Podcast
Questions and Answers
What happens to resistance when blood vessel radius decreases by a factor of 2?
What happens to resistance when blood vessel radius decreases by a factor of 2?
- It decreases by a factor of 2
- It increases by a factor of 2
- It increases by a factor of 16 (correct)
- It increases by a factor of 4
What is the effect on total resistance when an artery is added in parallel?
What is the effect on total resistance when an artery is added in parallel?
- It increases
- It becomes zero
- It decreases (correct)
- It remains the same
What is the equation for the total resistance of parallel arteries?
What is the equation for the total resistance of parallel arteries?
- Rtot = Ra × Rb × Rn
- Rtot = 1 / (1/Ra + 1/Rb + 1/Rn) (correct)
- Rtot = Ra - Rb - Rn
- Rtot = Ra + Rb + Rn
What is the relationship between resistance and vessel radius?
What is the relationship between resistance and vessel radius?
What is the effect on blood flow when resistance increases by a factor of 16?
What is the effect on blood flow when resistance increases by a factor of 16?
What type of resistance is illustrated by the systemic circulation?
What type of resistance is illustrated by the systemic circulation?
Which part of the series arrangement contributes the largest proportion of resistance?
Which part of the series arrangement contributes the largest proportion of resistance?
What is the main reason for the lower velocity of blood in the capillaries?
What is the main reason for the lower velocity of blood in the capillaries?
What is the unit of measurement for cardiac output (Q) in the equation Q=AP/R?
What is the unit of measurement for cardiac output (Q) in the equation Q=AP/R?
What is the analogy for blood flow in the equation Q=AP/R?
What is the analogy for blood flow in the equation Q=AP/R?
What is the direction of blood flow according to the equation Q=AP/R?
What is the direction of blood flow according to the equation Q=AP/R?
What is the relationship between blood flow and resistance in the equation Q=AP/R?
What is the relationship between blood flow and resistance in the equation Q=AP/R?
What is the factor that affects resistance according to the Poiseuille equation?
What is the factor that affects resistance according to the Poiseuille equation?
What is the effect of increasing hematocrit on blood flow?
What is the effect of increasing hematocrit on blood flow?
What is the relationship between resistance and length of the blood vessel according to the Poiseuille equation?
What is the relationship between resistance and length of the blood vessel according to the Poiseuille equation?
What is the relationship between blood flow through the largest artery and total blood flow through all capillaries?
What is the relationship between blood flow through the largest artery and total blood flow through all capillaries?
What type of flow is characterized by a streamlined, straight-line flow?
What type of flow is characterized by a streamlined, straight-line flow?
What is the purpose of the Reynolds number?
What is the purpose of the Reynolds number?
What is the effect of increasing blood viscosity on the Reynolds number?
What is the effect of increasing blood viscosity on the Reynolds number?
What is the main cause of the Korotkoff sounds used in the auscultatory measurement of blood pressure?
What is the main cause of the Korotkoff sounds used in the auscultatory measurement of blood pressure?
What is the relationship between shear and blood velocity in a blood vessel?
What is the relationship between shear and blood velocity in a blood vessel?
What is the relationship between capacitance and elastance in blood vessels?
What is the relationship between capacitance and elastance in blood vessels?
What is the effect of increasing blood velocity on the Reynolds number?
What is the effect of increasing blood velocity on the Reynolds number?
What is the primary determinant of pulse pressure?
What is the primary determinant of pulse pressure?
What happens to pulse pressure when arterial capacitance decreases?
What happens to pulse pressure when arterial capacitance decreases?
What is the highest arterial pressure during a cardiac cycle?
What is the highest arterial pressure during a cardiac cycle?
What is the lowest arterial pressure during a cardiac cycle?
What is the lowest arterial pressure during a cardiac cycle?
During which phase of the cardiac cycle is diastolic pressure measured?
During which phase of the cardiac cycle is diastolic pressure measured?
What is the effect on systolic pressure when blood is ejected into the arterial system?
What is the effect on systolic pressure when blood is ejected into the arterial system?
What is the relationship between pulse pressure and systolic pressure?
What is the relationship between pulse pressure and systolic pressure?
What is the effect of the aging process on pulse pressure?
What is the effect of the aging process on pulse pressure?
What is the relationship between elastance and compliance in blood vessels?
What is the relationship between elastance and compliance in blood vessels?
What happens to unstressed volume when venous capacitance decreases?
What happens to unstressed volume when venous capacitance decreases?
What is the effect of aging on the capacitance of arteries?
What is the effect of aging on the capacitance of arteries?
Where does the largest decrease in pressure occur in the systemic circulation?
Where does the largest decrease in pressure occur in the systemic circulation?
What is the mean pressure in the aorta?
What is the mean pressure in the aorta?
What is the characteristic of arterial pressure?
What is the characteristic of arterial pressure?
What is the relationship between volume and pressure in blood vessels?
What is the relationship between volume and pressure in blood vessels?
What is the main reason why mean arterial pressure is not the simple average of diastolic and systolic pressures?
What is the main reason why mean arterial pressure is not the simple average of diastolic and systolic pressures?
