Vander's Physiology 12 TQR (multiple choices)

Which of the following correctly ranks pressures during isovolumetric contraction of a normal cardiac cycle? a. left ventricular > aortic > left atrial b. aortic >left atrial > left ventricular c. left atrial > aortic > left ventricular d. aortic > left ventricular > left atrial e. left ventricular > left atrial > aortic

A normal cardiac cycle is characterized by recurring atrial and ventricular contractions and relaxations. There are two different periods; isovolumetric contraction and isovolumetric relaxation. Systole involves the ventricular contraction and blood ejection. Diastole includes ventricular relaxation and blood filling of the ventricles. During the cardiac cycle, the pressure and volume within the left atrium, left ventricle, and aorta will vary. This is determined by whether it is in the contraction or relaxation phases. During these phases, all valves are closed, so volume is constant, while pressure changes. CORRECT ANSWER: D During isovolumetric contraction, all valves are closed until the ventricular pressure is higher than the aortic pressure. This leads to ventricular ejection, which opens all the valves. During contraction, the aortic pressure is higher than ventricular and atrial pressures. The left ventricular pressure rises during contraction, and remains higher than the left atrial pressure throughout contraction and ejection. A is eliminated: During the cardiac cycle, the left ventricular pressure is greater than the aortic pressure during ventricular ejection. This occurs after isovolumetric contraction, and causes the aortic valves to open. During this contraction, the left atrial pressure is always the lowest. For this to be accurate, the aortic pressure would be higher than the left ventricular pressure. B is eliminated: Aortic pressure is always the highest during isovolumetric contractions, thus this part of the answer is correct. However, the left atrial pressure is high than the left ventricular pressure only during ventricular relaxation. C is eliminated: The left atrial pressure is never greater than the aortic pressure during relaxation or contraction. This is an impossible description of pressures. For this to be a plausible option, the left atrial pressure would be the lowest pressure and aortic pressure would have the greatest pressure. E is eliminated: It is possible for the left ventricular pressure to be greater than the aortic, but only during ventricular ejection. However, it is not possible for the left atrial pressure to be higher than the aortic pressure.

Hematocrit is increased a. when a person has a vitamin B12 deficiency b. by an increase in secretion of erythropoietin c. when the number of white blood cells is increased d. by a haemorrhage e. in response to excess oxygen delivery to the kidneys

CORRECT ANSWER : B Erythropoietin is the hormone that control erythrocyte production. When oxygen delivery to the kidneys is decreased, an increase in erythropoietin secretion is observed. During this process, the erythropoietin stimulates the bone marrow to produce hematocrit, which leads to an increase of RBCs in the body. A is eliminated: Hematocrit is the amount of blood volume that consists of erythrocytes, or red blood cells. If an individual presents with a deficiency of B12, the hematocrit will not increase. This is because vitamin B12 results in the production and maintenance of normal red blood cell concentration. C is eliminated: If an increase in the number of white blood cells, or leukocytes, os observed, it is unlikely to have an impact on the amount of hematocrit in the blood. This is because approximated 99% of the blood cells are red blood cells, which leaves 1% for the remaining white blood cells and platelets. With an increase in white blood cells, the difference is negligible on the overall concentration red blood cells. D is eliminated: A heamorrhage occurs when blood volume is lost. When this occurs, the red blood cell volume decreases E is eliminated: When there is excess delivery of oxygen to the kidneys is observed, there is a decrease in the production of red blood cells.

Which of the following would NOT result in tissue edema? a. an increase in the contraction of plasma proteins b. an increase in the pore size of systemic capillaries c. an increase in venous pressure d. blockage of lymph vessels e. a decrease in the protein concentration of the plasma

CORRECT ANSWER: A If an increase in plasma protein concentration is observed, it will not result in edema. This is because the increase in the colloid osmotic pressure allows for a decrease in the transfer of fluid into the tissues. Edema occurs when there is a large amoynt of fluid in the intercellular tissue spaces. To make this statement correct, a decrease in the concentration of plasma proteins would be necessary, because fluid flow from the capillaries into the tissues. B is eliminated: If the pore size of the systemic capillaries is increased, the amount of fluid drawn into the capillaries is increased. This increase results in edema C is eliminated: If the venous pressure is increased, an increase in the amount of fluid within the capillary is observed this has the potential to edema D is eliminated: If lymph vessels are blocked, this can lead to edema. An example of this is seen in patients that present with elephantiasis, because the lymph system is unable to function properly. When functioning properly, the lymph should be able to return to the cardiovascular system with ease. E is eliminated: If the plasma protein concentration decreases, edema is a result. This is typically observed when there is an increase in capillary permeability, which will allow an increased flow of proteins into the capillary. When this happens, there is an increase in the amount of fluid seen in the tissues, thus, causing the edema.

