NAS W2 - SOMATIC & SYNAPSE Flashcards

1
Q

AFFERENT

A
  • sensory - to brain

- carry sensory info from surface of body to the brain

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2
Q

EFFERENT

A
  • motor - to effectors
  • convey commands from brain (SNS) to skeletal muscles (lead to contraction)
  • has dendrites around the cell body & connects to axon BUT afferent has a naked cell body (no dendrites)
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3
Q

PNS

A

connects CNS to target organs & connects sensory organs to CNS

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4
Q

INITIATION SEGMENT

A

where AP is generated

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5
Q

GLIAL CELLS

A

produce myelin (for myelin sheath - to protect axon)

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6
Q

SNS CHARACTERISTICS

A
  • bi-stable state (always either active or inactive)

- effector organ is skeletal muscle & is responsible for muscle tone of body (tensing)

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7
Q

CRANIAL NERVES

A

transfer info to/from brain in relation to head & neck

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8
Q

FEATURES/JOB OF DENDRITES OF SOMATIC EFFERENTS

A
  • outside ones are thin & dendrite gets thicker as you get closer to cell body
  • increase SA of membrane cell body (for dendrite to receive signal)
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9
Q

DIF. IN INITIATION OF EFFERENT & AFFERENT IMPULSES

A

efferent - impulses generated in cell body to axons to muscles
afferent - peripheral end of axon creates impulse & passes it to side of axon which is in brain (cell body only used for metabolism & to make nutrients for cell)(not used to initiate any signals in afferent)

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10
Q

HOW TO TELL IF NEURONE IS HEALTHY

A

if nucleus in centre of body

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11
Q

SOMATIC MOTOR NEURONES

A
  • in ventral horn of spinal cord or cranial nerve motor of brain
  • heavily myelinated as very quick impulse transmission
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12
Q

STRIATED MUSCLE

A
  • all fibres travel in one direction & has sarcomere (skeletal & cardiac)
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13
Q

NON-STRIATED MUSCLE

A

fibres flow in opp. directions (smooth)

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14
Q

DISEASES THAT DEMYELINATE AXON

A

multiple sclerosis, diabetes, Guillain barre

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15
Q

MYELINATION IN PNS

A
  • 1 schwann cell myelinates each axon (insulated to speed up impulse conduction)
  • satellite cells support support the neurones
  • microglia used for immune & inflammatory functions
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16
Q

MYELINATION IN CNS

A
  • one single oligodendrocyte myelinates several axons at once
  • damage to oligodendrocyte cell way more dangerous than PNS damage as once cell myelinates all axons not one cell per axon
17
Q

CHROMATOLYSIS

A

nucleus pushed to side of cell (indicates injured neurone)

18
Q

MEMBRANE ENVELOPE OF NERVES (IN TO OUT)

A

ENDONEURIUM - encases a single cells axon
PERINEURIUM - encases nerve fascicle (collection of axons)
EPINEURIUM - encases entire nerve & has interfascicular bands attaching adjacent nerve fascicles (perineuriums)

19
Q

SPINAL NERVES

A

transmit info to & from spinal cord in relation to rest of body

20
Q

PRIMARY SENSORY NEURONES

A
  • cell bodies have no dendrites
  • cell bodies appear as ganglia (round clumps)
  • detect environment signals & convert them to electrical messages conducted to CNS neurones for processing
21
Q

NORMAL NEURONES (W/DENDRITES)

A
  • have cell bodies in CNS & involved in receiving signals from other cells via dendrites
22
Q

AXON STRUCTURE

A
  • has axon hillock (membranes of cell body that lead to axon (start as bulge))
  • has initiation segment where AP are initiated
23
Q

GREY MATTER

A
  • made of cell bodies of NS (more cell bodies = more grey)
24
Q

TYPES OF GLIAL CELLS

A
  • ependymal - secrete CSF
  • astrocytes - link neurones to blood supply
  • microglial cell - phagocyte pathogens
  • Schwann/oligodendrocyte - myelinate neurones
25
Q

GAP JUNCTION (ELECTRICAL SYNAPSE)

A
  • fastest & easiest means of communication between cells

- common between glia-neuron or glia-glia

26
Q

CHEMICAL SYNAPSE

A
  • uni-directional (pre synaptic to post)
  • neurotransmitter in vesicles bind with membrane & release neurotransmitter (exocytosis) which diffuses across synaptic cleft & goes to post-synaptic receptors
27
Q

RAPID TERMINATION OF SIGNAL (FOR EFFICIENCY)

A
  • by enzyme breakdown (enzymes around synapse breakdown neurotransmitter)(AcH esterase hydrolyses AcH into choline + acetate in post-synaptic & choline up-taken by choline carriers in pre-synaptic to form AcH)
  • by re-uptake of neurotransmitter (re-uptake proteins reuptake any neurotransmitter back into pre-synaptic to be broken down by enzyme)
28
Q

IONOTROPIC RECEPTOR

A
  • transmitter binds = structrural change = channel opens = ion movement (fast but slow lasting)
  • e.g. Ach nicotinic receptor
  • e.g. AP where channel opens & NA+ released
29
Q

METABOTROPIC RECEPTOR (GPCR)

A
  • transmitter binds = activates G-protein = activates effector = indirect effects on excitability (slower but last long)
  • activated GPCR can open/close ion channels or stimulate/inhibit enzymes
  • e.g. ACH muscarinic
30
Q

HOW SYNAPTIC INPUT LOCATION IMPACTS INFLUENCE

A

Synaptic input closer to cell body/axon hillock = more influence

31
Q

EPSP

A

small excitatory post synaptic potential (not big enough for threshold)

32
Q

SPATIAL SUMMATION

A

summing of post synaptic potentials generated at separate synapses (many small EPSP = more NA+ influx = reaches threshold)

33
Q

TEMPORAL SUMMATION

A

summary of rapid succession of post synaptic potential but from ONE synapse