microcirculation (midterm 2)

Question 1

what is microcirculation the site of

Answer 1

nutrient transport at the capillaries

Question 2

what is the total surface area of the 10 billion capillaries

Answer 2

500-700 m^2

Question 3

how far are most cells from a capillary

Answer 3

20-30 um

Question 4

what is the structure of microcirculation

Answer 4

artery (branches 6-8 times)->arterioles (branch 2-5 times)->capillaries

Question 5

what are precapillary sphincters

Answer 5

regulate the opening and closing of capillaries

Question 6

how is the capillary wall formed

Answer 6

from a unicellular layer of endothelial cells surrounded by a basement membrane

Question 7

what does the capillary wall contain

Answer 7

intercellular clefts - allows fluid transport between endothelial cells

Question 8

what is the blood-brain barrier

Answer 8

brain capillaries have tight junctions that tightly regulate transport

Question 9

why do kidneys allow regulated transport

Answer 9

they contain fenestrae

Question 10

are liver capillaries open

Answer 10

very open, allowing free transport

Question 11

how fast does water diffuse through the capillary

Answer 11

80x faster than the rate of plasma flow

Question 12

what is brownian motion

Answer 12

nutrient exchange from the capillary to the interstitial fluid (dominated by passive diffusion)

Question 13

what is interstitium

Answer 13

space between cells containing interstitial fluid

Question 14

what are the structural components of interstitium

Answer 14

• collagen fibers bundles (provide tensile strength)
• proteoglycan filaments

Question 15

what is interstitial “gel” fluid

Answer 15

hydrogel form of tissue (~99% diffusion rate of free fluid)

Question 16

what is intertitial “free” fluid

Answer 16

water based form of tissue - less than 1% of tissue volume

Question 17

what are the four forces that affect the movement of fluid between capillaries and interstitial spaces

Answer 17

capillary pressure (Pc)
interstitial fluid pressure (Pif)
plasma osmotic pressure (“pi”p)
interstitial fluid osmotic pressure (“pi”if)

Question 18

what do the fluid exchange forces do

Answer 18

capillary pressure (Pc) - pushes fluid out of cap (+)
interstitial fluid pressure (Pif) - pushes fluid in capillary (+)
plasma osmotic pressure (“pi”p) - pushes fluid in capillary (+)
interstitial fluid osmotic pressure (“pi”if) - pushes fluid out of capillary (+)

Question 19

what is arterial blood flow driven by

Answer 19

pressure (venous end is not)

Question 20

what is starling equilibrium

Answer 20

amount of fluid filtering outward from some capillaries = amount of fluid that is returned to the circulation by absorption through other capillaries

Question 21

what is the lymphatic system

Answer 21

route where fluid can flow from the interstitial spaces into the blood (where excess fluid drains into)

Question 22

what do liver, intestinal lymphs, and body lymphs carry proteins at

Answer 22

6 gm/dl
3-4 gm/dl
3-5 gm/dl