Heart and Vessels Ketchum

Question 1

what does the cardiovascular system arise from>

Answer 1

angiogeneic cell clusters of the mesoderm

Question 2

what is the order of blood vessels

Answer 2

arteries
arterioles
capillary 
venule 
vein

Question 3

what do arteries do?

Answer 3

carry blood from heart to capillary beds

Question 4

what do veins do

Answer 4

carry blood from capillary beds to heart

Question 5

what is the function of capillaries

Answer 5

site of exchange:
nutrients
oxygen
waste

SMALLEST blood vessels

Question 6

what is the structure of capillaries

what surrounds the capillary

Answer 6

single layer of simple squamous epithelium (endothelium)

surrounded by basement membrane

Question 7

what is the average diameter of the capillary

Answer 7

8 microns

Question 8

how can you tell apart lymphatic vessels and blood capillaries

Answer 8

blood capillaries have uniform vessel diameter

lymphatic capillaries have variable size lumen and incomplete basement membrane

Question 9

what is simple squamous epithelium

Answer 9

endothelium which all vessels are lined with

Question 10

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

Answer 10

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

Question 11

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

Answer 11

blood and colloid osmotic pressure

Question 12

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

Answer 12

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

squeeze through tight junctions

Question 13

what is the function of tight junctions in the capillary

Answer 13

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

Question 14

what are fenestrae

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

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

Question 17

what are the 3 types of capillaries

Answer 17

continuous capillary
fenestrated capillary
discontinuous capillary (sinusoid)

Question 18

What are sinusoids

how do they differ from true capillaries

Answer 18

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

Question 19

where are sinusoids located usually

Answer 19

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

allows direct communication and free movement of material

Question 20

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

Answer 20

these are actually continuous!

Question 21

what type of cell do some sinusoids possess?

Answer 21

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

Question 22

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

Answer 22

tunica intima
-nearest to the lumen

tunica media
-external to the TI

tunica adventitia
-outermost vessel coat
aka tunica externa

Question 23

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

Answer 23

all vessels larger than capillaries

Question 24

what are the main 4 components of the tunica intima

Answer 24

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

Question 25

what are the components of the tunica media

Answer 25

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

Question 26

what are the main components of the tunica adventitia

Answer 26

Composed primarily of moderately dense CT

CT fibers LONGITUDINALLY arranged

adventitial components formed by fibroblasts

adventitia merges with loose connective tissue

Question 27

what are the classifications of arteries

Answer 27

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

CONTINUOUS transitions b/w artery types

Question 28

what is the most prominent tunic in all arteries

Answer 28

tunica media

Question 29

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

Answer 29

small arterioles (due to lack of fiber mass)

elastic arteries (due to mass of fibers in media)

Question 30

external elastic lamina is visible in what?

Answer 30

larger muscular arteries

smaller elastic arteries

Question 31

how do we distinguish an arteriole on a histo slide?

Answer 31

less than 5 layers of smooth muscle

diameter 0.05-0.5 mm

Question 32

what is the tunica intima like in arteriole

tunica media?

tunica adventitia?

Answer 32

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

Question 33

what vessels regulate blood pressure

Answer 33

arterioles

Question 34

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

Answer 34

radial artery

0.5 mm-1.0 cm

Question 35

what is the tunica media of a medium artery like?

Answer 35

small amounts of subendothelial CT present

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

Question 36

what is the tunica media like in a medium artery

Answer 36

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

Question 37

what is the tunica adventitia like in a medium artery

Answer 37

usually thinner than media

some elastic fibers usually present near media

mostly composed of collagen type I

Question 38

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

what is the tunica intima like?

Answer 38

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

Question 39

what is the tunica media like in larger elastic arteries

Answer 39

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 ***

Question 40

what does the elasticity of larger elastic arteries allow?

Answer 40

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

Question 41

what is the tunica adventitia like in large elastic arteries

Answer 41

thinner than media, composed of loosely arranged coliagen bundles

spiral longitudinally around vessel

*** overdistention of intima and media prevented by adventitia

Question 42

what is vasa vasorum

Answer 42

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

Question 43

what are the nerves associated with arteries doing?

Answer 43

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

afferent fibers are also present

Question 44

what is the carotid body

Answer 44

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

Question 45

what is the carotid sinus

Answer 45

dilatation of internal carotid artery (small enlargement)

contains specialized nerve endings

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

Question 46

how are veins categorized

Answer 46

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

Question 47

what are the classifications of veins

Answer 47

venules (correspond to arterioles)

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

small veins

medium veins (with muscular arteries)

Large veins (with large elastic arteries)

Question 48

in veins what is the most prominent layer?

Answer 48

tunica adventitia

Question 49

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

Answer 49

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)