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Flashcards in Senses and Perceptions Deck (55)
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1

What is the function of specific sensory receptors

To convert stimulus into an electrical action potential

2

What type of cell is a sensory skin receptor

Pseudounipolar

3

What is the name of receptor and sensation for a mechanical stimulus

Mechanoreceptor
Touch

4

What is the name of receptor and sensation for a thermal stimulus

Thermoreceptor
Hot, cold

5

What is the name of receptor and sensation for a noxious stimulus

Nociceptor
Pain

6

What is the name of receptor and sensation for a chemical stimulus

Chemoreceptor
Taste, smell

7

What is the name of receptor and sensation for a light stimulus

Photoreceptor
Sight, vision

8

What is the name of receptor and sensation for a sound stimulus

Mechanoreceptor
Hearing

9

What is the name of receptor and sensation for a limb position stimulus

Proprioceter
Spatial awareness

10

What is the name of receptor and sensation for a blood pressure stimulus

Baroreceptor

11

What is a nerve receptor

A neuron with a cluster of peripheral nerve branches, each with a nerve ending

12

What is a receptive field

The distribution of a neurons receptors

13

What is two point discrimination

The ability to discern two separate mechanical stimuli
A measure of spatial awareness
An indication of receptive field size

14

How does two point discrimination relate to receptive fields and cortical representation

Areas with small two point discrimination have small receptive fields and large cortical representation

15

Give an example of an area with small receptive fields

Finger tips

16

Give an example of an area with large receptive fields

The trunk

17

How is a stimulus transduced

Stimulus causes change in receptor membrane permeability. This causes an influx of cations which causes depolarisation, changing the resting membrane potential. This generates an action potential

18

How are mechanoreceptors activated

Fore opens ion channel as structures tethered to the intracellular membrane move causing the pulling open of the channel

19

What are the different types of chemoreceptors

Ionotropic
G-protein coupled

20

How does a ionotropic chemoreceptor work

Binding to receptor protein causes opening of ligand gated channel leading to generation of AP

21

How does a G-protein coupled receptor work

Pore is recruited and chemical binds to receptor, causing channel to open
Chain of events takes longer so channel stays open for longer

22

How is the stimulus quality coded

Type of receptor

23

How are the stimuli magnitude and intensity coded

AP frequency

24

How are the stimuli duration and timing coded

Number of neurons activated
Duration of AP firing

25

How is the stimulus location coded

Where

26

How is action potential intensity coded

Frequency of AP discharge
High stimulus intensity = high AP frequency

27

How can APs adapt

Slowly and rapidly

28

What happens to neurons of the same function

They bundle together and are grouped into pathways

29

How are pathways specific

Modality specific eg - touch, pain, vision

30

Where are cell bodies of sensory neurons collected

In dorsal root ganglia

31

What are Ruffini’s and pacinian receptors related to

Slipping and vibration

32

Describe a hair follicle receptor

Axon is wrapped around receptor, when hair is pulled, the membrane is deformed - mechanical

33

What is the brachial plexus

Bundles of cables of sensory and motor axons providing innervation to the upper limb

34

What are the groups of nerves in the brachial plexus

Axillary
Musculocutaneous
Radial
Ulnar
Median

35

What is the epineurium

Tough connective tissue bundling nerves that supply separate skin regions

36

Describe A alpha axons

Thickest diameter and myelin sheath
Proprioceptors - sensory nerve that responds to position and movement

37

Describe A beta axons

Conduction velocity still quick but slower than A alpha - same for thickness of myelin sheath
Involved in i oculus tactile sensation and perception of mechanoreceptor in skin

38

Describe A delta axons

Small axon diameter, thin myelin sheath
Conduct APs pretty quickly but slower that A alpha and beta
Important in perception of sharp, stabbing pain
Also recruited in thermoreceptors

39

Describe C axons

Conduct APs slowly
Convey perception of dull aching pain

40

Where do sensory axons enter the CNS

Via the dorsal roots

41

Where do motor axons exit the CNS

Via the ventral roots

42

Describe the cervical spinal cord

Grey matter in the middle, surrounded by white matter
Dorsal surface closer to back, ventral surface closer to abdomen

43

Where are motor efferent axons derived from

Grey matter in the ventral horn - ventral root is motor axons only

44

Describe the trigeminal nerve

CN V
Ophthalmic and maxillary branch - sensory
Mandibular branch - motor

45

Which nerves control sensory pathways innervating the face

CNV

46

Which nerves control sensory pathways innervating the body apart from the head

Spinal nerves

47

Describe a sensory pathway

Primary sensory neuron in the periphery projecting into the CNS
Secondary sensory neuron in the CNS
Tertiary sensory neuron in the thalamus in the CNS

48

Describe the dorsal column - medial lemniscal all pathway

Mechanoreceptor (somatic)
A beta axon of secondary swaps to other side of the brain where it connects to the tertiary sensory neuron
It then projects to the appropriate region in the sensory cortex

49

Describe the posterior (dorsal) trigeminothalamic tract

Mechanoreception (trigeminal nerve)

50

Describe the spinothalamic pathway

Nociception (somatic)
Primary goes to spinal cord meeting secondary in dorsal horn, which crosses to the other side of the brain and ends in the thalamus. Tertiary goes from thalamus to sensory cortex

51

Describe the anterior (ventral) trigeminothalamic tract

Nociception (trigeminal nerve)

52

Why is the brain image distorted

The more sensory neurons that supply an area, the more brain space in the cortex
Areas with high density (small receptive fields) are represented more widely in the cortex
Sensation is recruitment of sensory pathways leading to appreciation of the stimulus

53

What is stereognosis

The ability to recognise objects by the feel alone
Requires a 3D mental image and need to compare with previous experiences - memory
Activates dorsal column pathway

54

What is proprioception

Appreciating where our body parts are in space without looking

55

Give examples of proprioception

Balance in the inner ear - utricle, saccule, semicircular canals, head posture, overall balance
Joint receptors - joint position, angle
Muscle receptors - muscle length tension
Periodontal receptors - tooth contact, bite force