Principles of Sensory Systems

Question 1

Recall the major types of sensory receptors.
Hearing
Balance
Vision
Touch
Temperature
Pain
Proprioception
Olfaction
Taste

Answer 1

Hearing - Mechanoreceptor
Balance - Mechanoreceptor
Vision - Photoreceptor
Touch - Mechanoreceptor
Temperature - Thermoreceptor
Pain - Nociceptor
Proprioception - Mechanoreceptor
Olfaction - Chemoreceptor
Taste - Chemoreceptor

Question 2

Describe the features common to most or all sensory receptors.

Answer 2

-Sensory receptors are cells
-Possess ion channels and G-protein coupled receptors
-Information from the environment turns into electrochemical signals in the sensory receptors
-Sensory transduction

Question 3

Define:
Sensory transduction

Answer 3

energy transformation from the external world to the internal world

Question 4

Define:
Receptive field

Answer 4

a specific region of sensory space in which an appropriate stimulus can drive an electrical response in a sensory neuron

Question 5

Define:
Tonic receptors

Answer 5

slow adapting receptors. They will respond to the stimulus as long as it persists, and produce a continuous frequency of action potentials. Hence, they convey information about the duration of the stimulus

Question 6

Define:
Phasic receptors

Answer 6

a sensory receptor that adapts rapidly to a stimulus. The response of the cell diminishes very quickly and then stops. It does not provide information on the duration of the stimulus; instead some of them convey information on rapid changes in stimulus intensity and rate

Question 7

Define:
Adaptation

Answer 7

a common property of all sensory receptors. As a stimulus constantly excites the receptor, there will be a decrease in the rate of action potentials

Question 8

Define:
Sensory modality

Answer 8

one aspect of a stimulus or what is perceived after a stimulus

Question 9

Describe, with examples, how sensory systems convey four basic types of information.

Answer 9

Modality
-Specificity for sensory modalities is achieved by the structure and position of the sensory receptor

Location
-Spatial arrangement of activated receptors within a sense organ gives information about the stimulus
-In the somatic system, a receptive field is the region of skin innervated by the terminals of the receptor neuron

Intensity
-The total amount of stimulus energy delivered to the receptor
-The lowest stimulus strength that can be detected is the sensory threshold
-Determined by the response amplitude of the receptor and thus the firing frequency of the afferent neurons

Timing
-Onset timing is determined by when the stimulus energy is received by the receptor and causes it to fire
-Stimulus duration is determined by adaptation rates of receptors