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Microanatomy 1 > Circulatory System > Flashcards

Circulatory System Flashcards

1
Q

The circulatory system includes…

A
  • heart
  • arteries
  • arterioles
  • capillaries
  • venules
  • veins

Lymph vessels are also included

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2
Q

What are the typical layers of a blood vessel?

A
  • tunica intima
  • tunica media
  • tunica adventitia
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3
Q

What is the major difference between elastic and muscular arteries?

A

Composition of the tunica media

  • elastic arteries contain many concentric sheets of elastin
  • muscular arteries only have a few fibers
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4
Q

How many layers of smooth muscle do arterioles have?

A

3 or fewer

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5
Q

How is flow regulated through capillary beds (microcirculation) ?

A

by precapillary sphincters at the arteriole-capillary junction

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6
Q

What allows blood to bypass the capillary beds?

A

arteriovenous shunts

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7
Q

endocardium

A
  • endothelium
  • some supporting connective tissue
  • adipose tissue deposits in places
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8
Q

myocardium

A
  • muscle of the heart

- contains cardiac myocytes and purkinje fibers

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9
Q

epicardium

A
  • adventitia
  • contains mesothelium that secretes serous fluid
  • some supporting CT like in endocardium
  • broad layer of adipose tissue
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10
Q

pericardium

A

outer membrane

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11
Q

Purkinje fibers

A
  • conduction system
  • derived from cardiac muscle
  • cells are larger than muscle fiber
  • no T-tubules
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12
Q

What connective tissue can be found in the endocardium?

A
  • delicate collagenous layer

- deeper fibroelastic layer

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13
Q

cardiac skeleton

A
  • fibrous skeleton of heart
  • annulus
  • trigone
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14
Q

What is the fibrous skeleton of the heart?

A

dense CT in heart that separates the atria from the ventricles

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15
Q

Annulus

A

surround valves in the heart

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16
Q

Trigone

A

triangular area between the two AV canals and aortic valve

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17
Q

Heart valves

A
  • folds of endocardium
  • supported by cardiac skeleton
  • edges of cusps of valves anchored by chordae tendineae
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18
Q

tunica intima

A
  • can have 3 layers
  • endothelium = always
  • subendothelial connective tissue = +/-
  • internal elastic lamina = +/-
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19
Q

tunica media

A
  • smooth muscle of vessel
  • varying amounts of elastic laminae
  • external elastic lamina = difficult to see usually
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20
Q

tunica adventitia

A
  • connective tissue of vessel wall
  • dense or loose CT
  • larger vessels also have a blood and nerve supply for that vessel
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21
Q

vasa vasorum

A
  • blood supply for the larger blood vessel
  • located in the tunica adventitia
  • too large to just pull what blood they need from the blood going through them
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22
Q

nervi vasorum

A
  • nerve supply for the larger blood vessels

- located in the tunica adventitia

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23
Q

tunica intima of elastic arteries

A
  • most inner layer, just inside endothelium
  • very thin layer = may be difficult to observe
  • usually contains fibroblasts and myointimal cells
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24
Q

What do myointimal cells do as they age?

A

deposit lipid and thicken

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25
Q

What is atherosclerosis?

A

disease of the arteries characterized by the deposition of plaques of fatty material on their inner walls

26
Q

tunica media of elastic arteries

A
  • thickest layer
  • many concentric layers of elastin
  • smooth muscle cells and reticular fibers between layers
  • external elastic lamina is not readily apparent
27
Q

In comparison with the tunica media, the tunica adventitia of elastic arteries is…

A

thin

28
Q

tunica intima of muscular arteries

A
  • endothelium
  • CT
  • IEL
29
Q

tunica media of muscular arteries

A
  • thick layer of smooth muscle

- contains fibers and proteoglycans

30
Q

What is the external elastic lamina? Where is it in muscular arteries?

A
  • made of elastin fibers

- divides tunica media and adventitia

31
Q

tunica adventitia of muscular arteries

A
  • external CT layer

- can be very thick

32
Q

Can the tunica intima be seen for muscular arteries under normal conditions with a light microscope?

A
  • Not really = difficult with light microscope and normal conditions
  • However it is visible in pathological conditions such as atherosclerosis
33
Q

What happens when the vascular intima becomes thicker?

Why is this a problem?

A
  • Increases peripheral blood pressure

- Leads to hypertension, coronary artery disease, stroke, aneurysm, etc.

34
Q

Differences between small muscular arteries and arterioles?

