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Biology 3A > Cell Physiology > Flashcards

Cell Physiology Flashcards

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
What is the pain nerve impulse speed?
12-30 m/sec (unmyelinated and myelinated) | - second smallest distance
26
What is the sensory nerve impulse speed?
70-120 m/sec (myelinated) | - biggest distance
27
what is endocrine signalling and an example?
Hormone is released into blood stream and acts on distant target - glutamate release during stress
28
What is paracrine signalling and an example?
Signalling molecules acting on targets in close proximity to releasing cell - synaptic transmission
29
What is autocrine signalling and an example?
Cells responding to signalling molecules that they themselves release - neurotransmitter auto-receptors
30
What us juxtacrine signalling and an example?
Signalling requiring close/direct contact between cells - gap junctions/T cell signalling
31
What is synchronising neural firing?
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
what does ionotropic mean?
Fast synaptic transmission (this is most of the main signal as its ion channel associated) - e.g. NMDA/AMPA
33
What does metabotropic mean?
Slower modulatory synaptic role, both pre- and post-synpatic - e.g. Group 1 (fast) , 2, 3 (slow). G-protein coupled.
34
what are endocannabinoids?
Classic retrograde signalling molecules in many neural systems.
35
What is receptor recycling (trafficking)?
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
what are the two distinguishable features of a stem cell?
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
What is the difference between asymmetrical and symmetrical division?
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
What can trigger cell differentiation?
internal signals - controlled by cells genes | external signals - includes chemicals secreted by other cells, physical contact with other cells etc
39
What distinguishes an adult stem cell?
1) they give rise to genetically identical cells in culture 2) They can repopulate tissue after transplant "Multipotent"
40
What distinguishes an ESC ?
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
What happens if ESC's clump together?
They form embyroid bodies and differentiate spontaneously - this is uncontrolled and not good if you want specific cells
42
How can we differentiate ESC's into specific cells?
1) change the composition of the culture 2) alter the surface of the culture dish 3) modify the cells by inserting genes
43
What are passive properties?
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
What do passive processes determine?
Conduction velocity and synaptic integration
45
what treatment was used to treat heart failure patients?
Vagus nerve stimulator and telemetry device - improved survival rates
46
what are Ilizarov frames?
Can be used to repair complex fractures, lengthen limbs or correct congenital malformations. (wires at different angels and levels)
47
what things would be considered when publicising a journal?
Ethics, aim, audience, rejection rate, turnaround time, impact factor.
48
what has the fastest propagation - heart or nerve cells?
Nerve cells are faster and have a higher frequency. This is due to prolonged depolarisation state in heart cells.
49
Why is the orderly sequence of atrial and ventricular contractions important?
Maximises efficiency of heat as a pump. If disordered, then arrhythmias - slowed conduction - VT and VF.
50
what speed do the nerve axons travel at?
Fastest A motor fibres - 50-120 ms-1 | Slowest C motor fibres - 0.5-3 ms-1
51
What speed do heart tissue cells move at?
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
What do gap junctions do in myocytes?
Allow movement of ions from one cell to another. Gap junctions held together by Connexon protein. Cx43 is the main type.
53
What happens if there is a low amount of Connexon?
Takes the ions longer to spread and reduces conduction velocities.
54
do heart and nerve cells have high or low membrane resistance?
High resistance
55
what can be used to visualise conduction?
optical mapping - fluorescent voltage-sensitive dye. Stimulated via electrodes.
56
What reduces cell coupling thus leads to slower conduction?
Higher resistance, Acidosis, high calcium concentrations, dephospho rylation.
57
What causes cell excitability to decrease?
``` Depolarisation as closer to Na inactivation. Dephosphorylation. Class 1 drugs (anti-arrhythmic). Genetic mutations affecting Na channel. TTX poisoning. ```
58
What affects conduction?
Gap junctions and excitability.
59
What mainly determines Excitability?
Na channels and Intracellular Na.
60
what can healthy mitochondria do?
Generate ATP, Mitophagy, Apoptosis, hormone synthesis, fat/ cholesterol metabolism. They also generate electrochemical gradient.
61
What happens when a cell is damaged?
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
What can a mitochondria do if it loses its MP?
It can fuse with healthy mitochondria. OPA1 can help with this fusion, where as DRP-1 can operate fission events.
63
What diseases are associated with mitochondrial dysfunction?
CVD, Mitochondrialopathie, kidney disease, sensory defect, liver disease, brain disorders.
64
Examples of rare mitochondrialpathoes?
MERRF, KSS, MELAS< CPEO.
65
what is Cas9?
A DNA cutting protein.
66
what is multistep atherosclerosis?
Extracellular fatigue drives plague rupture. Develops over decades and vessels try to accommodate the lesion by expanding.
67
why is the cap of human plaques most important?
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
what can the nernst equation be used for?
If there is a difference in chemical potential for an ion across a semi-permeable membrane. It measures activity of the ion.
69
How do ions pass across the membranes?
by passive diffusion. Via a pore/tear in lipid. via a carrier.
70
What does the Goldman Constant Field Equation predict?
The shape of the current voltage relationship.
71
What can the Goldman Hodgkin-katz equation predict?
The relative permeability of the membrane to K and NA - two ions. (outward rectification)

Biology 3A (5 decks)

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