Circulations_FlashCards

Question 1

Main function: aorta

Answer 1

maintain pressure

Question 2

Main function: arteries

Answer 2

distribute blood to and within organs

Question 3

Main fx: arterioles

Answer 3

control flow within organs

Question 4

Main fx: capillaries

Answer 4

metabolic exchange, greatest XS area, slowest flow

Question 5

Main fx: veins & vena cava

Answer 5

buffer blood volume, rtn blood to heart

Question 6

Layers of generic blood vessel

Answer 6

tunica intima, tunica media, adventitia

Question 7

Tunica intima

Answer 7

includes endothelium and internal elastic lamina

Question 8

Tunica media

Answer 8

smooth muscle celss and external elastic lamina

Question 9

Adventitia

Answer 9

albuminal to external elastic lamina

Question 10

Endothelium

Answer 10

simple squamous epithelium lining luminal surfaces of blood & lymph vessels

Question 11

Aorta and next largest arteries: fibers

Answer 11

large number of elastic fibers in tunica media -> maintain BP and Q during diastole (brachiocephalic, subclavian, common carotid, common iliac)

Question 12

Muscular arteries

Answer 12

thick tunica media containing smooth muscle, selectively alter lumen diameter (contract/relax) to direct and regulate blood flow to organs

Question 13

Medium arteries

Answer 13

smooth muscle, but fewer layers; type I collagen fibers in & near adventitia; no elastic laminae apparaent

Question 14

Small arteries

Answer 14

few layers of smooth muscle, less well-defined adventitia

Question 15

Arterioles

Answer 15

1-3 layers of smooth muscle to regulate BF to specific capillary beds; “resistance vessels” to arterial flow -> one of the main determinants of TPR and arterial BP

Question 16

Metarterioles

Answer 16

main regulators of capillary BF, between arterioles and capillary beds, 1 layer of smoth muscle (often discontinuous)

Question 17

Capillaries

Answer 17

9-12 microns in diameter; smallest allow single RBC through at a time

Question 18

3 types of capillaries

Answer 18

continuous, fenestrated, discontinuous

Question 19

Continuous capillaries & locations

Answer 19

continuous endothelium & basement membrane; transcytosis (caveolae and vesicles); micropinocytosis; gas exchange; muscle, brain, lung, bone, thymus

Question 20

Fenestrated capillaries & locations

Answer 20

fenestrated endothleimu w/ or w/o thin diaphragms; tissues w/ substantial fluid transport: gut (intestinal villi), endocrine, kidney (glomerular cells), ciliary processes of eye, choroid plexus (brian ventricles)

Question 21

Discontinuous capillaries & locations

Answer 21

sinusoid; discontinuous endotheilum and basement membrane; liver, bone marrow, spleen (blood cells pass readily through walls of splenic sinuses)

Question 22

Pericytes

Answer 22

contractile & regenerative function; wrap around the endothelial cells of capillaries and venules throughout the body

Question 23

Functional actions of endothelial cells

Answer 23

Metabolic: activation/inactivation of substances; lipolysis, production of vasoactive factors (endothelin: constrict; NO: vasodilate); Antithrombogenic; Inflammatory Response

Question 24

closing of pre-capillary sphincters

Answer 24

causes blood to flow through A-V shunts and bypass capillary bed

Question 25

Raynaud's phenomenon

Answer 25

spasm of small arteries & arterioles to fingers limits BF to finger tips -> turn pale; blood in capillaries of fingers and hand remain their longer than usual -> become more deoxygenated -> cyanosis; spasm release -> oxygenated blood flows into dilated capillary bed -> erythematous fingers (redder than normal)

Question 26

Venules

Answer 26

smallest vessels returning blood toward heart

Question 27

post-capillary venules

Answer 27

~15-20 microns; similar in structure to capillary but larger; continuation of gas/nutrient exchange

Question 28

Veins

Answer 28

thin media and adventitia; less smooth muscle -> thinner than accompanying arteries, but larger XS area; no definable elastic laminae; adventitia is dominant layer

Question 29

Large veins

Answer 29

adventitia is dominant layer and contains vasa vasorum

Question 30

Vasa Vasorum

Answer 30

"vessels of the vessels": network of small blood vessels supplying walls of large blood vessels; nourishment for tunica adventitia and outer parts of tunica media of large vessels

Question 31

Relaxation of longitudinal smooth muscle fibers in adventitia of large veins

Answer 31

allows vein walls to bulge outwards so vein can hold a larger volume of blood -> storage fx/volume buffering

Question 32

Venous valves

Answer 32

cusp-like valves allowing flow in one-direction only (toward heart)

Question 33

3 layers of heart

Answer 33

endocardium, myocardium, epicardium

Question 34

conduction system of the heart

Answer 34

SA and AV nodes, Purkinje fibers

Question 35

Purkinje fibers

Answer 35

modified cardiac muscle cells that carry electrical impulses to contractile muscle cells of ventricles

Question 36

Lymphatics

Answer 36

drain fluid from interstitial space; highly permeable (similar to capillaries in structure, but w/ incomplete basement membrane); do not contain blood cells (except occasional lymphocyte); multple valves permitting central flow only