All Exams >
MCAT >
Biology for MCAT >
All Questions
All questions of Circulatory System for MCAT Exam
What is the correct path through the circulatory system which describes the passage of blood originating in the left leg?- a)Vena cava → left atrium → right atrium → lungs → left ventricle → right ventricle → aorta
- b)Vena cava → right atrium → left atrium → lungs → right ventricle → left ventricle → aorta
- c)Vena cava → left atrium → left ventricle → lungs → right atrium → right ventricle → aorta
- d)Vena cava → right atrium → right ventricle → lungs → left atrium → left ventricle → aorta
Correct answer is option 'D'. Can you explain this answer?
What is the correct path through the circulatory system which describes the passage of blood originating in the left leg?
a)
Vena cava → left atrium → right atrium → lungs → left ventricle → right ventricle → aorta
b)
Vena cava → right atrium → left atrium → lungs → right ventricle → left ventricle → aorta
c)
Vena cava → left atrium → left ventricle → lungs → right atrium → right ventricle → aorta
d)
Vena cava → right atrium → right ventricle → lungs → left atrium → left ventricle → aorta
|
Victoria Moore answered |
B)Right atrium
c)Right ventricle
d)Pulmonary artery
e)Lungs
f)Pulmonary veins
g)Left atrium
h)Left ventricle
i)Aorta
j)Arteries of the left leg
c)Right ventricle
d)Pulmonary artery
e)Lungs
f)Pulmonary veins
g)Left atrium
h)Left ventricle
i)Aorta
j)Arteries of the left leg
Rank the following blood vessels in order of their average pressure, from highest to lowest: artery, vein, arteriole, venule, aorta, capillary.- a)Capillary > arteriole > venule > artery > vein > aorta
- b)Aorta > artery > arteriole > capillary > venule > vein
- c)Capillary > vein > venule > arteriole > artery > aorta
- d)Aorta > arteriole > venule > artery > vein > capillary
Correct answer is option 'B'. Can you explain this answer?
Rank the following blood vessels in order of their average pressure, from highest to lowest: artery, vein, arteriole, venule, aorta, capillary.
a)
Capillary > arteriole > venule > artery > vein > aorta
b)
Aorta > artery > arteriole > capillary > venule > vein
c)
Capillary > vein > venule > arteriole > artery > aorta
d)
Aorta > arteriole > venule > artery > vein > capillary
|
Matthew Turner answered |
B) Arteriole
c) Artery
d) Aorta
e) Venule
f) Vein
c) Artery
d) Aorta
e) Venule
f) Vein
How can the circulatory system promote heat retention/conservation, such as on a cold day?- a)Decreasing tunica media contraction
- b)Increasing capillary surface area
- c)Vasodilation
- d)Vasoconstriction
Correct answer is option 'D'. Can you explain this answer?
How can the circulatory system promote heat retention/conservation, such as on a cold day?
a)
Decreasing tunica media contraction
b)
Increasing capillary surface area
c)
Vasodilation
d)
Vasoconstriction
|
Harper White answered |
Vasoconstriction is the process by which blood vessels narrow, reducing blood flow and increasing resistance to blood flow. It is the correct answer because it helps to promote heat retention and conservation in the circulatory system.
Explanation:
1. Cold Weather Response:
In cold weather, the body needs to conserve heat to maintain a stable internal temperature. When the external temperature drops, the body's thermoregulatory system activates several mechanisms to retain heat and prevent hypothermia.
2. Role of the Circulatory System:
The circulatory system plays a crucial role in regulating body temperature. It helps to distribute heat throughout the body and maintain a stable core temperature.
3. Vasoconstriction:
Vasoconstriction is one of the primary responses of the circulatory system to cold temperatures. It involves the contraction of smooth muscles in the walls of blood vessels, leading to a decrease in their diameter. This constriction reduces blood flow to the skin's surface and extremities, minimizing heat loss through the skin.
4. Reducing Heat Loss:
By constricting blood vessels, the circulatory system minimizes the amount of warm blood reaching the skin's surface and extremities. This reduces the surface area available for heat exchange with the environment, effectively reducing heat loss. As a result, more warm blood is directed towards vital organs and tissues to maintain their temperature.
5. Shunting Mechanism:
The circulatory system employs a shunting mechanism during vasoconstriction. It redirects blood flow away from the skin's surface and extremities towards the body's core. This further assists in heat conservation by ensuring that warm blood is circulated internally, keeping vital organs adequately perfused and preventing heat loss through the skin.
6. Physiological Response:
Vasoconstriction is mediated by the sympathetic nervous system. When the body is exposed to cold temperatures, the sympathetic nervous system releases norepinephrine, a neurotransmitter that triggers vasoconstriction. The smooth muscles in the blood vessel walls contract, narrowing the vessels and decreasing blood flow to the skin and extremities.
