1
Q
What is the path of blood flow from the heart muscle wall?
A
left ventricle, ascending aorta, coronary arteries, myocardial capillaries, coronary sinus, right atrium.
2
Q
What are the components of the electrical conduction system of the heart? (5)
A
SA node, AV node, AV bundle, Right and left bundle branches, Purkinje fibers.
3
Q
What is the systemic circuit in the cardiovascular system?
A
The systemic circuit carries blood from the left ventricle to other body organs (except lungs) and tissues, returning to the right atrium.
4
Q
What is the pulmonary circuit in the cardiovascular system?
A
The pulmonary circuit carries blood from the right ventricle to the lungs and back to the left atrium.
5
Q
What are arteries and their primary function?
A
large, muscular vessels under high pressure that take blood away from the heart
6
Q
What are arterioles?
A
Arterioles are smaller arteries that lead to capillaries.
7
Q
What is the role of capillaries in the cardiovascular system?
A
gas and nutrient exchange
8
Q
What are venules?
A
larger vessels that collect blood from capillaries and lead to veins.
9
Q
What is the function of veins?
A
carry blood back toward the heart
10
Q
What is the ultimate function of the cardiovascular system?
A
To ensure adequate blood flow through capillaries.
11
Q
How is water lost by filtration in the cardiovascular system recovered?
A
Most is picked up by osmosis due to higher concentrations of proteins and solutes in blood plasma; the rest is collected by the lymphatic system.
12
Q
What causes blood to move through the cardiovascular system?
A
Blood moves due to bulk flow produced by pressure created by the pumping of the heart.
13
Q
What is the relationship between pressure and flow in the cardiovascular system?
A
As pressure increases, flow tends to increase; flow is opposed by peripheral resistance.
14
Q
What is the equation that describes blood flow in relation to pressure and resistance?
A
F = ∆P/R, where F is flow, ∆P is the difference in pressure, and R is resistance.
15
Q
What determines the direction and speed of blood flow?
A
difference in pressure (∆P) between two points
16
Q
Where is the average blood pressure highest and lowest in the cardiovascular system?
A
highest in the arteries, lowest in the veins.
17
Q
What three factors impact blood pressure?
A
cardiac output, blood volume, vessel diameter.
18
Q
What happens to average pressure as blood flows through the systemic circulation?
A
pressure falls
19
Q
What is the pathway of blood flow starting at the arteries?
A
(high pressure) arteries, arterioles, capillaries, venules, veins (low pressure)
20
Q
What is peripheral resistance (TPR)?
A
The difficulty for blood to flow between two points at a constant pressure difference (∆P).
21
Q
How does flow relate to resistance?
A
Flow is inversely proportional to resistance; as resistance increases, flow decreases.
22
Q
What is the primary factor determining resistance in blood vessels?
A
Friction
23
Q
What four factors impact friction and, therefore, affect resistance?
A
viscosity; vessel elasticity, length and diameter.
24
Q
What condition can impact vessel elasticity?
A
Arteriosclerosis, which is the hardening of the arteries.
25
What is viscosity in the context of blood flow?
thickness of the blood; relatively constant; changes with hematocrit and dehydration
26
hematocrit
percentage of blood volume occupied by red blood cells
27
How does vessel length affect resistance?
Longer vessels give more friction; vessel length is generally constant in adults, except with weight changes.
28
What is the general trend regarding vessel diameter and resistance?
Larger vessels have less resistance and greater flow; smaller vessels have more resistance and less flow.
29
What can cause changes in vessel diameter?
Regional, short-term vasoconstriction and vasodilation
30
What role does smooth muscle play in blood vessels?
vasoconstrict or vasodilate, affecting blood flow to organs.
31
What happens to blood flow when arterioles vasoconstrict before a capillary bed?
Decreases flow to that organ
32
What happens to blood flow when arterioles vasodilate before a capillary bed?
increases flow to that organ
33
Which factor is the primary mechanism of controlling resistance?
Vessel diameter
34
Low O, high CO, or low pH, when detected in a SPECIFIC CAPILLARY BED, will cause paracrine agents to be released causing ______________ in local arterioles feeding that capillary bed.
dilation
35
What is autoregulation of flow?
local (intrinsic) regulation of blood flow through capillary beds.
36
mean arterial pressure (MAP)
Average blood pressure in a person's arteries.
