Membrane potential Flashcards

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1
Q

What is membrane potential?

A

Difference in electrical charge between inside/outside of cell

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2
Q

What is polarisation?

A

One side +ve one side -ve (-70, at rest is resting potential = sodium in extra cellular/ potassium in intracellular)

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3
Q

Ion channels?

Ions?

A

Special pores for passage of ions.

=ve /-ve charged particles (remove /add electron)

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4
Q

What is an atom?

A

Nucleus with protons and neutrons

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5
Q

What two processes change ion concentration?

A

Concentration gradient and electrostatic pressure (polarised cell membrane)

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6
Q

What is the difference between depolarise and hyperpolarise?

A

Depolarise - reduce polarisation of membrane eg goes down 70..65..63
Hyperpolarise - increases polarisation of membrane (70, 73, 77)

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7
Q

What does excitatory/ inhibitory postsynaptic potential do?

A

E- increases possibility of neuron firing as excites neurons, reaches threshold - action potential)
I - decreases PSP (takes away from threshold level)

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8
Q

What 3 things happen in PSP?

A

1) Graded response (intensity determines amplitude)
2) Instantaneous
3) decremental (less amplitude as travels along axon)

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9
Q

What is action potential?

A

The reversal of membrane potential from -70 mv to +30 - 50 mv, lasts 1 millisecond. Depends on EPSP being enough to male cell reach threshold.

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10
Q

What is threshold of excitation?

A

When membrane depolarised enough to create action potential generation (all or nothing response UNLIKE PSP WHICH ARE GRADED

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11
Q

What are two integration possibilities?

A

1) Spatial summation - simutaneous PSP sum to form greater PSP OR cancel eahc other out.
2) Temporal summation - PSP formed rapidly, as same synapse for greater potential (hyperpolarise as more accumulate, no time for resting potential)

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12
Q

What are most common axons?

A

Somatic and dendritic

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13
Q

What are directed and non directed synapses?

What is dendritic spine?

A

1) Release of neuro and site of neuro reception are close by
2) Opposite to 1
3) Nodules located on spine of dendrite.

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14
Q

How do small Neurotransmitters travel?

A

To golgi complex, packed into vesicles, go and cluster near presynaptic membrane , until exocytosis

Have effect on IONOTROPIC and METABO receptors. Involved in brief, effects on neuron. Released over directed synapse.

(Large (created on ribosomes) - golgi - microtubules - terminal buttons

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15
Q

What are receptors and ligands ?

A

1) Proteins on surface of PS membrane

2) Molecule that binds to another molecule

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16
Q

What is a large neurotransmitter?

A

Neuropeptide - short proteins (made up of amino acids) about 3 to 36 in length (short protein chains)
Released more diffusely, not directed synapse.
Bind to METAB receptors that release 2nd messengers. Effects longer lasting etc etc.

17
Q

What do Calcium gated channels do

A

When action potential, open up - allow influx of calcium ions, causes small molecule NT vesicle to fuse with membrane and release content into synaptic cleft. BUT LNT - General level of calcium ions in intracellular fluid, not single action potential, more general rate/series of AP.

18
Q

What influences a neuron to act?

A

NT bind to specific proteins on surface of synaptic membrane called receptors. Influence on neuron depends if has specific receptors that bind to specific NT.
Many Neurons bind to many N receptors.

19
Q

What are two types of receptors?

A

1) Ionotropic - causes ligan gated ion channel to open/ close, ions flow into neuron or our (depending on NT and receptor being activated.) Can cause PSP, whether E or I depend on channel. eg. sodium channel in to neuron- excitatory.
2) Metabotrophic - more common– Not GATE. Signal protein has G protein attached - when released can a) break of and cause synthesis of 2nd messenger , this can go into cell nucleus and cause changes in DNA
OR b) can open /close channel

20
Q

Compare metabotropic to Ionotropic receptors.

A

M = more common, have slower effects, last longer, and act over greater area (more diffuse) and more varied.

21
Q

How are NT moved from synaptic cleft?

A

1) Reuptake - transporter mechanism reabsorb NT back into presynaptic neuron/
2) Enzymatic degradation. NT broken down by enzymes.

22
Q

What are glial cells?

A

Non neurol cells in CNS and PNS
No axons or dendrites
Smaller but more numerous than neurons
Conduct signals

23
Q

What are gap junctions and what do they do?

A

Narrow spaces between adjacent cells, bridged by tubular protein channels filled with cytoplasm (connexins)
Allow small molecules and electrical signals to pass between cells.
Quicker message.

24
Q

Where is a NT created?

A

IN the cytoplasm of a neuron