Lecture 19: Vascular Histology Flashcards

1
Q

What are the three layers of blood vessels?

A
Tunica Intima (innermost)
Tunica Media (middle)
Tunica Adventitia (outermost)
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2
Q

What is the tunica intima composed of?

A

1) Endothelium: reduces friction
2) Basal lamina
3) Subendothelial Layer

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3
Q

The endothelium of the tunica intima is composed of what type of cells?

A

Squamous epithelial cells (single layer)

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4
Q

The tunica media in the arteries is relatively ____.

The tunica media in the veins is relatively ____.

A

Arteries: thick
Veins: thin

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5
Q

Why does the tunica media have small openings?

A

Openings are for nutrients to diffuse

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6
Q

How is the tunica media arranged?

A

Circular pattern of arranged smooth muscle layers

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7
Q

What separates the tunica media from the tunica adventitia?

A

Layer of elastin

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8
Q

How is the tunica adventitia arranged?

A

Longitudinally (up/down) arranged

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9
Q

The tunica adventitia in the arteries is relatively ____.

The tunica adventitia in the veins is relatively ____.

A

Arteries: thin
Veins: thick

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10
Q

What is the vasa vasorum?

A

Vessels of tunica adventitia that supply blood to the tunics of the vessels (allows diffusion of nutrients)

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11
Q

What is the nervi vasorum?

A

Nerves of vessels that allow ANS input that can control the contraction

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12
Q

Describe the hallmarks of the large (elastic) arteries.

A
  • Elastin found in concentric sheets b/t tunica layers
  • No fibroblasts
  • Very thick tunica media
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13
Q

Describe the hallmarks of the medium (muscular) arteries.

A
  • Less elastin
  • Internal and external elastic membranes are more prominent
  • Smooth muscle in spiral fashion
  • Tunica media and tunica adventitia about same thickness
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14
Q

Describe the hallmarks of the small arteries.

A
  • Internal elastic membrane present

- Up to 8 layers of tunica media

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15
Q

Describe the hallmarks of the arterioles.

A
  • Internal elastic membrane may/may not be present

- Up to 1-2 layers of tunica media

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16
Q

In arterioles, what will sympathetic innervation to the tunica media cause?

A

Vasoconstriction

17
Q

In arterioles, what will parasympathetic innervation to the tunica media cause?

A

Vasodilation

18
Q

What are pericytes?

A

Contractile cells that wrap around the endothelial cells that line the capillaries and venules throughout the body

19
Q

What are the function of pericytes?

A

Promote stability of capillaries and postcapillary venules

20
Q

What controls pericytes?

A

Nitric Oxide

21
Q

What connects endothelial cells found in the innermost layer of tunica intima?

A

Cell-cell junction

22
Q

What is the function of endothelial cells?

A
  • Supports basement membrane
  • Produces collagen
  • Metabolically involved in blood coagulation and thrombosis, and local vasodilation/constriction
23
Q

Describe continuous capillaries.

A
  • Most common
  • Tight junctions don’t allow many molecules to enter
  • Pericytes present
  • Continuous basement membrane
24
Q

Describe fenestrated capillaries.

A
  • Located in organs where blood exchange is most important
  • Larger items can go through
  • small windows in capillaries
  • Continuous basement membrane
25
Q

Describe sinusoidal capillaries.

A
  • Open exchange for large molecules and cells

- Discontinuous basement membrane

26
Q

What are metarterioles?

A

First branch off of arteriole supplying tissues

27
Q

What are precapillary sphincters?

A

Regulate blood flow to capillaries

-can open/close

28
Q

What are true capillaries?

A

Between arterioles and venules

-where proper gas exchange occurs

29
Q

What is a thoroughfare channel?

A

Distal end of metarteriole

30
Q

What does a thoroughfare channel connect to?

A

Postcapillary venule

31
Q

Describe the hallmarks of veins.

A
  • Tunica not well defined
  • Thinner walls
  • Larger lumen (often collapsed)
32
Q

What does the tunica intima contain that arteries don’t have?

A

Have valves

33
Q

In what direction do lymph in lymphatic vessels flow?

A

Unidirectional

34
Q

In lymphatic capillaries, what are the openings between the endothelial cells called?

A

Anchoring filaments

35
Q

Describe the flow of lymph.

A
  • Lymphatic capillaries –> vessels –> trunks
  • Either right lymphatic duct or thoracic duct
  • Brachiocephalic vein