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Biology > 9.2 The Nervous System > Flashcards

9.2 The Nervous System Flashcards

(62 cards)

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1
Q

CNS

A

Brain + spinal cord

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2
Q

PNS

A

Pairs of nerves which originate form spinal cord

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3
Q

What is PNS made up of

A

Autonomic NS - communication with internal organs + glands
Voluntary NS - communication with sense organs + voluntary muscles

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4
Q

What is the Autonomic NS made up of

A

Sympathetic NS - Produces noradrenaline at synapse/ speeds up
Parasympathetic NS - Produces acetylcholine at synapse/ slows down

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5
Q

What is voluntary NS made up of

A

Sensory Neurones
Motor Neurones

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6
Q

Brain

A

Hypothalamus
Cerebellum
Cerebrum
Medulla Oblongata

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7
Q

Hypothalamus

A

Hormone secretions
Thermoregulation
Osmoreguation

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8
Q

Cerebellum

A

Smooth movements
Balance Posture

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9
Q

Cerebrum

A

Voluntary Behaviour
Personality

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10
Q

Medulla Oblongata

A

Breathing
Heart Rate

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11
Q

Schwann cell

A

Forms a fatty layer arounnd the neurone

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12
Q

Nodes of Ranvier

A

Gaps between the Schwann cell

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13
Q

Function of myelin sheath

A

Protects the nerve from damage
Speeds up transmission

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14
Q

Types of neurones

A

Sensory
Motor
Relay

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15
Q

Sensory neurones

A

Transmits impulses from receptors to the CNS

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16
Q

Motor Neurones

A

Transmits impulses from CNS to muscles + glands

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17
Q

Relay Neurones

A

Transmits impulses from sensory to motor neurones

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18
Q

Reflex Arc Steps

A

1) Stimulus is detected by a receptor
2) SN sends impulses to the spinal cord
3) Impulses are passed on to a RN in the spinal cord
4) RN connects to the MN + passes the impulse on
5) MN carries impulse to the muscle

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19
Q

What is Resting State

A

Outside the membrane is +vely charged compared to the inside
Membrane becomes polarised
Resting state = -70mV

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20
Q

How is resting state achieved

A

Caused by the Na - K pump
pumps 3 Na ions out
for every 2 K ions pumped in

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21
Q

Active state

A

Depolarisation
Repolarisation
Hyperpolarisation
Refractory Period

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22
Q

What happens in depolarisation

A

Na channels open
Na ions move into axon
causes -ve feedback

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23
Q

What happens in repolarisation

A

Na channels close
K channels open
K ions move out of axon

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24
Q

What happens in hyperpolarisation

A

K channels stay open for too long
Charge goes below -70mV

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25
What is the refractory period
The recovery time of an axon
26
What happens in the absolute refractory period
Na channels are blocked
27
What happens in the relative refractory period
K channel is open to repolarise neuron is less excitable than normal
28
What happens in the synapse to generate an EPSP
1) AP depolarises the presynaptic neuron 2) Ca channels open + Ca ions diffuse in 3) Synaptic vesicles move to + fuse with the presynaptic membrane 4) A neurotransmitter is released into the synaptic cleft 5) The neurotransmitter moves across the cleft by diffusion 6) Neurotransmitter binds to specific protein receptors on the postsynaptic membrane 7) Na channels open + Na ions diffuse in 8) This causes a change in the pd of the membrane + an EPSP to be generated
29
What is an IPSP
Makes a postsynaptic neuron less likely to generate an AP Allows the movement of -ve ions into the membrane makes the postsynaptic neuron more -ve than normal RP AP is less likely to occur
30
How is acetylcholine recycled
After it attaches to the receptors on the Na channels it is broken down by acetylcholinesterase this hydrolyses acetylcholine into acetate + choline they diffuse back across the cleft into the presynaptic neuron to be recycled
31
How does nicotine affect the synapse before stimulation
Binds to a type of acetylcholine receptor on the postsynaptic membrane This initiates an AP
32
How does nicotine affect the synapse after stimulation
Causes receptors to be unresponsive to other stimulation triggers a release of dopamine this increases heart rate + blood pressure
33
How does lidocaine affect the synapse
Blocks gated Na channels prevents an influx of Na ions in the postsynaptic neuron prevents an AP from being generated
34
Uses of lidocaine
Local anaesthetic Regulate heart beat
35
How does cobra venom affect the synapse
Binds to acetylcholine receptors on the postsynaptic membrane prevents an influx of Na ions + generation of an AP
36
Uses of Cobra venom
A muscle relaxant during asthma attacks
37
Cilary muscles
Pulls the lens for focusing
38
Cornea
Lets light into eye + begins focusing
39
Iris
Controls the amount of light entering he eye
40
Lens
Focuses light onto the retina
41
Optic Nerve
Sends signals to the brain
42
Pupil
Lets light through to the brain
43
Retina
Sends signals to the optic nerve
44
Suspensory Ligaments
Holds the lens in place
45
What is Transduction
Takes place in the retina Converts light into a pattern of nerve impulses
46
Rod cells
Spread across the retina except at fovea Images in black + white More of them than cone cells Used to detect light at low intensities
47
Summation in Rod Cells
Multiple rod cells are connected to 1 bipolar neuron much more likely that the threshold value will be reached by summation
48
Low light in Rod cells
Rhodopsin is broken down to create a generator potential low light intensities have enough energy to break it down rod cells can work in low light
49
Visual Acuity in Rod Cells
Rod cells can't distinguish 2 dots close together light received by different rod cells only generates 1 impulse brain can't distinguish between separate sources of light
50
Cone Cells
Found at fovea Connected to their own separate bipolar neurone Can only respond to high intensity light summation doesn't occur Brain can distinguish between separate sources of light high visual acuity
51
Fovea
part of retina where light is focused on It receives the highest intensity of light
52
Rhodopsin
Formed from opsin + retinal retinal exists as trans + cisretinal
53
retinal in the dark
All retinal is in the cis form
54
retinal in the light
All retinal is in the trans form Change of shape puts a strain on bonding between opsin +retinal breaks the molecule - known as bleaching
55
Bleaching
When rhodopsin is bleached Na channels close making it less permeable to Na Na pump still works Na ions are removed from the cell inside the rod cell is more -ve than normal this hyperpolarisaion is known as the generator potential
56
Chemoreceptors
Control Blood CO2 High CO2 = low pH of blood
57
Low blood CO2 (High pH)
Receptors send impulse to medulla Medulla sends impulses along the parasympathetic NS This secretes acetylcholine which binds to receptors on SAN Heart rate decreases
58
High blood CO2 (Low pH)
Receptors send impulse to medulla Medulla sends impulses along the sympathetic NS This secretes noradrenaline which binds to receptors on SAN Heart rate increases
59
Baroreceptors
Control blood pressure
60
High blood pressure
Receptors send impulse to medulla Medulla sends impulses along the parasympathetic NS This secretes acetylcholine which binds to receptors on SAN Heart rate decreases
61
Low blood pressure
Receptors send impulse to medulla Medulla sends impulses along the sympathetic NS This secretes noradrenaline which binds to receptors on SAN Heart rate increases
62
Hormones
When stressed the sympathetic nerves stimulate the adrenal medulla to release adrenaline this binds to receptors on SAN this increase the frequency of excitation this increases the heart rate so more oxygen + glucose are supplied to the muscle

Biology (30 decks)

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