A&P 2: Chapter 19 - Blood Vessels

What are the three layers of blood vessels?

Tunica intima (inner), tunica media (middle), tunica externa (outer)

How do arteries, capillaries, and veins differ structurally?

Arteries have thick walls for high-pressure flow, capillaries have one endothelial layer for exchange, and veins have thin walls and valves to aid blood return

Where is blood pressure highest and lowest?

Highest in arteries, lowest in veins.

Why is resistance greatest in smaller vessels?

Because their narrow diameter increases friction and resistance to blood flow.

Why doesn’t blood flow backward in veins?

Veins have valves and rely on skeletal muscle contractions to push blood toward the heart.

How does cardiac output affect blood pressure?

Higher cardiac output increases blood pressure.

How does vasoconstriction affect blood pressure?

It increases resistance and raises blood pressure.

What is systolic pressure?

The pressure in arteries during ventricular contraction (~120 mmHg).

What is diastolic pressure?

The pressure in arteries during ventricular relaxation (~80 mmHg).

What are baroreceptors?

Pressure-sensitive receptors in the carotid sinus and aortic arch that help regulate blood pressure.

Where is blood flow fastest and slowest?

Fastest in arteries, slowest in capillaries to allow gas and nutrient exchange.

Why does the brain have unique vascular needs?

It requires constant oxygen and glucose; autoregulation maintains stable blood flow.

What is hydrostatic pressure?

The force exerted by blood against capillary walls, pushing fluid out.

What is osmotic pressure?

The pull exerted by plasma proteins, drawing water into capillaries.

Why is albumin important in capillary exchange?

It maintains osmotic pressure to prevent excessive fluid loss.

What is hypovolemic shock?

Shock caused by severe blood loss, leading to inadequate circulation.

What is cardiogenic shock?

Shock caused by heart failure, preventing effective blood pumping.

What is vascular shock?

Shock caused by extreme vasodilation, leading to a dangerous drop in blood pressure.

What does Figure 19.7 show about blood pressure?

Blood pressure decreases as blood moves from arteries to veins.

How does the muscular pump help venous return (Figure 19.9)?

Skeletal muscle contractions squeeze veins, pushing blood back to the heart.

What is the role of baroreceptors in BP homeostasis (Figure 19.11)?

They detect pressure changes and signal the nervous system to adjust heart rate and vessel diameter.

What does bulk flow across capillary walls depend on (Focus Figure 19.1)?

The balance of hydrostatic and osmotic pressures.

What is the formula for net filtration pressure (NFP)?

NFP = (HPc + OPif) – (HPif + OPc).

What do the terms "filtration" and "reabsorption" mean?

Filtration moves fluid out of capillaries; reabsorption moves fluid into capillaries.

How do baroreceptors regulate blood pressure?

They detect changes in blood pressure and signal the brain to adjust heart rate and vessel diameter.

How do the kidneys contribute to long-term blood pressure regulation?

By adjusting blood volume through the renin-angiotensin-aldosterone system (RAAS).

What role does angiotensin II play in blood pressure control?

It causes vasoconstriction and stimulates aldosterone release to increase blood pressure.

How does vasodilation affect blood flow?

Increases vessel diameter, reducing resistance and lowering blood pressure.

How does vasoconstriction affect blood flow?

Decreases vessel diameter, increasing resistance and raising blood pressure.

What is hypertension, and why is it dangerous?

Chronic high blood pressure (>140/90 mmHg), increasing the risk of heart disease, stroke, and kidney damage.

What is the role of capillaries in the circulatory system?

They allow for gas, nutrient, and waste exchange between blood and tissues.

What is bulk flow in capillary exchange?

The movement of fluids based on pressure gradients (hydrostatic and osmotic pressure).

How does hydrostatic pressure regulate fluid movement in capillaries?

Pushes fluid out of capillaries (filtration).

How does osmotic pressure regulate fluid movement in capillaries?

Draws fluid back into capillaries (reabsorption).

What happens if capillary hydrostatic pressure is too high?

Excessive fluid loss into tissues, leading to edema.

What is the significance of the Net Filtration Pressure (NFP) equation?

It determines whether fluid moves into or out of capillaries.

How does blood flow distribution change during exercise?

Blood is redirected to muscles, heart, and skin, while flow to the digestive organs decreases.

What are the three types of circulatory shock?

Hypovolemic shock: Due to severe blood loss.

Cardiogenic shock: Due to heart failure.

Vascular shock: Due to extreme vasodilation (e.g., septic shock).