Nerve Coordination Flashcards
1
Q
what is a synpase?
A
junction between neurones
2
Q
cholinergic synpase process?
A
- AP arrives at pre-sn knob
- voltage gated calcium ion channels open - Ca2+ diffuse in
- vesicles full of neurotransmitter ACh fuse with pre-sn memb
- ACh diffuses across synaptic cleft
- ACh binds with receptors on post-sn memb
- some Na+ channels open - Na+ diffuse in
- if threshold reached, voltage gated Na+ channels open
- AP triggered in post-sn
- AChE breaks down ACh and stops response
- products reabsorbed into pre-sn knob and recycled
-
3
Q
how temp affects speed of conduction?
A
- high temp (up to 40 degrees)
- faster speed of AP
- mol have more kinetic energy
- diffuse faster
4
Q
how diameter of axon affects speed of conduction?
A
- greater diameter - faster speed of AP
- less resistance
- more surface area for ion movement
5
Q
what are nodes of ranvier?
A
tiny patches of bare membrane
(gaps in myelin sheath)
6
Q
what is saltatory conduction?
A
- when AP jumps between nodes of ranvier
- speeds up transmission of nerve impulses
- cytoplasm conducts enough electrical charge to depolarise next node
7
Q
myelin sheath
A
- made of schwann cells
- electrical insulator - prevents depolarisation
- prevents movement of ions in/out of neurone
8
Q
what happens at nodes of ranvier?
A
- lots of K+ and Na+ ion channels
- depolarisation only happens at nodes
- AP jumps between nodes (saltatory conduction)
9
Q
what is synaptic divergence?
A
- when one neurone joins many neurones
- spreads AP to other parts of body
10
Q
what is synaptic convergence?
A
- when many neurones join single neurone
- amplifies signal
11
Q
temporal summation
A
- single AP wont always trigger AP in post-sn memb
- strong AP will cause more frequent APs
- release more neurotransmitter
- add up to trigger AP in post-sn memb
12
Q
spatial summation
A
- weak stimulus may only create few AP
- doesnt always trigger AP in post-s neurone
- when neurotransmitter from multiple neurones combine to trigger AP in post-sn
13
Q
maintenance of resting potential
A
- sodium-potassium ion carrier protein (using ATP)
- actively transports 3 Na+ OUT and 2 K+ IN
- voltage gated sodium ion channel closes
- membrane not permeable to sodium ions
- potassium ion channel opens
- some K+ diffuse out down electro chem gradient
- doesnt reach equilib because of pos charge outside
14
Q
sensory neurone?
A
- single long dendron
- single short axon
15
Q
relay neurone?
A
- in CNS
- many short dendrites
- many short axons
16
Q
motor neurone?
A
- many short dendrites
- single long axon
- ends with neuromuscular junction
17
Q
receptor?
A
- specific - will only detect one type of stimulus
- cell OR protein
- transforms stimulus into electrical imp
18
Q
describe nervous communication?
A
- fast
- short lived
- localised
19
Q
what does nervous system split into?
A
CENTRAL NERVOUS SYSTEM
- brain
- spinal cord
PERIPHERAL NERVOUS SYSTEM
- all other neurones
20
Q
what does the peripheral nervous system split into?
A
SOMATIC nervous system
- conscious control
AUTONOMIC nervous system
- unconscious body activity
21
Q
what does the autonomic nervous system split into?
A
PARASYMPATHETIC nervous system
- slows things down
- neurotransmitter = ACh
SYMPATHETIC nervous system
- speeds things up
- neurotransmitter = noradrenaline
22
Q
what does it mean by synapses are unidrectional?
A
- only receptors on post-sm
- neurotransmitters rel from pre-synpatic knob
- diffuse from high to low conc across synaptic cleft
23
Q
PASSAGE OF AP
step 1 - RESTING POTENTIAL
A
- sodium potassium ion carrier protein
- actively transports (using ATP)
- Na+ out
- K+ in
- some K+ diffuses out via K+ channel
24
Q
PASSAGE OF AP
step 2 - GENERATOR POTENTIAL
A
- weak stimulus
- some Na+ channels open
- some Na+ ions diffuse in
- doesnt reach threshold
- Na+ K+ restores resting potential
25
PASSAGE OF AP -
step 3 - THRESHOLD
- GP reaches threshold
- many voltage gated Na+ channels open
- Na+ diffuse into axon
- positive feedback
26
PASSAGE OF AP
step 4 - depolarisation
- Na+ channels open
- Na+ diffuse rapidly in
27
PASSAGE OF AP
step 5 - repolarisation
- K+ channels open
- K+ diffuses out
- voltage gated Na+ close
28
PASSAGE OF AP
step 6 - hyperpolarisation
- when memb potential more negative than resting potential
- K+ channels slow to close
29
refactory period
- another AP cant be started
- make AP - DISCRETE (non overlap) , UNIDRECTIONAL (one way)
30
what is a neuromuscular junction?
synapse between motor neurone and muscle fibre
31
differences compared to a cholinergic synapse?
- more receptors on post-sn memb
- AP always generated
- AChE found in pits on post-sn memb
- receptors = nicotinic cholinergic receptors
32
what is the all or nothing law?
- if GP reaches threshold - triggers AP
- all AP = same size
- strong stimulus generates more frequent AP
33
wave of depolarisation?
- Na+ diffuse along neurone
- ahead of AP, neurone in resting potential
- Na+ triggers threshold
- AP moves along as wave of depolarisation
34
