Homework 2 Cardiovascular system

What is the average normal pH range of blood?

7.35-7.45

Which of the following structures receives the depolarization wave from the atria and passes impulses onto the ventricles?

AV node

The right side of the heart is considered the systemic circuit pump.

FALSE The right side of the heart pumps deoxygenated (oxygen-poor) blood into the pulmonary circuit of the lungs to be re-oxygenated. For this reason, the right side of the heart is considered the pulmonary circuit pump. The left side of the heart pumps blood into the systemic circuit, which serves the tissues of the body, and is therefore considered the systemic circuit pump.

What is a hematocrit?

Hematocrit is the percentage of erythrocytes in a whole blood sample. Although the percent sign is usually omitted, the hematocrit, which in this figure is 45, is the percentage of erythrocytes in whole blood. The height of the erythrocyte layer is divided by the total height of the material.

sinusoidal capillary

Most permeable. Occurs in special locations (e.g., liver, bone marrow, spleen).

Electrical impulses pass through the conduction system of the heart in the following sequence:

SA node, AV node, bundle of His, bundle branches, and Purkinje fibers The impulses of the heart originate at the SA node (pacemaker). The impulse is then transmitted to the AV node (atrioventricular node), where the impulse slows down to allow the atria to completely contract and thereby fill the adjacent ventricles. The AV node then transmits the impulse to the bundle of His, which branches into left and right bundle branches. The bundle branches give rise to the Purkinje fibers, which transmit the impulse to the ventricle walls and stimulate ventricular contraction.

Continuous capillaries are the most common capillaries in the body.

TRUE Continuous capillaries, found in the skin, muscles, lungs and CNS, are the most common capillaries. Fenestrated capillaries are found only in sites of active filtration or absorption. Sinusoidal capillaries are limited to a few organs, like the spleen, bone marrow, liver, and adrenal medulla.

What would happen to the SA node if a chemical blocker was used to reduce transport of Na+ into the pacemaker cells?

The SA node would depolarize more slowly, reducing the heart rate. Diffusion of Na+ into the pacemaker cell causes a gradual depolarization of the cell membrane, called the pacemaker potential. If the rate of depolarization slows down, it will take longer for the membrane to reach threshold and trigger the next action potential, which will reduce heart rate.

The source of blood carried to capillaries in the myocardium would be the ________.

coronary arteries

fenestrated capillary

endothelial cells have filtration pores facilitating exchange

Which is most responsible for the synchronized contraction of cardiac muscle tissue?

gap junction

The plateau phase of an action potential in cardiac muscle cells is due to the _______.

influx of Ca2+ through slow Ca2+ channels

continuous capillary

least permeable and most common

Failure in a particular structure of the heart tends to cause a backup of blood in the lungs, known as pulmonary congestive heart failure. Failure of which structure of the heart would lead to such a backup?

left ventricle Failure in the left ventricle can cause increased blood hydrostatic pressure in the lungs, causing fluid buildup in the alveoli.

Specifically, what part of the intrinsic conduction system stimulates the atrioventricular (AV) node to conduct impulses to the atrioventricular bundle?

sinoatrial (SA) node The sinoatrial node, by spontaneously depolarizing faster than the atrioventricular node, initiates heart contraction.

The most permeable capillaries, which contain fenestrations and large intercellular clefts, are called __________.

sinusoid capillaries Sinusoid capillaries are the most permeable type of capillary due to large fenestrations and intercellular clefts among their endothelial cells. These capillaries allow large molecules-even blood cells- to pass into the surrounding tissue. Sinusoid capillaries are found in the liver, bone marrow, spleen, and adrenal medulla.

Which of the following increases stroke volume?

stroke volume