The Hardest Human Heart Quiz

1. _____ are the anchors of the inter-ventricular valves.

Leaflets

Chordae tendineae

Ventricular muscle fibers

Atrial muscle fibers

Chordae tendineae are the anchors of the inter-ventricular valves. These fibrous cords connect the valves to the papillary muscles in the ventricles of the heart. When the ventricles contract, the papillary muscles also contract, pulling on the chordae tendineae and preventing the valves from inverting into the atria. This helps to ensure that blood flows in the correct direction through the heart.

Explanation

Chordae tendineae are the anchors of the inter-ventricular valves. These fibrous cords connect the valves to the papillary muscles in the ventricles of the heart. When the ventricles contract, the papillary muscles also contract, pulling on the chordae tendineae and preventing the valves from inverting into the atria. This helps to ensure that blood flows in the correct direction through the heart.

2. Which of the following about heart sounds is incorrect :

The first heart sound is LUP

The second heart sound is DUB

The second Heart sound is LUP

Heart sounds occur due to valve closure

The second Heart sound is not LUP. The second heart sound is actually DUB. Heart sounds occur due to valve closure, and the first heart sound is LUP.

Explanation

The second Heart sound is not LUP. The second heart sound is actually DUB. Heart sounds occur due to valve closure, and the first heart sound is LUP.

3. Cardiac output is equal to :

Stroke volume / heart rate

Stroke volume × heart rate

Systolic pressure - Diastolic pressure

Diastolic pressure + (pulse pressure/3)

Cardiac output refers to the amount of blood pumped by the heart in one minute. It is calculated by multiplying the stroke volume (the amount of blood pumped by the heart in one contraction) by the heart rate (the number of contractions per minute). Therefore, the correct answer is "stroke volume × heart rate."

Explanation

Cardiac output refers to the amount of blood pumped by the heart in one minute. It is calculated by multiplying the stroke volume (the amount of blood pumped by the heart in one contraction) by the heart rate (the number of contractions per minute). Therefore, the correct answer is "stroke volume × heart rate."

4. The second heart sound is associated with which one of the following :

Opening of the pulmonary and aortic valves

Closing of the pulmonary and aortic valves

Closing of the mitral and tricuspid valves

Opening of the mitral and tricuspid valves

The second heart sound, also known as S2, is produced by the closing of the semilunar valves - the pulmonary and aortic valves. This sound is heard during the diastolic phase of the cardiac cycle when the ventricles are relaxing and filling with blood. As the ventricles relax, the pressure within them decreases, causing the blood to flow back towards the heart. The backflow of blood fills the semilunar valves, causing them to close and produce the second heart sound.

Explanation

The second heart sound, also known as S2, is produced by the closing of the semilunar valves - the pulmonary and aortic valves. This sound is heard during the diastolic phase of the cardiac cycle when the ventricles are relaxing and filling with blood. As the ventricles relax, the pressure within them decreases, causing the blood to flow back towards the heart. The backflow of blood fills the semilunar valves, causing them to close and produce the second heart sound.

5. Nor-epinephrine is released from _______ nerves, causing heart rate to _______ :

Sympathetic, reduce

Para-Sympathetic, increase

Para-Sympathetic, reduce

Sympathetic, increase

Nor-epinephrine is a neurotransmitter that is released from sympathetic nerves. The sympathetic nervous system is responsible for the "fight or flight" response, which increases heart rate and prepares the body for action. Therefore, the release of nor-epinephrine from sympathetic nerves would cause an increase in heart rate.

Explanation

Nor-epinephrine is a neurotransmitter that is released from sympathetic nerves. The sympathetic nervous system is responsible for the "fight or flight" response, which increases heart rate and prepares the body for action. Therefore, the release of nor-epinephrine from sympathetic nerves would cause an increase in heart rate.

6. Plateau in cardiac muscles action potential will occur due to :

Inward diffusion of Na+

Inward diffusion of K+

Inward diffusion of Ca²+

Inward diffusion of H+

During the plateau phase of the cardiac muscle action potential, there is a sustained inward diffusion of Ca²+. This influx of calcium ions prolongs the depolarization phase and helps to maintain the plateau, which is important for the contraction of the cardiac muscles. The influx of calcium ions also triggers the release of more calcium ions from the sarcoplasmic reticulum, leading to further contraction of the cardiac muscles. Therefore, the inward diffusion of Ca²+ is responsible for the plateau in the cardiac muscle action potential.

Explanation

During the plateau phase of the cardiac muscle action potential, there is a sustained inward diffusion of Ca²+. This influx of calcium ions prolongs the depolarization phase and helps to maintain the plateau, which is important for the contraction of the cardiac muscles. The influx of calcium ions also triggers the release of more calcium ions from the sarcoplasmic reticulum, leading to further contraction of the cardiac muscles. Therefore, the inward diffusion of Ca²+ is responsible for the plateau in the cardiac muscle action potential.

7. If the arterial blood pressure is recorded at 132/84, what is the mean arterial pressure :

110 mm Hg

100 mm Hg

120 mm Hg

90 mm Hg

The mean arterial pressure (MAP) is calculated by taking the average of the systolic and diastolic blood pressures, weighted more towards the diastolic pressure. In this case, the systolic pressure is 132 mm Hg and the diastolic pressure is 84 mm Hg. The formula for calculating MAP is (2 * diastolic pressure + systolic pressure) / 3. Plugging in the values, we get (2 * 84 + 132) / 3 = 100 mm Hg. Therefore, the correct answer is 100 mm Hg.

