Cardiophysiology Chapter 12 Q/A

Autonomic nerve on pacemaker potential in SA node

(see picture)

Blood volume and blood osmolarity regulation

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Body of water distribution

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Cardiac output regulation

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Sympathetic innervation of the heart

- Increased cardiac rate - Increased strength of contraction

Could potentially result in an increase in arterial blood pressure

- Vasoconstriction of arterioles - Increase in cardiac rate - Increase in stroke volume

Baroreceptor reflex

1. Activated by changes in blood pressure detected by baroreceptors (stretch receptors) in the aortic arch and carotid sinuses 2. Increased blood pressure stretches these receptors, increasing action potentials to the vasomotor and cardiac control centers in the medulla. 3. Most sensitive to drops in blood pressure 4. The vasomotor center controls vasodilation and constriction. 5. The cardiac center controls heart rate. 6. Fall in blood pressure = Increased sympathetic and decreased parasympathetic activity, resulting in increased heart rate and total peripheral resistance 7. Rise in BP has the opposite effects. 8. Good for quick beat-by-beat regulation like going from lying down to standing

Approximately what percent of fluid that exits in the capillaries at the arterial end reenters the capillaries at the venous end?

90%

Which of the following is TRUE concerning the cardiac conduction system? - Action potentials pass slowly through the ventricle wall. - Action potentials pass slowly through the atrioventricular bundle. - Action potentials pass slowly through the Purkinje fibers. - Action potentials pass slowly through the bundle branches. - Action potentials pass slowly through the atrioventricular node.

Action potentials pass slowly through the atrioventricular node.

Which is TRUE regarding the regulation of heart rate? - Stimulation of parasympathetic nerves to the heart causes a slowing of heart rate. - Stimulation of sympathetic nerves to the heart causes an increase in heart rate. - A person whose heart lacks autonomic innervation has a faster heart rate at rest than a person with a normally innervated heart. - The slope of diastolic depolarization in SA node cell action potentials determines the heart rate. - All of the choices are true.

All of the choices are true.

Fluid in the extracellular environment

At the arterial end of the capillary, the net filtration pressure is equal to the net hydrostatic pressure (33 mm Hg) minus the net osmotic pressure (20 mm Hg) The net filtration pressure is 13 mm Hg This causes fluid to move from the capillary into interstitial fluid. At the venous end of the capillary, the net filtration pressure is equal to the net hydrostatic pressure (13 mm Hg) minus the net osmotic pressure (20 mm Hg) The net filtration pressure is -7 mm Hg This causes fluid to move from the interstitial fluid into the capillary. Approximately *9/10* of the fluid that *leaves* capillary at its *arterial end reenters* the capillary at the *venous end* About 1/10 of the fluid passes into lymphatic capillaries and returns to bloodstream via lymphatic system mm = millimeters Hg = mercury

At what point of the cardiac cycle do the semilunar valves close?

Between the ventricular ejection phase and the isovolumetric relaxation phase

Which of the following would be most likely to be determined with a patient's ECG recording? - A heart murmur - Stroke volume - Cardiac output - Blockage of conduction of electrical signals between the atria and the ventricles - A leaky atrioventricular valve

Blockage of conduction of electrical signals between the atria and the ventricles

Result of an increase in blood flow to skeletal muscles

Epinephrine stimulates beta-adrenergic fibers Intrinsic metabolic changes cause vasodilation

Sally has had too many alcoholic drinks. Alcohol is a systemic vasodilator and it increases urine volume, thereby decreasing blood volume. In order to maintain cardiac output, what can her body do?

Increase heart rate

What is the sequence in which depolarization occurs during a normal heart beat?

Sinoatrial node, atrioventricular node, atrioventricular bundle, bundle branches, Purkinje fibers

Relationship between blood flow, vessel radius, and resistance

The *smaller the radius* of a vessel, the *greater the resistance* As the *radius* of a vessel *increases*, the *resistance decreases* As the *resistance decreases*, the *blood flow increases* The *larger the radius* of a vessel, the *less the resistance* The *resistance* in a vessel is *inversely proportional* to the *fourth power* of the *radius* of the vessel. *Blood flow* to an *organ* will: *decrease* with *vasoconstriction* *increase* with *vasodilation*

Which of these correctly states differences between a trained athlete and a sedentary individual at rest? - The athlete would have a lower heart rate and larger stroke volume. - The athlete would have a higher heart rate and larger stroke volume. - The athlete would have a lower heart rate and smaller stroke volume. - The athlete would have a higher heart rate and smaller stroke volume. - There would be no differences when the individuals were at rest.

The athlete would have a lower heart rate and larger stroke volume.

