Cardiovascular - Blood Vessels

Question 1

What is a circulatory system?

Answer 1

• system that circulates blood and lymph through the body
• supplies nutrients and removes waste
• source of tissue fluid

Question 2

How do blood plasma and tissue fluids work together?

Answer 2

Blood plasma and tissue fluids freely exchange through permeable walls of capillaries, the smallest blood vessels. Capillaries are in intimate contact with almost all tissues

Question 3

What are the circulatory system components?

Answer 3

1) heart: pump
2) systemic vessels: closed circuit, supplies tissues of body
3) pulmonary vessels: circuit to lungs, exchange oxygen and carbon dioxide with the atmosphere

Question 4

What are the 3 layers of the blood vessels?

Answer 4

1) tunica intima
2) tunica media
3) tunica externa/adventitia

Question 5

Describe tunica intima

Answer 5

Innermost layer. In intimate contact with the blood in the lumen.
Contains:
- Endothelium- simple squamous epithelium lining the lumen of all blood vessels.
- Loose CT - sub endothelial layer
- Internal elastic membrane (lamina) - sheet of protein elastic (like elastic fibers).

Question 6

Describe tunica media

Answer 6

The middle tunic.
- Consists primarily of circularly arranged sheets of smooth muscle fibers, between which lie in circular sheets of elastin and collagen fibrils.

Question 7

Describe tunica externa/adventitia

Answer 7

External layer

• consists of external elastic lamina
• protects the vessel, further strengthens its wall, and anchors the vessel to surrounding structures
• contains vasa vasorum = small blood vessels that supply wall of very large arteries

Question 8

What is a lumen?

Answer 8

space in between the vessels, where the blood is contained

Question 9

What are blood vessels?

Answer 9

Blood vessels form a network of tubes that carry blood from the heart to the tissues via the arterial system and return blood to the heart via the venous system.

Question 10

What is the function of arteries?

Answer 10

• Carry blood away from the heart.

- Branch, diverge or fork as they form smaller and smaller division

Question 11

What is the function of veins?

Answer 11

• Carry blood towards the heart.

- Join, merge, and converge into the successively larger vessels approaching the heart.

Question 12

What are the classes of arteries?

Answer 12

1) elastic
2) muscular
3) arterioles

Question 13

What are the classes of veins?

Answer 13

1) venules

2) small, medium, large veins

Question 14

What are capillaries?

Answer 14

• smallest blood vessels in the body
• composed of only a single layer of endothelial cells surrounded by a basement membrane
• the body’s most important blood vessels because they renew and refresh the surrounding tissue fluid
• deliver to this fluid the oxygen and nutrients cells need, and they remove the carbon dioxide and nitrogenous wastes that cells deposit into the fluid

Question 15

What is the blood brain barrier?

Answer 15

prevents all but the most vital molecules (and normally even leukocytes) from leaving the blood and entering brain tissue, derives from the structure of capillaries in the brain

Question 16

What are the structural features of the blood brain barrier?

Answer 16

• Capillaries have complete tight
  junctions
• No intercellular clefts are present
• Vital molecules pass through (highly selective transport)
• Not a barrier against: Oxygen, carbon dioxide, anesthetics, other drugs

Question 17

What are sinusoids and its features?

Answer 17

• wide, leaky capillaries
• Intercellular clefts are wide open
• Occur in bone marrow and spleen
• Sinusoids have a large diameter and twisted course

Question 18

What is the function of valves?

Answer 18

Valves keep venous blood moving in one direction; the valves are opened by blood flowing toward the heart and are closed by backflow.