Explanation

The mean arterial pressure (MAP) is calculated by taking the average of the systolic and diastolic blood pressures, weighted more towards the diastolic pressure. In this case, the systolic pressure is 132 mm Hg and the diastolic pressure is 84 mm Hg. The formula for calculating MAP is (2 * diastolic pressure + systolic pressure) / 3. Plugging in the values, we get (2 * 84 + 132) / 3 = 100 mm Hg. Therefore, the correct answer is 100 mm Hg.

8. After forceful expiration and glottis is closed :

IAP=Positive and IPP = Positive

IAP=Negative and IPP = Negative

IAP=0 and IPP = 0

IAP=0 and IPP = Negative

After forceful expiration, the glottis is closed, which means that the air pressure inside the thoracic cavity increases. This increase in pressure leads to a positive intra-abdominal pressure (IAP) and a positive intra-pulmonary pressure (IPP).

Explanation

After forceful expiration, the glottis is closed, which means that the air pressure inside the thoracic cavity increases. This increase in pressure leads to a positive intra-abdominal pressure (IAP) and a positive intra-pulmonary pressure (IPP).

9. Intra alveolar pressure will be _____ during normal inspiration and _____ during normal expiration :

+1,-1

-1, 0

-1, +1

0, +1

During normal inspiration, the diaphragm contracts and the intercostal muscles expand the ribcage, causing an increase in the volume of the thoracic cavity. This increase in volume leads to a decrease in intra-alveolar pressure, creating a pressure gradient that allows air to flow into the lungs. On the other hand, during normal expiration, the diaphragm and intercostal muscles relax, causing a decrease in the volume of the thoracic cavity. This decrease in volume leads to an increase in intra-alveolar pressure, creating a pressure gradient that allows air to flow out of the lungs. Therefore, the intra-alveolar pressure is -1 (decreased) during normal inspiration and +1 (increased) during normal expiration.

Explanation

During normal inspiration, the diaphragm contracts and the intercostal muscles expand the ribcage, causing an increase in the volume of the thoracic cavity. This increase in volume leads to a decrease in intra-alveolar pressure, creating a pressure gradient that allows air to flow into the lungs. On the other hand, during normal expiration, the diaphragm and intercostal muscles relax, causing a decrease in the volume of the thoracic cavity. This decrease in volume leads to an increase in intra-alveolar pressure, creating a pressure gradient that allows air to flow out of the lungs. Therefore, the intra-alveolar pressure is -1 (decreased) during normal inspiration and +1 (increased) during normal expiration.

10. The first heart sound is associated with which one of the following :

Opening of the pulmonary and aortic valves

Closing of the pulmonary and aortic valves

Closing of the mitral and tricuspid valves

Opening of the mitral and tricuspid valves

The first heart sound is associated with the closing of the mitral and tricuspid valves. This sound, often referred to as "lub," occurs during the isovolumetric contraction phase of the cardiac cycle when the ventricles are contracting and the atrioventricular valves close to prevent blood from flowing back into the atria. This closure of the valves creates the first heart sound that can be heard using a stethoscope.

Explanation

The first heart sound is associated with the closing of the mitral and tricuspid valves. This sound, often referred to as "lub," occurs during the isovolumetric contraction phase of the cardiac cycle when the ventricles are contracting and the atrioventricular valves close to prevent blood from flowing back into the atria. This closure of the valves creates the first heart sound that can be heard using a stethoscope.

11. The pressure in pleural space :

More than atmospheric pressure

Positive in valvular pneumothorax

Equal to atmospheric pressure

Negative in valvualr pneumothorax

In valvular pneumothorax, air enters the pleural space but cannot escape, leading to an increase in pressure within the pleural space. This increased pressure causes the lung to collapse further and compresses the mediastinal structures. Therefore, the pressure in the pleural space is positive in valvular pneumothorax.

Explanation

In valvular pneumothorax, air enters the pleural space but cannot escape, leading to an increase in pressure within the pleural space. This increased pressure causes the lung to collapse further and compresses the mediastinal structures. Therefore, the pressure in the pleural space is positive in valvular pneumothorax.

12. Which one of the following parts of the circulation has the highest compliance :

Veins

Arteries

Arterioles

Capillaries

Veins have the highest compliance in the circulation. Compliance refers to the ability of blood vessels to expand and accommodate changes in blood volume. Veins are highly compliant due to their thin and elastic walls, allowing them to stretch and hold a large volume of blood. This high compliance helps veins to store and return blood to the heart, especially during periods of increased blood flow or when there is a need for blood redistribution in the body. Arteries, arterioles, and capillaries have less compliance compared to veins.

Explanation

Veins have the highest compliance in the circulation. Compliance refers to the ability of blood vessels to expand and accommodate changes in blood volume. Veins are highly compliant due to their thin and elastic walls, allowing them to stretch and hold a large volume of blood. This high compliance helps veins to store and return blood to the heart, especially during periods of increased blood flow or when there is a need for blood redistribution in the body. Arteries, arterioles, and capillaries have less compliance compared to veins.