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applied physiology > CNS: structure and function - week 3 > Flashcards

CNS: structure and function - week 3 Flashcards

1
Q

what are the 3 main functions of the CNS?

A

control of internal environment

voluntary control of movement

Spinal cord reflexes

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2
Q

what are the 4 divisions of the nervous system ?

A

CNS- brain + spinal cord

Peripheral NS - neurons outside the CNS

sensory division - afferent fibres transmit impulses from receptors to CNS

motor devision - efferent fibres transmit impulses from CNS to effector organs

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3
Q

what are the 2 elements of the input sensory NS in functional organisation?

A

somatic sensory - consciously perceived

visceral sensory - not conscious

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4
Q

what is an axon ?

A

carries electrical message(AP) away form cell body

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5
Q

what are Schwann cells ?

A

form myelin sheath over length of axon

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6
Q

what is a synapse ?

A

contact points between axon of one neuron and dendrite of another neuron

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7
Q

the greater the__ of the axon, the greater the __ of neural transmission

A

diameter

speed

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8
Q

what is a dendrite?

A

sends input from synapse to the axon

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9
Q

what are the nodes of ranvier ?

A

propagation of signal/impulse along axon

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10
Q

the inside of cell have a __ charge at rest (__)

A

negative

polarised

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11
Q

what determines the magnitude of resting membrane potential ? (2)

A

permeability of plasma membrane to ions

difference in ion concentrations across membrane

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12
Q

at rest __ channels are closed and __ channels are open.
this causes a _ membrane potential

A

sodium
potassium
negative

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13
Q

how is a negative membrane potential maintained ?

A

sodium-potassium pump

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14
Q

what is a sodium-potassium pump ?

A

moves 2K+ in and 3 NA+ out

uses ATP to maintain environment

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15
Q

what is an action potential?(2)

A

occurs when stimulus of sufficient strength depolarises the cell

opens Na+ channels to make cell positive charge

(depolarisation)

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16
Q

what is repolarisation ? (2)

A

return to resting membrane potential

K+ leaves cells rapidly
Na+ channels close

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17
Q

what is the all or none law?

A

one nerve impulse initiated it travels length of neuron

(doesn’t stop)

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18
Q

what is a neurotransmitter ?

A

chemical messenger released from presynaptic membrane

binds to receptors on post synaptic membrane

causes depolarisation of postsynaptic membrane

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19
Q

what is excitatory postsynaptic potentials (EPSP)?

A

help achieve depolarisation

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20
Q

how do EPSPs achieve depolarisation ? (2)

A

temporal summation

spatial summation

21
Q

what is temporal summation ?

A

rapid repetitive excitation from a single excitatory presynaptic neuron

22
Q

what is spatial summation ?

A

summing EPSPs from several different presynaptic neurons

23
Q

what are inhibitory post synaptic potentials (IPSP) ?(2)

A

cause hyperpolarisation (more neg resting potential)

a more neg membrane potential resist depolarisation

24
Q

what are the joint proprioceptors ? (3)

A

free nerve endings - touch/pressure

Golgi type receptors - ligaments

pacinian corpuscles - tissues around joints/skin

25
Q

what are the muscle proprioceptors/ mechanoreceptors ? (2)

A

muscle spindles

Golgi tendon organs

26
Q

what is another sensory info/reflex other than muscle proprioceptors?

A

muscle chemoreceptors

27
Q

what is proprioception ?

A

the boy’s sense of position based on specialised receptors that reside in the muscles, tendons and joints

28
Q

what are proprioceptors ?

A

sensors that provide info about joint angle, muscle length, and muscle tension which is integrated to give info about position of limb

29
Q

what are muscle spindles ? (3/4)

A

respond to changes in the muscle length

intrafusal fibers - run parallel to normal fibres

gamma motor neurons - stimulate intrafusal fibres to contract with extrafusal

(muscle spindle loses so spindle reflex makes it taught again)

30
Q

what is the stretch reflex ?

A

stretch on muscle causing reflex contraction

31
Q

how does the muscle spindle work ?

muscle spindles detect __ of muscle

___ neuron conduct action potentials to ____ ____

___ neurons synapse with ___ ___ neurons

stimulation of the ____ ____ neurons causes the muscle to contract and _____ being stretched

A

stretch

sensory
spinal cord

sensory
alpha motor

alpha motor
resist

32
Q

what does the gogli organ tendon do ? (2)

A

monitors force development in muscle - prevents damage during excessive force generation

stimulation results in reflex relaxation of muscle - inhibitory neurons send inhibitory post synaptic potentials to muscle alpha motor neurons

33
Q

how does the Golgi tendon organ work ?

gogli organ tendons detect ___ applied to a ___

___ neurons conduct APs to the spinal cord

____ neurons synapse with____interneurons that synapse with ___ ___ neurons

_____ of ___ ____ neuron cause muscle _____, relieving the tension applied to tendon

A

tension
tendon

sensory

sensory
inhibitory
alpha motor

inhibition
alpha motor
relaxation

34
Q

what are muscle chemoreceptors ?

A

sensitive to changes in the chemical environment surrounding a muscle

35
Q

what is a motor unit ?

A

motor neuron and all the muscle fibres it innervates

36
Q

if there’s a low ratio of muscle fibres to motor neuron what does this mean?

A

allows fine motor control

37
Q

if there’s a high ratio of muscle fibres to motor neurons what doe this mean ?

A

greater/gross motor control

38
Q

what happens in terms of motor unit recruitment in terms of force needed ?

A

if more force is needed , more motor units are recruited

39
Q

what is the size principle in terms of motor unit recruitment?

A

smaller motor units are recruited first during exercise

40
Q

what are the 3 types of motor units ?

A

Type S - slow type 1 fibres

type FR- type 2a fast fatigue resistant

type FF - type 2x fast fatigable

41
Q

what is role of cerebrum ? (3)

A

organisations of movement

storage of learned experiences

reception of sensory info

42
Q

what is role of cerebellum ?

A

control of movement and integration of sensory info

43
Q

what is the role of the brainstem ? (3)

A

Cardiorespiratory function

locomotion

muscle tone

posture

receive info from special senses

44
Q

what are the functions of the midbrain in the brainstem ? (1 but gave 3)

A

body movement - most important

control responses to sight, eye movement and pupil dilation

hearing

45
Q

what is the role of the medulla oblongata in the brain stem ?

A

coordination of body movement - important

relay signals between brain and spinal cord

46
Q

what is the role of Pons in the brainstem ?

A

relay of sensory info between cerebrum and cerebellum

47
Q

what is spinal tuning ?

A

intrinsic neural networks in the spinal cord that refine voluntary movement after reviewing messages from higher brain centres

48
Q

what is the withdrawal reflex ?

A

via reflex arc

contraction or muscles in response to sensory input - doesn’t need higher brain centres

applied physiology (22 decks)

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