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Flashcards in Physiology Deck (199)
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1

what do dendrites do

receive inputs from other neurones and convey graded eletrical signals passively to the soma

2

what does the soma contain

nucleus, ribosomes, mitochondria, endoplasmic reticulum

3

what is the axon hillock and initial segment

site of initiation of the all or non action potential

4

what is the role of the axon

conducts ouput signals as action potentials to the presynaptic terminal

5

what is the synapse

point of chemical communication between neurones

6

what type of neurones are: peripheral autonomic neurones

unipolar

7

what type of neurones are: dorsal root ganglions

pseudounipolar (one neurite that bifurcates)

8

what type of neurones are: retinal neurones

bipolar (2 neurites)

9

what type of neurones are: lower motor neurones

mulitpolar (3 or more neurites)

10

what is a neurite

process that arises from a soma

11

why do passive signals not spread far from their site of origin

as the diminish as they spread (leaky membranes) - action potentials is different, have constant amplitude and dont diminish

12

what is membrane potential change

as the current passes through axons it leaks into extracellular space creating a potential change

13

how does passive conduction affect action potential velocity

passive conduction is a factor in AP propagation
the further the local current spread the fast the AP conduction velocity

14

how is passive current spread (and therefore AP velocity) sped up

increase membrane resistance (myelination)
decrease axial resistance of axoplasm (increase axon diameter)

15

what cells myelinate

schwann cells in PNS
oligodendrocytes in the CNS
(both macroglia)

16

is conduction in myelinated axons faster or slower than unmyelinated axons of the same diameter

faster

17

what is saltatory conduction

the action potential jumps from one node of ranvier to the next

18

name two demyelinating disorders

mulitple sclerosis (CNS)
guillian barre (PNS)

19

what are the steps of chemical neurotransmission

1. uptake of precursor
2. synthesis of transmitter
3. storage of transmitter
4. depolarisation by action potential
5. Calcium influx
6. calcium induces release of transmitter (exocytosis)
7. receptor activation
8. enzyme mediated inactivation of transmitter or re uptake of transmitter

20

what is the synaptic cleft

gap between pre and post synaptic membranes

21

what is in the synaptic cleft

fibrous extracellular protein

22

what holds the neurotransmitter in the synapse

vesicles in the pre synaptic terminal

23

what are the synaptic membrane differentiations

presynaptically- active zones around which vesicles cluster

postsynaptically- the postsynaptic density which contains neurotransmitter receptors

24

what are the morpholgical types of synapses

axodendritic
axosomatic
axoaxonic

(the location of the presynaptic terminal upon the post synaptic cell)

25

what is the most common CNS neurotransmitter for excitatory synapses

glutamate

26

what is the most common CNS neurotransmitter for inhibitory synapses

GABA or glycine

27

what is the inhibitory/ excitatory post synaptic potential

a local graded excitatory (depolarising) or inhibitory (hyperpolarising) response to transmitter (glutamate or GABA or glycine)

28

what type of neurotransmitters are glutamate, GABA and glycine

amino acid

29

what is synaptic integration

when either:
-many inputs converge upon a neurone to determine its output (spacial summation)
or
-when a single input modulates output by variation in action potential frequency of that input (temporal summation)

30

what type of neurotransmitter are dopamine, histamine, noradrenaline and serotonin

amines