37
What regulates the autoregulation of local blood flow?
organs or tissues regulate blood flow through their own capillary beds through the release of local paracrine factors that control vasoconstriction or vasodilation
38
Does autoregulation of flow involve nerves or hormones?
No
39
What two mechanisms determine short-term local control of blood flow?
metabolic and myogenic control mechanisms.
40
What metabolic changes stimulate vasodilation in autoregulation?
Decreased O2 & pH, increased CO2 & H+.
41
What is hyperemia?
Increased blood flow due to vasodilation in response to metabolic changes.
42
What happens to arterioles during high systemic blood pressure?
They constrict to decrease perfusion and prevent damage through myogenic control
43
What is the long-term local control of blood flow?
Enlargement of existing vessels and development of collateral circulation.
44
How does blood flow to skeletal muscles change with activity?
It is extremely variable and increases during exercise (exercise hyperemia).
45
What is the main stimulus for autoregulation of flow in skeletal muscle?
Decreased O2.
46
Which type of capillary bed has the most variable blood flow?
skeletal muscle
47
How is blood flow in the brain characterized?
It is relatively constant due to the rigid cranium and neuronal intolerance of ischemia.
48
What metabolic changes stimulate autoregulation of blood flow in the brain?
Decreased pH and increased CO2.
49
What hormone do some cardiac muscle cells secrete in response to atrial wall stretching?
Atrial natriuretic factor (ANF or ANP)
50
What is the primary function of the hormone ANF/ANP?
To target the kidney and help decrease blood pressure.
51
What types of substrates can cardiac muscle cells metabolize for energy?
Glucose, fatty acids, and lactic acid.
52
What is a critical requirement for cardiac muscle cells to produce ATP?
A constant supply of oxygen (O2).
53
ischemia
reduced or restricted blood flow to a tissue, organ, or region of the body
54
What happens to cardiac muscle cells during ischemia?
They are intolerant of ischemia and cannot function properly.
55
What are pacemaker cells in cardiac muscle tissue?
Cells that can generate their own action potentials and specialize in transmitting impulses.
56
What percentage of cardiac muscle cells are considered pacemaker cells?
About 1%.
57
What is the variable resting membrane potential of pacemaker cells?
About -60 mV
58
What initiates the action potential in pacemaker cells?
When the threshold of -40 mV is reached.
59
What type of channels open at threshold in pacemaker cells?
Fast voltage-gated Ca+2 channels.
60
Do pacemaker cells contract following an action potential?
No, contraction does not follow in pacemaker cells.
61
How do pacemaker cells propagate impulses to other cardiac muscle cells?
They move through gap junctions to stimulate contractile cardiac muscle cells.
62
What channels are involved in repolarization of pacemaker cells?
V.G. K+ channels, Na/K and Ca+2 pumps.
63
Which part of the nervous system partially controls the rate of excitation in pacemaker cells?
The autonomic nervous system.
64
Where do sympathetic fibers synapse in the heart?
At the SA and AV nodes.
65
Where do parasympathetic fibers synapse in the heart?
At the SA and AV nodes via the vagus nerve.
66
What initiates the contraction of cardiac muscle cells?
Na+ and Ca+2 received through gap junctions from pacemaker cells causes fast voltage-gated Na+ channels to open, resulting in AP on sarcolemma of cardiac muscle cells.
67
What role do slow voltage-gated Ca+2 channels play in cardiac muscle contraction?
They open in the sarcolemma, prolonging the action potential.
68
What is the role of Ca+2 during the repolarization of cardiac muscle cells?
Ca+2 is pumped back into the sarcoplasmic reticulum and ECF, allowing the muscle cell to relax.
69
How does the refractory period of cardiac muscle compare to that of skeletal muscle?
The refractory period in cardiac muscle is much longer (250 ms) compared to 1-2 ms in skeletal muscle.
70
Why is the long refractory period important for cardiac muscle function?
It prevents summation and tetanic contractions, which would stop the heart's pumping action.
71
Why is heart relaxation necessary?
It is essential for chamber filling and ensuring blood supply to the myocardium.
72
What is diastolic pressure?
pressure in the arteries during cardiac relaxation
73
What is systolic pressure?
the maximum pressure achieved during ventricular contraction
74
What is cardiac output?
The amount of blood ejected from each ventricle per minute, measured in L/min.
75
What are the two main factors that determine cardiac output?
Heart rate (HR) and stroke volume (SV).
