Vasculature

Question 1

What are capillaries and postcapillarey venules designed for?

Answer 1

exchange (of gas/ nutrients/ waste)

Question 2

Where is blood flow slowest?

Answer 2

capillaries and venules

Question 3

What is the basic structure of a large artery?

Answer 3

Tunica intima
- enothelial cells in contact with blood
- elastic/ loose collagenous tissue with intimal cells
Tunica media
- layers of elastic laminae/ smooth muscle/ collagen
Tunica adventitia 
- collagenous tissu
- vasa vasorum
- nervi vascularis

Question 4

What is the function of the elastic layers in arteries and arterioles?

Answer 4

permit expansion after systolic contraction of heart

- dampen systolic bp

Question 5

What is the function of smooth muscle in the arterioles?

Answer 5

control blood flow to capillary beds

Question 6

How are the aorta and other large arteries described?

Answer 6

Elastic arteries

• layer of collagen/ elastin rich fibers containing fibroblasts and myointimal cells
• 30-40 elastic layers ( collagen/ smooth muscle between)

Question 7

Describe the muscular arteries

Answer 7

2 defined elastic layers:

1. inner elastic lamina (intima - media)
2. outer elastic lamina (media - adventitia)

Thin intima
media = smooth muscle
adventitia = thick

Question 8

How do the smaller muscular arteries differ from the muscular arteries

Answer 8

No outer elastic lamina

thin intima
media = lots of smooth muscle
adventitia = same size as media - blends into surrounding connective tissue

Question 9

Describe arterioles

Answer 9

endothelial -> thin basement membrane -> 1-2 layers smooth muscle -> outer blends into surrounding

Question 10

Why are arterioles important?

Answer 10

gatekeepers to local capillary beds

- restrict as needed

Question 11

What are metarterioles

Answer 11

arteriole-venule shunts

vasoconstriction here = bypass of capillary bed

Question 12

Describe the structure of capillaries

Answer 12

1-2 cells form endothelium
- 0 muscular layer
Pericytes
- collagenous fibrils connecting caps to adjacent tissue

Question 13

What are pericytes?

Answer 13

unspecialized cells
(smooth muscle during growth/ wound healing)
- contractile?

Question 14

What are the two types of capillaries?

Answer 14

continuous

fenestrated

Question 15

How does exchange/ transfer occur in continuous capillaries?

Answer 15

pinocytosis

- uninterrupted endothelium

Question 16

How does exchange/ transfer occur in fenestrated capillaries?

Answer 16

pass through pores
- sometimes covered by diaphragm

occur in glomerulus of kidney, spleen, liver
- permit bulk flow

Question 17

What are the unique functions of post-capillary venules?

Answer 17

allow diapedesis

sensitive to controlled permeability (respond to vasoregulatory substances)

Question 18

What is diapedesis?

Answer 18

When leukocytes squeeze through into surrounding tissue

=> essential in immune response

Question 19

What are end arteries?

Answer 19

arteries supplying tissue with out alternative arterial supply (0@)
ex) parts of kidney & lung, sometimes heart

Question 20

What are portal systems

Answer 20

begin and end in capillary bed
Ex) hypothalamic anterior pituitary portal system
Ex) hepatic portal system

Question 21

What is important about the pampiniform plexus?

Answer 21

countercurrent system between aa and vv

- optimal heat exchange

Question 22

How do veins differ from arteries?

Answer 22

thin walled (2-4 up to 5-7 layers of smooth muscle)

• thickness increases with diameter of lumen
• often collapsed in histological samples
• adventitia blends in with surrounding tissue
• have one-way valves to help return blood to heart

Question 23

Describe the structure of lyphatics

Answer 23

spaces in connective tissue -> single cell epithelium (compressed)

• often contain lymphocytes
• lymph stains light color
• many flap like valves
• one way: tissue to Right and left angles (internal jugular & subclavian vv)