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Nervous Control Flashcards

1
Q

what is a receptor

A

Cells or proteins which detect specific stimuli

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2
Q

what are stimuli

A

changes to the environment

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3
Q

what are co-ordinators

A

receive and process information from receptors
e.g. brain or pancreas

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4
Q

what is an effector

A

bring about responses to return body to optimum conditions
e.g. muscles or glands

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5
Q

what is the Central nervous system

A

made up of brain and spinal chord
nerves branch from spinal chord to all parts of the body, connecting receptors to CNS and CNS to effectors

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6
Q

what are nerves

A

bundles of neurones/ nerce cells which connect receptors to CNS, CNS to effectors

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7
Q

what is a sensory neurone

A

neurones which carry nerve impulses from receptors towards the CNS, cell body is on neurone fibre

runs from receptor organ to CNS

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8
Q

what is a relay neurone

A

a neurone which transmits impulses between neurones
cell body is in CNS

runs from sensory neurones to motor neurones

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9
Q

what is a motor neurone

A

neurones which carry electrical impulses away from the CNS
cell body is at the beginning of the neurone

runs from CNS to effectors

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10
Q

what is a synapse
and what happens at them

A

the gap where one nerve ends and another begins

electrical signal is transferred into a chemical signal that diffuses across gap and binds with receptor molecules on membrane of next neurone

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11
Q

what is a neurotransmitter

A

the chemical released at a synapse which allows the signal to be transferred between neurones

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12
Q

what is a reflex

A

automatic response coordinated by relay neurones in the spinal chord
happen so fast you dont have time to ‘think’

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13
Q

describe the reflex arc

A

stimulus
receptor
sensory neurone
coordinator
relay neurone (spinal chord)
motor neurone
effector
response

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14
Q

why are reflexes important

A

to avoid danger and protect body from harm

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15
Q

reflex examples

A
  • light acts as stimulus, pupil size changes in size
  • sudden jerky withdrawal when pricked by a pin
  • jerk of knees when hit shins
  • blinking when insect flies around eyes
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16
Q

What is an action potential

A

A temporary reversal of the charges across an axon membrane which increase from -70 to +40, depolarising the membrane

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17
Q

What is depolarisation

A

When the inside of the membrane has a positive charge of around +40mV (during an action potential)

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18
Q

What is a nerve impulse

A

A safe propagating wave of electrical disturbance that travels along the surface of an axon membrane

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19
Q

What is a generator potential

A

A nervous impulse produced by a sponsors receptor following transduction of one form of energy into electrical energy

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20
Q

What is a neurone

A

Specialised cells adapted to rapidly carry electrochemical changes (nerve impulses) from one part of the body to another

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21
Q
A
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22
Q

What is a pacinian corpuscle

A

A sensory receptor which responds to change in mechanical pressure

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23
Q

What does polarised mean

A

Condition used to describe the axon when the inside of an axon is more negatively charged relative to the outside
Usually -70 at resting potential