In conclusion, vasoconstriction is an important physiological response of the circulatory system to cold temperatures. It reduces blood flow to the skin's surface and extremities, minimizing heat loss and promoting heat retention in vital organs and tissues.
Explanation:
1. Cold Weather Response:
In cold weather, the body needs to conserve heat to maintain a stable internal temperature. When the external temperature drops, the body's thermoregulatory system activates several mechanisms to retain heat and prevent hypothermia.
2. Role of the Circulatory System:
The circulatory system plays a crucial role in regulating body temperature. It helps to distribute heat throughout the body and maintain a stable core temperature.
3. Vasoconstriction:
Vasoconstriction is one of the primary responses of the circulatory system to cold temperatures. It involves the contraction of smooth muscles in the walls of blood vessels, leading to a decrease in their diameter. This constriction reduces blood flow to the skin's surface and extremities, minimizing heat loss through the skin.
4. Reducing Heat Loss:
By constricting blood vessels, the circulatory system minimizes the amount of warm blood reaching the skin's surface and extremities. This reduces the surface area available for heat exchange with the environment, effectively reducing heat loss. As a result, more warm blood is directed towards vital organs and tissues to maintain their temperature.
5. Shunting Mechanism:
The circulatory system employs a shunting mechanism during vasoconstriction. It redirects blood flow away from the skin's surface and extremities towards the body's core. This further assists in heat conservation by ensuring that warm blood is circulated internally, keeping vital organs adequately perfused and preventing heat loss through the skin.
6. Physiological Response:
Vasoconstriction is mediated by the sympathetic nervous system. When the body is exposed to cold temperatures, the sympathetic nervous system releases norepinephrine, a neurotransmitter that triggers vasoconstriction. The smooth muscles in the blood vessel walls contract, narrowing the vessels and decreasing blood flow to the skin and extremities.
In conclusion, vasoconstriction is an important physiological response of the circulatory system to cold temperatures. It reduces blood flow to the skin's surface and extremities, minimizing heat loss and promoting heat retention in vital organs and tissues.
A given arteriole has a resistance of 2. What would the new resistance of this vessel be if its radius were to double?- a)1
- b)1/16
- c)1/8
- d)4
Correct answer is option 'C'. Can you explain this answer?
A given arteriole has a resistance of 2. What would the new resistance of this vessel be if its radius were to double?
a)
1
b)
1/16
c)
1/8
d)
4
|
Amelia Taylor answered |
Given Information:
- Resistance of the arteriole = 2
- The radius of the arteriole doubles
To find:
- The new resistance of the arteriole after the radius doubles
Formula:
- Resistance (R) is inversely proportional to the fourth power of the radius (r) of the vessel.
- Mathematically, R ∝ 1/r^4
Solution:
1. Initial Resistance:
- According to the given information, the initial resistance of the arteriole is 2.
2. Relationship between Resistance and Radius:
- The resistance of a vessel is inversely proportional to the fourth power of its radius.
- When the radius of a vessel doubles, the resistance will change accordingly.
3. Doubling the Radius:
- Let's assume the initial radius of the arteriole is 'r'.
- When the radius doubles, the new radius becomes '2r'.
4. Relationship between Initial and New Resistance:
- According to the formula, the initial resistance is inversely proportional to the fourth power of the initial radius: R ∝ 1/r^4.
- The new resistance will be inversely proportional to the fourth power of the new radius: R' ∝ 1/(2r)^4.
5. Calculating the New Resistance:
- Substituting the new radius (2r) into the formula, we get: R' ∝ 1/(2r)^4 = 1/16r^4.
- The new resistance is 1/16 times the initial resistance.
- Therefore, the new resistance of the arteriole after the radius doubles is 1/16 of the initial resistance.
6. Answer:
- The new resistance of the arteriole after the radius doubles is 1/8 (which is equivalent to 1/16).
- Resistance of the arteriole = 2
- The radius of the arteriole doubles
To find:
- The new resistance of the arteriole after the radius doubles
Formula:
- Resistance (R) is inversely proportional to the fourth power of the radius (r) of the vessel.
- Mathematically, R ∝ 1/r^4
Solution:
1. Initial Resistance:
- According to the given information, the initial resistance of the arteriole is 2.
2. Relationship between Resistance and Radius:
- The resistance of a vessel is inversely proportional to the fourth power of its radius.
- When the radius of a vessel doubles, the resistance will change accordingly.
3. Doubling the Radius:
- Let's assume the initial radius of the arteriole is 'r'.
