Lecture 5: Hemodynamics and Cappilary Exchange

Question 1

interstitial Fluid (ISF)

Answer 1

between and amng tissues

Question 2

Arteriole

Answer 2

epithelial and smooth muscle

Question 3

Oxygen and nutrients move

Answer 3

out of blood, across capilary wall, into ISF

CO2 and waste go opposite

Question 4

total cappilaries in body:

Answer 4

60000 mines, SA of 5,000 cm 2

Question 5

capilary sizes

Answer 5

about 1 mm long
lumen about 8 micrometers
just about the diameter of an RBC
shorter distance is better
every tisue cell usualy about 2-3 cell diameters from capillary (important for diffusion)

Question 6

blood flow velocity in cap

Answer 6

0.1 cm/sec

slooooooow

Question 7

conc or density of capilareises is

Answer 7

proportional to tissues metabolic activity

more active, more blood vessles

Question 8

capillary bed

Answer 8

netwrok of caps

exchange takes place

Question 9

entry into caps

Answer 9

sometimes controlled by 2 smooth muscle cells

Question 10

Intercellular Clefts

Answer 10

pores
water and most small molecs can move through by diffusion
deep to tunica (lumen is superficial!)

Question 11

Endothelial cell membranes

Answer 11

some small molecs and gases can pass through

oxygen concs: higer in BV lower in cells that use it

Question 12

fenestrations

Answer 12

large molecs can pass through
little holes in cell
intnetnional holes al the way through cell

Question 13

Continuous Capillaries

Answer 13

in lungs, skeletal muscle, CT
just gases move through, pretty sealed
formed by endothelial cells

Question 14

Fenestrated Capillaries

Answer 14

kidneys, endocrine glands, small intestine

“little window”

Question 15

Sinusoid (cappilary type)

Answer 15

liver, spleen, bone marrow, anterior pituitary gland
missing cells, giant caps
so free access to blood. BE CAREFUL!
liver: clotting factors
Spleen: purify blood (of infectious agents and old cells)

Question 16

Random: BSA

Answer 16

albumin from class
purpose: just to be in blood

Question 17

Mechanisms of Fluid Exchange

Answer 17

2 mechs for blood to plass through cap walls

Passive or active

Question 18

Diffusion

Answer 18

Passive
molecs and ions
movement form high conc to low conc
reach equlibrium

Question 19

Bulk Flow

Answer 19

Passive
movement of fluid
high pressure to low pressure

Question 20

Transcytosis

Answer 20

active
substances enter pinocytosis vesicles
move to endothelail cells (endocytosis)
exit opp side (exocytosis)

Question 21

More on Bulk flow

Answer 21

fluid exchange between ISF and caps
based on bulk flow
2 major fources to push OUT of caps
BHP and IFOP
2 forces to pull fluid INTO capps

Question 22

Blood Hydrostatic Pressure (BHP)

Answer 22

pushes fluid out through cap pores
Bulk Flow
push out

Question 23

Interstitial Fluid Osmptic Pressure (IFOP)

Answer 23

pulls fluid out via osmosis
pressure small compared to BHP!
Bulk Flow
push out

Question 24

Osmotic Pressure

Answer 24

fluid pressue due to water moving from high to low activity (conc)

Question 25

Blood Colloid Osmotic Pressure (BCOP)

Answer 25

result of diff in proten concs between plasma and ISF
tends to pull water from ISF into caps
pull in
* suspension of protein in fluid: albumin
*big things in blood cant move across membrane are always there
*protein conc in blood different than in IFC

Question 26

Interstital Fluid Hydrostatic Pressure (IFHP)

Answer 26

due to pressure exerted by ISF
normal very small!!!
pull in

Question 27

Net Filtration Pressure

Answer 27

net movement of fluids driven by difference between inward and outward pressures

Question 28

NFP=

Answer 28

(BHP + IFOP) - (BCOP +IFHP)
or
outward (filtration)- Inward (reabsorption)

Question 29

Outward (respect to NFP)

Answer 29

filtration

Question 30

Inward (Respect to NFP)

Answer 30

reabsorption

Question 31

Negative NFP

Answer 31

fluid goes into blood (venous)

Question 32

Positive NFP

Answer 32

fluid goes out of blood (probs arterial)

Question 33

major factors that determine fluid movement across cap wall

Answer 33

BHP and BCOP

Question 34

Filtration

Answer 34

result: constant flow of fluid washes over tissue cells at arterial end of capps
carries nutrients and oxygen with it

Question 35

Reabsorption

Answer 35

result: return of fluid to capps at venous end

deposit wastes into venous system

Question 36

Normal conditions fluid

Answer 36

slightly more fluid leaves than enters caps (3L/day)

Lymphatic vessles absorp excess fluid and return it to circulatory system