Consider the equation F = ΔP/R. It describes the flow (F) of fluid in a tube in which there is a pressure difference (ΔP) between the two ends and a resistance (R) to flow. Based on this equation, which is a correct conclusion?

The rate of fluid flow in a tube will increase if the pressure at the beginning is increased while the pressure at the end of the tube stays the same.

True or false: In the ventricles, action potentials travels along the interventricular septum to the apex of the heart, then spread up the endocardial surface of the walls of the ventricles.

True

True or false: The ventricles begin to fill during ventricular diastole.

True

You are dissecting a species of amphibian that has just been discovered in the rainforest. You find a blood vessel where the blood travels at a low pressure and velocity. If the frog is in an upright position, blood flow through this vessel would also be against gravity. Anatomically, what do you expect of this blood vessel?

Valves that allow only one-way flow of blood

During which phase of the cardiac cycle do the atrioventricular valves open?

Ventricular diastole

You have a patient who has pernicious anemia. Which of the following supplements should she take to improve her symptoms? - Iron - Vitamin B12 - Vitamin E - Vitamin D - Bilirubin

Vitamin B12

Baroreceptors are located in the..

aorta and carotid arteries

You just ate a huge, delicious breakfast and now are going to head out for your morning run. As you try picking up the pace, you find running to be quite difficult because

blood flow to the abdominal organs is dominant.

Chemoreceptors in the carotid and aortic bodies detect all of the following except:

blood pressure

Chemoreceptors are also located in the..

carotid and aortic bodies

Heart rate will increase as a result of...

decreased blood oxygen

Chemoreceptors in the hypothalamus monitor blood carbon dioxide and pH.

false

Heart rate and stroke volume decrease under decreased parasympathetic stimulation.

false

Increased sympathetic stimulation causes increased heart rate and stroke volume.

false

The lymphatic capillaries reabsorb as much as 20% of the fluid lost by the blood capillaries.

false

According to the Starling Law, _________ effects on cardiac rate and contractility include decreasing the rate of contraction and increasing the filling time resulting in a stronger contraction.

parasympathetic.

All of the following might result in a physician prescribing erythropoietin except - polycythemia. - cancer patient undergoing chemotherapy and radiation treatments. - accident victim suffering multiple lacerations. - kidney disease.

polycythemia

The fluids reenter the capillaries at the venous end because...

the hydrostatic pressure of the interstitial fluid is higher at the venous end than it is at the arterial end.

The fluids leave the capillaries at the arterial end because

the net filtration pressure of the blood is higher at the arterial end than it is at the venous end

Action potentials are conducted from the baroreceptors to the brain via

the vagus and glossopharyngeal nerves

The action potential from the brain to the heart travels along

the vagus nerve

Increased sympathetic stimulation causes vasoconstriction, bringing the blood pressure back within homeostasis.

true

The net osmotic pressure is equal at both the arterial and the venous ends of the capillary.

true

The *sum of all* the vascular resistance within the systemic circulation is called the

*total peripheral resistance*

Hypertension

- Approximately 20% of the population suffers from hypertension. - A diet high in salt is associated with an increased risk of hypertension. - Blood pressure over 120/80 is considered to put a person at risk for cardiovascular disease. - Hypertension can cause atherosclerosis and stroke.

Chemical composition of the blood and heart rate

Chemoreceptors in the carotid and aortic bodies monitor blood oxygen, carbon dioxide and pH. Impulses from these chemoreceptors are conducted to the control center for the heart and blood vessels (Cardioregulatory and Vasomotor center in medulla oblongata) via the glossopharyngeal and vagus nerves. Chemoreceptors in the medulla oblangata monitor blood, carbon dioxide, and pH. Decreased blood oxygen, increased carbon dioxide, or decreased pH, decreased parasympathetic stimulation of the heart, which increases the heart rate. (via vagus nerve- parasymp) Decreased blood oxygen, increased carbon dioxide, and decreased pH, increase sympathetic stimulation of the heart (via sympathetic nerves) which increases heart rate and stroke volume. Increased sympathetic stimulation of blood vessels, increases vasocontriction.

You are a synthetic chemist and have created a compound that appears to bind to acetylcholine receptors. When applied to the inside of the right atrium, what will the affect be?

Decreased heart rate

Tina is a hard-working sales clerk in a busy department store. She has stood completely still behind the check-out counter for an 8-hour shift. At the end of Tina's shift she finds that she feels somewhat dizzy and guesses that her blood pressure is quite low. All of the following factors normally contribute to homeostatic blood pressure regulation. Which one is most likely contributing to her symptoms?

Decreased skeletal muscle pump

Which of the following summary statements about vessel resistance is TRUE? - An inverse relationship exists between radius and resistance—as vessel radius decreases, resistance decreases. - A direct relationship exists between radius and resistance. - Proportionately small changes in vessel radius result in relatively large changes in resistance. - As vessel radius increases, there is a concurrent increase in resistance.

