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Sec 4 Pure Bio > The Nervous System > Flashcards

The Nervous System Flashcards

1
Q

Define stimulus

A
  • a change in environment that triggers a reaction (response)
  • organism responds in way that benefits itself
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2
Q

Define Response

A
  • organism reaction to stimulus
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3
Q

Define sensitivity

A
  • ability of organism to detect and respond to changes in environment
  • survival dependent on appropriate response to stimuli
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4
Q

Role of nervous system

A
  • control activities of body and how it reacts to stimuli
  • transmit info as nerve signals
  • senses stimuli in surroundings, determines and directs responses to surroundings
  • enable coordination of diff parts of body
  • consist of well-developed brain, spinal cord, spianl nerves, highly specialised sense organs
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5
Q

Define involuntary actions

A
  • automatic activities

- not controlled consciously

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6
Q

Define voluntary actions

A
  • activities that are controlled consciously
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7
Q

Voluntary actions (e.g. patting cat) Nervous pathway

A
  1. cat rubs against leg (stimuli)
  2. touch receptors at leg stimulated
  3. nerve impulses transmitted thru sensory neurones to spinal cord
  4. relay neurones conduct nerve impulses to brain
  5. brain evaluates info, decides response (pat cat)
  6. brain generate nerve impulses
  7. nerve impulses transmitted along relay neurones to motor neurones
  8. impulses transmitted to effector muscles (causes contraction of arm muscles, pat cat)
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8
Q

Sense organs

A
  1. help body adjust quickly to stimuli

2. enable various parts of body to coordinate quickly

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9
Q

Central Nervous System (CNS)

A
  • brain
  • spinal cord
  • integrate and process impulses received frm PNS
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10
Q

Peripheral Nervous System (PNS)

A
  • cranial nerves
  • spinal nerves
  • provide comm link between CNS and other parts body
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11
Q

How does nervous system process info? (nervous pathway)

A
  1. info gathered by receptors (sense organs)
  2. info converted to electrical signals (nerve impulses)
  3. nerve impulses transmitted by peripheral nerves to CNS
  4. brain process info based on pattern of impulses
  5. sends nerve impulses to effectors (muscle/glands)
  6. intended action carried out
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12
Q

Nervous tissue (neurones)

A
  • consist of 3 types of nerve cells (neurones)

- sensory, relay, motor neurones

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13
Q

Basic structure of neurone

A
  • cell body (nucleus, cytoplasm)
  • axon
  • dendron
  • dendrites
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14
Q

Cell body

A
  • 1 nucleus and cytoplasm
  • mitochondria and ribosomes present
  • metabolic activities carried out
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15
Q

Dendron

A
  • receives info
  • nerve fibres (conduct impulses towards cell body)
  • small, break up into terminal branches (dendrites)
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16
Q

Dendrites

A
  • many short branching processes frm dendron (increase SA:V, faster transmission rate)
  • specialised in receiving excitation, stimuli, impulses frm another neurone, conducting impulses towards cell body
17
Q

Axon

A
  • long nerve fibre, sometimes branced (may rch more than 1m)
  • 1 axon per neurone
  • diameter frm 0.5mm (increase SA:V)
  • conduct impulse from dendrites, away frm cell body to synapse
18
Q

Structure of motor neurone (Dendron, dendrites, axon)

A
  • Dendron: nerve fibres that transmit nerve impulses towards cell body
  • Dendrites: receive nerve impulses frm other neurones
  • Axon: nerve fibres that carry impulses away frm cell body, ends of axon transmit nerve impulses to effector
  • Pathway: dendrites, dendron, cell body, axon, effectors
19
Q

Nodes of Ranvier

A
  • regions where myelin sheath is absent on cell fibre

- speed up transmission of impulses (allow them to jump frm node to node)

20
Q

Myelin sheath

A
  • layer of fatty substance
  • shields and insulates nerve fibre
  • surrounded by neurilemma (thin membrane)
  • ensures impulse isn’t lost (lesser needs to be generated)
21
Q

Motor end plate

A

junction between axon terminal and muscle fibre

22
Q

What happens if Myelin Sheath is damaged?

A

-some glands won’t work, muscles might not contract (may lead to paralysis)

23
Q

Sensory neurone

A
  • found between sensory receptors and CNS
  • transmit nerve impulse frm sense organs to CNS
  • pathway: Dendrites, dendron (towards cell body in middle of neurone), axon, relay neurone in CNS
24
Q

Diff between sensory and motor neurone (3)

A
  • S: long dendron, short axon ; M: short dendron, long axon
  • S: circular cell body ; M: irregular shaped cell body
  • S: conducts nerve impulse frm sensory receptors to CNS ; M: conducts impulse frm CNS to effectors
25
Q

Synapse

A
  • junction/connection between 2 neurones
  • impulses transmitted frm axon to dendron across a synapse
  • transmission across synapse is via chemical means (thru transmission of neurotransmitters in synaptic vesicles)
26
Q

Define nerves

A
  • bundle of nerve fibres bundled in sheath of connective tissue
  • cranial nerves: nerves frm brain
  • spinal nerves: nerve frm spinal cord, mixed fibres (sensory and motor nerve fibres)
27
Q

Grey matter

A
  • contains cell bodies of neurones

- found at outer layer of brain, central parts of spinal cord

28
Q

White matter

A
  • contains mainly nerve fibres of neurones

- found in central part of brain, outer layer of spinal cord

29
Q

Spinal cord and spinal nerves

A
  • spinal cord encased in vertebral column
  • spinal nerves emerge frm spinal cord (31 pairs)
  • grey matter in central part of spinal cord “H” shape
  • known as central canal, contains cerebrospinal fluid (runs thru middle of spinal cord)
30
Q

Spinal nerve (dorsal and ventral roots)

A
  • each spinal nerve divides into 2 roots
  • subdivides into branches, supply nerve fibres to various parts of body
  • dorsal (top)root: contain only sensory neurones
  • dorsal root ganglion: cluster of sensory neurones (bulge)
  • ventral (bottom) root: contains only motor neurones
31
Q

Relay neurones (nerve impulse transmission)

A
  • relay neurones lie within grey matter of spinal cord
  • transmit nerve impulses from sensory neurones to brain; brain to motor neurones; sensory neurones to motor neurones (reflex)
  • relay neurones form synapses with sensory and motor neurones

Sec 4 Pure Bio (13 decks)

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