Heart and Vessels Ketchum Flashcards

1
Q

what does the cardiovascular system arise from>

A

angiogeneic cell clusters of the mesoderm

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2
Q

what is the order of blood vessels

A
arteries
arterioles
capillary 
venule 
vein
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3
Q

what do arteries do?

A

carry blood from heart to capillary beds

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4
Q

what do veins do

A

carry blood from capillary beds to heart

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5
Q

what is the function of capillaries

A

site of exchange:
nutrients
oxygen
waste

SMALLEST blood vessels

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6
Q

what is the structure of capillaries

what surrounds the capillary

A

single layer of simple squamous epithelium (endothelium)

surrounded by basement membrane

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7
Q

what is the average diameter of the capillary

A

8 microns

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8
Q

how can you tell apart lymphatic vessels and blood capillaries

A

blood capillaries have uniform vessel diameter

lymphatic capillaries have variable size lumen and incomplete basement membrane

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9
Q

what is simple squamous epithelium

A

endothelium which all vessels are lined with

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10
Q

most interchange between capillary lumen and extravascular space results from …
BUT how else can this exchange occur?

A

simple diffusion

(water, gases, salts and nutrients)

can also occur via active transport using PINOCYTOSIS (transports soluble high MW molecules across endothelial wall)

we aren’t bloated b/c there is fluid movement inside and outside

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11
Q

what does the rate of simple diffusion in capillary depend on?

A

blood and colloid osmotic pressure

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12
Q

how do cells cross endothelium? (such as white blood cells or macrophages)

A

pass endothelium by movement known as diapedesis (squeeze through the endothelial cells)

squeeze through tight junctions

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13
Q

what is the function of tight junctions in the capillary

A

prevent fluid loss BUT aren’t a strong adhesion so this is where diapedesis occurs

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14
Q

what are fenestrae

A

windows (pores) that are closed by diaphragm thinner than unit membrane

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15
Q

what are the support cells of the capillaries (pericytes) function?

A

these are basically inside the basement membrane and are closely associated with the capillary

they have a role in angiogenesis and vessel repair

in injury repair they can transform:
they can become vascular smooth muscular
augment BM production
function as fixed macrophages

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16
Q

what is the application of adipose-derived adult stem cells regarding pericytes

A

adipose-derived adult stem cells assume perictye-like morphology which may play a role in wound healing and angiogenesis

these cells developed greater cross-sectional vascular areas

involved in new vessel growth and enlargement of already existing vessels

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17
Q

what are the 3 types of capillaries

A

continuous capillary
fenestrated capillary
discontinuous capillary (sinusoid)

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18
Q

What are sinusoids

how do they differ from true capillaries

A

specialized enlarged capillary-like vascular channels

Differ:
larger than capillaries with irregular lumen up to 30 microns
the endothelium is discontinuous (gaps) and possess’ a discontinuous basement membrane

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19
Q

where are sinusoids located usually

A

exist in places where you need excessive exchange (liver, spleen, bone marrow)

allows direct communication and free movement of material

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20
Q

what are the sinusoids in the hypophysis and adrenal glands like?

A

these are actually continuous!

21
Q

what type of cell do some sinusoids possess?

A

phagocytic cells:
called macrophages in the bone marrow and spleen
called Kupffer cells in the liver

22
Q

what are the 3 concentric tunics (coats/layers) of vessels

A

tunica intima
-nearest to the lumen

tunica media
-external to the TI

tunica adventitia
-outermost vessel coat
aka tunica externa

23
Q

what types of vessels is the inner elastic lamina present in?

A

all vessels larger than capillaries

24
Q

what are the main 4 components of the tunica intima

A

endothelium surrounds lumen

basement membrane underlies endothelium

subendothelial connective tissue
-fibroblasts and CT fibers some of which run longitudinally

inner elastic lamina (IEL)

  • fenestrated layer composed of accumulated elastic fibers
  • outermost component of the tunica intima
25
Q

what are the components of the tunica media

A

1) composed mostly of smooth muscle connective tissue fibers

numerous CT fibers formed by specialized smooth muscle cells CIRCUMFERENTIALLY arranged
fibroblasts may be present

2) External elastic lamina
- this is elastic fibers which form the outmost component of the tunica media

26
Q

what are the main components of the tunica adventitia

A

Composed primarily of moderately dense CT

CT fibers LONGITUDINALLY arranged

adventitial components formed by fibroblasts

adventitia merges with loose connective tissue

27
Q

what are the classifications of arteries

A

arterioles
medium sized (muscular) arteries
large (elastic) arteries

CONTINUOUS transitions b/w artery types

28
Q

what is the most prominent tunic in all arteries

A

tunica media

29
Q

inner elastic lamina (outermost part of tunica intima) is nearly always present in arteries but may not be discernible in which two types?

