Chapter 20 Summary - Blood Vessels and Circulation

Question-and-answer flashcards covering key concepts from Chapter 20: Blood Vessels and Circulation.

What is the primary function of arteries and how do they change along the path from the heart to capillaries?

Arteries carry blood away from the heart; they transition from elastic (large) arteries to muscular arteries to arterioles as they branch and reduce diameter.

What are capillaries and what are the three types of capillaries?

Capillaries are the smallest vessels where exchange occurs; types are continuous, fenestrated, and sinusoidal.

What is the role of veins and what feature helps prevent backflow?

Veins return blood to the heart and contain valves to prevent backflow.

Name the three tunics of vessel walls and their primary components.

Tunica intima (endothelium), tunica media (smooth muscle), tunica externa (connective tissue).

What is the lumen in a blood vessel?

The hollow passageway through which blood flows.

What are vasa vasorum?

Vasa vasorum are the small vessels that supply the walls of large arteries and veins.

Capillary exchange: what drives filtration and what pulls fluid back in?

Hydrostatic pressure pushes fluid out of capillaries; oncotic (colloid osmotic) pressure pulls fluid in.

What determines filtration vs. reabsorption at the capillary and where does the excess fluid go?

Net Filtration Pressure (NFP) determines filtration vs. reabsorption; excess fluid enters the lymphatic system.

What is MAP and how is it calculated?

Mean arterial pressure; typically approximated as diastolic pressure plus about one-third of the pulse pressure.

Which factors influence Total Peripheral Resistance (TPR)?

Vessel diameter, blood viscosity, vessel length, and turbulence.

Why are veins called capacitance vessels?

Veins can store large volumes of blood and expand to accommodate more blood.

What two pumps assist venous return?

Skeletal muscle pump and respiratory pump.

What is autoregulation in cardiovascular physiology?

Local control of blood flow based on tissue needs, driven by O2, CO2, and metabolites.

What neural components regulate cardiovascular function?

Baroreceptors and chemoreceptors acting through the autonomic nervous system.

Name the hormonal regulators of cardiovascular function listed in the notes.

ADH, angiotensin II, aldosterone, ANP, erythropoietin.

What are the major effects of exercise on circulation?

Vasodilation in active muscles, increased cardiac output, and redistribution of blood flow to muscles.

What happens during hemorrhage in the short term and long term?

Short term: vasoconstriction and increased TPR; long term: restoration of blood volume via hormones and RBC production.

What are the Pulmonary and Systemic Circuits?

Pulmonary circuit: heart → lungs → heart. Systemic circuit: heart → body → heart.

Describe the hepatic portal system.

Digestive tract blood → hepatic portal vein → liver → hepatic veins → inferior vena cava (IVC).

What are continuous, fenestrated, and sinusoidal capillaries and where are they typically found?

Continuous capillaries in most tissues; fenestrated capillaries in kidney/small intestine; sinusoidal capillaries in liver/bone marrow.

What is a capillary bed?

A network of capillaries where exchange with tissues occurs.

What is a precapillary sphincter?

A ring of smooth muscle at the entrance to a capillary bed that regulates blood flow into the capillaries.

What is a metarteriole?

A short vessel connecting arterioles to the capillary bed, often giving rise to multiple capillaries.

What is an anastomosis in the circulation?

A direct connection between two blood vessels that can bypass a capillary bed.

What is angiogenesis and which growth factor drives it?

Formation of new blood vessels; vascular endothelial growth factor (VEGF) promotes it.

What are venous valves and why are they important?

Valves in veins prevent backflow, ensuring one-way blood flow toward the heart.

What is a capacitance vessel and which vessels are they primarily?

Veins; they hold the majority of blood volume and can expand to store more blood.

What is venoconstriction?

Contraction of venous smooth muscle that decreases venous compliance and moves blood toward the heart.

What is the pressure gradient in circulation and why is it important?

The difference in pressure between two points that drives blood flow through the system.

What is elastic rebound in arteries?

The rebound of elastic arteries after systole, helping to maintain blood flow during diastole.

What are hydrostatic pressure, oncotic pressure, net hydrostatic pressure, net osmotic pressure, and net filtration pressure?

Pc: capillary hydrostatic pressure; nc: capillary oncotic pressure; NHP: net hydrostatic pressure; NOP: net osmotic pressure; NFP: net filtration pressure; together they govern fluid movement across the capillary wall.

What is Circle of Willis and its function?

A circular arterial network at the base of the brain that provides collateral blood flow to cerebral regions.