- When the radius doubles, the new radius becomes '2r'.
4. Relationship between Initial and New Resistance:
- According to the formula, the initial resistance is inversely proportional to the fourth power of the initial radius: R ∝ 1/r^4.
- The new resistance will be inversely proportional to the fourth power of the new radius: R' ∝ 1/(2r)^4.
5. Calculating the New Resistance:
- Substituting the new radius (2r) into the formula, we get: R' ∝ 1/(2r)^4 = 1/16r^4.
- The new resistance is 1/16 times the initial resistance.
- Therefore, the new resistance of the arteriole after the radius doubles is 1/16 of the initial resistance.
6. Answer:
- The new resistance of the arteriole after the radius doubles is 1/8 (which is equivalent to 1/16).
What layer of the heart would be most immediately susceptible to infections caused by bacteria circulating in the blood?- a)Epicardium
- b)Myocardium
- c)Pericardium
- d)Endocardium
Correct answer is option 'D'. Can you explain this answer?
What layer of the heart would be most immediately susceptible to infections caused by bacteria circulating in the blood?
a)
Epicardium
b)
Myocardium
c)
Pericardium
d)
Endocardium
|
Eduskill Classes answered |
The endocardium is the innermost layer of the heart wall, lining the chambers and valves of the heart. It consists of a thin layer of endothelial cells supported by connective tissue.
Infections caused by bacteria circulating in the blood, known as bacterial endocarditis, primarily affect the endocardium. This condition occurs when bacteria enter the bloodstream and adhere to damaged or abnormal heart valves or other areas of the endocardium. The bacteria can form colonies (vegetations) on these surfaces, leading to inflammation and potential damage to the endocardium.
The endocardium is susceptible to infections because it comes into direct contact with circulating blood. It is also more prone to damage and exposure to bacteria due to the turbulent flow of blood through the heart, especially around the valves.
On the other hand, the epicardium (outermost layer), myocardium (middle muscular layer), and pericardium (fibrous sac surrounding the heart) are not in direct contact with the circulating blood. While infections can occasionally affect these layers, they are less immediately susceptible to bacterial infections compared to the endocardium.
Which heart valves are NOT actively closed by the contraction of muscular structures?- a)Mitral valves
- b)Semilunar valves
- c)Atrioventricular valves
- d)Tricuspid valves
Correct answer is option 'B'. Can you explain this answer?
Which heart valves are NOT actively closed by the contraction of muscular structures?
a)
Mitral valves
b)
Semilunar valves
c)
Atrioventricular valves
d)
Tricuspid valves
|
Orion Classes answered |
- The papillary muscles contract during systole to prevent blood from flowing backwards within the heart.
- Blood flows from high pressure to low pressure. The papillary muscles are only necessary in areas where this fact may propagate flow in a backwards direction.
- The pressure generated by ventricular systole is substantial enough that it overcomes the pressure of the blood vessels they supply. This force opens the pulmonary and aortic valves, which then shut passively when the pressure of the ventricles is equal to or less than the pressure upstream.
- The mitral and tricuspid valves are both atrioventricular valves.
- Semilunar valves are not associated with the papillary muscles, and are not actively closed.
What vessels carry deoxygenated blood away from the heart?- a)Pulmonary artery only
- b)Coronary arteries only
- c)Neither coronary arteries or pulmonary artery
- d)Both coronary arteries and pulmonary artery
Correct answer is option 'A'. Can you explain this answer?
What vessels carry deoxygenated blood away from the heart?
a)
Pulmonary artery only
b)
Coronary arteries only
c)
Neither coronary arteries or pulmonary artery
d)
Both coronary arteries and pulmonary artery
|
|
Orion Classes answered |
The pulmonary artery is the blood vessel that carries deoxygenated blood away from the heart. It is the only artery in the body that carries deoxygenated blood. The pulmonary artery originates from the right ventricle of the heart and divides into two branches, which lead to the left and right lungs.
The deoxygenated blood is pumped from the right ventricle into the pulmonary artery and is then transported to the lungs. In the lungs, the blood undergoes oxygenation through the process of gas exchange, where carbon dioxide is released, and oxygen is taken up by the red blood cells. After oxygenation, the blood returns to the heart through the pulmonary veins as oxygenated blood.
Coronary arteries, on the other hand, are responsible for supplying oxygenated blood to the heart muscle itself. They originate from the aorta, the main artery leaving the heart, and supply the heart with oxygen and nutrients.
In terms of being open or closed, what is the state of the mitral and tricuspid valves (left and right atrioventricular valves, respectively) at the end of the first heart sound?- a)Mitral is closed, tricuspid is open
- b)Mitral is open, tricuspid is closed
- c)Both are open
- d)Both are closed
Correct answer is option 'D'. Can you explain this answer?
