How nerves work 1-5 Flashcards

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1
Q

Nervous system (2 areas)

A

CNS and PNS

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2
Q

CNS

A

Brain and spinal cord encased in bone

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3
Q

PNS

A

Somatic and autonomic

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4
Q

Autonomic

A

Sympathetic and parasympathetic

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5
Q

Meninges

A

3 membranes that envelop brain and spinal cord and protect the spinal cord

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6
Q

Gyrus

A

Ridge on cerebral cortex - high

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7
Q

Sulcus

A

Ridge on cerebral cortex - low

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8
Q

Where is the cerebellum?

A

Back of the brain for balance

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9
Q

4 cerebral cortexes

A

Frontal, parietal, temporal and occipital

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10
Q

Diencephalon

A

In forebrain below cerebrum

Thalmus and hypothalamus

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11
Q

Thalmus

A

Last relay of information from spinal cord q

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12
Q

Hypothalmus

A

Hormones and endocrine gland

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13
Q

3 parts of brainstem

A

Pons, midbrain and medulla

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14
Q

How many spinal nerves are there?

A

31

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15
Q

Name how many nerves there are at each vertebrate level

A
7 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
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16
Q

Axon hillock/initial segment

A

Make action potential

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17
Q

Axon terminal

A

Release neurotransmitter

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18
Q

Astrocytes

A

Maintain external environment and make blood brain barrier and surround blood vessels

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19
Q

Oligodendrocytes

A

Wrap feet around axon to form myelin sheath in CNS

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20
Q

Microglia

A

Little cells in immune system and mop up infection

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21
Q

What is the function of the resting membrane potential?

A

Keep cell ready to respond

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22
Q

Is the inside of the cell negative or positive to the outside of the cell

A

Negative = -70mV

23
Q

Why is the inside of the cell negative in comparison?

A

Leaky potassium membrane moves out of cell down concentration gradient

24
Q

Equilibrium potential

A

Membrane potential at which the electrical gradient is equal and opposite to the concentration gradient

25
Q

Why is more K+ in ECF bad?

A

Less concentration gradient
Smaller electrical gradient
RMP reduced so fire at random time due to less -ve
Capillaries in blood brain barrier prevent this but heart ==>ventricular fibrillation

26
Q

Why is normal RMP -70mV

A
  • leaky channels
  • Electrogenic nature of the pumps
  • large intracellular proteins
27
Q

When RMP is an action potential fired at?

A

-55mV

28
Q

Name the 4 graded potentials

A
  • Generator => sensory
  • endplate => neuromuscular
  • pacemaker => heart
  • Post synaptic => at synapses
29
Q

Name some properties of graded potentials

A
  • Decremental - current leaks out
  • non propagated
  • graded - more channels= bigger potential
  • electrotonic potentials
30
Q

In graded potentials where is the intensity encoded?

A

Amplitude

31
Q

Are graded potentials hyperpolarising or depolarising?

A

Both

32
Q

Hyperpolarising

A
  • inhibitory IPSP
  • fast - CL- in
  • slow - g protein coupled K+ out
    eg GABA and glycine
33
Q

Depolarising

A
fast = ATPase 
slow = gprotein coupled stop K+ leaving
34
Q

Ligand gated ion channel

A

Neurotransmitter

35
Q

Voltage gated ion channel

A

Depolarisation of membrane potential

36
Q

Temporal summation

A

2 EPSP added together

37
Q

Spatial summation

A

2 different stimulations added together

38
Q

Postsynaptic inhibition

A

Straight on to dendrite

39
Q

Synaptic integration

A

the process of summing all those inputs in space and time, to determine whether or not the initial segment reaches threshold.

40
Q

Action potentials

A
  • Have a threshold = fired once depolarised
  • all or none - all the same size
  • Encodes stimulus intensity in frequency, fire more
  • Self propagate - Can’t travel back as all neurons in the refractory period
41
Q

Gaps in myelin

A

Nodes of ranvier

42
Q

Big axons

A

Lower axial resistance

Depolarisation travel further and spread out sodium channels

43
Q

Myelination

A

Increase resistance - AP spreads

less leaky and saltatory reduction

44
Q

Demyelination

A

MS - resistance so low so will decay and not big enough to fire AP

45
Q

Compound action potential

A

Axons variable size and myelination with different conduction velocities
A alpha big and myelinated and C opposite

46
Q

Endplate

A

Where sarcolemma invaginates

47
Q

Neurotransmitter released in vesicles to fuse with presynaptic membrane due to what?

A

Exocytosis triggered by calcium concentration changes

48
Q

Brief steps

A

AP-Calcium channels open- vesicles of acetylcholine released, NA/K, graded potential, depolarise, Na and acetylcholinesterase

49
Q

CNS receptors

A

Acetylcholine, NO, serotonin, dopamine, GABA

50
Q

axo somatic synapse

A

Synapse on cell body

51
Q

axo dendritic synapse

A

Synapse on dendrite

52
Q

axo axonial

A

Synapse on axo dendritic

53
Q

Feedback inhibition

A

Inhibitory interneuron close to axon hillock

54
Q

Why is CNS more complex than neuromuscular?

A
  • Bigger range of receptors
  • Range of postsynaptic potentials
  • small potentials - integration
  • variations on connectivity and anatomical arrangement