BIO PSYC - NEURONS & NTRS Flashcards

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1
Q

What are the main 3 functions of the nervous system?

A
  • to collect information about eh environment (internal and external)
  • to process and integrate theat information
  • to send out signals to actuations upon that information
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2
Q

What are the tyo types of nervous system cells

A
  • neurons
  • supporting cells (glia and glial cells)
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3
Q

List 5 organelles in a neurone and their function:

A
  1. dendrite - recieve the signal
  2. cell body or soma - metabolic centre of the neuron
  3. axon - thin fibre which conveys the impulse
  4. myelin sheath = made by shwann cells is an insulating material with breakes calles nodes of ranvier
  5. axon terminal - transmits the signal on
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4
Q

What are afferent neutrons? (sensory)

A
  • transmit information about the external and internal body to the CNS
  • communicate information about
    pain
    temperature
    hunger
    touch/ pressure
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5
Q

What are efferent neurons (motor)

A
  • transmit information FROM the CNS
  • carry signals to act to muscles, skin, glands
    allows us to move, sweat and eat
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6
Q

What are interneurons?

A
  • connect various neurons within CNS to form complex networks
  • integrates information recieved from afferent neurons
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7
Q

Random facts about neurons:

A
  • adult human brain contains 100 billion neurons
  • cell body ranges from 0.05mm to 0.1mm in mammals
  • the length of an axon can be a meter or more
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8
Q

What is Glia?

A
  • helper cells
  • DO NOT transmit information
  • smaller and more numerous that neurons (90%)
  • help protect, feed and insulate neurons
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9
Q

What is an impulse?

A
  • the way in which messages are sent along neurons
  • reception, conduction and transmission of electrochemical signals
  • information passes down the axon
  • into the axon terminal
  • over the synapse
  • into the dendrites of the next neutron
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10
Q

What are the three substances taht are key in neuronal transmission?

A
  • sodium
  • potassium
  • calcium
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11
Q

What is resting potential?

A

At rest
- no impulse
- positive on the outside (respect to inside)
- more sodium ions outside the axon than potassium
- there is a concentratiuon gradient
- sodium trying to get in
- potassium trying to get out
- some seepage of ions
- this is maintained by a sodium potassium pump
- requires energy
- moves sodium out and potassium into the axon
- ‘artificial’ concentration gradient
- membrane potential in the axon (-70mV)
- net negative charge inside the axon
- membrane said to be polarised
- membrane potential changes when the neuron fires
- causes an action potential

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12
Q

What is depolarisation

A
  • whena. neuron receives a signal it causes sodium channels in the axon to open
  • ## sodium ions flow in and the inside of the axon becomes positive with respect to the outside
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13
Q

What is repolarisation?

A
  • sodium channels close and potassium channels open
  • potassiumions flow out - movement swaps the polarity
  • outside becomes more positive with respect to the outside
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14
Q

What is hyperpolarisation?

A
  • potassium channels open and close very slowly
  • too much potassium diffuses out
  • the membrane potential drops below -70mV
  • this is corrected by the sodium and potassium leaking through the membrane
    (membrane back to resting potential)
  • hyperpolarisation (the refractory period)- no other action potential can occur
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15
Q

Explain the all or nothing law:

A
  • if a stimulus is above -55mV threshold, a neuron will fire
  • strength of action poytential is dependent of the intensity of the stimulus that initiated it
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16
Q

How do we gauge stimulus intensity?

A
  • a neuron firing at a faster rate indicates a stronger intensity stimulus
  • numerous neurons firing simultaneously or in rapid succession would also indicate a stronger stimulus
17
Q

How do we determine different sensory inputs?

A

Different type sof sensory receipt
- smell
- taste
- vision
- auditory
- temperature
- mechanical
- internal

these detect different changes in the environment, but the resulting action potential is always the same

18
Q

How do anaesthetic drugs work?

A
  • novocain ans xylocaine attatch to the sodium ion channels preventing the sodium ions from entering
  • this stops action potentials
  • receptions are screaming PAIN but the message is not transmitted
19
Q

What are myelinated neurons?

A
  • glial cells form myelination
  • action potential only occurs at the nodes of ranvier
  • faster impulse as it jumps from one node to the next
20
Q

What are synapses?

A
  • the impulse needs to pass out of the one neurone to another
  • over the synaptic gap or cleft
  • done via electrical synapses or chemical synapses
21
Q

What are electrical synapses?

A
  • two neurons are connected by small holes called gap junctions
  • allows the action potential to pass from one neuron to the other
22
Q

What are chemical synapses?

A
  • they have a gap for the action potential to jump
  • when action potential reaches the terminal end of the pre synaptic neuron calcium channels open
  • calcium flows in
  • the calcium causes the synaptic vesicle to. move to and merge with the pre synaptic membrane
  • these neurotransmitters fuse with the receptor cells in the post synaptic membrane
23
Q

What are neurotransmitters?

A
  • important in synaptic transmission
  • they are released from the axon by action potentials
  • chemical messengers that carry, boost and balance signals
  • many different types
  • could influence heart rate, sleep, apetite and mood
24
Q

What are excitatory neurotransmitters?

A
  • increase the likihood that the neuron will fire an action potential

e.g noradrenaline
- attention/ arousal

25
Q

What are inhibitory neurotransmitters?

A

Decrease the likelihood that the neuron will fire an action potential

E.g
- seretonin
regulating emotions
selective seretonin reuptake inhibitors used in treating depression

26
Q

Give 2 examples of neurotransmitters that are both inhibitory and excitatory?

A

Dopamine
- reward motivated behaviour

Acetylcholine
- important in muscle contraction and cognitive functions

27
Q

What are agonist and antagonist drugs?

A

Antagonistic - blocks neurotransmitter

Agonist - mimics/ increases neurotransmitter

28
Q

What are stimulant drugs?

A

Amphetamine, cocain ect..
- supress re-uptake of dopamine
- small dose - enhance attention
- high dose - impair attention and learning
- dopamine depleted after a few hours

29
Q

What are the associations between depressiona nd neurotransmitters?

A
  • depression is a disturbance in the brain circuits associated with monoamines - seratonin and noradrenaline
  • drugs that depletes monoamines lead to depression
  • drugs that inhibit breakdown improve mood