In terms of being open or closed, what is the state of the mitral and tricuspid valves (left and right atrioventricular valves, respectively) at the end of the first heart sound?
a)
Mitral is closed, tricuspid is open
b)
Mitral is open, tricuspid is closed
c)
Both are open
d)
Both are closed
|
Freak Artworks answered |
The first heart sound, also known as S1, is produced by the closure of the mitral and tricuspid valves. These valves close at the beginning of ventricular systole, which is the contraction phase of the ventricles.
During ventricular systole, the pressure in the ventricles increases as they contract, causing the blood to be forcefully ejected into the pulmonary artery and aorta. In order to prevent backflow of blood into the atria during this contraction, the mitral and tricuspid valves close tightly.
As the ventricles contract, the pressure within the ventricles rises above the pressure in the atria, causing the mitral and tricuspid valves to close simultaneously, generating the first heart sound.
Therefore, at the end of the first heart sound, both the mitral and tricuspid valves are closed (option D). This marks the beginning of ventricular systole and the ejection of blood into the circulation.
What physical feature of large systemic arteries (resistance vessels) makes them relatively more responsive to changes in intracellular calcium concentrations?- a)Absent tunica intima
- b)Thick tunica media
- c)Absent tunica media
- d)Thick tunica intima
Correct answer is option 'B'. Can you explain this answer?
What physical feature of large systemic arteries (resistance vessels) makes them relatively more responsive to changes in intracellular calcium concentrations?
a)
Absent tunica intima
b)
Thick tunica media
c)
Absent tunica media
d)
Thick tunica intima
|
|
Orion Classes answered |
The tunica media is the middle layer of the arterial wall and is composed primarily of smooth muscle cells. The smooth muscle cells in the tunica media are responsible for regulating the diameter (vasoconstriction and vasodilation) of the arteries.
In large systemic arteries, such as the aorta and the major arterial branches, the tunica media is relatively thicker compared to smaller arteries and arterioles. This increased thickness provides a greater amount of smooth muscle tissue.
Smooth muscle contraction is regulated by intracellular calcium concentrations. When intracellular calcium levels increase, it triggers the contraction of smooth muscle cells, leading to vasoconstriction and narrowing of the arterial diameter. On the other hand, when intracellular calcium levels decrease, smooth muscle relaxation occurs, resulting in vasodilation and widening of the arterial diameter.
Due to the greater amount of smooth muscle tissue in the thick tunica media of large systemic arteries, these arteries are more responsive to changes in intracellular calcium concentrations. Even small changes in calcium levels can have a significant effect on smooth muscle contraction and arterial diameter.
Therefore, the relatively thick tunica media in large systemic arteries makes them more responsive to changes in intracellular calcium concentrations (option B).
At the instant following the second heart sound, which heart valves are open?- a)Both atrioventricular valves and semilunar valves
- b)Semilunar valves only
- c)Atrioventricular valves only
- d)All valves are closed
Correct answer is option 'D'. Can you explain this answer?
At the instant following the second heart sound, which heart valves are open?
a)
Both atrioventricular valves and semilunar valves
b)
Semilunar valves only
c)
Atrioventricular valves only
d)
All valves are closed
|
|
Orion Classes answered |
The second heart sound (S2) occurs when the semilunar valves (pulmonary valve and aortic valve) close at the end of ventricular systole. After the closure of the semilunar valves, all four heart valves (both atrioventricular valves and both semilunar valves) are closed. This marks the beginning of ventricular diastole, during which all valves remain closed momentarily before the next cardiac cycle begins.
During ventricular diastole, the atrioventricular valves (mitral valve and tricuspid valve) are closed to prevent the backflow of blood from the ventricles to the atria. Simultaneously, the semilunar valves are closed to prevent the backflow of blood from the aorta and pulmonary artery back into the ventricles.
Therefore, at the instant following the second heart sound, all heart valves are closed (option D). This brief period of closure allows the ventricles to relax and refill with blood before the next contraction.
Chapter doubts & questions for Circulatory System - Biology for MCAT 2025 is part of MCAT exam preparation. The chapters have been prepared according to the MCAT exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for MCAT 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
Chapter doubts & questions of Circulatory System - Biology for MCAT in English & Hindi are available as part of MCAT exam.
Download more important topics, notes, lectures and mock test series for MCAT Exam by signing up for free.
Biology for MCAT
233 videos|16 docs|32 tests
|
|
© EduRev
|
Education Revolution
|
|
Signup to see your scores
go up
within 7 days!
within 7 days!
Takes less than 10 seconds to signup