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pharmacology > sensory reception > Flashcards

sensory reception Flashcards

1
Q

what does the sensory system coordinate ?

A 
vision 
olfaction(smell) 
auditory ( hearing) 
Balance / movement proprioception
Gustatory /taste 
somatic sensory / touch
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2
Q

what is the function of the sensory reception?

A

maintains homeostasis

detects and reacts to changes in the environment such as temperature changes

protects the body from noxious ( damaging) stimuli.

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3
Q

mechanism of sensory reception ( diagram flow ) ?

A

stimuli is sensed by the sensory receptor , this then travels in the afferent neurone to the CNS ( integration centre) , then the efferent neurone travels to the effector organ which could be a muscle or gland and a response is produced.

The response affects the stimuli and a feedback loop occurs.

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4
Q

cutaneous receptors?

A

These are located within the skin and they sense touch , pressure , temperature and pain.

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5
Q

proprioceptors ?

A

senses body position and movement.

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6
Q

special senses ?

A

these sense sight , hearing , taste and smell

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7
Q

what is similar between all 3 of these receptors ?

A

the structure

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8
Q

what is the main nerve (long) ?

A

afferent nerve that travels from the receptor to the CNS

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9
Q

what type of receptor does this lecture focus on ?

A

cutaneous

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10
Q

what are the nerve endings like and where are they located ?

A

free nerve endings , located close to the surface of the skin

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11
Q

what are they sensitive to ?

A

pain and temperature

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12
Q

for pain reception , ATP is released. Where to and what receptor does it stimulate ?

A

into the extracellular space and they stimulate the P2W3 .

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13
Q

what does the stimulation of the receptors cause ?

A

causes Na+ to enter the sensory nerve and depolarisation occurs and an action potential.

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14
Q

when are prostaglandin’s released and what type of receptors do they act on ?

A

in response to stress and they act on GPCR’s which results in an action potential.

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15
Q

what is prostaglandin synthesis inhibited by ?

A

aspirin and ibuprofen which is used to treat pain.

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16
Q

when are the cold sensory receptors activated and what by ?

A

below 15 degrees celsius and my menthol.

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17
Q

when are the noxious hot sensory receptors activated and what happens when they are ?

A

active at high temperatures and they result in the TRPv1 channel opening which allows Na+ to enter. They are activated by capsicum which is found in chilli’s.

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18
Q

in C fibres what do the Schwann cells form and why ?

A

form a meshwork in the skin , not around the neurone and this helps to detect mechanical pain and the signal is transmitted along the C fibre.

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19
Q

what is found in the pacinian corpuscle ?

A

mechanoreceptors which are sensitive to pressure and vibration

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20
Q

what are the nerves in the mechanoreceptors surrounded by.

A

connective tissue

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21
Q

what can the Merkel discs detect , also what does the stimulation result in ?

A

can detect texture and sharp edges , the physical stimulation of these discs cause 5HT to be released and this activates the 5HT3 – R receptors on the Aß fibres. This causes depolarisation and action potentials.

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22
Q

what do the Merkel discs help to protect against ?

A

innocuos mechanical itch

23
Q

what occurs to the Merkel discs in old age and dry skin ?

A

the Merkel discs decrease in number and the mechanical itch increases

24
Q

if the stimuli is weak and it doesn’t cause a change in the receptor potential why is there no action potential ?

A

as the threshold hasn’t been reached

25
Q

what occurs to the receptor potentials and action potentials as the stimuli strength increases?

A

the R.P and A. P increase in frequency and number

26
Q

if the stimuli is applied for a long time what happens ?

A

the A.P and R.P decrease and this is called adaptation

27
Q

slow adaptation ?

A

this occurs in response to pain , temperature and body position. The frequency of A.P decrease but they never stop fully ,there is a continual awareness of the stimuli. This is crucial for awareness of pain so we do not hurt ourselves.

28
Q

fast adaptation ?

A

this is when the R.P has a rapid depolarisation to baseline and the A.P stop. The A.P start again if the stimuli is removed. This adaptation occurs so we can ignore unimportant information such as a watch on our wrist.

29
Q

1st order neurone ?

A

project’s from the stimuli receptor to the spinal cord/brainstem.

30
Q

2nd order neurone ?

A

extends from the spinal cord/brain stem to the thalamus where it synapses with the 3rd order neurone

31
Q

3rd order neurone ?

A

travels from the thalamus to the cortex

32
Q

what are the 2 different sensory pathways of the brain ?

A

dorsal column system ( DLS) and the spinothalamic system ( STS).

33
Q

is the DLS pathway myelinated ?

A

yes

34
Q

describe it ?

A

travels along the spinal cord to the medulla oblongata where it synapses with the 2nd order neurons where decussation occurs , which is a pathway cross to the other side of the brain.

35
Q

is the STS myelinated ?

A

sparsely

36
Q

describe it ?

A

where the pathway goes straight from the spinal cord to immediately synapse with the second order neuron , it doesn’t pass the medulla. It then crosses over and enters the thalamus then the 3rd order neuron to the cortex.

37
Q

what is the main difference between the 2 pathways ?

A

2nd order neurons

38
Q

what is the post central gyrus ?

A

what we sense and are aware of , all the information is processed via the 3rd order neurons.

39
Q

what are the 2 types of nociceptors ( pain) receptors and describe them ?

A
  • A ß fibres which are myelinated so travel faster to CNS and they an sense sharp pain
  • C fibres which are un-myelinated and they sense a slow dull aching pain.
40
Q

what pathway is responsible for the transmission of pain and temperature ?

A

Spinothalamic pathway.

41
Q

referred pain ?

A

when the perceived pain comes from a different part of the body than where it was generated. This occurs because the 2 neurons synapse in the same place.

42
Q

what is the modulation of pain carried along ?

A

the C fibre

43
Q

what do enkephalins do ?

A

bind to opioid receptors that release controls the levels of pain , ( pain killer effects). They bind to the same receptor as morphine.

44
Q

what is the spinal cord - gate control theory of pain ?

A

In C fibres Interneurons have an inhibitory effect and they inhibit the release of enkephalins so you are aware of the pain.

The Aß fibre is activated by rubbing and this stimulates the interneurons and enkephalins are released. This inhibits the pain signal travelling to the thalamus.

45
Q

does the A beta fibres and C fibres synapse in the same area of the spinal cord ?

A

nope different

46
Q

what is different between the A beta and C fibre ?

A

when the A beta fibres are compared to the C fibres and there are no inter-neurones that release enkephalins to control the pain as a result the 5-HT is ineffective. There is no opiate receptors = morphine ineffective and as a result sharp pain is harder to treat.

47
Q

what stimulates enkephalin release and what is the result?

A

5-HT and inhibition of pain transmission

48
Q

can you treat C fibre pain ( slow ache) with opioids ?

A

yes

49
Q

can you treat A beta fibre pains ( sharp) with opioids ?

A

nope as no opioid receptors

50
Q

everyone modulates pain differently such as childbirth , why is this ?

A

could be due to previous experience , genetics , sensitisation and mood

51
Q

what are NSAIDS ?

A

non steroidal anti inflammatory drugs such as aspirin and ibuprofen, They block COX-1 and Cox-2 which blocks inflammation and the release of prostaglandins.

52
Q

anaesthetics such lidocaine are injected locally , how do they work ?

A

block the voltage dependent Na+ channels which blocks action potentials occurring as there is no depolarisation from Na ions.

53
Q

how to opioids work ?

A

morphine and they inhibit the release of neurotransmitter which hyper- polarise the neurons. They become less effective over time.

pharmacology (21 decks)

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