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Revision lectures (Year 1) > ICPP (1-11) > Flashcards

ICPP (1-11) Flashcards

1
Q

purpose of membrane

A
  • control of the enclosed chemical environment
  • communication
  • recognition
  • signal generation in response to stimuli- electrical or chemical
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2
Q

composition of the membrane (dry rate)

A

protein-60%
lipid- 40%
carbohydrates - 1-10%

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3
Q

membrane lipids

A

phospholipids, cholesterol and sphringolipids

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4
Q

phospholipids

A

predominant lipid

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5
Q

cholesterol

A

plasma membran elipid (45% of total lipid)

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6
Q

spingolipids

A

Spingomyelin

Glycolipids

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7
Q

Glycolipids

A

sugar containing lipid e.g. cerebrosides and ganfgliosides

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8
Q

Spingomyelin

A

only phospholipid not based on glycerol

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9
Q

membran lipids

A

amphiphatic

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10
Q

lipid bilayer formed by

A

forms when inc contact with an agues media- glycolipids can form either rebillers or micelles
- favour lipid bilayer

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11
Q

Bonds in the lipid membrane

A

Van der waals link hydrophobic tails

Hydrophilic heads linked by:

  • Hydrogen bonds
  • Electrostatic forces
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12
Q

Lipid dynamics

A
  • flexion
  • axial rotation
  • lateral diffusion
  • flip flop (rare– thermodynamically unfavourable)
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13
Q

protein dynamics

A
  • lateral diffusion
  • rotational
  • conformational change
  • NO FLIP FLOP- too thermodynamically unfavourable
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14
Q

single Nicholson model

A

mosaic lipid model

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15
Q

integral membrane proteins

A

e.g. channels

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16
Q

peripheral membrane proteins

A

do not run through the lipid bilayer- on the top

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17
Q

Erythrocyte membrane

A
  • anatyis of the erythrocyte cell embark has revealed there are over 10 proteins making up the membrane
  • Named 1-10
  • Cytoskeleton is like a network of spectrum and actin
  • spectrin winds together to form an antiparallel helix
  • these are join by a short chain of actin, band 4.1 and ended with adducing molecules
  • ankyrin (band 4.9) links spectrin and band 3 proteins
  • Band 4.1 links spectrin and glycophorin A together.
  • attachment to the integral proteins help restrict lateral movement of membrane proteins
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18
Q

Erythrocyte membrane malformation -

A

Haemolytic anaemia and hereditary ellipocytosis

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19
Q

Haemolytic anaemias e.g.

A

Hereditary spherocytosis- Spectrin

  • levels are depleted up to 50%
  • less robust cytoskeeltion
  • rounded erythrocytes
  • more prone to lysis and puts pressure on the spleen to remove due to decreased life space- haemolytic
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20
Q

Hereditary elliptocytosis

A

defect present in spectrin molecules leads defective formation of spectrin heterotramers 9rugby balls)
- leads to fragile ellipsoid erythrocytes

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21
Q

Membrane protein synthesis

A

1) AA,inp acid signal sequence a the N-terminus (hydrophobic)
2) signal sequence is noticed SRP
3) SRP halts protein synthesis
4) SRP caused ribosome and protein to bind to the receptor on the RER (docking protein)
5) signal sequence interacts with signal sequence receptor within proteins y
translocator cxomplex
6) Signal peptidase chops off the signal sequence
6) ribosome that is bound to complex translates peptide chain

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22
Q

secreted proteins

A

signal peptidase chops off signal sequence

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23
Q

membrane proteins

A

synthesis is arrested by stop transfer signal

- hydrophobic N terminus directed into the lumen and C terminal placed into the cytosol

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24
Q

Trasnport across membrane

A

passive
facilaited
active

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25
Q

passive

A

high conc to low conc

- no energy

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26
Q

facilitated

A

through channels e.g. through protein pores

through carriers (ping png)

gated channels (ligand, ion and gap junctions

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27
Q

Types of trransprters

A

uniport- one molecule in one driection

Symport- two molecules in one direction

Antiport- molecule in and out in opp direction

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28
Q

calcium in human body

A

> 1kg (99% in bones)

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29
Q

calcium is regulated by

A

by intestinal uptake, reabsorption in the kidneys and bone calcium regulation

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30
Q

calcium hoemsostias under

A

endocrine corntrol

  • ca2+ in the parathyroid glands
  • parathyroid hormeones
  • 1,25 Dihydroxybita,ine D3
  • calcitonin
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31
Q

calcium is much higher in

A

extracellular space

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32
Q

Why is calcium important

A
  • muscle contraction
  • neurotransmission
  • fertilisation
  • cell death
  • regulation of metabolism
  • learning and memory
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33
Q

Regulation of internal calcium (maintaining intracellular calcium)

A
  • SERCA
  • PMCA
  • NCX
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34
Q

[calcium] intracellular

A

low

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35
Q

ATP dependent calcium homeostasis

A

PMCA (membrane)

SERCA (SR)

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36
Q

transporters of calcium out of the cell

A

NCX- sodium calcium exchanger

- antiport

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37
Q

cell membrane is relatively impermeable to

A

calcium

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38
Q

mechanisms that increase intracellular calcium

A
  • voltage gated calcium channels (VOCCs)

- ligand gated ion channels (LGIC)

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39
Q

calcium movement out of the ER/SR

A

Found on the ER/SR membrane:

1) Calcium induced calcium release- Ryanodine receptors
2) IP3R

40
Q

pH regulation occurs based on the amount of

A

protons and hCO3- in the cells

- controlled by ion channels

41
Q

Acid extrusion

A

when H+ is expelled form he cell, increasing pH

42
Q

alkalisation is

A

opposed by expulsion of HCIO3-

43
Q

water does not

A

have a concentration

44
Q

cell shrinkage

A

ions will move in (same amount of positive and negative ions) e.g. Na+ and Cl-
- water will move in