A

SMA
- greater than 3 layers of muscle cells

Arterioles

  • no external elastic lamina
  • diminishing internal elastic lamina
  • 3 or less layers of muscle cells
35
Q

Arterioles

A
  • smallest branch of arterial system
  • delivers and regulates blood flow to the capillary beds
  • regulates systemic blood pressure
36
Q

How do arterioles regulate systemic blood pressure?

A

Through constrictions of arterioles, which increases resistance to peripheral blood flow

37
Q

Layers of Arterioles

A
  • tunica intima = present
  • internal elastic lamina = disappearing
  • tunica media = 1-3 layers of smooth muscle cells
  • tunica adventitia = narrow layer of connective tissue
38
Q

What kind of cells produce nitric oxide?

What does nitric oxide do?

A
  • produced by vascular endothelial cells and macrophages

- potent vasodilator = open arteries/arterioles up and lowers blood pressure

39
Q

What layers are found in capillaries?

A

endothelium and basement membrane

40
Q

What types of capillaries are there?

A
  • continuous
  • fenestrated
  • discontinuous
  • sinusoidal
41
Q

What is the diameter of a capillary?

A

Generally about the same as a RBC (7-9 micrometers)

Sinusoids are much larger at 30-40 micrometers (5x the size of RBC!) and are found in the liver, spleen, lymph nodes, and bone marrow

42
Q

Why are capillaries so thin?

A

To allow for exchanges

  • water and solutes between blood and tissues (tissue beds)
  • between blood and environment (lung)
43
Q

Continuous capillaries

A
  • no pores in endothelial cells

- most common types = muscle, brain, thymus, bone, lung

44
Q

Fenestrated (windowed) capillaries

A
  • have pores w/in endothelial cells (+/- diaphragm)

- found in tissues with substantial fluid transport: intestine, kidney, endocrine glands

45
Q

Sinusoids

A
  • special capillaries found in the liver, spleen, and bone marrow
  • have wide lumen
  • incomplete basal lamina
46
Q

Discontinuous capillaries

A
  • found in liver and spleen

- have discontinuous endothelium = gaps between the endothelial cells themselves

47
Q

What is microcirculation?

A
  • interaction of arterioles and venules through capillaries at peripheral tissues
  • for gas, nutrients, fluid, and metabolic waste exchange
48
Q

How is blood flow in capillary circulation controlled/

A
  • autonomic nervous system
  • circulating hormones
  • precapillary sphincters
49
Q

Layers of Venules

A
  • tunica intima =endothelium only
  • tunica media = thin or not present
  • tunica adventitia = present
50
Q

Blood flow through a capillary bed

A

arterioles -> capillaries -> post-capillary venule -> collecting venule ->muscular venule

51
Q

Layers of Veins

A
  • tunica intima = present
  • tunica media = few layers of smooth muscle; may be discontinuous; irregularly arranged
  • tunica adventitia = thickest part
52
Q

Keys to differentiating arteries from veins

A
  • veins and venules have a thinner wall for all layers
  • compare them = arteries and veins often found together, same with arterioles and venules
  • most arteries do not have valves; many veins have valves
53
Q

Why can it be a problem that lymph vessels are a very low pressure system?

A
  • easily occluded, obstructed, or overwhelmed

- leads to edema

54
Q

Why do lymph vessels have valves?

A

help assure fluid continues toward large veins cranial to the heart

55
Q

What does it mean that the lymph system is a one-way system?

A
  • smallest lymph vessels (lymph capillaries) are blind-ended

- begin in the perivascular space in the tissue beds

56
Q

Function of Lymph Vessels?

A
  • transport excess interstital fluid, proteins, solutes, and macromolecules through lymph nodes and back to venous system
  • safety valve between extravascular and intravascular fluid pools
  • filtering system to impede microorganisms and cancer cells
57
Q

What do lymph vessels look like on a slide?

A
  • no basement membranes
  • endothelium only
  • look like a space in the tissue = look for the endothelium
  • have valves
  • thinner walls than veins of similar size
  • should NOT fnd RBCs in lymph vessels
58
Q

Circulatory Shock

A
  • acute symptom
  • life-threatening
  • widespread inadequacy of tissue perfusion
  • hypovolemia of 25% or greater can lead to it = can be due to blood loss or extreme vasodialtion by endotoxin, etc.
59
Q

What damage does circulatory shock do?

A
  • cellular hypoxia
  • cellular injury
  • organ damage
  • lactic acidosis = lactic acid released from damaged cells
60
Q

How does peripheral vasoconstriction relate to circulatory shock?

A
  • compensation for circulatory shock
  • preserves blood flow to vital organs
  • decreases capillary hydrostatic pressure to facilitate the flow of interstital fluid into the circulation

Microanatomy 1 (13 decks)

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