Circulatory and Respiratory Systems - MCAT Biological and Biochemical Foundations of Living Systems
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Where is blood pressure the greatest?
Where is blood pressure the greatest?
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Blood pressure tends to be the greatest near the heart, and decreases as blood flows to the capillaries. The pressure is greatest at the aorta and gradually decreases as blood moves from the aorta to large arteries, smaller arteries, and capillaries. The pressure is lowest in the venous system, which is why blood can pool in the veins and act as a "blood reservoir". Veins contain valves that allow them to pump blood back to the heart.
Blood pressure tends to be the greatest near the heart, and decreases as blood flows to the capillaries. The pressure is greatest at the aorta and gradually decreases as blood moves from the aorta to large arteries, smaller arteries, and capillaries. The pressure is lowest in the venous system, which is why blood can pool in the veins and act as a "blood reservoir". Veins contain valves that allow them to pump blood back to the heart.
In what form is carbon dioxide usually circulated in human blood?
In what form is carbon dioxide usually circulated in human blood?
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Carbon dioxide is usually circulated in human blood in the form of 
, or bicarbonate. This is an important part of the blood buffering system, as the bicarbonate ion is the conjugate base of carbonic acid.
Carbon dioxide is usually circulated in human blood in the form of
In mammals, what muscles are involved in inhalation?
In mammals, what muscles are involved in inhalation?
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During inhalation, the external intercostal muscles and diaphragm both contract to help expand the thoracic cavity and draw in air. The internal intercostal muscles are involved in exhalation, and compress the thoracic cavity during contraction.
During inhalation, the external intercostal muscles and diaphragm both contract to help expand the thoracic cavity and draw in air. The internal intercostal muscles are involved in exhalation, and compress the thoracic cavity during contraction.
Which two muscles do humans use primarily for inhalation?
Which two muscles do humans use primarily for inhalation?
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The two muscles that help with breathing are the diaphragm and the external intercostal muscles. The diaphragm pulls the thoracic cavity downward and the external intercostal muscles expand the cavity outward. This expansion of the thoracic cavity leads to a decrease in pressure and allows air to be drawn into the lungs.
The two muscles that help with breathing are the diaphragm and the external intercostal muscles. The diaphragm pulls the thoracic cavity downward and the external intercostal muscles expand the cavity outward. This expansion of the thoracic cavity leads to a decrease in pressure and allows air to be drawn into the lungs.
Which structures contain deoxygenated blood?
Which structures contain deoxygenated blood?
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When blood returns to the heart via the superior and inferior vena cavae, it is deoxygenated. It remains this way as it passes through the right atrium, the right ventricle, and the pulmonary arteries, through which it travels to the lungs to conduct gas exchange with the alveoli. Both the right ventricle and the pulmonary artery contain deoxygenated blood.
All of the other answer choices contain at least one component that carries oxygenated blood.
When blood returns to the heart via the superior and inferior vena cavae, it is deoxygenated. It remains this way as it passes through the right atrium, the right ventricle, and the pulmonary arteries, through which it travels to the lungs to conduct gas exchange with the alveoli. Both the right ventricle and the pulmonary artery contain deoxygenated blood.
All of the other answer choices contain at least one component that carries oxygenated blood.
When blood moves from the right atrium to the right ventricle, it must pass through which heart valve?
When blood moves from the right atrium to the right ventricle, it must pass through which heart valve?
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When blood passes from the right atrium into the right ventricle, it must pass through the tricuspid valve.
The mitral, or bicuspid, valve separates the left atrium and ventricle. The semilunar valves are the aortic and pulmonary valves. The aortic valve separates the left ventricle and aorta, while the pulmonary valve separates the right ventricle and pulmonary arteries.
When blood passes from the right atrium into the right ventricle, it must pass through the tricuspid valve.
The mitral, or bicuspid, valve separates the left atrium and ventricle. The semilunar valves are the aortic and pulmonary valves. The aortic valve separates the left ventricle and aorta, while the pulmonary valve separates the right ventricle and pulmonary arteries.
Which is the only valve in the heart to have two operational flaps?
Which is the only valve in the heart to have two operational flaps?
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The semilunar valves refer to the aortic valve and pulmonary valve, both of which have three flaps. The atrioventricular valves separate the atria from the ventricles. The right side of the heart is separated by the tricuspid valve, while the left is separated by the bicuspid, or mitral, valve. The mitral valve is the only heart valve with two flaps.
