Weeks 5 & 6 - Senses

Receptive field

An area monitored by a single sensory neuron.

Receptor specificity

A receptor that prefers a specific type of receptor (e.g. insulin specifically binds to insulin receptors in the pancreases).

How does a receptor respond to a stimulus?

Chemically or mechanically gated channels open and causes a graded potential (changing the permeability of the membrane), producing an action potential.

How does the type of stimulus (sensory modality) contribute to the interpretation of sensory information?

Sensory modality determines which type of stimulus has been detected depending what type of receptor is discharging the action potential.

How does the stimulus location contribute to the interpretation of sensory information?

Stimulus location determines where the sensory information originated from in the body.

How does stimulus intensity contribute to the interpretation of sensory information?

Stimulus intensity determines how many receptors are activated and the frequency of discharge of action potentials.

How does stimulus duration contribute to the interpretation of sensory information?

Stimulus duration determines how long does the sensory neuron discharge action potentials.

What are the four classes of receptors?

• Thermoreceptors

• Chemoreceptors

• Mechanoreceptors

• Nociceptors

Thermoreceptors

A class of receptors activated by body temperature.

Chemoreceptors

A class of receptors activated by small changes in the concentration of specific chemicals (e.g. carbon dioxide) or pH.

Mechanoreceptors

A class of receptors activated by stimuli that physically distorts their plasma membrane (e.g. bending, stretching).

Nocieceptors

A class of receptors activated by actual or potential tissue damage like extreme temperature, mechanical damage, and certain dissolved chemicals.

What are the three classes of mechanoreceptors?

• Tactile receptors

• Baroreceptors

• Proprioceptors

Tactile receptors

A class of mechanoreceptors found in the skin which respond to different types of stimuli.

Baroceptors

A class of mechanoreceptors found in the walls of carotid artery and aorta and in-distensible organs (like heart and tracts) which monitor changes in pressure.

Proprioceptors

A class of mechanoreceptors found in different areas of the body and monitors joint position, tendon tension, and skeletal muscle stretch.

Where are muscle spindles and Golgi tendon organs found and what type of stimulus do they detect?

Muscle spindles are found in skeletal muscles that detect increased muscle stretch whereas Golgi tendon organs are found in tendons of skeletal muscles that detect increased muscle tension.

What shape are sensory neurons and where is the receptor, axon, and cell body located?

Sensory neurons are unipolar where the receptors are in the dendrites, merging into one axon, and cell bodies are located towards the middle of axon on the side.