76
What is the equation for calculating cardiac output?
CO = HR x SV.
77
What is the average stroke volume for an adult?
Approximately 0.07 L/beat (~1/4 cup).
78
What is the average heart rate for an adult?
72 beats per minute.
79
What is afterload in relation to stroke volume?
The arterial pressure against which the ventricles must pump; increased afterload decreases stroke volume.
80
What is end-diastolic volume (EDV)?
The volume of the ventricles just before contraction, at the end of diastole.
81
How does increased end-diastolic volume (EDV) affect stroke volume?
Increased EDV tends to increase stroke volume.
82
What causes an increase in EDV?
increased venous return, stronger atrial contraction
83
What is preload?
The amount of tension in the cardiac muscle cells of the ventricles before contraction; increased preload increases stroke volume. (EDV is preload)
84
What factors impact preload?
Ventricular EDV & atrial pressure, filling time (dependent on HR)
85
What is Starling's Law?
As venous return increases, cardiac sarcomeres stretch and increase the force of contraction.
86
How does exercise affect stroke volume and cardiac output?
Exercise increases stroke volume, which in turn increases cardiac output.
87
What is cardiac reserve?
The maximum amount that cardiac output can increase above normal, which can be enhanced by cardiovascular training.
88
What role does the skeletal muscle pump play in stroke volume?
It aids venous return, which stretches muscle fibers and optimizes sarcomere length, increasing stroke volume.
89
What is the respiratory pump's role in cardiac output?
It assists in venous return, contributing to increased stroke volume.
90
What happens to muscle fiber sarcomere length during increased venous return?
It stretches, leading to a stronger contraction and more blood ejected.
91
How does heart rate affect filling time?
As heart rate decreases, filling time and preload both increase.
92
What is the relationship between hypertension and stroke volume?
Increased arterial pressure from hypertension tends to decrease stroke volume.
93
Ventricular Contractility
Independent of EDV VOLUME, stroke volume increases due to the sympathetic nervous system telling the cardiac muscles to squeeze harder, FORCING a volume increase
94
How does Stirling's Law differ from ventricular contractility, as it relates to stroke volume?
According to the Starling law, stroke volume increases when the ventricular volume rises, stretching the cardiac muscle fibers and resulting in a stronger contraction. In contrast, during increased contractility, ventricular volume remains the same, but sympathetic stimulation causes the heart muscle to contract more forcefully, thereby increasing stroke volume.
95
What effect does sympathetic nervous system stimulation have on ventricular contraction?
It increases the strength of contraction, not just the rate.
96
How does circulating epinephrine affect ventricular contraction?
It increases the strength and rate of contraction.
97
What physiological response occurs if stroke volume falls dangerously low due to excessive bleeding or weak myocardium?
The body attempts to maintain cardiac output (CO) by raising the heart rate
98
The __ nervous system has a direct correlation to stroke volume, but the __ does not.
sympathetic; parasympathetic
99
What are the two main factors that impact heart rate?
autonomic nervous system, hormones
100
What part of the brain regulates heart rate?
The medulla oblongata
101
What are the two centers in the medulla oblongata that control heart rate?
The cardioacceleratory and cardioinhibitory center
102
How does the sympathetic nervous system affect heart rate?
It increases heart rate and strength of contraction through norepinephrine.
103
What type of receptors are involved in sympathetic nervous system stimulation of heart rate?
Beta adrenergic receptors
104
Beta adrenergic receptors
Receptors to norepinephrine/epinephrine that generally produce a sympathetic response
105
What neurotransmitter is secreted by sympathetic neurons?
Norepinephrine
106
How does the parasympathetic nervous system affect heart rate?
It decreases heart rate through acetylcholine (ACh).
107
What type of receptors are involved in parasympathetic nervous system stimulation of heart rate?
Cholinergic receptors
108
Cholinergic receptor
A nerve receptor stimulated by acetylcholine.
109
What nerve is involved in parasympathetic control of heart rate?
The vagus nerve
110
What happens to heart rate if all autonomic nerve supply to the heart is cut?
The heart will speed up to approximately 100 bpm
111
What factors stimulate the autonomic nervous system regulation of heart rate?
Changes in blood pressure and chemical content of the blood
112
What is the role of cardiovascular control centers?
They regulate cardiac muscle contraction and systemic vasoconstriction/vasodilation.
