Lecture 20

Question 1

4 Somatic senses

Answer 1

1. touch
2. Temperature
3. Proprioception
4. nociception, i.e. pain and itch

Question 1

5 Special senses

Answer 1

1. Vision
2. Hearing
3. Equilibrium
4. Taste
5. smell

Question 2

transduction

Answer 2

The conversion of stimuli from receptors into electrical signals

Question 3

The receptors’ adequate stimulus

Answer 3

is the form of energy to which it is most responsive, e.g. thermoreceptors respond most sensitively to temperature.

Question 4

Chemoreceptors

Answer 4

respond to specific molecules or ions, e.g. to + glucose, or oxygen, or H .

Question 5

Mechanoreceptors

Answer 5

respond to mechanical energy such as pressure, vibration, gravity, and sound.

Question 6

Thermoreceptors

Answer 6

respond to temperature

Question 7

Photoreceptors

Answer 7

respond to light

Question 8

receptor threshold

Answer 8

the weakest stimulus that will cause a response in the receptor

Question 9

perceptual threshold

Answer 9

it is the weakest stimulus that will cause a conscious perception in the organism, e.g. it takes ~40 odorant molecules for you to perceive a smell.

Question 10

Stimulus modality

Answer 10

Sensory systems indicate modality by labelled lines, meaning that the modality is revealed by which axons carry the signal

e.g. activity on neurons in the visual pathway means light

Question 11

Groups of neurons can represent intensity in 2 ways…

Answer 11

1. Stronger stimuli may activate more neurons.
2. Stronger stimuli may make the individual neurons fire at a faster rate.

Question 12

6 types of retinal cells

Answer 12

Rods.
Cones.
Retinal Ganglion cells.
Bipolar cells.
Horizontal cells.
Amacrine cells.

Question 13

Phasic cells

Answer 13

respond briefly to any change and then cease firing.

Question 14

Tonic cells

Answer 14

maintain their activity when the stimulus is not changing, signaling its present level.

Question 15

Phasic-tonic

Answer 15

cells react to change but don’t return all the way to zero firing when the stimulus is constant, so they also carry information about its steady level.

Question 16

Lateral inhibition

Answer 16

means that cells inhibit their neighbors, or they inhibit the cells their neighbors excite.

Question 17

Most sensory pathways run via the ________ to the __________

Answer 17

thalamus
cortex
(olfactory pathways are an exception)