The semilunar valves refer to the aortic valve and pulmonary valve, both of which have three flaps. The atrioventricular valves separate the atria from the ventricles. The right side of the heart is separated by the tricuspid valve, while the left is separated by the bicuspid, or mitral, valve. The mitral valve is the only heart valve with two flaps.
Albumin is created in the liver and is an important protein found in the blood. If a vial of blood is centrifuged, in which of the following layers would albumin be found?
Albumin is created in the liver and is an important protein found in the blood. If a vial of blood is centrifuged, in which of the following layers would albumin be found?
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When centrifuged, blood will divide into three parts: the plasma layer, the buffy coat layer, and the red blood cell layer. The plasma layer contains albumin, immunoglobulins, and blood clotting factors. The buffy coat is composed of leukocytes, and the red blood cell layer is composed of erythrocytes.
When centrifuged, blood will divide into three parts: the plasma layer, the buffy coat layer, and the red blood cell layer. The plasma layer contains albumin, immunoglobulins, and blood clotting factors. The buffy coat is composed of leukocytes, and the red blood cell layer is composed of erythrocytes.
What characteristics of arteries and veins allow the heart to pump blood strong enough to travel through the body against gravity without backing up?
What characteristics of arteries and veins allow the heart to pump blood strong enough to travel through the body against gravity without backing up?
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Areteries need to be thick and able to withstand strong, sudden increases in pressure because they recieve blood more directly from the heart. The aorta in particular is very thick and able to expand with a large increase in blood volume. "Compliance" is the word that decsribes a vessel's ability to do this. Veins are thin and collapsable, and contain one-way valves to prevent blood from flowing backwards as it moves against gravity towards the heart.
Areteries need to be thick and able to withstand strong, sudden increases in pressure because they recieve blood more directly from the heart. The aorta in particular is very thick and able to expand with a large increase in blood volume. "Compliance" is the word that decsribes a vessel's ability to do this. Veins are thin and collapsable, and contain one-way valves to prevent blood from flowing backwards as it moves against gravity towards the heart.
Which of the following incorrectly matches the type of blood with the vessel or structure carrying it?
Which of the following incorrectly matches the type of blood with the vessel or structure carrying it?
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Arteries always carry blood away from the heart. Most carry oxygenated blood, but the pulmonary artery carries deoxygenated blood from the right ventricle to the lungs so that it can reoxygenated and sent back to the heart.
Arteries always carry blood away from the heart. Most carry oxygenated blood, but the pulmonary artery carries deoxygenated blood from the right ventricle to the lungs so that it can reoxygenated and sent back to the heart.
Which of the following statements about capillaries is FALSE?
I. The blood flow to a capillary bed can be interrupted by constriction of pre-capillary sphincters.
II. There is a continuous, slow exudation of intravascular fluid into all capillary beds.
III. Together with small arteries, capillaries constitute the "resistance bed" of an organ.
IV. The blood in the distal capillaries of many tissues has a higher osmotic pressure than the blood in the same proximal capillaries.
V. In the pituitary vascular portal system, capillaries take up releasing hormones from the hypothalamus.
Which of the following statements about capillaries is FALSE?
I. The blood flow to a capillary bed can be interrupted by constriction of pre-capillary sphincters.
II. There is a continuous, slow exudation of intravascular fluid into all capillary beds.
III. Together with small arteries, capillaries constitute the "resistance bed" of an organ.
IV. The blood in the distal capillaries of many tissues has a higher osmotic pressure than the blood in the same proximal capillaries.
V. In the pituitary vascular portal system, capillaries take up releasing hormones from the hypothalamus.
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Some—but not all—capillary beds experience transudation of fluid from the vessels. Recall that capillaries can be discontinuous (spaces between adjacent cells), completely closed with tight junctions between cells (as in the brain), or fenestrated (pores through their cytoplasmic membranes (as in the kidney). Closure of arteriolar pre-capillary sphincters can reduce or eliminate the blood flow to a region of tissue. This is why your fingers blanche in very cold weather. Although the arterioles are the major resistance vessels in a circuit, the capillary beds have some contribution. Transudation of fluids, but not large molecules such as protein, from inside to outside a capillary indeed raises the osmotic pressure of the remaining blood; this is Starling's Law, not to be confused with the Frank-Starling law of the heart.
