Human Circulatory System Quiz

Have a small lumen and thick walls composed of collagen, smooth muscle, and elastic fibers.
No valves present; blood flows under high pressure.
Transport oxygenated blood away from the heart, except for the pulmonary artery which carries deoxygenated blood.
Blood flow is rapid and pulsatile.

Characterized by a large lumen and thin walls.
Contain valves to prevent backflow of blood.
Transport deoxygenated blood back to the heart, except for the pulmonary vein which carries oxygenated blood.
Blood flow is slow and steady, supported by surrounding muscle contractions.

Comprise tiny vessels with walls only one cell thick, facilitating material exchange between blood and cells.
Carry both oxygenated and deoxygenated blood.
Blood flows slowly, allowing substance exchange due to low pressure.

Arterioles are small branches of arteries capable of constricting to control blood flow.
Venules are small veins formed from joining capillaries, carrying low-pressure, rich CO₂ blood toward the heart.

Deoxygenated blood from the right ventricle flows into the pulmonary artery, the only artery carrying deoxygenated blood.
Blood travels through lung capillaries, losing CO₂ and gaining oxygen.
Oxygen-rich blood returns to the heart via the pulmonary vein, the only vein carrying oxygenated blood.
Blood moves from the left atrium to the left ventricle, then into the aorta for distribution to the body.
Specific arteries, such as the hepatic, mesenteric, and renal arteries supply blood to respective organs.
As blood passes through capillaries in these organs, it loses pressure and oxygen before returning via the interior vena cava.

Deoxygenated blood enters the heart from the superior and inferior vena cavas into the right atrium.
The 'dub' sound occurs when the semilunar valves close due to arterial backpressure.
Heart tissue is auto-rhythmic, but the sino-atrial (SA) node regulates contractions, with the atrioventricular (AV) node relaying signals.

The cardiac cycle consists of diastole (relaxation) and systole (contraction).
During diastole, atria and ventricles fill with blood.
The SA node initiates atrial contraction to transfer blood into the ventricles, followed by AV node-initiated ventricular contraction.
Blood exits the heart through semilunar valves into the arteries during systole, preventing backflow.

Blood pressure is the force of blood on arterial walls, determined by blood volume and vessel capacity.
Measured using a sphygmomanometer, with an inflatable cuff assessing the pressure needed to halt blood flow.