L29-structure Of Blood Vessels

Question 1

What are the 3 layers of blood vessels

Answer 1

Tunica intima
Inner most layer
Tunica media
Middle layer
Tunica adventitia
Outer most layer

Question 2

Describe the tunica intima

Answer 2

▪️Endothelial cells provide a physical barrier between blood and rest of blood vessel wall

Question 3

What is an important step in development of atheroma

Answer 3

Disruption Of endothelial layer in tunica intima

Question 4

Describe the tunica media

Answer 4

▪️two layers of elastic tissue:internal and external elastic laminae
▪️smooth muscle
▪️source of mechanical strength for blood vessel and as it contains sm the means by which the diameter of the vessel can be altered

Question 5

Describe the tunica adventitia

Answer 5

▪️layer of CT
▪️serves to hold Bvs in place
▪️contains vasa vasorum

Question 6

Describe the arteries

Answer 6

High pressure side of circulation
Contains about 12% of total blood volume
Classified in to:
1-large arteries(elastic)
2-small arteries(muscular)
3-arterioles

Question 7

Describe large arteries

Answer 7

Aorta and its major branches
Distensible=elastic
Play little role in regulation of peripheral circulation

Question 8

What does the wall of large arteries contain

Answer 8

1-fibrous tissue(collagen) which provides strength and inc with age
2-elastic tissue which is inflated by entry of additional blood during systole
3-smooth muscle(less than small arteries)

Question 9

What is the windkessel effect

Answer 9

Large arteries are inflated by entry of additional blood in systole
During diastole when blood is no longer entering the arteries they recoil and help to maintain peripheral tissue perfusion

Question 10

Describe small arteries

Answer 10

Radial artery,cerebral and coronary
More smooth ms than large
Poses a considerable resistance to blood flow
Some involvement in circulatory control mechanisms

Question 11

What does wall of small arteries contain

Answer 11

Smooth muscle
Fibrous tissue(less than large)
Elastic tissue(some)

Question 12

Describe arteriols

Answer 12

Smooth muscle is a major component of vessel wall
Resistance vessels
1-major sure for regulation of distribution of blood flow
2-arterial blood pressure regulation
3-pulsatile blood flow is smoothed out to a constant pressure

Question 13

What is the pre capillary sphincter in arteriols

Answer 13

Small cuff SM at entrance to a capillary bed
When sphincter is closed capillary is not perfused with blood
In resting 90% are closed
No nerve supply but are regulated by local metabolite concentrations

Question 14

Describe capillaries

Answer 14

▪️Site of exchange of nutrients and waste products between circulation and interstitial fluid surrounding cells
▪️6% of blood vol

Question 15

What is the bolus flow

Answer 15

Volume of trapped plasma in between successive red cells

Question 16

What is capillary formed by

Answer 16

Tube is made up of a single layer of endothelial surrounded by BM
Pores and clefts present
Pericyte around endothelium

Question 17

What are the types of capillaries

Answer 17

Continuous
Fenestrated
Discontinuous

Question 18

Describe cont cap

Answer 18

Location:lung,skin,muscular tissue, adipose,nervous,brain
Endothelial cells held together by tight junctions
Bm is cont and consists mainly of collagen
Larger molecules exist via caveolae which cover both surfaces of endothelial cells

Question 19

Describe fenestrated cap

Answer 19

Location:tissues that have high transcapillary water flux
1-glomerulus of kidney
2-intestinal villi
3-choroid plexus of brain
Fenestrae are not completely open holes but are covered by a very thin diaphragm derived from the glycocalyx
14 wedgeshaped gaps
Intact BM

Question 20

Describe discont cap

Answer 20

Location:bone marrow, liver, soleen
Gaps in between adj endothelial cells
Incomplete BM

Question 21

What are the 3 types of veins

Answer 21

Large(vena cava)
Small(most named veins)
Venules

Question 22

Describe venules

Answer 22

Wall is made of endothelial+small amounts of fibrous tissue+incomplete layer of sm
Capillaries and venules are imp site for movement of water and nutrients

Question 23

Describe small veins

Answer 23

Wall:collagen+elastic+smooth ms(less than small arteries)
Distensible
45% of total blood vol

Question 24

What are the mechanisms of venous return and prevention of venous pooling

Answer 24

1-have effective venoconstrictor sympathetic nerve supply

2-have valves

Question 25

Describe large veins

Answer 25

Wall is made of excess collagen+some elastic+smooth Ms

15% of total blood vol

Question 26

Function of pericytes

Answer 26

Provide support

Contractile