When a person engages in strenuous, prolonged exercise, a. bloodflow to the kidney is reduced. b. cardiac output is reduced. c. total peripheral resistance increases. d. systolic arterial blood pressure is reduced. e. blood flow to the brain is reduced.

CORRECT ANSWER: A During strenuous exercise, there is a decrease in blood flow to the kidneys observed. This is seen because there is an increase in sympathetic outputs and norepinephrine release when an individual is exercising. While exercising, vasoconstriction of the arterioles is seen in the kidneys, because this attempts to compensate for vasodilation of skeletal muscle, cardiac muscle, and the skin. B is eliminated: During strenuous, ongoing exercise, cardiac output increases. This is because there is also an increase in heart rate. The muscles that are being exercised will reap the benefits of the increased cardiac output. C is eliminated: During strenuous exercise, the total peripheral resistance (TPS) is decreased. This is seen because there is vasodilation of arterioles in the muscles being used, muscles in the heart, and the skin. This decrease in TPR along with the increase in cardiac output allows for a small increase in mean arterial pressure. D is eliminated: During exercise, the systolic arterial pressure increases. This is observed because the heart is beating faster, which increases the amount of blood flowing through the arteries. This leads to increased pressure on the arteries, which leads to this increase in systolic arterial pressure. E is eliminated: During exercise, an increase of blood flow to the brain observed. Many control centers are activated during exercise by the brain, including the sympathetic and parasympathetics pathways necessary during exercise.

What us mainly responsible for the delay between the atrial and ventricular contractions? a. The shallow slope of AV node pacemaker potentials b. Slow action potential conduction velocity of AV node cells. c. Slow action potential conduction velocity along atrial muscle cell membranes d. Slow action potential conduction in the Purkinje network of the ventrices e. Greater parasympathetics nerve firing to the ventricles than to the atria.

CORRECT ANSWER: B Depolarization of the AV node leads to an action potential that spreads through the right atrium of the heart. These potentials are always slow, because it allows for contractions in the atrium to complete before the ventricle excitation process begins. The AV node is only point where the atria and ventricles are connected. A is eliminated: It is not the AV node that is involved in pacemaker potentials, but the SA node. When an action potential spreads through the SA node, the atrial excitation process begins. Following this, the AV node will become activated. There is a pause between atrial and ventricular excitations. C is eliminated: The action potential velocity along the atrial muscle cells membranes will not affect the delay between the atrial and ventricular excitation. This is because the depolarization of these cells will lead to contractions in both the right and left atria. However, the atrial muscle cells membranes fo not connect to the ventricular cell membranes at any point, except the AV node. D is eliminated: The Purkinje fibers are located in the ventricles, and only make contact with the myocardial cells within the ventricles. These fibers are responsible for the impulse throughout the ventricles, and not the atria. The action potential in these fibers would come after the AV node had already excited the ventricles. E is eliminated: The parasympathetic nerves only innervate cardiac muscle located in the atria. Therefore it is implausible for there to be greater nerve firing in the ventricles by parasympathetics nerves.

Which of the following pressures is closest to the mean arterial blood pressure in a person whose systolic blood pressure is 135 mmHg and pulse is 50 mmHg? a. 110 mmHg b. 78 mmHg c. 102 mmHg d. 152 mmHg e. 85 mmHg

CORRECT ANSWER: C

Which of the following contains blood with the lowest oxygen content? a. Aorta b. left atrium c. right ventricle d. pulmonary veins e. systemic arterioles

CORRECT ANSWER: C The right ventricle has the lowest oxygen blood content. This is because it has just returned from the tissues, leaving the blood relatively deoxygenated. A is eliminated: Oxygenated blood leaves the heart to reach the peripheral organs before it returns to the heart with deoxygenated blood. This oxygenated blood leaves the left ventricle through the aorta. B is eliminated: The left atrium also contains oxygenated blood, and transfers the blood from the pulmonary veins to the left ventricle. D is eliminated: The pulmonary veins also contain oxygenated blood. After the deoxygenated blood passes through the lungs, it passes through the pulmonary veins. E is eliminated: The systemic arteries transfer oxygenated blood to all of the peripheral organs.