A

small arterioles (due to lack of fiber mass)

elastic arteries (due to mass of fibers in media)

30
Q

external elastic lamina is visible in what?

A

larger muscular arteries

smaller elastic arteries

31
Q

how do we distinguish an arteriole on a histo slide?

A

less than 5 layers of smooth muscle

diameter 0.05-0.5 mm

32
Q

what is the tunica intima like in arteriole

tunica media?

tunica adventitia?

A

TI-
very thin
little or no subendothelial CT
inner elastic lamina not distinct

TM
-1-5 layers of smooth muscle ***
controls blood flow to capillaries
regulates blood pressure
no visible external elastic lamina 

TA- usually thinner than media not well developed

33
Q

what vessels regulate blood pressure

A

arterioles

34
Q

what is an example of a medium (muscular size artery)

A

radial artery

0.5 mm-1.0 cm

35
Q

what is the tunica media of a medium artery like?

A

small amounts of subendothelial CT present

prominent, well-developed inner elastic lamina (IEL)***

36
Q

what is the tunica media like in a medium artery

A

very thick, 5-40 layers of smooth muscle* so know its a medium artery ***

smaller arteries have lower elastic fiber content

larger arteries have increasing quantities of elastin*** to maintain the size and pressure for efficient delivery

ANS control of smooth muscle regulates blood flow

some collagen present

external elastic lamina well developed (but less visible

37
Q

what is the tunica adventitia like in a medium artery

A

usually thinner than media

some elastic fibers usually present near media

mostly composed of collagen type I

38
Q

what is the typical size of the larger (elastic) artery

what is the tunica intima like?

A

diameter of 1.0- to 2.5cm

tunica intima
endothelial cells may be polygonal
subendothelial CT relatively thick with many fibers

IEL present, but not as distinct as in muscular arteries

39
Q

what is the tunica media like in larger elastic arteries

A

smooth muscle fibers, much elastic fiber accumulation *** VERY THICK

elastic lamina – numerous thin tubular elastic “membranes”

high elastic content retains shape while preventing excessive expansion ***

receives excess blood during ventricular contraction

diminishes pulsatile delivery to peripheral vessels

**More than 40 layers of smooth muscle ***

40
Q

what does the elasticity of larger elastic arteries allow?

A

Elasticity allows you to reduce pulsatile influence at the capillary bed

-don’t want pulsing blood at capillary bed b/c you want smooth flow for exchange

41
Q

what is the tunica adventitia like in large elastic arteries

A

thinner than media, composed of loosely arranged coliagen bundles

spiral longitudinally around vessel

*** overdistention of intima and media prevented by adventitia

42
Q

what is vasa vasorum

A

vessel of the vessel

need these to prevent cell death in the wall of the artery

these are small nutrient arteries supplying walls of larger arteries

43
Q

what are the nerves associated with arteries doing?

A

these are nerve fibers from the ANS that terminate on arterial smooth muscle

afferent fibers are also present

44
Q

what is the carotid body

A

mass of epithelioid cells and nerve endings (epithelial like)

found at bifurcation of common carotid artery

stimulates respiration in response to lowered blood 02
can also lower respiration

45
Q

what is the carotid sinus

A

dilatation of internal carotid artery (small enlargement)

contains specialized nerve endings

sensitive to blood pressure change (allows to monitor heart rate)

46
Q

how are veins categorized

A

somewhat arbitrary and variable

thus, structure reflects physiologic stress to which vein is subject

e.g. veins of leg subject to higher pressure than veins of face

thus, these veins have markedly different structure

47
Q

what are the classifications of veins

A

venules (correspond to arterioles)

	- post-capillary venules (pericytic venules)
	- muscular venules

small veins

medium veins (with muscular arteries)

Large veins (with large elastic arteries)

48
Q

in veins what is the most prominent layer?

A

tunica adventitia

49
Q

where are valves in the venous system? which type of vein

what are they composed of

where are valves most often found

where are they not found

what is their function

A

usually in medium sized veins

made up entirely of endothelium of tunica intima NOT tunica media

free edges face in the direction of blood flow

valves most often found in lower limb due to gravity

ABSENT in portal systems

assist under low blood pressure (muscular contraction aids in blood movement and then the valve closes so blood doesn’t run back down)