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Biology 3A > Cell Physiology > Flashcards

Cell Physiology Flashcards

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1
Q

How many neurones in the human brain?

A

Approx 100 billion

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2
Q

What do neurones do?

A

Receive, process and transmit info via electrochemical signalling

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3
Q

What are lysosomes?

A

They contain enzymes which break down organelles

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4
Q

What are the 3 components of the cytoskeleton?

A

Microtubules, Microfilaments and Neuro filaments

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5
Q

Describe the structure of the neuronal membrane?

A

Phospholipid bilayer containing transmembrane proteins

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6
Q

Define resting potential?

A

-70mV. High Na and Low K outside cell. Low Na and High K inside cell.

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7
Q

Define depolarisation?

A

Na+ influx

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8
Q

Define hyperpolarisation?

A

K+ efflux

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9
Q

What are the 3 types of dendrites

A

Thin, stubby and mushroom

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10
Q

What are the different groups of fibres?

A

A and B (myelinated)

C (unmyelinated)

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11
Q

What is the axon hillock?

A

Site of summation of EPSP’s and IPSPs from synapses

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12
Q

What is the initial segment?

A

Where the AP is generated

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13
Q

what affects AP conduction velocity?

A

Axon diameter nd myelination

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14
Q

Anterograde transport?

A

Soma to axon terminal. Kinesins.

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15
Q

Retrograde transport?

A

Axon terminal to soma. Dyneins.

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16
Q

What may cause an ion channel to open/close?

A

Conformational change due to NT binding, pH or pressure.

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17
Q

How does the MP change?

A

1) opposite charges attract 2) Concentration (ionic) gradients
3) Electrochemical gradient

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18
Q

What are lipofuscin bodies?

A

They are pigmented granules seen through electron microscopy. They are yellow/brown and contain lysosomal waste. They increases with age and are referred to as the “wear and tear pigment”.

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19
Q

What is the 2 examples of spatial summation?

A

1) one synapse with one neurone - small depolarisation

2) More synapses firing simultaneously - large depolarisation - must be at least 3 to be spatial.

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20
Q

What is the 1 example of temporal summation?

A

One synapse repeatedly firing - large depolarisation

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21
Q

What is the threshold potential?

A

-55mV (this is with 3 x +5mV) - when enough EPSP’s add together to start an AP.

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22
Q

What is a rough mV for AP?

A

+35mV

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23
Q

How many ions are exchanged per AP?

A

1/3000

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24
Q

What is the autonomic nerve impulse speed?

A
  1. 7-2.2m/sec (unmyelinated)

- smallest distance

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25
Q

What is the pain nerve impulse speed?

A

12-30 m/sec (unmyelinated and myelinated)

- second smallest distance

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26
Q

What is the sensory nerve impulse speed?

A

70-120 m/sec (myelinated)

- biggest distance

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27
Q

what is endocrine signalling and an example?

A

Hormone is released into blood stream and acts on distant target - glutamate release during stress

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28
Q

What is paracrine signalling and an example?

A

Signalling molecules acting on targets in close proximity to releasing cell - synaptic transmission

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29
Q

What is autocrine signalling and an example?

A

Cells responding to signalling molecules that they themselves release - neurotransmitter auto-receptors

30
Q

What us juxtacrine signalling and an example?

A

Signalling requiring close/direct contact between cells - gap junctions/T cell signalling

31
Q

What is synchronising neural firing?

A

Insertion of two electrodes in neighbouring cells attached by a gap junction. A current is added to one to reach AP, and this affects the other neurones and causes it to have numerous AP but not as large.

32
Q

what does ionotropic mean?

A

Fast synaptic transmission (this is most of the main signal as its ion channel associated) - e.g. NMDA/AMPA

33
Q

What does metabotropic mean?

A

Slower modulatory synaptic role, both pre- and post-synpatic - e.g. Group 1 (fast) , 2, 3 (slow). G-protein coupled.

34
Q

what are endocannabinoids?

A

Classic retrograde signalling molecules in many neural systems.

35
Q

What is receptor recycling (trafficking)?

A

Receptors are capable of lateral movement and/or membrane insertion/removal. This is due to receptors not being fixed at the membrane. It alters the strength of synaptic signalling.

36
Q

what are the two distinguishable features of a stem cell?

A

1) Capable of self-renewal after long periods of inactivity.

2) Differentiation - can be induced to become tissue/organ- specific cells with specific functions.

37
Q

What is the difference between asymmetrical and symmetrical division?

A

Asymmetrical -> a stem cell produces one differentiated cell and one stem cell
Symmetrical -> a stem cell produces 2 stem cells or 2 differentiated cells.

38
Q

What can trigger cell differentiation?

A

internal signals - controlled by cells genes

external signals - includes chemicals secreted by other cells, physical contact with other cells etc

39
Q

What distinguishes an adult stem cell?

A

1) they give rise to genetically identical cells in culture
2) They can repopulate tissue after transplant
“Multipotent”

40
Q

What distinguishes an ESC ?

