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Biology > NERVOUS SYSTEM:PARTS/ACTION POTENTIAL > Flashcards

NERVOUS SYSTEM:PARTS/ACTION POTENTIAL Flashcards

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1
Q

Functions of the nervous system?

A

Sensory input- conduction of electrical signals from sensory receptors
Integration-info is integrated and response generated (CNS)
Motor output- signals from CNS are conducted to effector cells to carry out response

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2
Q

how are electrical signals conducted?

A

nerves

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3
Q

main types of cells in the nervous system?

A

neurons(nerve cells)-transmit messages in the form of nerve impulses
Supporting cells-provide structure, protection, insulation and nourishment to neurons

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4
Q

3 parts of a neuron

A

dendrites
cell body
axon

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5
Q

What do dendrites do?

A

receive signal and conduct impulse to the cell body

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6
Q

What does the cell body do?

A

contains the nucleus

maintains the cells

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7
Q

What does the axon do?

A

conducts impulse away from the cell body

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8
Q

3 types of neurons?

A

Sensory
interneurons
motor neurons
MAKE UP THE REFLEX ARC

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9
Q

what is the reflex arc?

A

automatic response to large stimulus

  • allows for immediate response without waiting for brain
  • must reach a certain threshold
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10
Q

path of reflex arc

A 
stimuli
receptor cell
sensory neuron 
interneuron--->brain
& TO motor neuron
effector (muscle or gland)
reaction
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11
Q

What is a receptor?

A

detects stimuli that surpasses the threshold
initiates impulse in the sensory neuron
ex) photoreceptors in eyes

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12
Q

What is a sensory neuron?

A

long dendrite, short axon

takes sensory info from sensory receptors to cell body

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13
Q

What is an interneuron

A

short dendrite and short or long axon
entirely in the spinal cord of CNS
integrates sensory neuron info with correct motor neuron for correct response

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14
Q

What is a motor neuron?

A

Short dendrites very long axon
Dendrites are in CNS and axon outside of spinal cord
takes impulse to an effector

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15
Q

What in an effector?

A

either a muscle or gland
MUSCLE- will contract
GLAND- will release hormone

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16
Q

What is the myelin sheath

A

fatty sheath that covers the long fibers of neurons

-composed of schwann cells that wrap around nerve fiber

17
Q

functions of myelin sheath?

A

insulate neurons from each other

speeds up impulse

18
Q

What are the points between the schwann cells called? what do they do

A

Nodes of ranvier

speed up impulse as it jumps from node to node

19
Q

What is the threshold?

A

minimum amount of stimuli required to produce an impulse

neuron only fires if threshold is reached

20
Q

Nerve impulses are ____ in nature

A

electric

21
Q

What happens when a nerve impulse travels along a nerve fibre?

A

There is a wave of ionic changes that occurs

  • produces a membrane potential difference (measured in Millivolts)
  • very large difference
22
Q

describe resting potential

A

at rest membrane is not permeable to ions & they cant move in or out
outside slightly positive compared to inside
NA/K voltage channel is closed

23
Q

Describe depolarization

A

-stimulus surpasses threshold (-40mV)
-membrane becomes permeable to Na (gates open)
-Na floods inside the axon
-inside of axon becomes positive
MAX MILLIVOLT REACHED IS +40MV

24
Q

Describe Repolarization

A

-voltage reaches 40mV
-K gates now open and K floods outside
-Initial polarity is restored but ions are positioned in reverse
-channels closed
MIN MILLIVOLT IS -70MV

25
Q

Describe refractory period

A
  • voltage reaches -70mV
  • channels are closed
  • NA/K pump then uses ATP to pump NA and K ions to original position

resting position restablished

26
Q

What is the all or none response

A
  • means that either nothing happens or something happens
  • all impulses over -40mV are the same
  • stronger impulse does not mean bigger, just that there will be a greater number of impulses
27
Q

Where can action potential only occur?

A

@ nodes of ranvier due to insulation of ion loss along myelinated membrane

28
Q

How does the process of action potential occur?

A

like dominoes
-as AP occurs, it shocks neighboring protein ion channels to open thus starting AP at that protein and so forth down the axon

Biology (14 decks)

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