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CRAAB 3 > Downing- Blood Vessel Histology > Flashcards

Downing- Blood Vessel Histology Flashcards

1
Q

What are the three layers of a blood vessel?

A
  1. intima
  2. media
  3. adventitia
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2
Q

What is the innervation for blood vessels?

A

Postganglionic unmyelinated sympathetic nerve fibers

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3
Q

Do the nerves enter the tunica media?

A

No

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4
Q

What do the sympathetic nerves do to the blood vessels?

A

Release NE that causes contraction. Impulses are than propagated via GAP junctions.

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5
Q

What are the largest arteries called and what are examples of them?

A

Elastic Conducting Arteries

Aorta
Common carotid and subclavian arteries
Common iliac arteries
Pulmonary trunk

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6
Q

What do the elastic arteries look like?

A

Appear yellowish in fresh specimens d/t abundance of elastin in arterial walls

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7
Q

What is the endothelium of the tunica intima of the elastic arteries composed of?

A
  1. Elongated simple squamous endothelial cells 2. oriented in a longitudinal plane
  2. connect by occluding junctions.
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8
Q

Why does the plasma membrane of the tunica intima of Elastic arteries contain small vesicles?

A

For transport of water, macromolecules and electrolytes.

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9
Q

What are Weibel-Palade bodies?

A

WPBs are membrane bound inclusions contained in arterial endothelial cells.

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10
Q

What do Weibel Palade bodies contain?

A
  1. vWF (facilitates coagulation of platelets during clot formation)
  2. P selectin
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11
Q

Why do the endothelial cells of the EA contain blunt processes that reach through the internal elastic lamina?

A
  1. To form gap junction w/ nearby smooth muscle cells of the tunica media
    * Gap junctions metabolically couple endothelial cells w/ smooth muscle cells
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12
Q

What is the internal elastic lamina of the EA?

A

thin lamina of elastic fibers that is the boundary between the intima nad the media

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13
Q

What is the tunica media of the EA?

A

Circularly arranged smooth muscle bands alternated with elastin that contains a fenestrated membrane.

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14
Q

What is the dominant component of hte tunica media of hte EA?

A

Elastin

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15
Q

Extracellular matrix is produced by what cells in the tunica media?

A

Smooth muscle cells

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16
Q

How does the adventitia of EA compare to the intima and the media?

A

It’s relatively thin.

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17
Q

What is the t. adventitia of the EA composed of?

A

Loose fibroeleastic CT w/ fibroblasts

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18
Q

What does the t. adventitia of the EA contain?

A

vasa vasorum (blood vessels of the blood vessels) that give rise to capillary beds that nourish the tunica media

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19
Q

What are examples of Muscular arteries?

A

Pretty much most of the named arteries that we know.

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20
Q

What are the chief characteristics of the muscular arteries?

A
  1. Thick tunic media

2. Composed primarily of smooth muscle cells

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21
Q

Is the t. intima of the MA thinner or thicker than the EA?

A

THINNER

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22
Q

What is prominent in the t. intima of MA?

A

Internal elastic lamina (has an undulating contour which the endothelium conforms to)

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23
Q

What’s the role of blunt processes in the MA?

A

Similar to the EA endothelial cells have blunt processes that reach through the internal elastic lamina, forming gap junctions and coupling the metabolic activity of endothelial with smooth muscle cells.

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24
Q

What is the t. media composed of and arranged in MA?

A

Smooth muscle cells

circumferrentially arranged

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25
Q

How many layers of smooth muscle in smaller muscular arteries?

A

4-3 layers

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26
Q

How many layers of smooth muscle in large muscular arteries?

A

up to 40 layers

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27
Q

What encloses each muscle cell of the t. media in the MA?

A

external basal lamina

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28
Q

What connects adjacent muscle cells in teh t. media of the MA?

A

gap junctions

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29
Q

What produces the extracellular matrix of the t. media in MA?

A

Smooth muscle cells

Chondroitin sulfate, elastic fibers, type III colagen

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30
Q

What is present in large muscular arteries and helps define the boundary between the t. media and t. adventitia?

A

External elastic lamina

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31
Q

What produces the t. adventia of the MA?

A

fibroblasts produces CT containing elastic fibers, collagen and ground substance.

