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Block C - Circulation > Histology Lecture 2 -- Blood Vessels > Flashcards

Histology Lecture 2 -- Blood Vessels Flashcards

1
Q

What are the efferent vessels?

A

Arteries

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2
Q

Artery function

A

Conduct oxygen and nutrients to the tissues which diffuse out through a capillary network

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3
Q

What are the afferent vessels?

A

Veins

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4
Q

Vein function

A

Convey the product of metabolism of tissues such as waste products and CO2 to the heart

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5
Q

3 distinct layers of the walls of arteries and arterioles

A

Intima
Media
Adventitia

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6
Q

What does the adventitia often merge with?

A

Dense or loose connective tissue surrounding the vessels

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7
Q

Describe the walls of veins or venules

A

Equivalent layers to arteries and arterioles are generally difficult to identify, or boundaries are poorly defined

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8
Q

Location of capillaries

A

Between metarterioles and postcapillary veins

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9
Q

Dimensions of capillaries

A

1 mm in length

8 - 10 micrometers in diameter

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10
Q

Approximate number of capillaries in myocardium

A

2000 per cubic mm

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11
Q

Histology of capillaries

A

Simply squamous endothelium with tight junctions sitting on a basement membrane and surrounded by reticular fibers

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12
Q

What support do capillaries have structure-wise?

A

Intermediate vimentin filaments within endothelial cells

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13
Q

Describe the adventitia of capillaries

A

Absent or minor

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14
Q

What is the relative area of the capillary network?

A

800 times larger than the area of the aorta

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15
Q

Blood flow in the capillary network

A

0.3 mm/s

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16
Q

Blood flow in the aorta

A

320 mm/s

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17
Q

What substances increase the permeability of capillaries

A

histamine

bradykinin

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18
Q

4 roles of capillaries

A

Gas exchange
Thermoregulation
Regulation of blood pressure
Inflammation

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19
Q

3 classifications of capillaries plus 2 subclassifications

A

Impermeable
Continuous
Permeable (fenestrated, sinusoid)

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20
Q

How are arteries and veins classified?

A

According to their size and histological features

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21
Q

4 types of arteries

A

Large elastic arteries
Muscular arteries
Arterioles
Metarterioles

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22
Q

4 types of veins

A

Large veins
Medium and small size veins
Venules
Postcapillary venules

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23
Q

Function of muscular arteries

A

Distribute blood to organs

Help regulate blood pressure by contracting or relaxing smooth muscle

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24
Q

Location of smooth muscle in arteries

A

Media

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25
Location of muscular arteries
Branching tree between the large elastic arteries and arterioles
26
Accompanying veins for muscular arteries
Medium and small size veins
27
Shape of muscular arteries
Circular/oval profile
28
Shape of medium and small veins
Irregular profile, often larger collapsed lumen
29
Muscular arteries: 3 layers of the intima
Endothelium (with gap and tight junctions) Sub-endothelial layer (thin) IELM (Internal Elastic Limiting Membrane; or internal elastica)
30
Muscular arteries: media
4 - 10 layers of smooth muscle cells | Collagen type III
31
Muscular arteries: adventitia
Dense connective tissue containing (or not) small blood vessels (vasa vasorum(
32
Medium and small size veins: intima
Endothelium (with gap and tight junctions) Sub-endothelial layer (thin or absent) Poorly defined IELM
33
Medium and small size veins: media
Incomplete layers (usually 2) of smooth muscle cells
34
Medium and small size veins: adventitia
Dense C.T. with or without vasa vasorum
35
Largest vessels of the body
Elastic arteries and large size veins
36
Most prominent feature of large elastic arteries
Thick media in which elastic lamellae (fenestrated membranes) alternate with layers of smooth muscle cells
37
What are the large elastic arteries?
Aorta | Carotid
38
How many elastic lamellae in adult aorta?
50
39
What is the effect of hypertension on the media layers of elastic arteries?
Number increases
40
Elastic arteries: intima
Well developed Endothelium: endocytic vessels, gap junctions, tight junctions Sub-endothelial layer: thin IELM: fenestrated (difficult to differentiate from media elastic membranes)
41
Elastic arteries: media
Approximately 50 layers of smooth muscle cells in adults intercalated with layers of perforated elastic membranes Rich in collagen type III and chondroitin SO4 proteoglycans
42
Elastic arteries: adventitia
Dense connective tissue rich in elastic fibres and collagen type I Vasa vasorum
43
Purpose of alternating layers of smooth muscle and elastic fibers in elastic arteries' media
Solidity and resilience of the wall since these arteries are submitted to the strong rhythmic pulsations of the heart
44
Notable feature of large veins
Presence of valves
45
Where do the valves of the large veins come from?
Projections of the intima
46
Large veins: intima
Endothelium Connective tissue Diffuse small muscle cells Internal elastic is undefined or absent
47
Large veins: media
Five layers (or less) or smooth muscle cells separated by connective tissue and collagen
48
Large veins: adventitia
Often the thickest layer. Dense connective tissue Vasa vasorum
49
Diameter of arterioles
Less than 0.1 mm
50
Describe the internal elastic of the arteriole intima
absent or fibrous
51
How are functional bypasses formed?
When arterioles anastamose directly to venules
52
What special function does the smooth muscle of metarterioles have?
Sphincter function (may direct blood to venules via the functional bypass)
53
Major role of arterioles
Regulation of systemic blood pressure
54
Arterioles: intima
Endothelium (gap and tight junctions) Subendothelial (thin-absent) Fibrous IELM
55
Arterioles: media
One or two layers of smooth muscle cells may be present
56
Arterioles adventitia
Thin without vasa vasorum
57
Shape of arterioles
Regular shape
58
Venules intima
Endothelium (gap and tight junctions) Absent subendothelial layer Absent IELM
59
Venules media
Incomplete | Pericytes
60
Venules adventitia
Thin
61
Shape and diameter of venules
Larger diameter than arterioles, but irrgular shape | 0.2 mm to 20 micrometers
62
4 function categories of the endothelium
Permeability Metabolic Production of vasoactive factors Antithrombogenic
63
2 metabolic functions of the endothelium
Conversion of angiotensin I to angiotensin II | Inactivation of bradykinin
64
2 vasoactive factors produced by the endothelium
Endothelins and nitric oxide
65
Describe the antithrombogenic function of the endothelium
Desquamation of endothelial cells --> fibrin aggregation and formation of thrombi
66
Describe lymphatic vessels
Anastomic network of vessels that start as blind tubules that converge into larger lymphatic vessels, which drain into large veins
67
Function of lymphatic vessels
Conduct lymph
68
What is lymph?
Plasma enriched with immunoglobulins and lymphocytes produced by lymphatic organs
69
Describe the lymphatic endothelium
Very thin with no occluding junctions
70
Describe the basement membrane of the lymphatic endothelium
Absent or partial
71
Valves are sometimes found in lymphatic vessels. What are they made of?
Folds on endothelium
72
Where can smooth muscle be found in terms of lymphatic vessels?
In the walls of large lymphatics (i.e. thoracic duct)
73
Where do thoracic duct lymph vessels empty into?
The venous system at the junction of jugular and subclavian veins
74
Define varicose veins
Veins whose valves cannot close completely, thus causing retrograde flow
75
5 potential causes for varicose veins
``` High BP in superficial veins from: Obesity Pregnancy Lack of movement Smoking Genetic predisposition ```

Block C - Circulation (26 decks)

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