vascular physiology

Question 1

artery

Answer 1

thicker walls - varying in diameter - more smooth muscle for contraction - most elastic tissue to maintain the pressure and help maintain the driving pressure from ventricular contraction “resistance”

Question 2

arteriole

Answer 2

variable resistance, smallest vessel that still has smooth muscle

Question 3

capillary

Answer 3

no connective tissue, single layer of endothelial cells, all exchange happens, no variable resistance because no smooth muscle - radius is fixed because no smooth muscle

Question 4

venule

Answer 4

smallest vein

Question 5

vein

Answer 5

largest diameter of veins, wall thickness can be less not much elastic tissue because it is the volume reservoir “capacitance”

Question 6

veins vs arteries valves

Answer 6

valves keep it going in one direction to go against gravity and back to the heart prevents no back flow - arteries have no valves because it has high pressure and there is a low pressure in the veins

Question 7

why are arterioles important

Answer 7

main site of variable resistance in the circulatory system because they have smooth muscle
contribute to more than 60% of total peripheral resistance or resistance to blood flow in the circulatory system - relaxes smooth muscle and wont relate

Question 8

Metarteriole

Answer 8

allows materials to get around capillaries if the beds are too large. WBC are larger than the size of the capillary

Question 9

pre-capillary sphincter

Answer 9

At the point where each of the capillaries originates from an arteriole, a smooth muscle fiber encircles the capillary.

Question 10

pericytes

Answer 10

line the outer surface of the endothelial cell and compromise the adventitia. undifferentiated and serve as support cells. they can differentiate further into smooth muscle, fibroblasts or macrophage cells if needed. important in forming the BBB

Question 11

paracellular capillary exchange

Answer 11

around the cells through pores between cells

Question 12

transcellular capillary exchange

Answer 12

fenestrations or pores in the endothelial cell membrane

Question 13

transcytosis

Answer 13

vesicle-assisted diffusion - small peptides can cross through this process

Question 14

bulk flow

Answer 14

movement of H2O and dissolved solutes - filtration and absorption

Question 15

how does most capillary exchange occur

Answer 15

diffusion (paracellular or transcellular) or transcytosis

Question 16

continuous capillaries

Answer 16

found in muscles, nerves, connective tissues - leaky junctions and transcytosis

Question 17

fenestrated capillaries

Answer 17

found in GI and kidney - large pores and transcytosis

Question 18

alterations in capillary exchange can cause

Answer 18

ascites (fluid accumulation in abdominal cavity) and peripheral edema

Question 19

Hydrostatic (filtration) pressure > osmotic (absorption) pressure

Answer 19

net outward flow, can cause edema in the tissues

Question 20

Hydrostatic (filtration) pressure < osmotic (absorption) pressure

Answer 20

net inward flow

Question 21

hydrostatic (filtration) pressure

Answer 21

Pcap - PIF, essentially BP

Question 22

osmotic (absorption) pressure

Answer 22

osmotic IF - osmotic cap

Question 23

why doesn’t colloid osmotic pressure change

Answer 23

it is composed of the proteins, this can change if protein is lost in the urine or malnutrition

Question 24

why is there ankle edema

Answer 24

there is a reduced blood pressure the farther it gets from your heart, if the hydrostatic pressure (BP) is below the osmotic pressure then there will be a net outward filtration and this filtration can go into the tissues causing edema

Question 25

3 main functions of the lymph system

Answer 25

returns excess fluid from capillary filtration
filters pathogens
transfers lipids from digestive system to circulatory system

Question 26

why is lymph system a pumpless system

Answer 26

there is a pressure gradient. only flows towards the heart

Question 27

lymph vessel features that help lymph flow back to the circulatory system

Answer 27

large lymph vessels have smooth muscle
skeletal muscle pump helps lymph flow uphill back towards the heart
some lymph vessels have valves

Question 28

lymphedema

Answer 28

surgery which the lymph nodes are removed due to diagnosis or cancer (can be breast cancer)

Question 29

lymphedema treatment

Answer 29

NISAIDs - reduce inflammation

exercise or compression

Question 30

Central Venous Pressure (CVP)

Answer 30

pressure found in large veins that lead back to the heart (vena cava) driving pressure for venous return to the heart. veins are capacitance vessels that are reservoirs for more than 50% of blood volume in the circulatory system. venous constriction is a mech that blood can be shunted to area of higher need. assess cardiac preload and volume status in critically ill patients, assist in the diagnosis of right-sided heart failure

Question 31

4 factors that contribute to CVP

Answer 31

1. skeletal muscle pump
2. respiratory pump
3. blood volume
4. venomotor- amount oof veins are constricted

Question 32

venomotor

Answer 32

resting tone generated response to SNS from NE that acts on alpha 1 keeping the veins contracted against the pressure of the blood flowing through them. w/o - blood will pool in the veins bc of their compliance to stretch and expand.

Question 33

increase in venomotor tone will

Answer 33

increase CVP, EDV, SV, CO, MAP, venous return, preload, arterial pressure- decrease venous compliance, regulated by alpha receptors or vasodialators