Mandatory Assignment - Circulatory System: Heart

How is increased muscle perfusion during exercise accomplished? Check all that apply.

Arterioles dilate in response to epinephrine and norepinephrine. Precapillary sphincters dilate in response to muscle metabolites such as lactic acid, CO2, and adenosine. Blood is diverted from other organs such as the digestive tract and kidneys to meet the needs of the working muscles.

During exercise, the adrenal medulla and sympathetic nerves cause which of the following to occur?

Arterioles to dilate in response to epinephrine and norepinephrine.

Choose the correct statement(s) that accurately explain(s) impulse conduction to the myocardium. Check all that apply.

Firing of the SA node excites atrial cardiocytes and stimulates the two atria to contract almost simultaneously. In the AV node, the signal slows down to about 0.05 m/sec because the cardiocytes have fewer gap junctions over which the signal can be transmitted. Signals travel through the AV bundle and Purkinje fibers at a speed of 4 m/sec, the fastest in the conduction system.

Action potentials are conducted from the baroreceptors to the brain via which nerve?

Glossopharyngeal Nerves

Which of the following is the correct formula for calculating cardiac output?

HR x SV

Heart sound __________ is thought to result from the transition from expansion of the empty ventricles to their sudden filling with blood.

S3

In the heart, an action potential originates in the __________.

Sinoatrial Node.

Which of the following is the correct sequential path of an action potential in the heart?

Sinoatrial node, atrioventricular node, atrioventricular bundle, bundle branches, Purkinje fibers.

What is the best way to estimate the MAP?

Take the diastolic pressure and add one-third of the pulse pressure.

Match the heart sound with the action or event believed to cause it.

The AV valves close as blood backs up against their cusps. 1st Heart Sound (S1) Blood rebounds from the closed semilunar valves and the ventricles expand. 2nd Heart Sound (S2) It is thought to result from the transition from the expansion of the empty ventricles to their sudden filling with blood. 3rd Heart Sound (S3)

Which of the following is caused by ventricular contraction?

The atrioventricular valves close, and then the semilunar valves open.

When the pressure in the ventricles becomes lower than the pressure in the atria, __________.

The atrioventricular valves open.

Which of the following does not aid in venous return?

Venule Suction

Choose the accurate statements regarding the effects of edema. Check all that apply.

- Cerebral edema can produce headaches, nausea, and sometimes delirium, seizures, and coma. - As the tissues become congested with fluid, oxygen delivery and waste removal are impaired and the tissues may begin to die. - Pulmonary edema presents a threat of suffocation as fluid replaces air in the lungs.

Place the labels in order denoting the flow of blood through the systemic circuit beginning with the left atrioventricular valve and ending in the right atrium. The first and last structures are given.

1. Left Ventricle: Pumps blood to the rest of the body. 2. Aortic Valve: Also known as the left semilunar valve. 3. Ascending Aorta: First vessel of systemic circulation. 4. Coronary Arteries: Exits the systemic circulation at the base of the aorta. 5. L. Subclavian Artery: Last vessel of the aortic arch. 6. Systemic Capillaries: Site of gaseous exchange in the systemic circuit. 7. Systemic Veins: Bring blood back toward the heart. 8. Venae Cavae: The two large veins that return blood to the right atrium.

Approximately what percent of fluid that exits the capillaries at the arterial end reenters the capillaries at the venous end?

90%

Match the action of the AV and semilunar heart valves with the correct statement regarding pressure differences in the heart chambers.

Atrial pressure is greater than ventricular pressure -AV valves open Ventricular pressure rises above atrial pressure -AV valves closed Pressure in the ventricles is greater than the pressure in the great arteries -semilunar valves open Ventricular pressure is lower than arterial pressure -semilunar valves closed

Which of the following is not detected by chemoreceptors in the carotid and aortic bodies?

Blood Pressure

What is(are) the advantage(s) of there being a low blood pressure in the pulmonary circuit? Check all that apply.

Blood flows more slowly through the pulmonary capillaries and therefore has more time for gas exchange. It prevents fluid accumulation in the alveolar walls and lumens, which would compromise gas exchange. Oncotic pressure overrides hydrostatic pressure, so pulmonary capillaries are engaged almost entirely in absorption.

Identify the incorrect statement regarding the fundamental causes of edema.

Capillary reabsorption does not depend on oncotic pressure.

The difference between the maximum and resting cardiac output is called __________.

Cardiac Reserve

Choose the correct statement(s) associated with the metabolism of cardiac muscle. Check all that apply.

Cardiac muscle depends almost exclusively on aerobic respiration to make ATP. It is very rich in myoglobin (a source of stored oxygen) and glycogen (for stored energy).

Where are baroreceptors found?

Carotid Sinuses

Which of the following is not a mechanism that assists venous return?

Central venous pressure being greater than pressure in the venules.

The Frank-Starling law of the heart states that an additional stretch of the myocardium produces a significant increase in __________ on the next beat.

Contraction Force

How do materials get from the blood to the surrounding tissues?

Diffusion, filtration & absorption, and transcytosis.

Match the layer of the heart with its description.

Endocardium - Covers the valve surfaces and is continuous with the endothelium of the blood vessels. Myocardium - Thickest layer; made of muscle and performs the work of the heart. Epicardium - Serous membrane; mainly simple squamous epithelium over areolar connective tissue with an adipose covering.

Which of the following has a strong, positive inotropic effect, meaning it increases the strength of each contraction of the heart?

Hypercalcemia

Where are arterial anastomoses, in which two arteries merge, found?

In the coronary circulation.

As exercise progresses, muscular activity __________ venous return. This increases the __________ on the right ventricle.

Increases, pre-load

Which of the following is the correct sequence of events regarding the cardiac cycle?

Isovolumic contraction, ejection, isovolumic relaxation, passive ventricular filling, active ventricular filling.

Which of the following contains chemoreceptors?

Medulla Oblangata

Blood usually passes through one network of capillaries from the time it leaves the heart until the time it returns, but there are exceptions, notably the __________.

Portal Systems and Anastomoses

If the right ventricle begins to pump an increased amount of blood, this soon arrives at the left ventricle, stretches it more than before, and causes it to increase its stroke volume and match that of the right. This is an example of __________.

Preload

The amount of tension in the ventricular myocardium immediately before it contracts is called _________.

Preload

Exercise has which of the following effects on cardiac output? Check all that apply.

The main reason the heart rate increases at the beginning of exercise is that proprioceptors in the muscles and joints transmit signals to the cardiac centers. As the exercise progresses, muscular activity increases venous return. A sustained program of exercise causes hypertrophy of the ventricles, which increases their stroke volume.

Why do fluids leave the capillaries at the arterial end?

The net filtration pressure of the blood is higher at the arterial end than it is at the venous end.

Which of the following statements is not true regarding ventricular systole?

The ventricles relax.

What is(are) the physiological purposes of vasoreflexes?

To cause a generalized raising or lowering of blood pressure throughout the body and to selectively modify the perfusion of a particular organ by rerouting blood from one region of the body to another.