Homework

Lec. 14 Notes

Neurophysiology III

Introduction:

Sensory neurons provide our bodies with information from our surrounding environment.

Specialized sensory neurons include:

1. Nerve cells-photoreceptors of the eye/hair cells-olfactory cells of the nose.

2. Nerve endings –naked endings and respond to pain or encapsulated in pacinian

corpuscle.

3. Epithelial cells-taste cells on the tongue> these are non-neuronal!!

Somatic Senses

vs.

-involve receptors in the skin, muscles,

tendons, joints, and visceral organs.

Special Senses

-The five senses (details about these later).

1. Exteroceptive senses=changes on

the body surface from light, pressure

etc.

2. Proprioceptive senses = have to do with

the body’s position as well as it’s movement

Ex. muscle length/tension, equilibrium etc.

3. Visceroceptive/interoceptive senses=changes in

the body’s internal environment. Ex. Blood pressure

Types of Stimulus:

*Photoreceptors> light

*Chemoreceptors>chemicals Ex. Changes in pH, metabolite concentrations etc.

*Mechanoreceptors>respond when deformed by mechanical forces. Receptors for sound and

balance in the ear also involved with these.

*Thermoreceptors> warmth/cold

*Nociceptors>pain receptors. Specifically, tissue damage provides stimulus.

Definitions:

 Transduction= the receptor in a cell converts some of the stimulus energy into an

electrical signal that provides information for the nervous system.

 Threshold=minimal level of excitement required for a nerve receptor to be excited.

 General Potential=weak stimulus that initiates a depolarization below threshold.

 Frequency code=the frequency of action potentials increases as the stimuli intensity

increases.

Objectives I-III are all pretty well covered in the intro. , so the bulk of the notes are started with

Objective IV.

Objective IV: Threshold

In order to excite a receptor it has to have its specific, corresponding stimulus as well as

intense/strong enough to activate a threshold...