What is the approximate formula to calculate mean arterial pressure?
What is the approximate formula to calculate mean arterial pressure?
What is the reason why venous pressure is very low?
What is the reason why venous pressure is very low?
What does the P wave in an electrocardiogram (ECG) represent?
What does the P wave in an electrocardiogram (ECG) represent?
What is the PR interval in an electrocardiogram (ECG)?
What is the PR interval in an electrocardiogram (ECG)?
What is the effect on the PR interval if AV nodal conduction decreases?
What is the effect on the PR interval if AV nodal conduction decreases?
What is the purpose of measuring pulmonary wedge pressure?
What is the purpose of measuring pulmonary wedge pressure?
What is the typical location where the largest decrease in pressure occurs in the systemic circulation?
What is the typical location where the largest decrease in pressure occurs in the systemic circulation?
What is the period during which a conducted action potential cannot be elicited?
What is the period during which a conducted action potential cannot be elicited?
What is the effect of a negative chronotropic effect on heart rate?
What is the effect of a negative chronotropic effect on heart rate?
What is the effect of a positive dromotropic effect on conduction velocity?
What is the effect of a positive dromotropic effect on conduction velocity?
What is the period during which an action potential can be elicited, but more than the usual inward current is required?
What is the period during which an action potential can be elicited, but more than the usual inward current is required?
What is the effect of a positive chronotropic effect on heart rate?
What is the effect of a positive chronotropic effect on heart rate?
What is the effect of a negative dromotropic effect on conduction velocity?
What is the effect of a negative dromotropic effect on conduction velocity?
What is the primary cause of the slow conduction velocity in the AV node?
What is the primary cause of the slow conduction velocity in the AV node?
What is the period during which no action potential can be initiated, regardless of how much inward current is supplied?
What is the period during which no action potential can be initiated, regardless of how much inward current is supplied?
What is the function of the absolute refractory period?
What is the function of the absolute refractory period?
What is the relationship between autonomic effects on heart rate and conduction velocity?
What is the relationship between autonomic effects on heart rate and conduction velocity?
What determines the conduction velocity in cardiac tissue?
What determines the conduction velocity in cardiac tissue?
What is the consequence of increased conduction velocity in the AV node?
What is the consequence of increased conduction velocity in the AV node?
What is the characteristic of cardiac cells during the absolute refractory period?
What is the characteristic of cardiac cells during the absolute refractory period?
What is the purpose of the relative refractory period?
What is the purpose of the relative refractory period?
Which part of the heart has parasympathetic vagal innervation?
Which part of the heart has parasympathetic vagal innervation?
What is the relationship between the size of the inward current and conduction velocity?
What is the relationship between the size of the inward current and conduction velocity?
What is the effect of acetylcholine on the heart rate?
What is the effect of acetylcholine on the heart rate?
What is the mechanism of the negative chronotropic effect?
What is the mechanism of the negative chronotropic effect?
Where is conduction velocity fastest in the heart?
Where is conduction velocity fastest in the heart?
What is the effect of parasympathetic stimulation on conduction velocity through the AV node?
What is the effect of parasympathetic stimulation on conduction velocity through the AV node?
What is the neurotransmitter responsible for sympathetic effects on the heart?
What is the neurotransmitter responsible for sympathetic effects on the heart?
What is the receptor type involved in sympathetic effects on the heart?
What is the receptor type involved in sympathetic effects on the heart?
What is the effect of parasympathetic stimulation on the PR interval?
What is the effect of parasympathetic stimulation on the PR interval?
What is the mechanism of the negative dromotropic effect?
What is the mechanism of the negative dromotropic effect?
What is the primary mechanism by which the positive chronotropic effect increases heart rate?
What is the primary mechanism by which the positive chronotropic effect increases heart rate?
What is the functional unit of the myocardial cell?
What is the functional unit of the myocardial cell?
What is the primary function of intercalated disks in cardiac muscle cells?
What is the primary function of intercalated disks in cardiac muscle cells?
What is the sliding filament model of muscle contraction?
What is the sliding filament model of muscle contraction?
What is the result of the positive dromotropic effect on the cardiac conduction system?
What is the result of the positive dromotropic effect on the cardiac conduction system?
What is the primary component of the thick filaments in cardiac muscle cells?
What is the primary component of the thick filaments in cardiac muscle cells?
What is the purpose of gap junctions in intercalated disks?
What is the purpose of gap junctions in intercalated disks?
What is the functional significance of the positive chronotropic effect?
What is the functional significance of the positive chronotropic effect?
What is the primary function of the sarcoplasmic reticulum in muscle physiology?
What is the primary function of the sarcoplasmic reticulum in muscle physiology?
What is the structural characteristic of sarcoplasmic reticulum in relation to the contractile elements?
What is the structural characteristic of sarcoplasmic reticulum in relation to the contractile elements?
What is the ion primarily involved in the contraction of muscle fibers, stored and released by the sarcoplasmic reticulum?
What is the ion primarily involved in the contraction of muscle fibers, stored and released by the sarcoplasmic reticulum?
