Human Physiology Ch 6

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1

what is the plasma membrane permeable to?

nonpolar molecules

2

non carrier mediated membrane transport

diffusion

lipid soluble

ions

3

osmosis

difusion of water

4

carrier mediated transport

facilitated transport

active transport

5

diffusion

molecules in a solute become evenly dispersed throughout the solution

movement of particles in a solution due to random thermal motion

solutes go from high concentration areas to low concentration areas in order to achieve equilibrium

no energy is required

6

characteristics of diffusion

passive

random

molecules move high to low

no energy is required

example- exchange of O2 and CO2 between blood and air in lungs

7

concentration gradient

the difference in the concentration of substance between 2 locations

8

net diffusion

is down the concentration gradient (high to low)

continues until there is no difference in concentration

9

molecules undergoing diffusion through membrane?

nonpolar diffuse easily

10

types of protein channels?

open or gated

11

factors affecting rate of diffusion

magnitude of concentration gradient (big difference = faster diffusion)

permeability of the membrane (how easily can substance get through membrane)

surface area of the membrane (greater surface area=fasterdiffusion)

molecular weight of substance

distance to diffuse (less = faster)

temperature (higher=faster

12

osmosis

net diffusion of water down its own concentration gradient

driven by differences in solute concentration

13

osmolarity

number of total solute particles per liter of solution

more stuff= more osmolarity

water moves down concentration gradient to area of highest osmolarity

14

osmotic pressure

more stuff = higher osmotic pressure

15

tonicity

effect of the solute concentration on the osmosis of water

determines if cell stays the same size, swells, or shrinks

16

hypertonic solution

more solutes in solution causes water to move out of cell

17

isotonic solution

equilibrium

18

hypotonic solution

less solutes in solution causes water to move into cell and cell swells

19

osmoreceptors

in the hypothalamus detect increases in osmolarity

can be increased after eating or when dehydrated

this triggers thrist and ADH-decreased excretion of water in urine

20

carrier mediated transport steps

bind to transported substance on one side of membrane

undergo shape change

release substance on opposite side of membrane

21

characteristics of carrier proteins

highly specific

have a maximum rate of transportation-saturation

competition

22

facilitated diffusion

substances move from hi to low

requires carrier molecule but no energy

different than regular diffusion because carrier proteins can become saturated

23

transcellular transport

across a membrane

24

paracellular transport

between/around cells

25

types os interactions

tight junctions

adherens

desmosomes

26

tight junctions

seal adjacent cells

limit passage between cells

to pass, materials must enter cell

27

desmosomes

common in skin

localized patches that hold two cells together

gives strength

28

adherens

holds cells together via fibers

29

Na+/K+ ATP pump

3 Na out of cell

2 K into cell

this generates a concentration gradients and electrical charge difference between inside and outside of cell

-70 mV inside of cell relative to exterior

30

why is Na/K pump important

generation of electrical impulses

drives co-transport of other substances across the plasma membrane

31

membrane potentials

selective permeability leads to unequal distribution of ions between inside/outside of cell

this creates a difference in charge across the membrane

measured as a voltage,inside vs outside

32

where does Na+ want to move

into cell due to electrochemical charge inside

33

where does K+ want to move

moves in and out of cell

34

what causes resting membrane potential

differences in K+ concentration across the plasma membrane

35

K+ leaky channel

means it is open all the time

this means the membrane is much more permeable to K+

36

what does it mean that neurons and muscle are excitable

they can rapidly change their membrane potential

37

equilibrium potential

an ionic concentration gradient across a membrane permeable to only one ion-this is theoretical

38

Nernst equation

calculates theoretical equilibrium potential

39

gap junctions

allow adjacent cels to pass ions and regulatory molecules through a channel between cells

40

paracrine factors

short distance communications-neurotransmitters

hormones-long distance communications

41

autocrine

effects itself

42

what to target cells possess?

receptor proteins that bind to specific signaling molecules

43

where are receptor proteins

depends on solubility ie polar or nonpolar

44

G-proteins are made of what 3 subunits

alpha

beta

gamma

45

alpha g-protein subunit

dissociates when a signal molecule binds to the receptor and travels to the enzyme or ion channel

46

second messengers-cAMP

g=protein couple to enzyme

cyclic adenosine monophosphate (cyclic AMP aka cAMP)