Lec 3 Flow Down Gradients

Question 1

Starling Forces

Answer 1

fluid movement between blood and tissues are determined by hydrostatic and osmotic pressures between plasma inside microvessels and interstitial fluid outside

Question 2

Movement of a substance from point A in system to point B in system

Answer 2

Flow
measured in amount of substance over time

Question 3

Poiseulle’s Law: F = (P1-P2)x[(pie r^4)/(8ul)]

Answer 3

F = flow
P = hydrostatic pressure (difference between 2)
r = radius of tube
l = length of tube
u = viscosity of fluid

Question 4

P’s Law - When this variable increases so does flow:

Answer 4

P and r

Question 5

P’s Law - When this variable increases flow decreases:

Answer 5

l and u

Question 6

P’s law - What variable has the largest impact on flow?

Answer 6

r - the radius

Question 7

random movement of solute/gas in gas mixture from area of high concentration to area of lower concentration

Answer 7

Diffusion

Question 8

What law quantifies rate of diffusion?

Answer 8

Fick’s Law

Question 9

What parameters affect Fick’s Law?

Answer 9

• Flow = flux = amount of solute moving across barrier per unit time
• force driving flux -> concentration gradient
• restistances: membrane SA and thickness, premeability of membrane

Question 10

Ficks law - flow increases when these variables increase:

Answer 10

• concentration gradient
• SA of membrane
• k (constant - permeability)

Question 11

Fick’s Law - Flow decreases when these variables increase:

Answer 11

t - thickness of memrbane

Question 12

What is P’s law only accurate for?

Answer 12

rigid, simply-shaped tubes with non-turbulent flow

Question 13

Where can Fick’s Law be applied within the body?

Answer 13

Cappillaries, substances through cell membranes, O2 and CO2 from alveolus to blood

Question 14

What does the movement of dissolved, charged particles across a barrier depend on?

Answer 14

• charge of particle
• concentration difference across membrane (type of potential energy)
• the permeability of the membrane

Question 15

the rate of flow of charged across a membrane is known as current (I) and is defined by:

Answer 15

Ohm’s Law (I = V/R)

Question 16

What are the variables in Ohm’s Law - I=V/R

Answer 16

• I = current - number or charges/charged particles moving across membrane per unit time
• V = voltage - energy generated by separating charges across membrane
• R = resistance - more channels for charged particle -> less resistance

Question 17

current increases when what variables increas?

Answer 17

V

Question 18

Current decreases when this variable increases?

Answer 18

R

Question 19

How have tissues/cell structures adapted to meet the constraints of Fick’s Law?

Answer 19

Cell membranes having channels and transporters