What is the significance of the sarcoplasmic reticulum in regulating muscle contraction?
What is the significance of the sarcoplasmic reticulum in regulating muscle contraction?
What is the functional relevance of the sarcoplasmic reticulum in muscle physiology?
What is the functional relevance of the sarcoplasmic reticulum in muscle physiology?
What is the primary function of the sarcoplasmic reticulum (SR) in muscle physiology?
What is the primary function of the sarcoplasmic reticulum (SR) in muscle physiology?
What is the structural characteristic of sarcoplasmic reticulum (SR) in relation to muscle fibers?
What is the structural characteristic of sarcoplasmic reticulum (SR) in relation to muscle fibers?
What is the significance of the sarcoplasmic reticulum (SR) in muscle contraction?
What is the significance of the sarcoplasmic reticulum (SR) in muscle contraction?
What is the relationship between the sarcoplasmic reticulum (SR) and the contractile elements of the muscle fiber?
What is the relationship between the sarcoplasmic reticulum (SR) and the contractile elements of the muscle fiber?
What is the functional significance of the sarcoplasmic reticulum (SR) in muscle physiology?
What is the functional significance of the sarcoplasmic reticulum (SR) in muscle physiology?
What is the primary function of the sarcoplasmic reticulum in muscle physiology?
What is the primary function of the sarcoplasmic reticulum in muscle physiology?
What is the close proximity of the sarcoplasmic reticulum to the contractile elements important for?
What is the close proximity of the sarcoplasmic reticulum to the contractile elements important for?
What is the significance of the small-diameter tubules of the sarcoplasmic reticulum?
What is the significance of the small-diameter tubules of the sarcoplasmic reticulum?
What would be the consequence of a sarcoplasmic reticulum dysfunction in muscle physiology?
What would be the consequence of a sarcoplasmic reticulum dysfunction in muscle physiology?
What is the primary role of calcium ions in muscle physiology, as related to the sarcoplasmic reticulum?
What is the primary role of calcium ions in muscle physiology, as related to the sarcoplasmic reticulum?
What is the effect of a decrease in total peripheral resistance on cardiac output?
What is the effect of a decrease in total peripheral resistance on cardiac output?
What is the equation for ejection fraction?
What is the equation for ejection fraction?
What is the result of a simultaneous decrease in total peripheral resistance and increase in venous return?
What is the result of a simultaneous decrease in total peripheral resistance and increase in venous return?
What is the equation for cardiac output?
What is the equation for cardiac output?
What is the effect of a decrease in aortic pressure on cardiac output?
What is the effect of a decrease in aortic pressure on cardiac output?
What is the effect of an increase in venous return on right atrial pressure?
What is the effect of an increase in venous return on right atrial pressure?
What is the equation for stroke volume?
What is the equation for stroke volume?
What is the result of a simultaneous decrease in total peripheral resistance and decrease in venous return?
What is the result of a simultaneous decrease in total peripheral resistance and decrease in venous return?
What is the main cause of the first heart sound?
What is the main cause of the first heart sound?
What is the name of the phase where ventricular pressure increases isovolumetrically?
What is the name of the phase where ventricular pressure increases isovolumetrically?
What is the term for the phase where ventricular volume is constant?
What is the term for the phase where ventricular volume is constant?
What is the ECG wave that represents electrical activation of the atria?
What is the ECG wave that represents electrical activation of the atria?
What is the term for the increase in atrial pressure caused by atrial systole?
What is the term for the increase in atrial pressure caused by atrial systole?
When does the first heart sound occur?
When does the first heart sound occur?
What is the phase that immediately follows atrial systole?
What is the phase that immediately follows atrial systole?
What is the name of the fourth heart sound?
What is the name of the fourth heart sound?
What is the primary energy source for stroke work in the heart?
What is the primary energy source for stroke work in the heart?
What is the equation that expresses stroke work?
What is the equation that expresses stroke work?
What is the factor that increases cardiac oxygen consumption?
What is the factor that increases cardiac oxygen consumption?
What is the formula for calculating cardiac output using the Fick principle?
What is the formula for calculating cardiac output using the Fick principle?
What is the unit of measurement for cardiac output?
What is the unit of measurement for cardiac output?
What is the calculation for stroke volume?
What is the calculation for stroke volume?
What is the effect of increased heart rate on cardiac oxygen consumption?
What is the effect of increased heart rate on cardiac oxygen consumption?
What is the relationship between cardiac oxygen consumption and ventricular tension?
What is the relationship between cardiac oxygen consumption and ventricular tension?
What occurs during the rapid ejection phase of the cardiac cycle?
What occurs during the rapid ejection phase of the cardiac cycle?
What marks the end of ventricular contraction and rapid ventricular ejection?
What marks the end of ventricular contraction and rapid ventricular ejection?
What is the reason for the C wave on the venous pulse curve?
What is the reason for the C wave on the venous pulse curve?
What happens to ventricular pressure during the reduced ejection phase?
What happens to ventricular pressure during the reduced ejection phase?
What is the relationship between aortic pressure and ventricular pressure during the rapid ejection phase?