113
What hormone is secreted by the adrenal medulla during sympathetic activity?
Epinephrine
114
What effect does epinephrine have on heart rate?
It increases heart rate (HR) and strength of contraction.
115
How do thyroid hormones (T3 and T4) affect heart rate?
An increase in thyroid hormones causes an increase in heart rate, lasting longer but not as dramatically as epinephrine.
116
How does body temperature influence heart rate?
Increased body temperature raises heart rate, while decreased body temperature lowers heart rate and oxygen requirements.
117
What role do emotions play in heart rate regulation?
Emotions can impact heart rate through the autonomic nervous system and stress hormones.
118
Which ions are crucial for normal heart rate function?
Potassium (K+), Sodium (Na+), and Calcium (Ca+2) must be at normal levels.
119
What effect does endurance training have on heart rate?
It decreases resting heart rate and increases stroke volume (SV).
120
What is congestive heart failure (CHF)?
A condition characterized by a weakened heart, decreased cardiac output (CO), and reduced circulation.
121
What are the symptoms of left heart failure in CHF?
It causes pulmonary congestion (edema), especially when lying down.
122
What are the symptoms of right heart failure in CHF?
It leads to peripheral congestion, resulting in swollen feet, even in the morning.
123
What are common treatments for congestive heart failure?
Digitalis drug, diuretics to eliminate excess sodium and water, and vasodilators.
124
What are the three types of extrinsic control of blood pressure?
Nervous, endocrine, and renal control.
125
What role do baroreceptors play in blood pressure regulation?
Baroreceptors detect changes in blood pressure by stretch and send sensory input to medullary cardiovascular control centers to initiate appropriate responses.
126
How does the autonomic nervous system (ANS) regulate blood pressure in the short term?
The ANS activates sympathetic or parasympathetic responses to control cardiac output (CO) and vasoconstriction/vasodilation.
127
What are the five arterial baroreceptors of the autonomic nervous system?
carotid sinus, aortic arch, right atrial, left atrial, chemoreceptor.
128
What is the purpose of the carotid sinus baroreceptor reflex?
To control blood pressure in the brain by regulating blood flow through the internal carotid arteries.
129
What happens when blood pressure increases in the carotid sinus?
Baroreceptors activate the parasympathetic nervous system, decreasing heart rate and blood pressure.
130
What occurs when blood pressure decreases in the carotid sinus?
It stimulates the sympathetic nervous system, increasing heart rate, strength of contraction, and blood pressure.
131
Low pH, if detected in the aortic arch, will cause the medulla oblongata to activate the
sympathetic nervous system
132
What is the role of right atrial baroreceptors?
They respond to venous blood pressure and help regulate heart rate and cardiac output based on venous return.
133
What triggers the chemoreceptor reflex in the carotid sinus and aorta?
Decreased O2, increased CO2, and decreased pH activate the sympathetic nervous system to increase cardiac output and blood pressure.
134
How do hormones influence blood pressure?
Hormones can increase/decrease blood pressure through adjusting vasoconstriction/dilation, cardiac output, and blood volume.
135
What is the function of the renin-angiotensin-aldosterone system (RAAS)?
RAAS responds to low arterial blood pressure by releasing renin, which leads to vasoconstriction and increased blood volume.
136
What triggers the release of renin from juxtaglomerular cells in the kidney?
Low arterial blood pressure detected by juxtaglomerular cells in the kidney.
137
Angiotensinogen
a plasma protein produced by the liver that turns into andiotensin I (in the bloodstream) if met with renin, which is released from the kidney in response to low BP/BV
138
What is angiotensin II and its role in blood pressure regulation?
Angiotensin II is a powerful vasoconstrictor that also stimulates aldosterone release, leading to sodium and water retention to increase blood volume.
139
What is the relationship between aldosterone and blood pressure?
Aldosterone promotes sodium and water retention in the kidneys, which increases blood volume and blood pressure.
140
How does alcohol affect blood pressure regulation?
Alcohol inhibits ADH release, acts as a diuretic, and inhibits the vasomotor center, leading to a flushed appearance.
141
What is the primary function of the sympathetic nervous system in blood pressure regulation?
To increase heart rate, strength of contraction, and vasoconstriction to raise blood pressure.
142
What is the role of the medullary cardiovascular control centers?
They integrate sensory input from baroreceptors and initiate autonomic responses to regulate blood pressure.