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32
Q

Unmyelinated nerve endings enters the ______ of the t. adventitia of the MA?

A

vaso vasorum

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33
Q

What is the typical diameter of arterioles?

A

< .1 mm

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34
Q

How does the diamter of the wall compare to the diameter of the lumen in an arteriole?

A

They’re the same

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35
Q

What does the t. intima look like in the arteriole?

A
  1. endothelium
  2. thin layer of CT
  3. internal elastic lamina
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36
Q

What does the t. media look like in small and larger arterioles?

A

small- one layer of smooth muscle cells

larger- 2-3 layers smooth muscle cells

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37
Q

Is an external elastic lamina present in an arteriole?

A

NO

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38
Q

Does an arteriole have a t. adventitia?

A

NO

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39
Q

What are metarterioles?

A

Smooth muscle cells that can act as sphincters and control blood flow into the capillary bed by encircling the vessel where a capillary comes from

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40
Q

Are smooth muscle cells in metarterioles continuous?

A

NO

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41
Q

What are the carotid sinuses?

A

BARORECEPTORS that perceive changes in blood pressure

42
Q

Where are the carotid sinuses located?

A

In the walls of the internal carotid arteries just above the bifurcation of the common carotid arteries

43
Q

What is unique about the adventitia in the carotid sinuses?

A

It’s thicker and heavily endowed w/ sensory nerve endings from CN 9 (glossopharyngeal)

44
Q

What does the t. media of the carotid sinus do?

A

It’s thin, so it permits distention of the blood vessels w/ increasing BP which stimulates the nerve endings and leads to appropriate adjustments in vasoconstriction to maintain proper blood pressure.

45
Q

What are the carotid and aortic bodies?

A

Chemoreceptors

46
Q

Where are carotid bodies located?

A

At the bifurcation of the common carotid arteries

47
Q

What is the function of carotid and aortic bodies?

A

They have special chemoreceptor nerve endings that monitor changes in oxygen, carbon dioxide, and H ions in the blood

48
Q

What supplies afferent fibers to the carotid bodies?

A

CN 9 and 10 (glossopharyngeal and vagus)

49
Q

Where are aortic bodies located?

A

Arch of the aorta between the r. subclavian and L. common carotid and between the l. common carotid and l. subclavian

50
Q

What is the general length and diameter of capillaries?

A

usually short (1 mm) and 8-10 um in diameter

51
Q

What type of cells makes up a capillary? What are they joined together by?

A
  1. single layer of elongated simple squamous endothelial cells
  2. fasciae occludentes
52
Q

What is associated with the plasmalemma of hte capillary?

A

pinocytotic vesicles

53
Q

What is hte external surface of a capillary covered by?

A

basal lamina

54
Q

Where are pericytes found?

A
  1. Outside capillaries and small venules and they share a basal lamina of endothelial cells.
  2. Have primary and secondary processes that run longitudinally and circumferentially along and around the capillary
55
Q

What do pericytes do?

A

Contractile and help regulate blood flow through capillaries

56
Q

What may pericytes do if they’re injured?

A

Give rise to smooth muscle and endothelial cells

57
Q

What are the three types of capillaries?

A
  1. continuous
  2. fenestrated
  3. sinusoidal
58
Q

What are the characteristics of continuous capillaries?

A
  1. no interruptions (pores/fenestrae)
  2. found in muscle, nervous and CT
  3. joined by fascia occludentes
59
Q

What are the characteristics of fenestrated capillaries?

A

Pores in walls of capillaries, that occur in clusters, that are covered by a thin diaphram (glycocalyx).

60
Q

Where are fenestrated capillaries found?

A

pancreas, intestines and ENDOCRINE GLANDS

61
Q

What are the characteristics of sinusoidal capillaries?

A
  1. irregularly shaped pools/channels
  2. LARGER diametr than otehr capillaries
  3. Contain many fenestrae
62
Q

Where are sinusoidal capillaries found?

A

Bone marrow, liver, spleen, lymphoid organs, and certain glands.

63
Q

Where do AVAs occur?

A

Where an artery joins a venous channel

64
Q

What are the three segments of an AVA?

A
  1. arterial segmennt
  2. intermediate segment (thickened t. media)
  3. venous segment
65
Q

Which segment is richly innervated w/ adrenergic and cholinergic fibers?

