized cardiac muscle fibers that are self excitable
* repeatedly generate action potentials that trigger heart contractions
* pacemaker /form conduction system
autorhythmic fibers
27
1. SA node in right atrial wall propagates thru atria(via gap junctions) to contrac atria
2. reaches AV node in interatrial septum
3. enters AV bundle of his where action potentials can conduct from atria to ventricles due to fibrous skelton
4. enters R and L bundle branches which extend thru interventricular septum toward apex
5. largediameter purkinje fibers conduct action potential to remainder of ventricular myocardium where ventricles contract
conduction system
28
1. SA node
2. AV node
3. AV bundle(bundle of his)
4. right and left bundle branches
5. purkinje fibers
conduction system
29
* initiates 100x per sec
* nerve impules form ANS and hormones modify timing and strength of each heartbeat but doesnt est fundamental rhythm
(in the conduction system)SA node
30
initiated by SA node spreads out to excite “working” fibers called contractile fibers
Stages :
1. Depolarization
2. Plateau
3. Repolarization
action potential
31
* contractile fibers have stable resting membrane potential
* Voltage-gated fast Na+ channels open
* Na+ flows in
* Then deactivate and Na+ inflow decreases
depolarization in action potential
32
– period of maintained depolarization
* Due in part to opening of voltage-gated slow Ca2+ channels
* Ca2+ moves from interstitial fluid into cytosol
* Ultimately triggers contraction
* Depolarization sustained due to voltage-gated K+ channels balancing Ca inflow with K outlflow
plateua (2nd stage of action potential)
33
recovery of resting membrane potential
* Resembles that in other excitable cells
* Additional voltage-gated K+ channels open
* Outflow of K+ restores negative resting membrane potential
* Calcium channels close
repolarization- last stage of action potential
34
* time interval during which second contraction cannot be triggered
* Lasts longer than contraction itself
* Tetanus (maintained contraction) cannot occur
refractory period of action potentials
35
* Composite record of action potentials produced by all the heart muscle fibers
* Compare tracings from different leads with one another and with normal records
* 3 waves: P, QRS, and T
ECG or EKG(electrocardiogram)
36
* systole=contraction
* diastole=\_\_
relaxation
37
wave in which: cardiac action potential arises in SA node
P wave
38
* Atrial contraction (atrial systole)
* Action potential enters AV bundle and out over ventricles
* Masks atrial repolarization
QRS complex wave
39
contraction of ventricles(ventricular systole) begins shortly after QRS complex appears and continues during ____ segement
S-T
40
wave of repolarization of ventricular fibers and then ventricular relaxation (diastole)
T wave
41
1. depolarization of atrial contractile fibers in SA node (P)
2. atrial systole (contraction)
3. depolarization of ventricular contractile fibers (QRS)
4. ventricular systole
5. repolarization of ventricular contractile fibers (T)
6. ventricular diastole [relaxation]
action potential and contraction on ECG
42
* All events associated with one heartbeat
* Systole and diastole of atria and ventricles
* Forces blood from higher pressure to lower pressure
* During relaxation period, both atria and ventricles are relaxed
* The faster the heart beats, the shorter the relaxation period
* Systole and diastole lengths shorten slightly
cardiac cycle
43
* During atrial systole, ventricles are relaxed
* During ventricle systole, atria are relaxed
In each cardiac cycle, atria and ventricles alternately contract and relax
44
* Auscultation
* Sound of heartbeat comes primarily from blood turbulence caused by closing of heart valves
* 4 heart sounds in each cardiac cycle – only 2 loud enough to be heard
* Lubb – AV valves close
* Dupp – SL valves close
heart sounds
45
the amount of blood pumped by each ventricle in one minute
cardiac output
46
Cardiac output (ml/min)= heart rate (beats/min) x stroke volume (ml/beat)
cardiac output equation
47
* = volume of blood ejected from left (or right) ventricle into aorta (or pulmonary trunk) each minute
* Entire blood volume flows through pulmonary and systemic circuits each minute
CO
48
* __ \_\_\_- difference between maximum CO and CO at rest
* Average ___ \_\_\_is 4-5 times resting value
cardiac reserve
49
1. Preload – effect of stretching
2. Contractility
3. Afterload – force to be overcome
all are factors that ensure left and right ventricles pump equal volumes of blood
regulation of stroke volume
50
* Degree of stretch on the heart before it contracts
* Greater preload increases the force of contraction
* Frank-Starling law of the heart – the more the heart fills with blood during diastole, the greater the force of contraction during systole
* Preload proportional to end-diastolic volume (EDV)
* Factors that determine EDV
* Duration of ventricular diastole
* Venous return – volume of blood returning to right ventricle
preoad
51
* Strength of contraction at any given preload
* Positive inotropic agents increase contractility
* Often promote Ca2+ inflow during cardiac action potential
* Increase stroke volume
* Epinephrine, norepinephrine, digitalis
* Negative inotropic agents decrease contractility
* Anoxia, acidosis, some anesthetics, and increased K+ in interstitial fluid
contractility
52
* Pressure that must be overcome before a semilunar valve can open
* Increase in afterload causes stroke volume to decrease
* Blood remains in ventricle at the end of systole
* Hypertension and atherosclerosis increase afterload
afterload
53
* Cardiac output depends on heart rate and stroke volume
* Adjustments in heart rate important in short-term control of cardiac output and blood pressure
* Autonomic nervous system and epinephrine/ norepinephrine most important
regulation of heart beat
54
* Originates in cardiovascular center of medulla oblongata
* Increases or decreases frequency of nerve impulses in both sympathetic and parasympathetic branches of ANS
* Noreprinephrine has two separate effects
* In SA and AV node speeds rate of spontaneous depolarization
* In contractile fibers enhances Ca2+ entry increasing contractility
* Parasympathetic nerves release acetylcholine which decreases heart rate by slowing rate of spontaneous depolarization
autonomic regulation
55
1. input to cardiovascular center:
* higher brain centers like cerebral cortex, limbic sys, and hypothalamus
* sensory receptors like proprioceptors,chemoreceptors, and baroreceptors
2. output to heart:
* cardiac accerlerator nerves(sympathetic)increased rate of spontaneous depolarization in SA node increases heart rate
* increased contractility of atria and ventricles increase stroke volume
* VAGUS nerves(parasympathetic)-\>descreased rate of spontaneous depolarization in SA node decreases heart rate
nervous system control of the heart
56
* Epinephrine and norepinephrine increase heart rate and contractility
* Thyroid hormones also increase heart rate and contractility
hormones
57
* Ionic imbalance can compromise pumping effectiveness
* Relative concentration of K+, Ca2+ and Na+ important
cations
58
superior part of the interventricular septum fails to form; blood mixes betwn 2 ventricles but bc the left is stronger, more blood shunted form left to righ [1 in every 500 births]
ventricular septal defect
59
part of the aorta is narrowed, increasing hte workload on the left ventricle[1 in ever 1500 births]
coartation of the aorta
60
multiple defects; pulmonary trunk too narrow and pulmonary valve stenosed resulting in a hypertrophied right ventricle; ventricular septal defect; aorta opens form both ventricles; wall of right ventricle thickened form over work(1 in every 2000 births]
tetralogy of fallot
61
A&P2
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