What is the relationship between aortic pressure and ventricular pressure during the rapid ejection phase?
What is the characteristic of the ventricular contraction phase?
What is the characteristic of the ventricular contraction phase?
What occurs during the isovolumetric ventricular contraction phase?
What occurs during the isovolumetric ventricular contraction phase?
What is the significance of the PR interval in an electrocardiogram?
What is the significance of the PR interval in an electrocardiogram?
What does the V wave on the venous pulse curve represent?
What does the V wave on the venous pulse curve represent?
What happens during the isovolumetric ventricular relaxation phase?
What happens during the isovolumetric ventricular relaxation phase?
What is the characteristic of the third heart sound?
What is the characteristic of the third heart sound?
What is the longest phase of the cardiac cycle?
What is the longest phase of the cardiac cycle?
What is the reason for the splitting of the second heart sound?
What is the reason for the splitting of the second heart sound?
What is the name of the 'blip' in the aortic pressure tracing?
What is the name of the 'blip' in the aortic pressure tracing?
What happens when ventricular pressure becomes less than atrial pressure?
What happens when ventricular pressure becomes less than atrial pressure?
What is the relationship between aortic pressure and ventricular volume during the isovolumetric ventricular relaxation phase?
What is the relationship between aortic pressure and ventricular volume during the isovolumetric ventricular relaxation phase?
What is the primary response of the vasomotor center to a decrease in mean arterial blood pressure?
What is the primary response of the vasomotor center to a decrease in mean arterial blood pressure?
What is the effect of increased sympathetic tone on the heart?
What is the effect of increased sympathetic tone on the heart?
What is the effect of increased sympathetic outflow on arterioles?
What is the effect of increased sympathetic outflow on arterioles?
What is the net effect of the baroreceptor reflex on mean arterial pressure?
What is the net effect of the baroreceptor reflex on mean arterial pressure?
What is the role of the parasympathetic nervous system in the baroreceptor reflex?
What is the role of the parasympathetic nervous system in the baroreceptor reflex?
What is the effect of increased sympathetic tone on venous return?
What is the effect of increased sympathetic tone on venous return?
What is the relationship between heart rate and contractility in the baroreceptor reflex?
What is the relationship between heart rate and contractility in the baroreceptor reflex?
What is the primary mechanism by which the baroreceptor reflex increases arterial pressure?
What is the primary mechanism by which the baroreceptor reflex increases arterial pressure?
Which of the following is a result of vasoconstriction of veins?
Which of the following is a result of vasoconstriction of veins?
What happens to cardiac output and arterial pressure during the Valsalva maneuver?
What happens to cardiac output and arterial pressure during the Valsalva maneuver?
What is the role of the baroreceptor reflex in the Valsalva maneuver?
What is the role of the baroreceptor reflex in the Valsalva maneuver?
What is the function of angiotensinase in the renin-angiotensin-aldosterone system?
What is the function of angiotensinase in the renin-angiotensin-aldosterone system?
What is the effect of the rebound increase in venous return after the Valsalva maneuver?
What is the effect of the rebound increase in venous return after the Valsalva maneuver?
What is the main function of the renin-angiotensin-aldosterone system?
What is the main function of the renin-angiotensin-aldosterone system?
What is the effect of increased sympathetic outflow on cardiac output?
What is the effect of increased sympathetic outflow on cardiac output?
What is the response to acute blood loss?
What is the response to acute blood loss?
What is the primary function of angiotensin-converting enzyme in the renin-angiotensin-aldosterone system?
What is the primary function of angiotensin-converting enzyme in the renin-angiotensin-aldosterone system?
Which of the following effects of angiotensin II leads to contraction alkalosis?
Which of the following effects of angiotensin II leads to contraction alkalosis?
What is the site of angiotensin II conversion from angiotensin I?
What is the site of angiotensin II conversion from angiotensin I?
Which of the following is a slow effect of angiotensin II?
Which of the following is a slow effect of angiotensin II?
What is the target of angiotensin receptor antagonists, such as losartan?
What is the target of angiotensin receptor antagonists, such as losartan?
What is the effect of angiotensin II on blood volume?
What is the effect of angiotensin II on blood volume?
What is the primary role of juxtaglomerular cells in the renin-angiotensin-aldosterone system?
What is the primary role of juxtaglomerular cells in the renin-angiotensin-aldosterone system?
What is the effect of angiotensin II on aldosterone synthesis and secretion?
What is the effect of angiotensin II on aldosterone synthesis and secretion?
What is the response of the brain to cerebral ischemia?
What is the response of the brain to cerebral ischemia?
What is the effect of constriction of arterioles on blood flow?
What is the effect of constriction of arterioles on blood flow?
What is the role of the renin-angiotensin-aldosterone system in response to acute blood loss?
What is the role of the renin-angiotensin-aldosterone system in response to acute blood loss?
What is the effect of the Cushing reaction on mean arterial pressure?
What is the effect of the Cushing reaction on mean arterial pressure?
What is the response of chemoreceptors in the vasomotor center to cerebral ischemia?
What is the response of chemoreceptors in the vasomotor center to cerebral ischemia?