Choice V is a true statement regarding the hypothalmo-hypophyseal portal system.
Some—but not all—capillary beds experience transudation of fluid from the vessels. Recall that capillaries can be discontinuous (spaces between adjacent cells), completely closed with tight junctions between cells (as in the brain), or fenestrated (pores through their cytoplasmic membranes (as in the kidney). Closure of arteriolar pre-capillary sphincters can reduce or eliminate the blood flow to a region of tissue. This is why your fingers blanche in very cold weather. Although the arterioles are the major resistance vessels in a circuit, the capillary beds have some contribution. Transudation of fluids, but not large molecules such as protein, from inside to outside a capillary indeed raises the osmotic pressure of the remaining blood; this is Starling's Law, not to be confused with the Frank-Starling law of the heart.
Choice V is a true statement regarding the hypothalmo-hypophyseal portal system.
Edema is a condition caused by a build-up of fluid in the interstitium.
Which of the following is associated with edema?
Edema is a condition caused by a build-up of fluid in the interstitium.
Which of the following is associated with edema?
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Increased blood vessel wall permeability can lead to edema. Edema is the result of abnormal fluid homeostasis; proper fluid homeostasis is achieved by balancing hydrostatic pressure and oncotic pressure in blood vessels. If hydrostatic pressure is greater than oncotic pressure in a blood vessel, fluid will filter out of the blood vessel and into the interstitium. The Starling Equation describes fluid movement across capillary membranes in relation to hydrostatic pressure and oncotic pressure within the blood vessel.
Increased blood vessel wall permeability can lead to edema. Edema is the result of abnormal fluid homeostasis; proper fluid homeostasis is achieved by balancing hydrostatic pressure and oncotic pressure in blood vessels. If hydrostatic pressure is greater than oncotic pressure in a blood vessel, fluid will filter out of the blood vessel and into the interstitium. The Starling Equation describes fluid movement across capillary membranes in relation to hydrostatic pressure and oncotic pressure within the blood vessel.
Pressure throughout the body is lowest in the .
Pressure throughout the body is lowest in the .
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The aorta is where the blood pressure is greatest, in order to pump blood to the entire body. Capillaries have relatively low blood pressure, but have greater pressure than veins due to their small diameter. Veins carry blood that has traveled a greater distance from the heart; the flow is slower and the pressure is lower. In order to bring the blood back to the heart, the veins must contain valves which prevent the back flow of blood. Arteries, on the other hand, do not need valves because of their great pressure that keeps continuous flow in one direction.
The aorta is where the blood pressure is greatest, in order to pump blood to the entire body. Capillaries have relatively low blood pressure, but have greater pressure than veins due to their small diameter. Veins carry blood that has traveled a greater distance from the heart; the flow is slower and the pressure is lower. In order to bring the blood back to the heart, the veins must contain valves which prevent the back flow of blood. Arteries, on the other hand, do not need valves because of their great pressure that keeps continuous flow in one direction.
Hemoglobin is the principal oxygen-carrying protein in humans. It exists within erythrocytes, and binds up to four diatomic oxygen molecules simultaneously. Hemoglobin functions to maximize oxygen delivery to tissues, while simultaneously maximizing oxygen absorption in the lungs. Hemoglobin thus has a fundamentally contradictory set of goals. It must at once be opitimized to absorb oxygen, and to offload oxygen. Natural selection has overcome this apparent contradiction by making hemoglobin exquisitely sensitive to conditions in its microenvironment.
One way in which hemoglobin accomplishes its goals is through the phenomenon of cooperativity. Cooperativity refers to the ability of hemoglobin to change its oxygen binding behavior as a function of how many other oxygen atoms are bound to the molecule.
Fetal hemoglobin shows a similar pattern of cooperativity, but has unique binding characteristics relative to adult hemoglobin. Fetal hemoglobin reaches higher saturation at lower oxygen partial pressure.
Because of cooperativity, adult and fetal oxygen-hemoglobin dissociation curves appear as follows.
Beyond its ability to carry oxygen, hemoglobin is also effective as a blood buffer. The general reaction for the blood buffer system of hemoglobin is given below.