A

1) presence of transcription factors (Oct4)
2) presence of cell surface markers
3) ability to regrow the cells after freeze-thawing
4) test pluripotency by:- ability to differentiate spontaneously, differentiate into 3 germ layers, testing for formation of teratoma.

41
Q

What happens if ESC’s clump together?

A

They form embyroid bodies and differentiate spontaneously - this is uncontrolled and not good if you want specific cells

42
Q

How can we differentiate ESC’s into specific cells?

A

1) change the composition of the culture
2) alter the surface of the culture dish
3) modify the cells by inserting genes

43
Q

What are passive properties?

A

Dont rely on activity of gated channels and are not involved in the generation of action potentials but have an effect on whether and how quickly they are initiated/travel.

44
Q

What do passive processes determine?

A

Conduction velocity and synaptic integration

45
Q

what treatment was used to treat heart failure patients?

A

Vagus nerve stimulator and telemetry device - improved survival rates

46
Q

what are Ilizarov frames?

A

Can be used to repair complex fractures, lengthen limbs or correct congenital malformations. (wires at different angels and levels)

47
Q

what things would be considered when publicising a journal?

A

Ethics, aim, audience, rejection rate, turnaround time, impact factor.

48
Q

what has the fastest propagation - heart or nerve cells?

A

Nerve cells are faster and have a higher frequency. This is due to prolonged depolarisation state in heart cells.

49
Q

Why is the orderly sequence of atrial and ventricular contractions important?

A

Maximises efficiency of heat as a pump. If disordered, then arrhythmias - slowed conduction - VT and VF.

50
Q

what speed do the nerve axons travel at?

A

Fastest A motor fibres - 50-120 ms-1

Slowest C motor fibres - 0.5-3 ms-1

51
Q

What speed do heart tissue cells move at?

A

Fastest (Purkinje fibres) - 2-4 ms-1
Slowest (AV node) - 0.02-0.1 ms-1
Middle (bulk ventricles) - 0.3-1 ms-1

52
Q

What do gap junctions do in myocytes?

A

Allow movement of ions from one cell to another. Gap junctions held together by Connexon protein. Cx43 is the main type.

53
Q

What happens if there is a low amount of Connexon?

A

Takes the ions longer to spread and reduces conduction velocities.

54
Q

do heart and nerve cells have high or low membrane resistance?

A

High resistance

55
Q

what can be used to visualise conduction?

A

optical mapping - fluorescent voltage-sensitive dye. Stimulated via electrodes.

56
Q

What reduces cell coupling thus leads to slower conduction?

A

Higher resistance, Acidosis, high calcium concentrations, dephospho rylation.

57
Q

What causes cell excitability to decrease?

A 
Depolarisation as closer to Na inactivation. 
Dephosphorylation.
Class 1 drugs (anti-arrhythmic).
Genetic mutations affecting Na channel. 
TTX poisoning.
58
Q

What affects conduction?

A

Gap junctions and excitability.

59
Q

What mainly determines Excitability?

A

Na channels and Intracellular Na.

60
Q

what can healthy mitochondria do?

A

Generate ATP, Mitophagy, Apoptosis, hormone synthesis, fat/ cholesterol metabolism. They also generate electrochemical gradient.

61
Q

What happens when a cell is damaged?

A

ATM/R (damage repair protein) activates p53. p53 is stabilised and activates p21 and p16. These respond with cell arrest or cell senescence respectively.
DNA polymerase is recruited by ATM/R as well and causes DNA to unwind and repair.

62
Q

What can a mitochondria do if it loses its MP?

A

It can fuse with healthy mitochondria. OPA1 can help with this fusion, where as DRP-1 can operate fission events.

63
Q

What diseases are associated with mitochondrial dysfunction?

A

CVD, Mitochondrialopathie, kidney disease, sensory defect, liver disease, brain disorders.

64
Q

Examples of rare mitochondrialpathoes?

A

MERRF, KSS, MELAS< CPEO.

65
Q

what is Cas9?

A

A DNA cutting protein.

66
Q

what is multistep atherosclerosis?

A

Extracellular fatigue drives plague rupture. Develops over decades and vessels try to accommodate the lesion by expanding.

67
Q

why is the cap of human plaques most important?

A

It has lots of DNA damage, this causes a defect in the way cells respire, so measuring oxygen present can examine this. (Can use O2K or XF24 )

68
Q

what can the nernst equation be used for?

A

If there is a difference in chemical potential for an ion across a semi-permeable membrane. It measures activity of the ion.

69
Q

How do ions pass across the membranes?

A

by passive diffusion. Via a pore/tear in lipid. via a carrier.

70
Q

What does the Goldman Constant Field Equation predict?

A

The shape of the current voltage relationship.

71
Q

What can the Goldman Hodgkin-katz equation predict?

A

The relative permeability of the membrane to K and NA - two ions. (outward rectification)

Biology 3A (5 decks)

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