Cardiac Cycle and Blood Pressure

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What is the term used to describe the portion of the heartbeat during which ejection takes place?

Ventricular diastole

Atrial systole

Diastole

Systole (correct)

What valves remain open during atrial systole?

AV valves (correct)

Semilunar valves

Pulmonary valve

Aortic valve

What is the duration of atrial systole?

0.5 s

1 s

0.1 s (correct)

0.3 s

What occurs during ventricular diastole?

Ventricles undergo refilling Signup and view all the answers

How long does ventricular systole last?

0.3 s Signup and view all the answers

What is the term used to describe the portion of the heartbeat during which chamber refilling takes place?

Diastole Signup and view all the answers

What is the thickness of the walls of capillaries?

One cell layer thick Signup and view all the answers

What is the estimated surface area of all the capillaries in the entire system?

500 m2 Signup and view all the answers

What is the average length of a capillary in the peripheral circulation?

1 mm Signup and view all the answers

What surrounds the endothelial cells in arterioles?

A single or double layer of smooth muscle cells Signup and view all the answers

What is the function of precapillary sphincters?

To regulate vascular resistance Signup and view all the answers

What determines the operation of arteriolar smooth muscle cells?

The concentration of oxygen or carbon dioxide Signup and view all the answers

What happens to the atria during ventricular systole?

They undergo diastole Signup and view all the answers

During which phase of the cardiac cycle are both the AV valves and the aortic and pulmonic valves open?

None of the above Signup and view all the answers

What is the purpose of the semilunar valves?

To prevent blood from flowing backward into the ventricles Signup and view all the answers

When do the aortic and pulmonic valves close?

When the pressure in the ventricle drops below the pressure in the aorta or pulmonary artery Signup and view all the answers

What happens when the pressure in the left ventricle rises above the pressure in the aorta?

The aortic valve opens Signup and view all the answers

What is the duration of the period shown in the figure?

0.4 s Signup and view all the answers

What allows the passage of water, inorganic ions, glucose, and amino acids through the capillary wall?

Pores Signup and view all the answers

What is the main function of the venous system?

To act as a huge blood reservoir Signup and view all the answers

What is the result of changing venule diameter in a 70-kg person?

A change in blood volume by 1.5 L Signup and view all the answers

What type of molecules are excluded from passage through the pores in the capillary wall?

Serum albumin and globular proteins Signup and view all the answers

What is the characteristic of tight junctions in venules compared to capillaries?

They are more frequent and have bigger pores Signup and view all the answers

What is the main site of diffusion in the microcirculation?

Venules Signup and view all the answers

What do lymphatic vessels primarily transport?

Fluid, serum proteins, lipids, and foreign substances Signup and view all the answers

What is the mechanism by which fluid enters the lymphatic vessels?

Passive movement due to pressure gradient Signup and view all the answers

What is the function of lymph valves in lymphatic vessels?

Prevent backflow and ensure unidirectional flow Signup and view all the answers