Lecture 6 Unit 1

Question 1

how do oxygen and nutrients move out of the blood?

Answer 1

by crossing the capillary wall and entering the interstitial fluid (ISF)

Question 2

how do carbon dioxide and metabolic waste products move?

Answer 2

in the opposite direction

Question 3

how long would body capillaries be if they were placed end to end?

Answer 3

60,000 miles and cross sectional area would be 5,000 cm^2

Question 4

how long is the average capillary? and the lumen diameter?

Answer 4

capillary- 1 mm

lumen- 8 micrometers

Question 5

what is the blow flow velocity in a capillary?

Answer 5

0.1 cm/sec

Question 6

what is the concentration or density of capillaries in a given tissue proportional to?

Answer 6

the tissue’s metabolic activity

Question 7

what does the term capillary bed refer to?

Answer 7

a network of capillaries where exchange of materials with the tissue cells can take place

Question 8

how far is every cell tissue usually from a capillary?

Answer 8

~1.3 cell diameters

Question 9

when is diffusion efficient?

Answer 9

only when diffusion distances are short

Question 10

how do most substances move?

Answer 10

by diffusion

Question 11

what can cross intercellular clefts?

Answer 11

pores, water and most small substances cross the capillary wall by diffusion through these pores

Question 12

what can cross endothelial cell membranes?

Answer 12

some small molecules and gases can diffuse or be transported across the endothelial cell layer

Question 13

what can cross fenestrations?

Answer 13

large molecules can pass easily through the fenestrations

Question 14

what are the 3 routes for capillary exchange?

Answer 14

• intercellular clefts
• endothelial cell membranes
• fenestrations

Question 15

where are continuous capillaries found?

Answer 15

found in lungs, skeletal muscle, and connective tissue

Question 16

where are fenestrated capillaries found?

Answer 16

kidneys, endocrine glands, small intestine

Question 17

what does fenestration mean?

Answer 17

little windows (70-100 nm)

Question 18

where are sinusoidal capillaries found?

Answer 18

liver, spleen, bone marrow, and anterior pituitary gland

Question 19

What two ways do materials pass through capillary walls?

Answer 19

active or passive transport

Question 20

what is diffusion?

Answer 20

movement of molecules or ions from a region of higher concentration to one of lower concentration until equilibrium is reacher

Question 21

is diffusion passive or active?

Answer 21

passive

Question 22

what is bulk flow?

Answer 22

bulk flow refers to the movement of a fluid from a region of higher pressure to one of lower pressure

Question 23

is bulk flow an active or passive process?

Answer 23

passive

Question 24

what is transcytosis?

Answer 24

substances enter pinocytotic vesicles, move to endothelial cells via endocytosis, and exit on opposite side via exocytosis

Question 25

is transcytosis active or passive?

Answer 25

active

Question 26

What is fluid exchange between ISF and capillaries based on?

Answer 26

bulk flow

Question 27

what are the two major forces that tend to push fluid out of capillaries and into ISF?

Answer 27

- blood hydrostatic pressure | - interstitial fluid osmotic pressure

Question 28

what does blood hydrostatic pressure (BHP) do?

Answer 28

pushes fluid out through the capillary pores

Question 29

what does interstitial fluid osmotic pressure (IFOP) do?

Answer 29

pulls fluid out via osmosis; this pressure is very small compared to the BHP

Question 30

what are the two forces that pull fluid INTO the capillaries?

Answer 30

- blood colloid osmotic pressure (BCOP) | - interstitial fluid hydrostatic pressure

Question 31

what does blood colloid osmotic pressure (BCOP) do?

Answer 31

the BCOP is the result of differences in protein concentration between plasma and ISF which tends to pull water from the ISF and into the capillaries

Question 32

what is the interstitial fluid hydrostatic pressure (IFHP)?

Answer 32

the IFHP is due to the pressure exerted by interstitial fluid, but it is normally very small

Question 33

what is the net filtration pressure?

Answer 33

the difference between the inward and outward pressures

Question 34

what is the equation for the NFP?

Answer 34

NFP= (BHP + IFOP) - (BCOP+IFHP)

Question 35

what determines the fluid movement across the capillary wall?

Answer 35

the BHP and BCOP

Question 36

what does filtration result in?

Answer 36

a constant flow of fluid that washes over the tissue cells at the arterial end of the capillary carrying nutrients and oxygen with it

Question 37

what does reabsorption result in?

Answer 37

a return of fluid to the capillary at the venous end, herby depositing wastes into the venous system

Question 38

under normal conditions how much fluid leaves the capillaries?

Answer 38

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

Question 39

what do the lymphatic vessels do?

Answer 39

they absorb this excess fluid and return it to the circulatory system