H+ + HbO2 ←→ H+Hb + O2
The hemoglobin gene can be the site of catastrophic genetic changes, one of which is the change seen in sickle cell anemia. In this disorder, hemoglobin mutations cause red blood cells to take on a sickled appearance. These cells are less able to flow freely in the blood through tight spaces. Which of the following vessels is most likely to be the site of accumulation of these misshapen cells?
Hemoglobin is the principal oxygen-carrying protein in humans. It exists within erythrocytes, and binds up to four diatomic oxygen molecules simultaneously. Hemoglobin functions to maximize oxygen delivery to tissues, while simultaneously maximizing oxygen absorption in the lungs. Hemoglobin thus has a fundamentally contradictory set of goals. It must at once be opitimized to absorb oxygen, and to offload oxygen. Natural selection has overcome this apparent contradiction by making hemoglobin exquisitely sensitive to conditions in its microenvironment.
One way in which hemoglobin accomplishes its goals is through the phenomenon of cooperativity. Cooperativity refers to the ability of hemoglobin to change its oxygen binding behavior as a function of how many other oxygen atoms are bound to the molecule.
Fetal hemoglobin shows a similar pattern of cooperativity, but has unique binding characteristics relative to adult hemoglobin. Fetal hemoglobin reaches higher saturation at lower oxygen partial pressure.
Because of cooperativity, adult and fetal oxygen-hemoglobin dissociation curves appear as follows.
Beyond its ability to carry oxygen, hemoglobin is also effective as a blood buffer. The general reaction for the blood buffer system of hemoglobin is given below.
H+ + HbO2 ←→ H+Hb + O2
The hemoglobin gene can be the site of catastrophic genetic changes, one of which is the change seen in sickle cell anemia. In this disorder, hemoglobin mutations cause red blood cells to take on a sickled appearance. These cells are less able to flow freely in the blood through tight spaces. Which of the following vessels is most likely to be the site of accumulation of these misshapen cells?
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With morphological changes, cells are most likely to be caught in regions with the smallest cross sectional area. Though capiallary beds have the highest TOTAL cross sectional area of any vessel bed in the body, individual capillaries are smaller than any other type of blood vessel. The result is that misshapen red blood cells, such as those in sickle cell anemia, can easily get stuck in capillaries.
With morphological changes, cells are most likely to be caught in regions with the smallest cross sectional area. Though capiallary beds have the highest TOTAL cross sectional area of any vessel bed in the body, individual capillaries are smaller than any other type of blood vessel. The result is that misshapen red blood cells, such as those in sickle cell anemia, can easily get stuck in capillaries.
Hemoglobin is the principal oxygen-carrying protein in humans. It exists within erythrocytes, and binds up to four diatomic oxygen molecules simultaneously. Hemoglobin functions to maximize oxygen delivery to tissues, while simultaneously maximizing oxygen absorption in the lungs. Hemoglobin thus has a fundamentally contradictory set of goals. It must at once be opitimized to absorb oxygen, and to offload oxygen. Natural selection has overcome this apparent contradiction by making hemoglobin exquisitely sensitive to conditions in its microenvironment.
One way in which hemoglobin accomplishes its goals is through the phenomenon of cooperativity. Cooperativity refers to the ability of hemoglobin to change its oxygen binding behavior as a function of how many other oxygen atoms are bound to the molecule.
Fetal hemoglobin shows a similar pattern of cooperativity, but has unique binding characteristics relative to adult hemoglobin. Fetal hemoglobin reaches higher saturation at lower oxygen partial pressure.
Because of cooperativity, adult and fetal oxygen-hemoglobin dissociation curves appear as follows.
Beyond its ability to carry oxygen, hemoglobin is also effective as a blood buffer. The general reaction for the blood buffer system of hemoglobin is given below.
H+ + HbO2 ←→ H+Hb + O2
During exercise the flow of blood is changed, and blood flow is preferentially directed toward working muscles. These muscles are then able to utilize the oxygen carried by hemoglobin. What vessels are most likely to be directly mediating changes in blood flow?
Hemoglobin is the principal oxygen-carrying protein in humans. It exists within erythrocytes, and binds up to four diatomic oxygen molecules simultaneously. Hemoglobin functions to maximize oxygen delivery to tissues, while simultaneously maximizing oxygen absorption in the lungs. Hemoglobin thus has a fundamentally contradictory set of goals. It must at once be opitimized to absorb oxygen, and to offload oxygen. Natural selection has overcome this apparent contradiction by making hemoglobin exquisitely sensitive to conditions in its microenvironment.
