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Medicine Unit 3 > Electrochemical gradients > Flashcards

Electrochemical gradients Flashcards

1
Q

what are cell membranes made up of

A

glycerophospholipids
bilayer
prevents movement of charged molecules

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2
Q

how does the cell membrane prevent the movement of charged molecules

A

extremely high resistance to the passage of current
gases and small amphiphilic compounds can diffuse easily

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3
Q

3 types of membrane proteins that enable charged molecules to cross the membrane

A

gap junctions
electrical synapses
membrane transporters

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4
Q

gap junctions

A

large pores that from between adjacent cells
can pass ions and small molecules

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5
Q

electrical synapses

A

specialised form of gap junctions

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6
Q

membrane transporters

A

integral membrane proteins that mediate facilitate diffusion or active transport
aka pumps

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7
Q

2 forms of active transport

A

primary
secondary

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8
Q

primary active transport

A

utilises an energy source

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9
Q

secondary active transport

A

uses the ion gradients established by primary active transport processes

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10
Q

3 types of membrane transporters

A

uniports
symports
antiports

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11
Q

uniport

A

transports single molecule

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12
Q

symports

A

moves multiples molecules in the same direction

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13
Q

antiports

A

move multiple molecules in opposing directions

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14
Q

channels

A

allow water or ions to flow rapidly through a water-filled pore

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15
Q

key properties of channels

A

represent a direct connection between intra and extra cellular spaces
move small molecules
always move charged molecules down concentration gradient
passive
dissipate concentration gradients
extremely high speed

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16
Q

pumps

A

never any connection between intra and extra cellular spaces
can move larger molecules
by using ATP anti ports can move molecules against their concentration gradients
build up concentration gradients
slower

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17
Q

what is membrane potential

A

difference in electrical potential between the interior and exterior of a biological cell

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18
Q

typical membrane potential value

A

+40mV to -70mV

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19
Q

Vm

A

potential difference
movement of one positive ion from the outside to the inside results in +2mV change in Vm

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20
Q

depolarisation

A

movement to a more positive membrane potential

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21
Q

hyperpolarisation

A

movement to a more negative membrane potential

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22
Q

inside of cell

A

more negative than the extracellular environment
due to cells permeability to certain ions and the numbers of those ions

23
Q

Na+ intra and extra cellular concentration

A

E;145
I: 12

24
Q

K+ intra and extra cellular concentration

A

E: 4
I: 120

25
Q

Cl- intra and extra cellular concentration

A

E: 110
I: 15

26
Q

Ca2+ intra and extra cellular concentration

A

E: 2.5
I: 0.0001

27
Q

principle intracellular cation

A

potassium

28
Q

principle extracellular cation

A

sodium

29
Q

principle anion

A

chloride
mainly extracellular

30
Q

resting potential

A

no active stimulus

31
Q

equilibrium potential across cell membrane

A

0

32
Q

mammalian neurone equilibrium potentials for Na+ and K+

A

Na= +60
K= -88

33
Q

calculating the reversal potential for an ion

A

using the Nerst equation

34
Q

calculating the reversal potential for a mammalian neutron at 37 degrees

A
35
Q

resting potential

A

-70mV
sodium potassium pump uses ATP to move 3 Na+ out and 2K+ in
creates negativity inside of the cell
leaky potassium channels to allow the K+ to diffuse out
cell is said to be polarised

36
Q

action potential generation

A

in the presence of a stimulus
sodium channels open
sodium ions move into the cell and the membrane is said to be depolarised
-70 to +40

37
Q

when does an action potential occur

A

threshold potential

38
Q

what happens when the threshold potential is reached

A

action potential is generated
opens all sodium channels
more sodium ions move into the cell
action potential moves along the entire length of the membrane until the entire membrane is depolarised

39
Q

increasing Vm past the threshold

A

can cause action potential in certain tissues like nerves

40
Q

repolarisation

A

once action potential is generated the Na+ close and K+ open
allows K+ to move out of the cell and recreates negativity inside the cell

41
Q

hyperpolarisation

A

if membrane potential becomes more negative than the resign membrane potential
no new action potential can be generated

42
Q

refractory period

A

no new action potential can be generated

43
Q

how does the cell return to resting potential l

A

sodium potassium pump

44
Q

hypokalaemia

A

more potassium ions leak out of the cell during resin state
changes membrane potential to more negative value of -90

45
Q

efflux of positive ions

A

cell membrane will become hyper polarised

46
Q

influx of positive ions

A

cell becomes depolarised
generate action potentia l

47
Q

hyperkalemia

A

elevated plasma K+ concentration

48
Q

effects of changing K+ concentration

A

effects the resting potential
ability of neurons and muscle cells to reach their action potential

49
Q

increased K+ causes

A

increased intake
decreased renal elimination
renal failsure
adrenal disease
medications that alter kidney function
ACE inhibitors
ARBs
potassium-sparing diuretics
NSAIDs
increased release from intracellular stores due to tissue damage

50
Q

effects of high potassium on the body

A

irregular heartbeat
chest pain
weakening pulse
kidney conditions
muscle weakeness
changes in mood
shortness of breath
heart palpitations
nausea,vomiting and diarrhoea
numbness or tingling

51
Q

normal k+ range

A

3.5-5

52
Q

hyperkalemic value

A

7

53
Q

what does hyperkalemic value do to the EK value

A

-90 to -83
cells depolarise
RMP closer to action potential
cells easily excited

54
Q

most life threatening consequence of hyperkalemia

A

arrhythmia and/or cardiac arrest
due to depolarisation of resting potential cardiac myocytes

Medicine Unit 3 (28 decks)

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