What is the effect of increased TPR on blood flow to other organs?
What is the effect of increased TPR on blood flow to other organs?
What is the role of aldosterone in the renin-angiotensin-aldosterone system?
What is the role of aldosterone in the renin-angiotensin-aldosterone system?
What is the response of the renin-angiotensin-aldosterone system to hemorrhage?
What is the response of the renin-angiotensin-aldosterone system to hemorrhage?
What is the effect of increased intracranial pressure on cerebral blood vessels?
What is the effect of increased intracranial pressure on cerebral blood vessels?
What is the response of chemoreceptors in the carotid and aortic bodies to decreased partial pressure of oxygen?
What is the response of chemoreceptors in the carotid and aortic bodies to decreased partial pressure of oxygen?
What is the primary function of vasopressin in response to hemorrhage?
What is the primary function of vasopressin in response to hemorrhage?
What is the effect of atrial natriuretic peptide on blood pressure?
What is the effect of atrial natriuretic peptide on blood pressure?
What is the effect of increased sympathetic outflow on arterial pressure?
What is the effect of increased sympathetic outflow on arterial pressure?
What is the response of the vasomotor center to increased intracranial pressure?
What is the response of the vasomotor center to increased intracranial pressure?
What is the effect of vasopressin on arterioles?
What is the effect of vasopressin on arterioles?
What is the effect of decreased blood volume on vasopressin release?
What is the effect of decreased blood volume on vasopressin release?
What is the primary mechanism by which coronary circulation is controlled?
What is the primary mechanism by which coronary circulation is controlled?
What is the main cause of vasodilation of the cerebral arterioles?
What is the main cause of vasodilation of the cerebral arterioles?
What is the effect of mechanical compression of the coronary vessels during systole?
What is the effect of mechanical compression of the coronary vessels during systole?
What is the role of sympathetic nerves in regulating cerebral circulation?
What is the role of sympathetic nerves in regulating cerebral circulation?
What is the effect of increased myocardial contractility on coronary vessels?
What is the effect of increased myocardial contractility on coronary vessels?
What is the effect of reactive hyperemia on blood flow?
What is the effect of reactive hyperemia on blood flow?
What is the primary factor that regulates skeletal muscle circulation?
What is the primary factor that regulates skeletal muscle circulation?
What is the effect of increased PCO2 on cerebral blood flow?
What is the effect of increased PCO2 on cerebral blood flow?
What is the primary regulator of blood flow to skeletal muscle at rest?
What is the primary regulator of blood flow to skeletal muscle at rest?
What is the effect of stimulating a1 receptors on blood vessels in skeletal muscle?
What is the effect of stimulating a1 receptors on blood vessels in skeletal muscle?
What is the main function of the cutaneous sympathetic nerves?
What is the main function of the cutaneous sympathetic nerves?
What is the response observed in skin due to trauma?
What is the response observed in skin due to trauma?
During exercise, what is the primary mechanism regulating blood flow to skeletal muscle?
During exercise, what is the primary mechanism regulating blood flow to skeletal muscle?
What is the effect of mechanical compression during exercise on blood flow to skeletal muscle?
What is the effect of mechanical compression during exercise on blood flow to skeletal muscle?
What is the primary determinant of total peripheral resistance (TPR)?
What is the primary determinant of total peripheral resistance (TPR)?
What is the effect of increased ambient temperature on cutaneous blood vessels?
What is the effect of increased ambient temperature on cutaneous blood vessels?
What is the primary mechanism underlying reactive hyperemia?
What is the primary mechanism underlying reactive hyperemia?
What is the result of increased arteriolar smooth muscle contraction in response to increased perfusion pressure?
What is the result of increased arteriolar smooth muscle contraction in response to increased perfusion pressure?
What happens to parasympathetic outflow to the heart in response to a coordinated response from the vasomotor center?
What happens to parasympathetic outflow to the heart in response to a coordinated response from the vasomotor center?
What is the primary match made by the metabolic hypothesis?
What is the primary match made by the metabolic hypothesis?
What occurs in individuals with impaired baroreceptor reflex mechanism?
What occurs in individuals with impaired baroreceptor reflex mechanism?
What is the origin of the central command in exercise?
What is the origin of the central command in exercise?
What is the effect of increased metabolic activity on blood flow to an organ?
What is the effect of increased metabolic activity on blood flow to an organ?
What is the effect of a decrease in venous return on cardiac output?
What is the effect of a decrease in venous return on cardiac output?
What is the effect of increased blood flow to an organ on O2 delivery?
What is the effect of increased blood flow to an organ on O2 delivery?
What is the primary cause of reactive hyperemia?
What is the primary cause of reactive hyperemia?
What is the effect of increased sympathetic outflow to the heart on heart rate?
What is the effect of increased sympathetic outflow to the heart on heart rate?
What is the relationship between the length of occlusion and the increase in blood flow?
What is the relationship between the length of occlusion and the increase in blood flow?
What is the effect of increased total peripheral resistance (TPR) on blood pressure?
What is the effect of increased total peripheral resistance (TPR) on blood pressure?