Proportionately small changes in vessel radius result in relatively large changes in resistance.

Which of the following cell types normally initiates action potentials in the cardiac conduction system? - Purkinje fibers - Sinoatrial node cells - Atrial myocardial cells - Atrioventricular node cells - Bundle branch conducting cells

Sinoatrial node cells

True or false: Purkinje fibers conduct action potentials to ventricular myocardial cells.

True

Edema can be caused as result of:

Hypertension, causing an increase in capillary filtration pressure so that more tissue fluid is formed at the arteriolar ends of capillaries Increased tissue protein concentration, causing a decrease in osmosis of interstitial fluid into capillaries Obstruction of lymphatic vessels, blocking lymphatic drainage Decreased plasma protein concentration, causing a decrease in osmosis of interstitial fluid into capillaries

Distribution of blood flow within the circulatory system at rest

(see picture)

Fluid distribution across walls of capillary

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Negative feedback involved with venous return

(see picture)

Which of the following is TRUE? - As blood viscosity increase, resistance to flow decreases. - Reductions in viscosity increase arteriolar resistance. - All other factors being equal, if viscosity increases, flow decreases. - An inverse relationship exists between viscosity and resistance.

All other factors being equal, if viscosity increases, flow decreases.

Frank-Starling Law of the heart

Demonstrates that the strength of ventricular contraction varies directly with the end-diastolic volume The Frank-Starling law of the heart is an *intrinsic* property of heart muscle As the myocardium is stretched, it contracts *more* forcefully The time necessary for contraction of the heart *does not* change due to increased stretch The Frank-Starling law of the heart explains why the left ventricle *does* match the pressure changes of the right ventricle As the myocardium stretches, the interactions between actin and myosin *increase*

What is the term that describes the production of red blood cells?

Erythropoiesis

True or false: Most of the blood entering the ventricle during diastole occurs while the atria are contracting.

False

Which of the following changes would most increase the resistance to blood flow in a blood vessel? - Halving the diameter of the vessel - Doubling the diameter of the vessel - Halving the length of the vessel - Doubling the length of the vessel - Decreasing the hematocrit from 50% to 40%

Halving the diameter of the vessel

In a patient with an abnormally leaky aortic valve, what would you expect?

Some backflow of blood into the left ventricle during ventricular diastole

Which of the following is NOT true for ventricular systole? - The atria contract during ventricular systole. - The ventricles contract during ventricular systole. - The semilunar valves open during ventricular systole. - Blood flows through the aortic and pulmonary semilunar valves during ventricular systole. - The atrioventricular valves close at the beginning of ventricular systole.

The atria contract during ventricular systole.

The kidneys help regulate blood volume by increasing or decreasing the amount of urine produced. If a person is dehydrated, there is an _____________ in plasma osmolality Which causes an ____________ in ADH production, stimulating the kidneys to reabsorb water from the filtrate.

increase, increase

Which of the following statements concerning control of blood flow through arterioles is TRUE? - Beta-adrenergic receptors are more abundant on most arteriolar smooth muscle than are alpha-adrenergic receptors. - Binding of epinephrine to alpha-adrenergic receptors causes vasodilation. - Increased stimulation of vascular smooth muscle by the parasympathetic nervous system causes increased vasoconstriction. - If the arterial blood pressure to an organ suddenly decreases, arterioles in the organ will dilate in response. - Body-wide constriction of arterioles results in a decrease in the total peripheral resistance (TPR).

If the arterial blood pressure to an organ suddenly decreases, arterioles in the organ will dilate in response.

Maintaining blood pressure

increased blood pressure stretches the carotid arteries and aorta, causing the baroreceptors to increase their basal rate of action potential generation. Action potentials are conducted by the glossopharyngeal and vagus nerves to the cardioregulatory and vasomotor centers in medulla oblongata. As a result of increased stimulation from the baroreceptors, the cardioregulatory center increases parasympathetic stimulation to the heart (via vagus nerve) which decreases the heart rate. Also, as a result of the increased stimulation from the baroreceptors, the cardiovascular center decreases sympathetic stimulation to the heart (via sympathetic nerves) which decreases heart rate and stroke volume. The vasomotor center decreases sympathetic stimulation to blood vessels, causing vasodilation. The vasodilation, along with the decreased heart rate and decreased stroke volume, bring the elevated blood pressure back to normal. If the initial problem were a decrease in blood pressure, the activities and effects of the baroreceptors, cardiovascular center, and vasomotor center would be the opposite.

During exercise, the rate of venous return of the blood __________ causing a(n) ________ in stroke volume

increases increase