143
What happens to cardiac output when venous return increases?
Increased venous return stretches the right atrial baroreceptors, activating the SNS leading to increased HR and strength of contraction.
144
Where is epinephrine hormone located and what impact does it have?
Adrenal medulla; Vasoconstriction; increase CO2
145
Where is ADH hormone located and what does it do?
Posterior pituitary; Vasoconstriction; ⇑ BV/BP
146
Angiotensin II hormone
Kidney*; Vasoconstriction; Causes aldosterone release; increase BP
147
Where is Aldosterone hormone located and what does it do?
Adrenal cortex; ⇑ blood volume (by ⇑ Na+ and water reabsorption at kidney); increase BP
148
Erythropoietin (EPO) hormone
Kidney; ⇑ BP/BV
149
What is ANP/ANF hormone and what does it do?
Heart; Vasodilation; ⇓ BP/BV (by allowing Na+ and water loss at kidney)
150
Which is the only hormone that decreases blood pressure?
ANP/ANF
151
What is classified as hypotension?
Systolic BP < 100 mm Hg
152
What are the causes of circulatory shock? (6)
Decrease in cardiac output, extreme vasodilation, loss of vasomotor tone, septicemia, severe allergy, and loss of blood volume.
153
What is septic shock?
A condition caused by septicemia where bacterial toxins and immune response lead to vasodilation.
154
What is anaphylactic shock?
A severe allergic reaction that causes massive histamine release and vasodilation.
155
What is classified as hypertension?
BP consistently > 140/90 mm Hg
156
What is a common cause of hypertension?
Often idiopathic, but commonly due to reduced vessel diameter from arteriosclerosis or vasoconstriction.
157
What are some risk factors for hypertension? (7)
Stress, heredity, African descent, obesity, high sodium/high fat diet, lack of exercise, and smoking.
158
What is the role of diuretics in hypertension treatment?
They strip sodium and water from the body, reducing blood volume and consequently lowering blood pressure.
159
How do beta blockers help manage hypertension?
They prevent epinephrine from binding to beta-adrenergic receptors, decreasing cardiac output and allowing vasodilation.
160
What is the function of calcium channel blockers in hypertension treatment?
They close calcium channels in smooth muscle of blood vessels, preventing vasoconstriction and lowering blood pressure.
161
What do ACE inhibitors do?
They inhibit the enzyme that converts angiotensin I to angiotensin II, preventing vasoconstriction and reducing aldosterone.
162
What initiates each cardiac cycle?
The sinoatrial (SA) node, which acts as the pacemaker of the heart.
163
What happens during atrial contraction?
It occurs near the end of ventricular filling, pushing the last 20% of blood into the ventricles.
164
What is isovolumetric ventricular contraction?
A phase where both AV and semilunar valves are closed, and the ventricles contract without changing volume.
165
What occurs during ventricular ejection?
The ventricles contract and blood is ejected into the great arteries as the semilunar valves open.
166
What is isovolumetric ventricular relaxation?
A phase where both AV and semilunar valves are closed, and the ventricles relax without changing volume. Second heart sound.
167
What is the significance of gap junctions in the heart?
They allow the rapid spread of the action potential from the SA node across the atria, leading to simultaneous contraction.
168
What is cardiac cycle timing at 75 beats per minute?
0.1 seconds for atrial contraction, 0.3 seconds for ventricular contraction, and 0.4 seconds for all chambers relaxed.
169
What is a common consequence of hypertension on the kidneys?
Damage to capillaries in the kidney due to high blood pressure.
170
What is the term for uncoordinated contractions of the heart?
Cardiac arrhythmias.
171
What is fibrillation?
A condition where cardiac muscle cells contract independently, which can be particularly problematic if it occurs in the ventricles.
172
What is an ectopic pacemaker?
An area of the heart that becomes hyperexcitable and generates impulses faster than the SA node, causing premature contractions.
173
What is a common nickname for hypertension due to its lack of symptoms?
Silent killer
174
How long can hypertension be asymptomatic?
10 to 20 years
175
What are two major risks associated with hypertension?
Stroke and damage to capillaries in the kidney and retina
176
What physical damage does hypertension cause to blood vessels?
Stretching, injuring, and scarring, leading to arteriosclerosis and thrombosis
177
How does hypertension affect the heart?
It wears out the heart by overcoming afterload
Physiology
flashcards
Decks in class (11)
# Cards