45
Q

cell swelling

A

ions will move out

- water will follow

46
Q

measuring membrane potentials

A

uses micro electrode- which is a fine glass pipette
- filled with conducting solution (KCL)
-

47
Q

resting membrane potnetial

A

electrical change that exist across a membrane
- always expressed as the potential inside the cell relative to the extracellular solution

  • mV
48
Q

Cardiac myocytes

A

-80mV

49
Q

Neurones

A

-70

50
Q

smooth muscle

A

-50

51
Q

skeletal muscle

A

-90

52
Q

equilibrium potentials of calcium

A

Eca +122mV

53
Q

equilibrium potentials of sodium

A

+70mv

54
Q

equilibrium potentials of K+

A

-95mV

55
Q

equilibrium potentials of Cl-

A

-96mv

56
Q

nicotinic ACh receptor found at the

A

NMJ

  • ACH binds, which causes the sodium and potassium to flow through
  • causing AP to be propagated across a neurone
57
Q

types of gated channel

A

ligand gated

voltage gated

mechanical gated

58
Q

Action potential is a

A

change in voltage across the membrane

59
Q

action potential depend on

A

ionic gradients and relative permebaility

60
Q

AP will only occur

A

if threshold is reach - all or nothing

- can propagate across without loss of amplitude

61
Q

AP

A
  • influx of sodium ion (moves towards sodium equilibrium (70mV) (positive feedback)
62
Q

refractory periods

A

1) Absolute refractory period

2) Relative refractory period

63
Q

Absolute

A

time between intitial opening and closing of the sodium channels
- NO ACTION POTNETIAL can be generated

64
Q

relative

A

time it takes for inactive sodium channels to recover

- if there is a strong enough stimulus it will genrate an AP

65
Q

local anaesthetics

A

act by binding to and blocking sodium channels- preventing generation of an AP

66
Q

anaesthetics are

A

weak bases

67
Q

Anaesthetics block conduction in nerves ions he following order

A
  • small myelinated axons
  • unmyelinated axons
  • large myelinated axons
68
Q

conduction velocity of AP

A

distance/time

69
Q

a change in membrane potential in one part can strand to the

A

adjacent areas of threw axon.

70
Q

conduction velocity affected by

A

affected by:

  • high membrane resistance e(less ions channels opne- less current open)
  • capacitance- ability to charge
  • large axon diameter
71
Q

myelinated areas created

A

saltatory conduction

  • ## conduction jumps from nodes of ranvier
72
Q

which cells form myelinated axons

A
  • Schwann

- Oligodendrites

73
Q

demyelination e.g.

A

Multiple sclerosis

  • muscle weakensss
  • visual problems
  • fatigue
74
Q

when AP gets to the end of the nerve

A

NT release in cleft between NMJ

75
Q

what causes NT release

A

AP opens calcium channels and calcium causes vesicle to fuse with pore- exocytosis

76
Q

NMJ

A

1) ACH released
2) binds to receptor on the sarcolemma
3) sodium influx
4) depolarisation
5) conduction down T-tubule
6) stimulates ryanodine receptor- calcium relase
7) calcium bins to TnC subunit of tropinina nd contraction cycle begins

77
Q

blockers of ACH receptors

A
  • competitive blockers

- depolarising blockers

78
Q

myasthenia gtavis

A

antibody targets ACh receptors on p[sot synaptic membrane

- muscle weakness

79
Q

myasthenia graves

A

antibody targets ACh receptors on p[sot synaptic membrane

- muscle weakness

80
Q

signalling targets

A

RITE

81
Q

RITE

A

R receptors
I ions channels

T transporters

E enzymes

82
Q

Types of receptors

A

KING

83
Q

KING

A

K- kinase linked receptors
I -ion channels
N- nuclear intracellular
G- G protein couple receptors

84
Q

alpha S

A

stimulate

85
Q

alpha I

A

Inhibits

86
Q

QISS

QIQ

A

Q- A1
I- A2
S- B1
S - B2

Q- M1
I- M2
QM3

87
Q

GPCR

A

7 transmembrane

- transduce signals generated by agonsits

88
Q

GPCR sturcuture

A

heterotirmeric- 3 subunits

89
Q

stops involved with GPCR

A

1) agonist bidnigns
2) stimulates GDP tp GTP exhange and dissociation nd aloha beta gamma subunuts
3) subunits go onto have different affects

90
Q

alpha S subunits

A

activates AC

  • hydrolyses ATP to cAMP
  • cAMP os secondary messenger which activates PKA
  • PKA phosphorylates to increase/ decrease other proteins activity
91
Q

e.g. of alpha S subunit agonist

A

peptides

glucagon

insulin

92
Q

alpha Q subiunit

A

1) agonist bins
2) GDP for GTP exchange
3) Alpha Q stimulates phospholipase C
4) hydrolysis of PIP2 –> IP3 and DAG
5) DAG stimulates PKC
6) IP3 binds to receptor on SR- calcium release

93
Q

signal amplificaiton

A

one GPCR that a citrated causes sequential GTP/GDP exchange

  • activate molecules released that a citrate several other effector molecules
  • effector molecules binds to many other proteins
94
Q

regulation of chronotropy (rate of heart)

A

ACH binding to M2

  • Alpha I
  • -> inhibition of AC
  • -> opens more potassium channels
  • -> Slows down rate of firing (reduced chronotropy)
95
Q

regulation of inotropy

A

Sympathetic innervation

  • ligand binding to B1 receptors
  • Alpha S unit
  • increase in cAMOP- VOCC channels
  • positive isotropy effect

Revision lectures (Year 1) (17 decks)

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