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24
Q

What is the threshold value

A

The minimum level of stimulus needed to trigger an action potential

25
What is a transducer
Converts physical or chemical stimuli into electrical or chemical signals which can be processed by the organism
26
What is a mechanoreceptor
A receptor which responds to a mechanical stimuli - eg pressure
27
Where are pacinan corpuscles found
Deep in the skin and in joints
28
Describe the structure of a pacinan corpuscle
Single seonsory neurone wrapped in layers of connective tissue called lamellae with viscous Cell membrane has stretched mediated sodium channels which only open to let sodium in when stretched
29
How is a generator potential initiated in a pacinan corpuscle
1. A pressure stimulus pushes on the lamellae which deforms the membrane of the sensory neurone 2. Stretch mediated sodium ion channels in the membrane of the neurone open 3. Sodium ions diffuse into the ion, creating a generator potential- greater pressure = more channels open 4. If enough sodium ions enter the cell to reach threshold, then an action potential will be generated and an electrical impulse will move along the sensory neurone
30
How does skin become desensitised to sustained pressure
- gel repositions itself to relieve pressure and becomes evenly distributed again - stretch mediated Na+ channels close - no more Na+ diffuses, generator potential slows/ stops, sensory neurone no longer activated
31
What is potential difference?
A measure of energy per unit of charge transferred between 2 points in a circuit
32
How are impulses generated in cells
ATP used to create electrical energy gradient Where there is a difference in charge, electrical energy can flow
33
What is an electrochemical gradient
A difference in both charge and concentration
34
What happens in a Na+/K+ pump
3Na+ actively transported out, creating a Low conc of Na outside the cell 2K+ actively transported in, creating a high conc of K+ inside the cell
35
What happens during resting membrane potential when stimulant applied
- stimulus applied - results in opening of Na+ channel -Na+ enters the neurone down an electrochemical gradient - initial stimulant produces a generator potential - if enough Na+ enters the cell due to the generator potential, an action potential is triggered - membrane potential must meet the threshold for action potential to be triggered
36
37
What happens during depolarisation
At threshold, potential difference is gated - Na+ channels open, massively increasing permeability of cell to sodium ions - Na+ enters neurone down the electrochemical gradient
38
What happens during repolarisation
- voltage gated K+ channels open - K+ leave the neurone down the electrochemical gradient
39
What happens during hyperpolarisation
- K+ channels are slow to close -too much K+ leaves - membrane potential is below resting potential at around -90mV
40
What is the refractory period
Duration of time when it is impossible for new action potential to be generated - keeps every action potential as a discreet event
41
What is the SAN
Sinal Atrial Node Distinct group of cells within the right atrium of the heart where the initial stimulus for contraction originates Has basic rhythm of stimulation that determines the beat of the heart
42
What is the AVN
Atrio ventricular node Distinct group of cells which lies between the atria After a short delay, it conveys a wave of electrical excitation between the ventricles along the purkinjie tissue
43
What is the bundle of His
A structure made of purkinje tissue that conducts a wave through the atrioventricular septum to the base of the ventricles
44
What are chemoreceptors
Found in the walls of the cacrotid artery and are sensitive to changes in the pH of blood ( due to changes in the CO2 concentration )
45
What is the medulla oblongata
Region of the brain which controls heart rate
46
What are the 2 centres of the medulla oblongata
1. Increases heart rate, linked to SAN through sympathetic nervous system 2. Decreases heart rate, linked to SAN through parasympathetic nervous system
47
What are baroreceptors
Occur within carotid arteries Regulate blood pressure
48
What is smooth muscle
Found in the walls of blood vessels and the gut Not in conscious control
49
Explain how the heart beats
- SAN generates electrical impulse, depolarisation spreads across cardiac muscle cells - aria contract - non conductive tissues prevents depolarisation spreading directly to ventricles - depolarisation reaches AVN which causes delay, giving ventricles time to fill with blood - depolarisation travels down the bundle of His and along purkinje fibres - causes ventricles to contact from apex
50
51
What is the parasympathetic nervous system function
Rest and digest Active when body is at rest and calm
52
What is the sympathetic nervous system function
Active and alert Fight or flight Active when body requires more oxygen and glucose for increased resoiration
53
Which 2 types of receptors are involved in controlling the rate of heart beats
Baroreceptoes Chemoreceptors
54
How does the body regulate blood pressure that is too high
Baroreceptors - more electrical impulses sent along sensory neurones travelling from baroreceptor to centre of medulla uses heart rate - medulla sends more electrical impulses to san via parasympathetic neurones - neurones release acetylcholine at SAN which decreases the rate of impulses to the AVN - heart rate slows and blood pressure reduced
55
How does the body regulate low blood pressure
- More electrical impulses sent along sensory neurones from baroreceptor to centre of medulla that increases heart rate - medulla sends increased electrical impulse down the sympathetic nerve to the SAN - sympathetic neurones release noradrenaline at the SAN which increases rate of impulses to the AVN - heart rate increases which prevents fainting
56
What is noradrenaline
Excitatory neurotransmitter which is released at SAN when increasing heart rate
57
How does the body regulate pH that is too low
- frequency of electrical impulses sent to the medulla increases - medulla increases frequency of electrical impulses to the SAN via the sympathetic nervous system - frequency of impulses from the SAN to the AVN increases - heart rate increases - more blood flows to lungs to remove Co2 and shift equilibrium away from carbonic acid - pH increases
58
When does the blood become more acidic
During excercise Low oxygen and high CO2 Carbon dioxide is an acidic gas

Biology (17 decks)

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