Senses And Perceptions 1

Question 1

What things need to be considered during mechanical stimulation of the skin

Answer 1

What type of touch? Quality
How big is it? Magnitude, intensity
How long? How often? Duration/timing
Where? Location

Question 2

How do we convert a stimulus into an electrical signal (action potential)?

Answer 2

Modality specific sensory receptors

Question 3

How is the information transmitted faithfully

Answer 3

Modality specific sensory pathways

Question 4

What receptor does a mechanical stimulus activate

Answer 4

Mechanoreceptors, sensation is touch

Question 5

What receptor does a thermal stimulus activate

Answer 5

Thermoreceptor

Question 6

What receptor does a noxious stimulus activate

Answer 6

Nociceptor

Question 7

What receptor does a chemical stimulus activate

Answer 7

Chemoreceptor

Question 8

What receptor does a licht stimulus activate

Answer 8

Photoreceptors

Question 9

What sensation does a mechanical stimulus provide

Answer 9

Touch

Question 10

What sensation does a thermal stimulus produce

Answer 10

Temperature

Question 11

What sensation does a noxious stimulus provide

Answer 11

Pain

Question 12

What sensation does a chemical stimulus provide

Answer 12

Taste, smell

Question 13

What sensation does licht stimulus provide

Answer 13

Sight, vision

Question 14

What are receptive field properties

Answer 14

Each sensory neuron has a cluster of peripheral nerve branches, each with receptor endings, the distribution of these receptor endings defines a neurons receptive field

Question 15

Describe the position of the receptor fields

Answer 15

All the receptor fields overlap, there are many in the body

The receptor fields overlapping means every area on the body will have some form of receptor ending

Question 16

Describe the sizes of receptor fields

Answer 16

They will vary in size in different regions in the body, they are small in the periphery and large on the trunk

Question 17

What is two point discrimination

Answer 17

The ability to discern two separate mechanical stimuli
- a measure of spatial resolution
- an indicator of receptive field size

Question 18

What is the sequence of signal transduction

Answer 18

Stimulus > change in receptor membrane permeability > influx of cations > depolarisation - receptor potential > action potential (AP)

Question 19

What is the difference between ionotropic receptors and G protein coupled receptors

Answer 19

Ionotropic has fast kinetics and G protein coupled has slow kinetics

Ionotropic - mechanoreceptor and chemoreceptor
G protein coupled - chemoreceptor

Question 20

Describe how ionotropic mecahnoreceptors are opened

Answer 20

On the inside of the cells membrane, in the inactive state it is closed, force changes the formation of the cell membrane, as a consequence of the mechanical force it pulls the fibrils away and the pore will open,this allows the transfer of both sodium and potassium ions

Question 21

Describe how the ionotropic chemoreceptors are opened

Answer 21

The channels become active when a ligand binds to the channel and opens it

Question 22

Describe how a G protein coupled chemoreceptor opens

Answer 22

A serious of proteins is linked to the G protein receptor when a ligand binds to the receptor this induces a protein cascade which will open the channels

Question 23

What is the coding for quality

Answer 23

Type of receptor

Question 24

What is the stimulus for AP frequency, number neurons activated

Answer 24

Magnitude/intensity

Question 25

What is the coding for duration/timing

Answer 25

Duration of AP firing

Question 26

What is the coding for the location

Answer 26

Receptive field

Question 27

What is the sensory homunculus

Answer 27

The body map in the brain
The receptor field sizings at different parts of the body

Question 28

What is the stimulus location

Answer 28

Coded by receptive field activated