What is the compensatory response to standing in terms of arterial blood pressure?
What is the compensatory response to standing in terms of arterial blood pressure?
What is the primary mechanism underlying active hyperemia?
What is the primary mechanism underlying active hyperemia?
What is the effect of increased central venous pressure on cardiac output?
What is the effect of increased central venous pressure on cardiac output?
What is the effect of histamine on blood vessels?
What is the effect of histamine on blood vessels?
What is the mechanism of action of nitric oxide (NO) in vascular smooth muscle?
What is the mechanism of action of nitric oxide (NO) in vascular smooth muscle?
What is the effect of autoregulation on blood flow to an organ?
What is the effect of autoregulation on blood flow to an organ?
What is the effect of standing on blood flow to the dependent limbs?
What is the effect of standing on blood flow to the dependent limbs?
What is the effect of severe liver disease on plasma protein concentration?
What is the effect of severe liver disease on plasma protein concentration?
What is the effect of burn injury on blood vessels?
What is the effect of burn injury on blood vessels?
What is the effect of protein malnutrition on plasma protein concentration?
What is the effect of protein malnutrition on plasma protein concentration?
What is the effect of heart failure on venous pressure?
What is the effect of heart failure on venous pressure?
What is the primary response to standing up, in terms of cardiovascular physiology?
What is the primary response to standing up, in terms of cardiovascular physiology?
What is the effect of exercise on total peripheral resistance?
What is the effect of exercise on total peripheral resistance?
What is the effect of sympathetic outflow on the heart during exercise?
What is the effect of sympathetic outflow on the heart during exercise?
What is the primary mechanism by which exercise increases cardiac output?
What is the primary mechanism by which exercise increases cardiac output?
What is the effect of parasympathetic outflow on the heart during exercise?
What is the effect of parasympathetic outflow on the heart during exercise?
What is the effect of vasodilation of skeletal muscle beds on blood flow during exercise?
What is the effect of vasodilation of skeletal muscle beds on blood flow during exercise?
What is the effect of exercise on venous return?
What is the effect of exercise on venous return?
What is the effect of exercise on baroreceptor reflex?
What is the effect of exercise on baroreceptor reflex?
What is the primary reason for the increase in cardiac output during exercise?
What is the primary reason for the increase in cardiac output during exercise?
What is the effect of increased metabolic activity of skeletal muscle during exercise?
What is the effect of increased metabolic activity of skeletal muscle during exercise?
What is the effect of increased venous return on cardiac output?
What is the effect of increased venous return on cardiac output?
What is the effect of exercise on blood flow to inactive muscles and organs such as the skin, splanchnic regions, and kidneys?
What is the effect of exercise on blood flow to inactive muscles and organs such as the skin, splanchnic regions, and kidneys?
What is the effect of hemorrhage on cardiac output?
What is the effect of hemorrhage on cardiac output?
What is the effect of sympathetic nervous system activation on total peripheral resistance (TPR)?
What is the effect of sympathetic nervous system activation on total peripheral resistance (TPR)?
What is the effect of exercise on total peripheral resistance (TPR)?
What is the effect of exercise on total peripheral resistance (TPR)?
What is the reason for the increase in oxygen delivery to the exercising muscle?
What is the reason for the increase in oxygen delivery to the exercising muscle?
What is the result of arteriolar vasoconstriction on capillary absorption?
What is the result of arteriolar vasoconstriction on capillary absorption?
What is the role of the adrenal medulla in the response to hypoxia?
What is the role of the adrenal medulla in the response to hypoxia?
What is the effect of angiotensin II on total peripheral resistance?
What is the effect of angiotensin II on total peripheral resistance?
What is the response of the renin-angiotensin-aldosterone system to a decrease in renal perfusion pressure?
What is the response of the renin-angiotensin-aldosterone system to a decrease in renal perfusion pressure?
What is the effect of ADH on blood pressure?
What is the effect of ADH on blood pressure?
What is the stimulus for the release of ADH?
What is the stimulus for the release of ADH?
What is the response of chemoreceptors in the carotid and aortic bodies to hypoxia?
What is the response of chemoreceptors in the carotid and aortic bodies to hypoxia?
What is the effect of cerebral ischemia on sympathetic outflow?
What is the effect of cerebral ischemia on sympathetic outflow?
What is the role of aldosterone in the response to hypoxia?
What is the role of aldosterone in the response to hypoxia?
What is the primary mechanism by which the body responds to hypoxia?
What is the primary mechanism by which the body responds to hypoxia?
What is the primary response of the carotid sinus baroreceptors to a decrease in arterial pressure?
What is the primary response of the carotid sinus baroreceptors to a decrease in arterial pressure?
What is the effect of hemorrhage on venous return?
What is the effect of hemorrhage on venous return?
What is the primary role of the renin-angiotensin-aldosterone system in response to hemorrhage?
What is the primary role of the renin-angiotensin-aldosterone system in response to hemorrhage?
What is the purpose of the compensatory responses to hemorrhage?
What is the purpose of the compensatory responses to hemorrhage?