A

Intermediate segment

66
Q

What happens in the AVA is the shunt is open?

A

Blood bypasses the capillary bed

67
Q

What happens in the AVA if the shunt is closed?

A

Blood passes into the capillary bed

68
Q

The AVA plays an important role in…

A

thermoregulation (skin)

69
Q

What is the central channel composed of?

A

Metarterioles and a capillary bed

70
Q

What is the role of the central channel?

A

It can bypass the capillary bed by closing the precapillary sphincters.

71
Q

Where does hte capillary bed drain into?

A

The venule

72
Q

What is transcytosis?

A

vesicle transport–substances are taken up by pincocytotic vessels on the adluminal side and discharged on the abluminal side of the endothelial cell

73
Q

What is leukocyte adhesion?

A

When leukocytes bind to the endothelium and pass through the endothelium to enter the extravascular spaces

74
Q

What does attachment and adhesion involve?

A
  1. selectins

2. integrins

75
Q

What is the role of histamine and bradykinin?

A

They accumulate at the site of inflammation and increase capillary permeability—> edema

76
Q

What do endothelial cells produce?

A

prostacyclin, plasminogen activator, IL-1, GFs, collagen types, fibronectin, laminin

77
Q

What type of enzymes does a capillary have?

A
  1. ACE enzymes that convert angiotensin I to II

2. enzymes that break down lipoproteins to fatty acids and triglycerides which can be stored in a fat droplet of a cell

78
Q

Are there more veins or arteries?

A

veins

79
Q

What can hold more blood: veins or arteries?

A

diameter of veins is larger than arteries, so 70% of blood volume is in the vessels

80
Q

What are postcapillary venules?

A

recieve blood from capillary bed

81
Q

Describe the endothelium of postcapillary venules?

A

Thin endothelium surrounded by pericytes

82
Q

What happens to pericytes in larger venules?

A

The pericytes are replaced by smooth muscle cels. As the venules get larger the smooth muscle cell layer becomes more complex.

83
Q

What is HEV?

A

Specialized versions of the small venules in certain lymphatic organs

84
Q

How is the HEV endothelium unique?

A

it is CUBOIDAL rather than squamous

85
Q

What does the HEV do?

A

Ensures that specific lymphocytes migrate into the proper regions of the lymphoid parenchyma

86
Q

What do the medium veins parallel and how big are they?

A

Muscular arteries

<1 cm in diameter

87
Q

What do medium veins do?

A

Have valves that help prevent backflow

88
Q

What is the thickest layer of the medium veins?

A

t. adventitia

89
Q

What are examples of large veins?

A

vena cavae, pulmonary, portal, renal, internal jugular, iliac and azygous veins

90
Q

What two layers blend together in large veins?

A

The t. intima and t. media

91
Q

What is unique about the t. adventitai of large veins?

A

The inferior vena cava has an abundance of LONGITUDINALLY oriented smooth muscle bundles

92
Q

What are varicose veins?

A

abnormally enlarged and tortuous veins

93
Q

What cause varicose veins?

A
  1. loses of muscle tone
  2. wall degeneration
  3. valvular incompetence
94
Q

Where else can varicose veins occur?

A 
lower esophagus (esophageal varices)
terminus of anal canal: hemorrhoids
95
Q

In what veins are valves found?

A

In small and medium sized veins–not many in the thorax and abdomen and they’re ABSENT in the brain and spinal cord

96
Q

What do valves consist of in veins?

A

Folds of intima: endothelium and CT core rich in elastic fibers

97
Q

What do valves do?

A

Prevent backflow

98
Q

How do lymph capillaries differ from blood capillaries?

A
  1. large diameter
  2. end blindly in the tissue
  3. have a scanty basement membrane (no barrier to entry of macromolecules)
  4. held together by few tight junctions
99
Q

The collecting vessels of the lymphatic system have a vein like structure except:

A
  1. walls tend to be thinner than walls of veins of equal size
  2. valves are MORE CLOSELY SPADED than in veins
100
Q

What are hte main trunks of the lymphatic system?

A
  1. thoracic and right lymphatic ducts and their tributaries

2. vein like structure

CRAAB 3 (7 decks)

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