Senses and Perceptions

Question 1

What is the function of specific sensory receptors

Answer 1

To convert stimulus into an electrical action potential

Question 2

What type of cell is a sensory skin receptor

Answer 2

Pseudounipolar

Question 3

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

Answer 3

Mechanoreceptor

Touch

Question 4

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

Answer 4

Thermoreceptor

Hot, cold

Question 5

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

Answer 5

Nociceptor

Pain

Question 6

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

Answer 6

Chemoreceptor

Taste, smell

Question 7

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

Answer 7

Photoreceptor

Sight, vision

Question 8

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

Answer 8

Mechanoreceptor

Hearing

Question 9

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

Answer 9

Proprioceter

Spatial awareness

Question 10

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

Answer 10

Baroreceptor

Question 11

What is a nerve receptor

Answer 11

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

Question 12

What is a receptive field

Answer 12

The distribution of a neurons receptors

Question 13

What is two point discrimination

Answer 13

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

Question 14

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

Answer 14

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

Question 15

Give an example of an area with small receptive fields

Answer 15

Finger tips

Question 16

Give an example of an area with large receptive fields

Answer 16

The trunk

Question 17

How is a stimulus transduced

Answer 17

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

Question 18

How are mechanoreceptors activated

Answer 18

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

Question 19

What are the different types of chemoreceptors

Answer 19

Ionotropic

G-protein coupled

Question 20

How does a ionotropic chemoreceptor work

Answer 20

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

Question 21

How does a G-protein coupled receptor work

Answer 21

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

Question 22

How is the stimulus quality coded

Answer 22

Type of receptor

Question 23

How are the stimuli magnitude and intensity coded

Answer 23

AP frequency

Question 24

How are the stimuli duration and timing coded

Answer 24

Number of neurons activated

Duration of AP firing

Question 25

How is the stimulus location coded

Answer 25

Where

Question 26

How is action potential intensity coded

Answer 26

Frequency of AP discharge | High stimulus intensity = high AP frequency

Question 27

How can APs adapt

Answer 27

Slowly and rapidly

Question 28

What happens to neurons of the same function

Answer 28

They bundle together and are grouped into pathways

Question 29

How are pathways specific

Answer 29

Modality specific eg - touch, pain, vision

Question 30

Where are cell bodies of sensory neurons collected

Answer 30

In dorsal root ganglia

Question 31

What are Ruffini’s and pacinian receptors related to

Answer 31

Slipping and vibration

Question 32

Describe a hair follicle receptor

Answer 32

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

Question 33

What is the brachial plexus

Answer 33

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

Question 34

What are the groups of nerves in the brachial plexus

Answer 34

``` Axillary Musculocutaneous Radial Ulnar Median ```

Question 35

What is the epineurium

Answer 35

Tough connective tissue bundling nerves that supply separate skin regions

Question 36

Describe A alpha axons

Answer 36

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

Question 37

Describe A beta axons

Answer 37

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

Question 38

Describe A delta axons

Answer 38

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

Question 39

Describe C axons

Answer 39

Conduct APs slowly | Convey perception of dull aching pain

Question 40

Where do sensory axons enter the CNS

Answer 40

Via the dorsal roots

Question 41

Where do motor axons exit the CNS

Answer 41

Via the ventral roots

Question 42

Describe the cervical spinal cord

Answer 42

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

Question 43

Where are motor efferent axons derived from

Answer 43

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

Question 44

Describe the trigeminal nerve

Answer 44

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

Question 45

Which nerves control sensory pathways innervating the face

Answer 45

CNV

Question 46

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

Answer 46

Spinal nerves

Question 47

Describe a sensory pathway

Answer 47

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

Question 48

Describe the dorsal column - medial lemniscal all pathway

Answer 48

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

Question 49

Describe the posterior (dorsal) trigeminothalamic tract

Answer 49

Mechanoreception (trigeminal nerve)

Question 50

Describe the spinothalamic pathway

Answer 50

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

Question 51

Describe the anterior (ventral) trigeminothalamic tract

Answer 51

Nociception (trigeminal nerve)

Question 52

Why is the brain image distorted

Answer 52

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

Question 53

What is stereognosis

Answer 53

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

Question 54

What is proprioception

Answer 54

Appreciating where our body parts are in space without looking

Question 55

Give examples of proprioception

Answer 55

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