Blood Vessels and Vasculature - MCAT Biological and Biochemical Foundations of Living Systems
Card 1 of 232
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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Which of the following vessels serves as the body's reservoir of blood?
Which of the following vessels serves as the body's reservoir of blood?
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Veins and venules hold approximately 65% of blood in the body at rest. Because of their large luminal diameters, veins are capable to storing much of blood in the human body.
Arteries carry blood away from the heart and have thick, elastic layers that allow for build up of high pressures due to high volume flow. Capillaries are the smallest vessels in the body, and act to facilitate exchange of gas, nutrients, and waste products between blood and tissues.
Veins and venules hold approximately 65% of blood in the body at rest. Because of their large luminal diameters, veins are capable to storing much of blood in the human body.
Arteries carry blood away from the heart and have thick, elastic layers that allow for build up of high pressures due to high volume flow. Capillaries are the smallest vessels in the body, and act to facilitate exchange of gas, nutrients, and waste products between blood and tissues.
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One component of the immune system is the neutrophil, a professional phagocyte that consumes invading cells. The neutrophil is ferried to the site of infection via the blood as pre-neutrophils, or monocytes, ready to differentiate as needed to defend their host.
In order to leave the blood and migrate to the tissues, where infection is active, the monocyte undergoes a process called diapedesis. Diapedesis is a process of extravasation, where the monocyte leaves the circulation by moving in between endothelial cells, enters the tissue, and matures into a neutrophil.
Diapedesis is mediated by a class of proteins called selectins, present on the monocyte membrane and the endothelium. These selectins interact, attract the monocyte to the endothelium, and allow the monocytes to roll along the endothelium until they are able to complete diapedesis by leaving the vasculature and entering the tissues.
The image below shows monocytes moving in the blood vessel, "rolling" along the vessel wall, and eventually leaving the vessel to migrate to the site of infection.
Capillaries, such as the one depicted in the passage, not only exchange immune cells, but also gas and nutrients with neighboring tissues. Which of the following is true of capillaries?
I. Hydrostatic pressure is greater at the arteriolar end.
II. Osmotic pressure is greater at the arteriolar end.
III. There is a net loss of fluid to the extravascular tissue from the arteriolar to the venule end of the capillary.
One component of the immune system is the neutrophil, a professional phagocyte that consumes invading cells. The neutrophil is ferried to the site of infection via the blood as pre-neutrophils, or monocytes, ready to differentiate as needed to defend their host.
In order to leave the blood and migrate to the tissues, where infection is active, the monocyte undergoes a process called diapedesis. Diapedesis is a process of extravasation, where the monocyte leaves the circulation by moving in between endothelial cells, enters the tissue, and matures into a neutrophil.
Diapedesis is mediated by a class of proteins called selectins, present on the monocyte membrane and the endothelium. These selectins interact, attract the monocyte to the endothelium, and allow the monocytes to roll along the endothelium until they are able to complete diapedesis by leaving the vasculature and entering the tissues.
The image below shows monocytes moving in the blood vessel, "rolling" along the vessel wall, and eventually leaving the vessel to migrate to the site of infection.
Capillaries, such as the one depicted in the passage, not only exchange immune cells, but also gas and nutrients with neighboring tissues. Which of the following is true of capillaries?
I. Hydrostatic pressure is greater at the arteriolar end.
II. Osmotic pressure is greater at the arteriolar end.
III. There is a net loss of fluid to the extravascular tissue from the arteriolar to the venule end of the capillary.
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There is greater hydrostatic pressure pushing fluid out of the capillary at the arteriolar end, and greater osmotic pressure pulling fluid back in at the venule end. Despite this balance, it is not exact, and there is a net loss of fluid to the extravascular compartment over the length of the capillary. This extra fluid is captured by lymphatics and recycled via lymph vessels.
There is greater hydrostatic pressure pushing fluid out of the capillary at the arteriolar end, and greater osmotic pressure pulling fluid back in at the venule end. Despite this balance, it is not exact, and there is a net loss of fluid to the extravascular compartment over the length of the capillary. This extra fluid is captured by lymphatics and recycled via lymph vessels.
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In which component of the circulatory system is blood flowing the fastest?
In which component of the circulatory system is blood flowing the fastest?
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Once blood enters the left ventricle, the left ventricle contracts and pushes blood out of the heart into the aorta. The contraction of the left ventricle pumps blood into the aorta at a fast velocity. Blood velocity becomes slower as it reaches the capillaries and then speeds up again in the veins. Veins must use valves to pump blood against gravity, and therefore does not move blood as quickly as the aorta. The aorta is the best answer.
