Vessel Anatomy and Pressures

Question 1

Describe arteries grossly

Answer 1

Thick, hold their shape; 3 tunics of the wall

Question 2

Describe veins grossly

Answer 2

Thin walls, collapsible, large lumen; low pressure; contain valves; 3 tunics but thinner

Question 3

Describe capillaries grossly

Answer 3

Thinnest vessel, site of gas exchange; just 1 tunic

Question 4

Describe blood flow from arteries to veins

Answer 4

Blood flows down artery, into arteriole, into capillary bed; drains into venule, flows into vein

Question 5

Which vessels contain valves?

Answer 5

Veins

Question 6

What is the purpose of valves in veins?

Answer 6

Low pressure vessels prone to backflow; valves prevent this

Question 7

What are the tunics of arteries and veins?

Answer 7

Tunica interna (endothelia, basement membrane); tunica media (smooth muscle); tunica externa

Question 8

Where is the external elastic lamina found?

Answer 8

Tunica interna and tunica media of arteries

Question 9

What are the tunics of capillaries?

Answer 9

Just tunica interna; endothelium and basement membrane

Question 10

Describe the tunica interna/intima

Answer 10

lines lumen, in contact with blood; smooth simple squamous endothelia. Beneath endothelia is the basement membrane; loose CT that contains collagen

Question 11

What is the function of the subendothelial layer/basement membrane?

Answer 11

Aids in clotting; collagen of the connective tissues draws platelets

Question 12

Describe the tunica media

Answer 12

Middle layer made of smooth muscle; contains elastin (elastic fibers) in arteries. Innervated by SNS fibers that control vasodilation/constriction; controls blood pressure

Question 13

Describe the tunica externa/adventitia

Answer 13

Loose collagen fibers & elastin; contains nerve, lymph and blood vessels that serve the vessel itself; anchors and protects the vessel

Question 14

What is the vasa vesorum?

Answer 14

The system of blood vessels that serve other blood vessels

Question 15

What is blood pressure?

Answer 15

Force per unit area exerted on the wall of a vessel by the blood; mmHg

Question 16

What is generally being referred to when talking about BP measures clinically?

Answer 16

systemic arterial BP in the largest arteries near the heart, like the radial artery

Question 17

What are the different types of arteries?

Answer 17

Elastic arteries, arterioles, muscular arteries

Question 18

What are elastic arteries?

Answer 18

Largest type of arteries; conducting vessels. Include aorta, pulmonary trunk, common carotid, etc. Thick walled, low resistance high in elastic tissue

Question 19

What are muscular arteries?

Answer 19

Distributing vessels; lots of smooth muscle and more fibrous tissue. Active in vasoconstriction

Question 20

What are arterioles?

Answer 20

Smallest arteries; resistance vessels. Control blood flow into capillaries

Question 21

What affects arterial blood pressure?

Answer 21

Stretch: how much can elastic arteries stretch?
Volume: how much blood is forced into the arteries?

Question 22

What is atherosclerosis?

Answer 22

Hardening of the elastic arteries due to plaque build up; increases blood pressure by greater resistance to blood flow through arteries

Question 23

What is the systolic BP measuring?

Answer 23

Pressure in artery resulting from ventricular ejection phase (higher number on top)

Question 24

What is a diastolic BP measuring?

Answer 24

Pressure in artery resulting from the non-ejection phase (lower number on bottom)

Question 25

What is pulse pressure?

Answer 25

The difference between systolic and diastolic blood pressure (sys-di)

Question 26

What is the mean arterial pressure?

Answer 26

Average pressure propelling blood to the tissues of the body; diastolic + 1/3 pulse pressure

Question 27

What are the 3 types of capillaries?

Answer 27

Continuous, fenestrated, and sinusoidal

Question 28

What are continuous capillaries?

Answer 28

Most common, fewest holes; intercellular clefts that allow for a little leakage. Found in brain and muscles & allow substances like glucose, H2O, O2, hormones, etc to exit the blood stream

Question 29

What are fenestrated capillaries?

Answer 29

have fenestrations/pores, not as common; found in places like the kidneys where the blood is filtered

Question 30

What are sinusoidal capillaries?

Answer 30

Contain large holes called sinusoids. Found in liver, red bone marrow and allow for passage of large molecules like RBCs

Question 31

What is the pressure in the different vessels?

Answer 31

Highest in the arteries, much lower in capillaries but slightly lower than that in the veins. Needs to be like this to allow for blood flow (high -> low pressure)

Question 32

Why is low pressure preferable in the capillaries?

Answer 32

They're very fragile; high pressure will cause rupture. They're highly permeable, and high pressure can cause edema

Question 33

What are venules?

Answer 33

Very small veins that carry blood intermediate to capillaries and veins; extremely porous

Question 34

What is the "volume sink" of vasculature?

Answer 34

Veins, because they carry ~65% of blood volume at any given time

Question 35

Compare veins to arteries.

Answer 35

Veins have larger lumen and thinner tunics, much lower pressure. Veins contain valves to prevent backflow from low pressure

Question 36

If veins are low pressure, how is blood flow back to the heart against gravity facilitated?

Answer 36

Muscular pump & respiratory pump. Backflow prevented by valves

Question 37

Describe a simple circulatory pathway

Answer 37

Flows from artery into one capillary bed, then to vein

Question 38

What is a portal system?

Answer 38

Blood flows through 2 consecutive capillary networks before returning to the heart. Found in places like the intestines, liver, kidneys, hypothalamus/pituitary (hypophyseal portal)

Question 39

What is an anastomoses?

Answer 39

System of blood vessels that allows blood to take alternate routes. Merging of multiple paths from artery to capillary; examples include the circle of willis and vasculature of the cardiac muscle