One way in which hemoglobin accomplishes its goals is through the phenomenon of cooperativity. Cooperativity refers to the ability of hemoglobin to change its oxygen binding behavior as a function of how many other oxygen atoms are bound to the molecule.
Fetal hemoglobin shows a similar pattern of cooperativity, but has unique binding characteristics relative to adult hemoglobin. Fetal hemoglobin reaches higher saturation at lower oxygen partial pressure.
Because of cooperativity, adult and fetal oxygen-hemoglobin dissociation curves appear as follows.
Beyond its ability to carry oxygen, hemoglobin is also effective as a blood buffer. The general reaction for the blood buffer system of hemoglobin is given below.
H+ + HbO2 ←→ H+Hb + O2
During exercise the flow of blood is changed, and blood flow is preferentially directed toward working muscles. These muscles are then able to utilize the oxygen carried by hemoglobin. What vessels are most likely to be directly mediating changes in blood flow?
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Arterioles serve an important sphincter function at the entry point to capillary beds. During exercise, capillary beds that are not in need of perfusion at a given moment may enlist the use of arterioles to constrict and divert blood where it is more needed.
Arterioles serve an important sphincter function at the entry point to capillary beds. During exercise, capillary beds that are not in need of perfusion at a given moment may enlist the use of arterioles to constrict and divert blood where it is more needed.
Hemoglobin is the principal oxygen-carrying protein in humans. It exists within erythrocytes, and binds up to four diatomic oxygen molecules simultaneously. Hemoglobin functions to maximize oxygen delivery to tissues, while simultaneously maximizing oxygen absorption in the lungs. Hemoglobin thus has a fundamentally contradictory set of goals. It must at once be opitimized to absorb oxygen, and to offload oxygen. Natural selection has overcome this apparent contradiction by making hemoglobin exquisitely sensitive to conditions in its microenvironment.
One way in which hemoglobin accomplishes its goals is through the phenomenon of cooperativity. Cooperativity refers to the ability of hemoglobin to change its oxygen binding behavior as a function of how many other oxygen atoms are bound to the molecule.
Fetal hemoglobin shows a similar pattern of cooperativity, but has unique binding characteristics relative to adult hemoglobin. Fetal hemoglobin reaches higher saturation at lower oxygen partial pressure.
Because of cooperativity, adult and fetal oxygen-hemoglobin dissociation curves appear as follows.
Beyond its ability to carry oxygen, hemoglobin is also effective as a blood buffer. The general reaction for the blood buffer system of hemoglobin is given below.
H+ + HbO2 ←→ H+Hb + O2
Hemoglobin takes time to unload oxygen at tissues that need it, as well as time to pick up carbon dioxide from working cells. Blood flow must slow down during the most active periods when hemoglobin is absorbing and releasing atoms. Since cross-sectional area is inversely proportional to flow velocity, which of the following vessel beds has the greatest total cross sectional area?
Hemoglobin is the principal oxygen-carrying protein in humans. It exists within erythrocytes, and binds up to four diatomic oxygen molecules simultaneously. Hemoglobin functions to maximize oxygen delivery to tissues, while simultaneously maximizing oxygen absorption in the lungs. Hemoglobin thus has a fundamentally contradictory set of goals. It must at once be opitimized to absorb oxygen, and to offload oxygen. Natural selection has overcome this apparent contradiction by making hemoglobin exquisitely sensitive to conditions in its microenvironment.
One way in which hemoglobin accomplishes its goals is through the phenomenon of cooperativity. Cooperativity refers to the ability of hemoglobin to change its oxygen binding behavior as a function of how many other oxygen atoms are bound to the molecule.
Fetal hemoglobin shows a similar pattern of cooperativity, but has unique binding characteristics relative to adult hemoglobin. Fetal hemoglobin reaches higher saturation at lower oxygen partial pressure.
Because of cooperativity, adult and fetal oxygen-hemoglobin dissociation curves appear as follows.
Beyond its ability to carry oxygen, hemoglobin is also effective as a blood buffer. The general reaction for the blood buffer system of hemoglobin is given below.