Which correctly pairs an ECG phase with the cardiac event responsible? a. P wave: depolarization of the ventricles b. P wave: depolarization of the AV node c. QRS wave: depolarization of the ventricles d. QRS wave: repolarization of the ventricles e. T wave: repolarization of the atria.

CORRECT ANSWER: C The QRS wave represents two aspects of action potentials of the heart, including ventricle depolarization and atria repolarization. Both of these occur at the same time. A and B is eliminated: An ECG is an important tool that assists physicians in the evaluation of any electrical events of the heart. Electrodes are placed on different areas of the body that allows these events to be recorded. The P wave is the first deflection observed on the ECG and represents aria depolarization. This wave expresses the electrical impulse that starts at the SA node and flows through both atria. P wave does not represent depolarization of the ventricles or the AV node. D is eliminated: The QRS wave is the second deflection observed on an ECG. Ventricle depolarization will determine the impulse recorded for the QRS wave. In this wave, three different deflections, because ventricle depolarization involves the following: depolarization of the interventricular septum and the subendocardial branches, and the third deflection will be determined by atria repolarization. E is eliminated: The T wave is the final deflection recorded on the ECG. It represents the repolarization of the ventricles. The T wave doe not represent atria repolarization.

The principal site of erythrocyte production is a. the liver b. the kidneys c. the bone marrow d. the spleen e. the lymph nodes

CORRECT ANSWER: C The primary locations for the red blood cell production is in the bone marrow A is eliminated: Erythrocyte production is essential to maintain the total volume of red blood cells that circulated within the body. The body's iron is stored in the liver until it is released into the plasma. Erythrocyte production does not occur in the liver. B is eliminated: The kidneys are responsible for the release of erythropoietin, which stimulates erythrocyte production. However, this is not the primary location of production D is eliminated: The spleen is the site of erythrocyte destruction when they have become damaged. E is eliminated: The primary location for red blood cell production is in the bone marrow.

Which statement comparing the systemic and pulmonary circuits is true? a. The blood flow is greater through the systemic. b. The blood flow is greater the pulmonary. c. The absolute pressure is higher in the pulmonary. d. The blood flow is the same in both. e. The pressure gradient is the same in both.

CORRECT ANSWER: D The blood flow is that same in both the systemic and the pulmonary systems. A higher pressure in the systemic circuit causes an increase in blood flow, but the cardiovascular system is a closed circuit. Thus, blood flow is the same in the systemic and pulmonary systems. The total blood flow through the whole body is equal to cardiac output. A is eliminated: There is no difference in blood flow between the pulmonary and systemic systems. This is because blood flow is determined by the cardiac output of the pulmonary system. B is eliminated: Blood flow is the same in both the pulmonary and systemic systems. This is because blood flow is determined by the cardiac output of the pulmonary system. The overall blood flow of the entire systemic systems (including arteries, veins, and capillaries) will equal the blood flow of the pulmonary system. C is eliminated: Pressures are higher in the systemic circuit, because of the sizes of the blood vessels in the systems. Other characteristics that allow for higher pressure include the different destinations of the blood vessels, as well as, the various areas where redirection is observed. E is eliminated: The pressure gradient is not the same in both, because a higher pressure is observed in the systemic system is not seen in the pulmonary system. In the pulmonary system, the lung volume in the circuit determines the pressure.

Considered as a whole, the body's capillaries have. a. smaller cross-sectional area than the arteries. b. less total blood flow than in the veins. c. greater total resistance than the arterioles. d. slower blood velocity than in the arterioles e. greater total blood flow than in the arteries.

CORRECT ANSWER: D The large total cross sectional area of capillaries result in very slow blood velocity.

Which of the following would help restore homeostasis in the first few moments after a person's mean arterial pressure became elevated? a. a decrease in baroreceptor action potential frequency b. a decrease in action potential frequency along parasympathetic neurons to the heart c. an increase in action potential frequency along sympathetic neurons to the heart d. a decrease in action potential frequency along sympathetic neurons to arterioles e. an increase in total peripheral resistance