Which vascular beds do not constrict in response to hemorrhage?
Which vascular beds do not constrict in response to hemorrhage?
What is the effect of increased sympathetic outflow on heart rate?
What is the effect of increased sympathetic outflow on heart rate?
What is the effect of hemorrhage on the release of circulating epinephrine and norepinephrine?
What is the effect of hemorrhage on the release of circulating epinephrine and norepinephrine?
What is the effect of increased total peripheral resistance on blood pressure?
What is the effect of increased total peripheral resistance on blood pressure?
Study Notes
Resistance in Blood Vessels
- Resistance is inversely proportional to the fourth power of the vessel radius
- If blood vessel radius decreases by a factor of 2, resistance increases by a factor of 16 and blood flow decreases by a factor of 16
Parallel and Series Resistance
- Parallel resistance is illustrated by the systemic circulation
- Each organ is supplied by an artery that branches off the aorta
- Total resistance is less than the resistance of any individual arteries
- In each parallel artery, the pressure is the same
Series Resistance
- Series resistance is illustrated by the arrangement of blood vessels within a given organ
- Each organ is supplied by a large artery, smaller arteries, arterioles, capillaries, and veins arranged in series
- The largest proportion of resistance is contributed by the arterioles
- Blood velocity is higher in the aorta than in the capillaries
Blood Flow
- Blood flow can be expressed by the equation: Q = AP/R
- Where Q is flow or cardiac output, AP is pressure gradient, and R is resistance or total peripheral resistance
- The equation is analogous to Ohm's law for electrical circuits
- Pressure gradient drives blood flow, which is from high pressure to low pressure
- Blood flow is inversely proportional to the resistance of the blood vessels
Poiseuille's Equation
- Resistance is directly proportional to the viscosity of blood and the length of the vessel
- Resistance is inversely proportional to the radius of the vessel to the fourth power
- Increasing hematocrit or blood viscosity increases resistance and decreases blood flow
Laminar and Turbulent Flow
- Laminar flow is streamlined, while turbulent flow is not
- Reynolds number predicts whether blood flow will be laminar or turbulent
- Factors that increase Reynolds number, such as increased blood viscosity or velocity, cause turbulence
Shear and Capacitance
- Shear is a consequence of adjacent layers of blood traveling at different velocities
- Shear is highest at the wall of the vessel and lowest at the center
- Capacitance, or compliance, is the distensibility of blood vessels
- Capacitance is inversely related to elastance, or stiffness
- Capacitance is not constant during a cardiac cycle
Arterial Pressure
- Systolic pressure is the highest arterial pressure during a cardiac cycle
- Diastolic pressure is the lowest arterial pressure during a cardiac cycle
- Pulse pressure is the difference between systolic and diastolic pressures
- Mean arterial pressure is the average arterial pressure with respect to time
- Mean arterial pressure is not the simple average of diastolic and systolic pressures
Venous Pressure
- Venous pressure is very low
- Veins have a high capacitance and can hold large volumes of blood at low pressure
- Atrial pressure is slightly lower than venous pressure
Cardiac Electrophysiology
- The electrocardiogram (ECG) represents the electrical activity of the heart
- The P wave represents atrial depolarization
- The PR interval is the interval from the beginning of the P wave to the beginning of the Q wave
- The PR interval depends on conduction velocity through the atrioventricular (AV) node
Autonomic Effects
- The autonomic nervous system affects heart rate and conduction velocity
- Parasympathetic effects:
- Decrease heart rate (negative chronotropic effect)
- Decrease conduction velocity through the AV node (negative dromotropic effect)
- Sympathetic effects:
- Increase heart rate (positive chronotropic effect)
- Increase conduction velocity through the AV node (positive dromotropic effect)
Cardiac Muscle and Cardiac Output
- Cardiac muscle structure:
- Sarcomere is the contractile unit of the myocardial cell
- Intercaled disks occur at the ends of the cells
- Gap junctions allow for rapid electrical spread of action potentials
- Cardiac output is the product of stroke volume and heart rate
- Stroke volume is the volume ejected from the ventricle on each beat
- Ejection fraction is the fraction of the end-diastolic volume ejected in each stroke volume
- Stroke work is the work the heart performs on each beat### Cardiac Cycle
- The cardiac cycle consists of two phases: ventricular diastole and ventricular systole
- Ventricular diastole:
- Atrial filling begins
- Ventricular volume is constant (isovolumetric)
- Aortic valve is closed
- AV valves are open
- Ventricular systole:
- Consists of four phases: isovolumetric ventricular contraction, rapid ventricular ejection, reduced ventricular ejection, and isovolumetric ventricular relaxation
- The aortic valve opens, and the AV valves are closed
- Ventricular volume decreases dramatically during rapid ventricular ejection
Venous Pulse Curve
- The C wave on the venous pulse curve occurs due to the bulging of the tricuspid valve into the right atrium during right ventricular contraction
- The V wave on the venous pulse curve represents blood flow into the right atrium (rising phase) and from the right atrium into the right ventricle (falling phase)
