week 3 Flashcards

1
Q

3 basic functions of NS

A

sensory - integrative - motor

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2
Q

general sensory receptors

A
  • sensory input
    Located: skin, skeletal muscles, tendons, joints and visceral organs
  • thermoreceptors, nociceptors, mechanoreceptors (tactile, baro, proprioceptors)
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3
Q

special sensory receptors

A
  • located eye, ears, mouth and nose
  • photoreceptors - chemoreceptors - mechanoreceptors (hair cells)
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4
Q

peripheral NS

A
  • sensory receptors and the cranial, spinal and peripheral nerves that link all parts of the body to the CNS
  • cranial (head and neck) and spinal nerves (all body)
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5
Q

2 functional divisions: PNS

A

sensory division (affarent)

motor division (efferent)

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6
Q

somatic NS

A

conveys somatic motor output from the CNS to bodies skeletal muscles
- control voluntary skeletal movements and involuntary skeletal muscle movements = somatic reflexes

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7
Q

autonomic NS

A

conveys autonomic motor output from the CNS to bodies cardiac and smooth muscles
- involuntary activities; heart rate, respiration, pupil diameter, blood vessel diameter, digestion of food, urination, defecation and salivation

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8
Q

ANS: sympathetic division

A
  • controls fight or flight activities
  • activates body functions that support physical activities
  • increases HR, respiratory airflow, blood flow to skeletal muscles and sweat glands, dilates pupils, digestive functions, inhibits urination and deification
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9
Q

ANS: parasympathetic NS

A

controls rest and digest activities - activates body functions that converse and restore body energy
- stimulates digestive functions, urination and deification, decreases heart rate and airflow

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10
Q

dendrites

A

main receptive (input) region of a neuron
- sensory receptors - detects stimuli - receives info from other neurons

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11
Q

cell body

A

receives information from other neurons and converts this into graded potential - integrates information and conveys info towards towards to the initial segment of the axon

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12
Q

axon

A

generates and conducts action potentials to convey the information from the initial segment to the axon terminals

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13
Q

myelin sheath

A

protects and insulates the axon terminal
- increases the speed of signal conduction

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14
Q

axon terminals

A

forms a synapse with another cell
- secretory region contains synaptic vesicles that store and release neurotransmitters

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15
Q

nuclei (nucleus)

A

clusters of neuron cell bodies in CNS

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16
Q

ganglia (ganglion)

A

clusters of neuron cell bodies in PNS

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17
Q

tracts

A

bundles of neuron axons in CNS

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18
Q

nerves

A

neuron axons bundled in PNS

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19
Q

sensory neurons

A
  • conduct sensory input from receptors to CNS
  • unipolar in structure
20
Q

interneurons

A
  • conduct information within the CNS
  • multipolar in structure
21
Q

motor neurons

A
  • conduct motor output away from the CNS to a muscle or gland
  • lower motor neurons: somatic motor output
  • pre and postganglionic neurons: autonomic motor output
  • multipolar in structure
22
Q

chemically gated channels

A

stimulus- open in response to chemical stimulus
located- dendrites and cell body

23
Q

mechanically gated channels

A

open in response to mechanical stimulation (touch, vibration, pressure)
located- along plasma membrane of dendrites

24
Q

voltage-gated channels

A

open and close in response to voltage gated changes (membrane potential)

25
Q

depolarisation

A
  • an influx of Na+ ions into ICF
  • ICF gains more positive ions
  • membrane potential becomes LESS negative
  • -70mv to -60mv
26
Q

hyperpolarisation

A
  • efflux of K+ ions out of ICF
  • ICF loses positive ions
  • membrane potential becomes MORE negative
  • -70 t0 -90mv
27
Q

graded potential : generated

A

a small change in the membrane potential (small depolarisation or hyperpolarisation)

28
Q

graded potential : conducted

A

originates in the dendrites or cell body of the neuron, when a stimulus opens chemically gated (dendrites and cell body) or mechanically gated channels (dendrites)
- short distance signal

29
Q

action potential : generated

A

depolarisation - repolarisation - hyperpolarisation - threshold

30
Q

action potential : conducted

A

originates at the initial segment of an axon
- long distance signal
- involve voltage-gated channels
- self propagating

31
Q

continuous conduction

A
  • occurs in unmyelinated axons
  • action potentials are generated at the voltage-gated channels along the length of an axon
  • conduction occurs at speeds <2m/s
32
Q

saltatory conduction

A
  • occurs in myelinated axons
  • action potentials are generated at the nodes of Ranvier
  • conduction occurs at speeds of >100m/s
33
Q

local anaesthetics impairing action potential

A
  • block voltage-gated Na+ channels
  • no action potential
  • no sensation of pain
  • no conduction of pain signal to brain
34
Q

ice packs + pressure impairing action potential

A

impairs signal conduction by restricting blood flow - reduced pain sensation

35
Q

step 1 information transfer

A

action potential arrives at and depolarises the axon terminal

36
Q

step 2 information transfer

A

depolarisation of the axon terminal stimulates voltage-gated calcium channels to open and calcium enters the axon terminal

37
Q

step 3 information transfer

A

calcium entry triggers synaptic vesicles to release stored neurotransmitters into the synaptic cleft

38
Q

step 4 information transfer

A

neurotransmitters diffuse across the synaptic cleft and bind to chemically gated channels (on postsynaptic membrane dendrites or cell body)

39
Q

step 5 information transfer

A

binding of neurotransmitters opens chemically gated channels
- an influx of sodium into the ICF
- plasma membrane of postsynaptic neuron depolarises
- graded potential known as excitatory postsynaptic potential is produced

40
Q

step 6 information transfer

A

EPSP travels to and depolarises initial segment of the postsynaptic neuron to the threshold (-55mv)
- action potential generated
- information successfully transmitted

41
Q

reuptake

A

when a neurotransmitter diffuses away from the synaptic cleft - is degraded by enzymes - re-enters the axon terminal and is destroyed by enzymes or reused

42
Q

step 1 neural transmission - across neuron

A
  • stimulus (touch, pain, neurotransmitter) opens chemically or mechanically gated Na+ channels of the dendrites (or cell body)
  • sodium enters ICF
  • membrane potential depolarises
  • graded potential produced
43
Q

step 2 neural transmission - across neuron

A
  • if graded potential travels to the initial segment of the axon and depolarises the membrane potential to threshold
  • voltage-gated Na+ channels open
  • Na+ enters the ICF
  • action potential generated
44
Q

step 3 neural transmission - across neuron

A

AP generated at the initial segment triggers the generation of another AP in the adjacent region
(2nd AP triggers 3rd AP and so on)

45
Q

step 4 neural transmission - across neuron

A

the AP arriving at the axon terminals triggers the presynaptic neuron to release a neurotransmitter which carries the signal to a post synaptic cell (neuron, muscle or gland)