Once blood enters the left ventricle, the left ventricle contracts and pushes blood out of the heart into the aorta. The contraction of the left ventricle pumps blood into the aorta at a fast velocity. Blood velocity becomes slower as it reaches the capillaries and then speeds up again in the veins. Veins must use valves to pump blood against gravity, and therefore does not move blood as quickly as the aorta. The aorta is the best answer.
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In extremely cold temperatures, which of the following is most directly responsible for constricting blood flow to the skin in order to preserve heat?
In extremely cold temperatures, which of the following is most directly responsible for constricting blood flow to the skin in order to preserve heat?
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The arterioles feed into the capillaries, and control which tissues and parts of the body get more oxygenated blood. During cold weather conditions, the arterioles are activated in vasoconstriction of oxygenated blood to the capillary beds in the skin.
The arterioles feed into the capillaries, and control which tissues and parts of the body get more oxygenated blood. During cold weather conditions, the arterioles are activated in vasoconstriction of oxygenated blood to the capillary beds in the skin.
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All of the following are examples of human capillary classifications except .
All of the following are examples of human capillary classifications except .
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Capillary beds can be broken down into three types: continuous, fenestrated, and sinusoidal.
Continuous capillaries have no pores, fenestrated have small pores, and sinusoidal have large, leaky pores. Hypodermic describes the region just beneath the skin; while this is the location of many capillaries, it is not a classification.
Capillary beds can be broken down into three types: continuous, fenestrated, and sinusoidal.
Continuous capillaries have no pores, fenestrated have small pores, and sinusoidal have large, leaky pores. Hypodermic describes the region just beneath the skin; while this is the location of many capillaries, it is not a classification.
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Which of the following vessels has the highest concentration of oxygen?
Which of the following vessels has the highest concentration of oxygen?
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The pulmonary veins have the greatest concentration of oxygenation, because they bring oxygenated blood from the lungs to the left atrium. They are the only veins that carry oxygenated blood.
Blood in the pulmonary arteries is deoxygenated and travels from the right ventricle to the lungs for gas exchange. Blood in the vena cavae is returning to the heart after systemic circulation, and is thus deoxygenated. Blood in the capillaries is a mixture of oxygenated and deoxygenated, but is always less oxygenated than the blood of the pulmonary veins.
The pulmonary veins have the greatest concentration of oxygenation, because they bring oxygenated blood from the lungs to the left atrium. They are the only veins that carry oxygenated blood.
Blood in the pulmonary arteries is deoxygenated and travels from the right ventricle to the lungs for gas exchange. Blood in the vena cavae is returning to the heart after systemic circulation, and is thus deoxygenated. Blood in the capillaries is a mixture of oxygenated and deoxygenated, but is always less oxygenated than the blood of the pulmonary veins.
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Where would one find the most deoxygenated blood?
Where would one find the most deoxygenated blood?
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The circulatory system follows both the systemic and pulmonary circuits. Deoxygenated blood is returned from the systemic circuit through the vena cavae into the right atrium. It then goes into the right ventricle after passing through the tricuspid valve. From the right ventricle it enters the pulmonary circuit through the pulmonary artery, which carries deoxygenated blood from the right ventricle to the lungs, where it gets oxygenated. From the lungs it goes through the pulmonary veins into the left atrium. From the left atrium it goes into the left ventricle through the mitral valve, and is returned to the systemic circuit through the aorta.
Deoxygenated blood would be found in mostly in systemic veins, including the vena cavae, pulmonary arteries, and the right side of the heart. Oxygenated blood would be found in systemic arteries, such as the femoral artery, pulmonary veins, and the left side of the heart.
The circulatory system follows both the systemic and pulmonary circuits. Deoxygenated blood is returned from the systemic circuit through the vena cavae into the right atrium. It then goes into the right ventricle after passing through the tricuspid valve. From the right ventricle it enters the pulmonary circuit through the pulmonary artery, which carries deoxygenated blood from the right ventricle to the lungs, where it gets oxygenated. From the lungs it goes through the pulmonary veins into the left atrium. From the left atrium it goes into the left ventricle through the mitral valve, and is returned to the systemic circuit through the aorta.
Deoxygenated blood would be found in mostly in systemic veins, including the vena cavae, pulmonary arteries, and the right side of the heart. Oxygenated blood would be found in systemic arteries, such as the femoral artery, pulmonary veins, and the left side of the heart.
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