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Flashcards in Week 2 Membrane Transport Lecture Deck (41):
1

What is passive transport? what are three types of passive transport?

movement down a concentration gradient that does not require energy input. Simple diffusion, ion channels, facilitated diffusion

2

What is active transport? what are two types of active transport?

movement against a concentration gradient. primary active and secondary active transport

3

What is Fick's law? what type of membrane transport does it apply to?

Net flux=((Kp)(A)(deltaCs))/(deltaX)

Kp: solute partition coefficient'
A: area
x: thickness
deltaCs: solute concentration gradient

Simple diffusion

4

As thickness increases, net flux...

decreases

5

As the partition coefficient, area, and concentration gradient increases, net flux...

increases

6

Describe simple diffusion

movement across a membrane without the aid of energy or transport proteins

7

The partition constant of simple diffusion is directly proportional to _____ and inversely proportional to _____

directly to lipid solubility

inversely to size of solute

8

rank the permeability of the following: CO2, glucose, Na+, water

Highly permeable: CO2
low permeability: water
almost no permeability: glucose
not permeable: Na+

9

What is pulmonary edema?

accumulation of fluid in the interstitial space

10

High altitude pulmonary edme: cause

low oxygen content @ high altitude is compensated for by increased blood flow. This increases NFP which causes net filtration at capillaries and the accumulation of interstitial fluid. The increased interstitial fluid decreases oxygen diffusion from alveoli to the lungs

11

What are the intracellular and extracellular concentrations of: Na, K, Ca

Na+: 140 mM ext, 10 mM intra

K+: 4.5 mM ext, 140 mM intra

Ca2+: 2-3 mM extra, 0.1 uM intra

12

What type of gated ion channels are there (3)? how do they open?

ligand gated: activated by binding of a chemical signaling agent

voltage gated: activated or inactivated by changes in the membrane potential

mechanically gated: activated by physical deformation of the surrounding plasma membrane

13

rank the speed of transport of: simple diffusion, ion channels, facilitated diffusion

ion channels>facilitated diffusion>simple diffusion

14

How does glucose cross the plasma membrane?

Via facilitated diffusion using the GLUT transporter protein.

15

the GLUT transporter has how many transmembrane domain?

12 transmembrane domains

16

what is primary active transport?

movement against a concentration gradient with the use of ATP

17

what % of total cell ATP does the N/K-ATPase use?

30%

18

What is the most well known example of a primary active transport protein?

Na/K ATPase

19

What is secondary active transport?

uses the energy released from pushing a molecule (Na) down its concentration gradient to pump another molecule against its concentration gradient

20

What are three examples of symporters that utilize secondary active transport?

Glucose/Na, AA/Na, and Cl/K/Na symporters (all pump inside of cells)

21

what are two examples of antiporters that utilize secondary active transport?

H/Na, and Ca/Na antiporters. H and Ca are pumped out of the cells.

22

Which types of transport experience saturation?

any that involve a protein (except ions because that one is just a pore) so Facilitated, prim active, and second active transport.

23

what are the "sides" of an epithelial cell?

apical/luminal side: faces the lumen

Basolateral side: faces the blood vessels

24

secretion refers to movement:

from the blood to the lumen

25

reabsorption refers to movement:

from the lumen to the blood

26

Define transcellular

movement through a cell

27

define paracellular

movement not through a cell

28

how does water flow through a membrane?

passively

29

define osmosis:

diffusion of water across a selectively permeable membrane from high concentration of water to low concentration of water

30

hyper-tonic means

high solute concentration

31

hypo-tonic mean

low solute concentration

32

how do you calculate osmolality?

mOsm=n(deltaC)

n: number of particles/moles
deltaC: concentration in mM

33

what is the normal osmolarity of a cell?

300 mOsm

34

if a cell is placed in a hypotonic soln what occurs?

cell will swell

35

what are aquaporins?

a water channel (not present in all cells)

36

how many aquaporins does a typical RBC contain?

200,000

37

what are three causes of edema?

higher than normal blood pressure, lower than normal protein content in blood, lymphatic obstruction

38

Cells in our body are in _____ equilibrium but in _____ AND _____ disequilibrium

osmotic equilibrium (300 mOsm in and out)

chemical and electrical disequilibrium (different concentrations of solutes inside and outside, more negative inside the cell -70 to -90 mV)

39

define Nernst equilibrium potential

the membrane potential in which a certain ion would not move into or out of the cell

40

which ion largely maintains the resting membrane potential?

potassium ion. it is a positively charged ion with a Nernst potential of -98mV. This means that at normal resting potential, K+ leaves the cell. A loss of positive cells creates a net negative. Usually about 95% of potassium channels are open.

41

in normal cellular conditions (-70mV) are any ions at their Nernst equilibrium?

No, this means that Na, K, Ca and Cl move across membrane

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