H+ + HbO2 ←→ H+Hb + O2
Hemoglobin takes time to unload oxygen at tissues that need it, as well as time to pick up carbon dioxide from working cells. Blood flow must slow down during the most active periods when hemoglobin is absorbing and releasing atoms. Since cross-sectional area is inversely proportional to flow velocity, which of the following vessel beds has the greatest total cross sectional area?
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Capillary beds have the greatest TOTAL cross-sectional area, but are composed of individual vessels that are smaller than any other type in the body. Because velocity is dependent on overall cross sectional area, capillary blood velocity is the lowest.
Capillary beds have the greatest TOTAL cross-sectional area, but are composed of individual vessels that are smaller than any other type in the body. Because velocity is dependent on overall cross sectional area, capillary blood velocity is the lowest.
Nutrients absorbed in the small intestine follow which of the following pathways before entering the tissues of the body?
Nutrients absorbed in the small intestine follow which of the following pathways before entering the tissues of the body?
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It is important to remember that these nutrients go through the liver before entering the general circulation. Amino acids and carbohydrates are absorbed through the intestine's epithelial cells into the hepatic portal circulation, then to the liver, through the inferior vena cava, and finally into the heart. From the heart, these nutrients are pumped from the left ventricle to the rest of the body's tissues.
It is important to remember that these nutrients go through the liver before entering the general circulation. Amino acids and carbohydrates are absorbed through the intestine's epithelial cells into the hepatic portal circulation, then to the liver, through the inferior vena cava, and finally into the heart. From the heart, these nutrients are pumped from the left ventricle to the rest of the body's tissues.
Which of the following areas in the general circulation has the lowest blood pressure?
Which of the following areas in the general circulation has the lowest blood pressure?
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In the general circulation, the highest blood pressure is found in the aorta and the lowest blood pressure is in the vena cava. As this suggests, blood pressure drops in the general circulation as it goes from the aorta to the rest of the body. Pressure drops form the aorta to the arteries, the arteries to the arterioles, and the arterioles to the capillaries. Flow rate reaches a minimum in the capillaries before blood begins to pool in the venules. Pressure continues to drop from the venules to the veins to the vena cavae.
In the general circulation, the highest blood pressure is found in the aorta and the lowest blood pressure is in the vena cava. As this suggests, blood pressure drops in the general circulation as it goes from the aorta to the rest of the body. Pressure drops form the aorta to the arteries, the arteries to the arterioles, and the arterioles to the capillaries. Flow rate reaches a minimum in the capillaries before blood begins to pool in the venules. Pressure continues to drop from the venules to the veins to the vena cavae.
The two main pressures found in capillary beds are oncotic pressure and hydrostatic pressure. Following the pathway from an arteriole to a venule (through a capillary bed), which of the following will have the biggest change in pressure from start to end?
The two main pressures found in capillary beds are oncotic pressure and hydrostatic pressure. Following the pathway from an arteriole to a venule (through a capillary bed), which of the following will have the biggest change in pressure from start to end?
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The hydrostatic pressure becomes much lower as blood travels through capillary beds. This is because the fluid pressue lessens as fluid leaves the inside of the capillaries and is forced into the interstitial fluid. The oncotic presssure remains relatively constant, since proteins are large and do not readily move across vessel walls. As fluids exit the capillary, the concentration of proteins within the vessel increases.
The hydrostatic pressure becomes much lower as blood travels through capillary beds. This is because the fluid pressue lessens as fluid leaves the inside of the capillaries and is forced into the interstitial fluid. The oncotic presssure remains relatively constant, since proteins are large and do not readily move across vessel walls. As fluids exit the capillary, the concentration of proteins within the vessel increases.
Of the listed answer choices, where would you expect blood pressure to be highest during normal, healthy circulation?
Of the listed answer choices, where would you expect blood pressure to be highest during normal, healthy circulation?
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Of the available answer choices, we would expect blood pressure to be the highest in the arterioles because they are closest to the aorta and major arteries, from where blood is directly pumped. Of the choices blood pressure is greatest in the arterioles and lowest in the veins.
Note that overall blood pressure is highest in the aorta, however the question specifies that we are only looking a a select portion of answers.
Of the available answer choices, we would expect blood pressure to be the highest in the arterioles because they are closest to the aorta and major arteries, from where blood is directly pumped. Of the choices blood pressure is greatest in the arterioles and lowest in the veins.
Note that overall blood pressure is highest in the aorta, however the question specifies that we are only looking a a select portion of answers.