Nervous System Flashcards

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1
Q

need for nervous system

A
  1. keeps us informed
  2. remember, think, reason
  3. controls and harmonises all voluntary muscular activities
  4. regulates involuntary activites`
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2
Q

what is myelin sheath

A

axon is covered by a white insulating sheath which is covered by an outermost think layer called neurolemma

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3
Q

what are collaterals

A

axons may have side branches called collaterals

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4
Q

define synaptic cleft

A

axon terminals are closely plased near the dendrites of another one or more neurons but are not connected, and gaps are called synaptic clefts

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5
Q

define impulse

A

electrical impulse that sweeps over a nervous cell

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6
Q

define receptors

A

the specialised epithelial cells which, on receiving the stimulus, set up waves of impulses towards the central nervous system

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7
Q

define effectors

A

muscles or glands which, on receiving impulse from brain or spinal cord, contract or secrete substances

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8
Q

polarised state

A

when outer side of nerve fibre carries positive charge, due to more Na ions outside the axon membrane

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9
Q

depolarised state

A

when, due to impulse, axon membrane becomes permeable. Na ions move inwards and causes loss of polarisation

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10
Q

repolarised state

A

previous area of nerve fibre becomes repolarised due to active transport of Na ions again on the outside, using ATP

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11
Q

define synapse

A

point of contact between the terminal branches of the axon of a neuron with the dendrites of another neuron separated by a fine gap

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12
Q

neurotransmitter

A

acetylcholine

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13
Q

types of neurons

A
  1. sensory (receptor to CNS)
  2. motor (CNS to effector)
  3. connecting (connects sensory and motor)
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14
Q

define nerves

A

nerve is a bundle of nerve fibres (axons) of separate neurons, enclosed in a tubular sheath.

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15
Q

function of myelin sheath in nerves

A

prevents mixing up of impulses in adjacent axons

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16
Q

kinds of nerves

A
  1. sensory
  2. motor
  3. mixed
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17
Q

define ganglia

A

aggregates of the cytons or cell bodies of nerve cells from which the nerve fibres may arise or enter into

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18
Q

subdivisions of PNS

A
  1. somatic nervous system
  2. autonomic nervous system
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19
Q

somatic nervous system

A

conveys information to voluntary muscles

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20
Q

autonomic nervous system

A

pair of chains of ganglia and nerves which control the involuntary muscles

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21
Q

weight of brain

A

1.35 kg

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22
Q

define meninges

A

the brain is protected by 3 membranous coverings called meninges which continue backward into the spinal cord

23
Q

3 layers of meninges

A
  1. dura mater (outermost, tough, fibrous)
  2. Arachnoid (thin delicate middle, web-like cushion)
  3. pia mater (innermost, highly vascular, rich in blood
24
Q

function of cerebrospinal fluid

A

protects the brain from shocks

25
Q

gray matter

A

made of cell bodies
brain- outer cortex
spinal cord- inner side

26
Q

white matter

A

axons
brain- inner part
spinal cord- outer part

27
Q

define corpus callosum

A

sheet of fibres connecting the two cerebral hemispheres and helps to transfer information from one hemisphere to the other

28
Q

function of cerebrum

A

seat of intelligence, consciousness, and will-power. controls all voluntary activities

29
Q

location of cerebellum

A

at the base and under the cerebrum

30
Q

function of cerebellum

A

maintain balance of body and coordinate muscular activity

31
Q

location of medulla

A

base of the skull, lowest portion of the brain. continues behind as the spinal cord

32
Q

function of medulla

A

controls activity of internal organs, involuntary actions

33
Q

thalamus

A

relays pain and pressure impulses to cerebellum

34
Q

hypothalamus

A

controls body temperature and pituitary

35
Q

location of pons

A

base of the brain just above medulla oblongata

36
Q

function of pons

A

carries impulses from one hemisphere of the cerebellum to the other hemisphere and coordinates muscular movements on both sides

37
Q

location of spinal cord

A

medulla to the second lumbar vertebrae, lies within neural canal of vertebrae

38
Q

functions of spinal cord

A
  1. reflexes below the neck
  2. conducts sensory impulses from the skin and muscles to the brain
  3. conducts motor responses from the brain to the muscles of trunk and limbs
39
Q

sets of nerves in somatic nervous system

A
  1. cranial nerves
  2. spinal nerves
40
Q

distribution of spinal nerves

A

8 in neck region
12 in thorax
5 in lumbar region
5 in sacral
1 in coccygeal

41
Q

structure of spinal nerve

A

at the junction of the dorsal and ventral root, sensory and motor fibres separate from spinal nerve. sensory fibre continues in the dorsal root and motor into the ventral root

42
Q

parts of autonomic nervous system

A
  1. sympathetic
  2. parasympathetic
43
Q

origin of sympathetic system

A

arise from spinal cord between the neck and waist region

44
Q

location of parasympathetic

A
  1. anteriorly in the head and neck
  2. posteriorly in sacral region
45
Q

sympathetic and parasympathetic system

A

sympathetic system prepares the body for violent action against abnormal conditions
the parasympathetic system re-establishes normal conditions

46
Q

define reflex action

A

automatic/quick involuntary action in the body brought about by a stimulus

47
Q

types of reflexes

A
  1. natural/inborn
  2. conditioned/ acquired
48
Q

natural reflex

A

no previous experience or learning is required. they are inherited from parents
ex: blinking, coughing, sneezing, salivation, peristalisis

49
Q

conditioned reflex

A

an involuntary, spontaneous, automatic response brought about due to a previously learned experience
ex: watering of mouth

50
Q

define reflex arc

A

the shortest route that can be taken by an impulse from a receptor to effector

51
Q

define sensory neuron

A

the neuron in the spinal cord which receives impulses through its axon terminals which are in contact with a receptor cell

52
Q

define CNS

A

a region in the spinal cord and brain where incoming sensory impulse generates an outgoing motor impulse

53
Q

define motor neuron

A

carries impulse generated by the association neuron in CNS to the effector organ

54
Q

define effector

A

an organ that responds to a motor nerve impulse