CORRECT ANSWER: D When a decrease in action potential frequency of the sympathetic neurons innervating the arterioles is observed, there is a reduction in the total peripheral resistance. This can be observed by understanding the equation for MAP. MAP=COxTPR From this equation, it can be determined that as the cardiac output is increased, a reduction of TPR is necessary to return blood pressure to the normal level. A is eliminated: If the mean arterial pressure (MAP) were increased, baroreceptor action potential frequencies would also increase. For homeostasis to be restored, the MAP would have to be decreased prior to the baroreceptor response. B is eliminated: A decrease in action potential frequencies along parasympathetic neurons in the heart would lead to an increase in blood pressure. This would make the elevated blood pressure worse, instead of better. For homeostasis to be restored, an increase C is eliminated: When an increase in action potential frequency of the sympathetic neurons to the heart occurs, they work along with the decreased action potential frequencies of the parasympathetic neurons. This causes to blood pressure to increase further instead of bringing it to a normal pressure. E is eliminated: When an increase in the total peripheral resistance is observed, there is a decrease in the blood flow. Blood flow is the same as cardiac output. This leads to an increase in blood pressure. This is seen because the cardiac output multiplied by the total peripheral resistance determines the MAP of a person

Which is FALSE about L-type Ca2+ channels in cardiac ventricular muscle cells? a. They are open during the plateau of the action potential. b. They allow Ca2+ entry that triggers sarcoplasmic reticulum Ca2+ released? c. They are found in the T-tubule membrane. d. They open in response to depolarization of the membrane. e. They contribut to the pacemaker potential.

CORRECT ANSWER: E Pacemaker potentials are not observed in ventricular muscles, but are seen in the nodal cells, specifically the SA node. During a pacemaker potential, the L-type Ca2+ are not open. However, a different type of Ca2+ channel is opened, known as T-type Ca2+ channels. These channels. These channels are open for a short period of time, unlike the L-type channels in the ventricular cells. A is eliminated: L-type Ca2+ channels located in the ventricular muscle cells of the heart are open for a long periods time. This is due to the slow openings of the channels. Only small quantities of calcium ions enter through these channels during the plateau of the action potential. This is because the flow of calcium will equal the amount of K+ flowing out of the cell. This allows depolarization to be maintained at the plateau. B is eliminated: L-type Ca2+ channels allows the influx of extracelular Ca2+ into the cell When this occurs during the plateau of the action potential, Ca2+ release form the sarcoplasmic reticulum is started. Ths is because the ryanodine receptors are activated, allowing for a larger release of Ca+ C is eliminated: In cardiac muscle, Ca2+ channels are found in the T-tubule membrane, similar to skeletal muscle D is eliminated: L-type Ca2+ channels are opened after depolarization of the cell. Depolarization occurs when Na+ enters the cell until it reaches approximately 0mV. At this point, the L-type Ca+ channels are opened.

Which is NOT part of the cascade leading to formation of a blood clot? a. contact between the blood and collagen found outside the blood vessels. b. prothrombin converted to thrombin c. formation of a stabilized fibrin mesh d. activated platelets e. secretion of tisue plasminogen activator (t-PA) by endothelial cells

CORRECT ASNWER: E When the tissue plasminogen activator (t-Pa) is secreted from endothelial cells, it catalyzes the reaction that will generate plasmin. Plasmin is essential in the destruction of blood clots. However, this is not part of the blood-clotting cascade. A is eliminated: When a vessel is injured, the endothelium is damaged and allows for the exposure of the connective-tissue fibers to platelets and blood. These connective tissues are collagen fibers. This aspect of the process is necessary for the production of a blood clot. B is eliminated: During the blood clotting process, another important aspect in the process is the conversion of prothrombin to thrombin. This is necessary because thrombin is the catalyst for the reaction that forms fibrin. C is eliminated: A fibrin meshwork is necessary during the clotting process, because erythrocytes, cells, and platelets will be trapped within the meshwork. This is also a necessary part of the blood clotting process. D is eliminated: Activated platelets are one of the most important aspects of the clotting cascade. This is because the reactions necessary for this cascade will take place on the platelet surface. The platelet surface is also necessary for clotting factors to bind, which allows the cascade to move forward.

If other factors are equal, which of the following vessels would have the lowest resistance? a. length= 1 cm, radius= 1cm b. length= 4 cm, radius 1 cm c. length= 8 cm, radius 1 cm d. length= 1 cm, radius 2 cm e. length= 0.5 cm, radius 2 cm

resistance describes how difficult it is for blood to flow between any two points. R= ηL/r^4 R-resistance L- length of the tube/vessel η- viscosity r^4- radius of the tube/vessel raised to the fourth power CORRECT ANSWER: E Since the viscosity is unknown, but is the same for all options, information about the equation will be used to determine the lowest resistance. When the length of the vessel is 0.5 cm and the radius is 2 cm, the resistance would be the lowest. This is because the radius is the largest, and the length is the shortest.