CAPILLARIES 1 : SOLUTE EXCHANGE

Question 1

What is the basic structure of a cell membrane

Answer 1

-2 layers of amphipathic phospholipids
-phosphate head is polar
-fatty acid tail non polar
-forms i layers In solution

Question 2

Roles of cells membrane

Answer 2

-provides support and protection
-cell to cell recognition
-controls what enters and leave the cell
-regulates cell function

Question 3

Describe passive transport

Answer 3

• movement of molecules down a gradient
  -doesn’t require energy
  -simple or facilitated

Question 4

Describe active transport

Answer 4

-movement of molecules against a gradient
-requires ATP

Question 5

Describe the endothelium

Answer 5

• blood vessel with the smallest diameter
  -one cell thick
  -semi permeable

Question 6

What type of transport is solute exchange

Answer 6

Passive diffusion

Question 7

Properties of passive diffusion

Answer 7

-do not require energy
-molecules move randomly
-move from area of high concentration to low
-good transport of lipid soluble solutes over short distances

Question 8

Properties of the solute

Answer 8

-concentration gradient
-size of solute
-lipid solubility of solute

Question 9

Properties of the membrane affecting transport

Answer 9

-membrane thickness/ composition
-aqueous pores in membrane
-carrier mediated transport
-active transport mechanisms

Question 10

Describe continuous capillaries

Answer 10

-moderate permeability
-tight gaps between neighbouring cells
-continuous basement membrane
-blood brain Barrier
Found in muscles , skin , fat , connective tissue

Question 11

Describe fenestrated capillaries

Answer 11

-High water permeability
-fenestration structures
-modest disruption tissues
-high water turnover

Question 12

Describe discontinuous capillaries

Answer 12

-very large fenestration structures
-disrupted membrane
-when movement in cells is needed

Question 13

Structural Properties of capillaries

Answer 13

-intercellular cleft 10-20nm wide
-caveolae & vesicles
-glycocalyx

Question 14

What is glycocalyx

Answer 14

-structural property of capillaries
-covers endothelium
-negatively charged material
-blocks solute permeation
-blocks access to transport mechanisms
- highly regulated

Question 15

What is permeability

Answer 15

Rate of solute transfer by diffusion across unit area of membrane per uni concentration difference

Question 16

How does a porous membrane interfere with the diffusion of a lipid insoluble solute

Answer 16

-reduction in area for diffusion
-increased path length through membrane
-restricted diffusion pore produces hydrostatic issues

Question 17

What is the glucose concentration in plasma

Answer 17

1g per litre

Question 18

Total volume of plasma filtrate flowing to tissues per day

Answer 18

8 litres

Question 19

Maximum filtration of glucose

Answer 19

8 g per day

Question 20

Glucose consumption of a human adult

Answer 20

400g per day

Question 21

What percentage of filtration transport only accounts for glucose transport

Answer 21

2%

Question 22

What controls diffusion rate

Answer 22

-recruitment of capillaries ( dilation of arterioles leads to increased number of capillaries per fused which increases total surface area for diffusion )
-blood flow ( more blood more solutes )
-fall in interstitial concentration ( during metabolism more solute is used up therefore increasing concentration difference)