Baroreceptor Reflex
- The baroreceptor reflex is a rapid response to changes in arterial pressure
- It is mediated by the vasomotor center, which responds to changes in baroreceptor activity
- The reflex helps to maintain a constant arterial pressure
- Examples of the baroreceptor reflex:
- Response to acute blood loss
- Valsalva maneuver
Renin-Angiotensin-Aldosterone System
- The renin-angiotensin-aldosterone system is a slow, hormonal mechanism that regulates blood pressure in the long term
- It is activated in response to decreased renal perfusion pressure
- The system increases blood pressure by:
- Stimulating the synthesis and secretion of aldosterone
- Increasing Na+ reabsorption
- Constricting arterioles
- Increasing thirst and water intake
Other Regulation of Arterial Blood Pressure
- Cerebral ischemia:
- Causes an increase in sympathetic outflow to the heart and blood vessels
- Leads to intense peripheral vasoconstriction and increased TPR
- Can cause a profound increase in arterial pressure
- Chemoreceptors:
- Respond to decreases in PaO2
- Activate vasomotor centers, which produce vasoconstriction and increase TPR
- Vasopressin (ADH):
- Released in response to decreased blood volume or blood pressure
- Causes vasoconstriction and increases water reabsorption
- Atrial natriuretic peptide (ANP):
- Released in response to increased blood volume and atrial pressure
- Decreases blood pressure by increasing Na+ excretion
Regulation of Blood Flow
- Autoregulation:
- Blood flow remains constant over a wide range of perfusion pressures
- Occurs in organs with high metabolic demand
- Local metabolic control:
- Blood flow is regulated by matching O2 supply to O2 demand
- Vasodilator metabolites (CO2, K+, lactate, and adenosine) accumulate during increased metabolic activity
- These metabolites cause arteriolar dilation and increase blood flow
- Sympathetic innervation:
- Plays a minor role in regulating blood flow to the brain and coronary circulation
- Plays a major role in regulating blood flow to skeletal muscle
Special Circulations
- Blood flow varies from one organ to another
- Blood flow to an organ is regulated by altering arteriolar resistance
- Examples of special circulations:
- Pulmonary circulation
- Renal circulation
- Skeletal muscle circulation
- Cerebral circulation
- Cutaneous circulation
Exercise
- The cardiovascular response to exercise is a combination of central command and local responses
- Central command:
- Initiates the cardiovascular response to exercise
- Increases sympathetic outflow to the heart and blood vessels
- Decreases parasympathetic outflow to the heart
- Local responses:
- Vasodilator metabolites accumulate in exercising muscle
- Arteriolar dilation occurs in active skeletal muscle
- Blood flow to active skeletal muscle is increased
- Cardiovascular responses to exercise:
- Increased heart rate and contractility
- Increased cardiac output
- Decreased TPR
- Increased blood flow to skeletal muscle
Hemorrhage
-
The compensatory responses to acute blood loss are:
- Decreased blood volume
- Decreased venous return
- Decreased cardiac output
- Decreased arterial pressure
-
The body responds to hemorrhage by:
- Increasing sympathetic outflow to the heart and blood vessels
- Constricting arterioles
- Increasing heart rate and contractility
- Decreasing unstressed volume### Compensatory Responses to Hemorrhage
-
Chemoreceptors in the carotid and aortic bodies are sensitive to hypoxia, increasing sympathetic outflow to the heart and blood vessels.
-
Cerebral ischemia increases Pc, which activates chemoreceptors in the vasomotor center to increase sympathetic outflow.
-
Arteriolar vasoconstriction decreases P, favoring capillary absorption and helping to restore circulating blood volume.
Sympathetic Nervous System
- The adrenal medulla releases epinephrine and norepinephrine, supplementing the sympathetic nervous system's actions on the heart and blood vessels.
- The sympathetic nervous system increases heart rate, contractility, and TPR (total peripheral resistance).
Renin-Angiotensin-Aldosterone System
- The decrease in renal perfusion pressure activates the renin-angiotensin-aldosterone system.
- Angiotensin II is a potent vasoconstrictor, reinforcing the sympathetic nervous system's stimulatory effect on TPR.
- Aldosterone increases NaCl reabsorption in the kidney, increasing circulating blood volume.
Antidiuretic Hormone (ADH)
- ADH is released when atrial receptors detect the decrease in blood volume.
- ADH causes both vasoconstriction and increased water reabsorption, increasing blood pressure.
Baroreceptor Reflex
- The carotid sinus baroreceptors detect the decrease in arterial pressure.
- The baroreceptor reflex increases sympathetic outflow to the heart and blood vessels, and decreases parasympathetic outflow to the heart.
- This leads to increased heart rate, contractility, TPR, and venoconstriction, which increases venous return.
Cardiovascular Responses
- Hemorrhage leads to constriction of arterioles in skeletal, splanchnic, and cutaneous vascular beds, but not in coronary or cerebral vascular beds.
- These responses aim to restore normal arterial blood pressure.
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Description
This quiz covers the principles of blood flow and circulation, including velocity, cross-sectional area, and the equation for cardiac output. It also explores the concept of total peripheral resistance.
