C13 1-4

Question 1

1. Define peripheral nervous system.

Answer 1

Portion of the nervous system consisting of nerves and ganglia that lie outside of the brain and spinal cord.

Question 2

1. Peripheral nervous system - list its components.

Answer 2

Sensory receptors, peripheral nerves and associated ganglia, efferent motor endings.

Question 3

Stimulus

Answer 3

A change in the environment that evokes a response; excitant/irritant.

Question 4

Sensation

Answer 4

Conscious or subconscious awareness of a stimulus

(much of sensory input is only relayed to lower areas (thalamus/brain stem) where a response is intiated without your awareness)

Question 5

Perception

Answer 5

Conscious awareness and interpretation of the meaning of the stimulus. (cerebral cortex)

Question 6

Why is a receptor a “biological transducer”?

Answer 6

It converts the stimulus into electrical graded potentials.

Question 7

What two features are critical to the function of sensory receptors?

Answer 7

1. Receptors establish and maintain a RMP
2. Receptors contain modality-gated channel within their plasma membrane. Modality gated channels open in response to a stimulus other than a chemical or voltage change.

Question 8

3. Describe sensory receptors, their role.

Answer 8

?

Question 9

What are the classifications of receptors by structural complexity?

Answer 9

Somatosensory receptors vs. sense organs

Somatosensory

• –Nonencapsulated, free/naked nerve endings, simple structure.
• –Encapsulated dendritic endings (wrapped in CT - mechanoreceptors for touch/pressure, more complex)

Sense organs = highly specialized receptor cells (nerve ending combined with epithelial/CT/muscular tissue that enhance or moderate the response to a stimulus.

Question 10

What are the classifications of receptors by stimulus detected?

Answer 10

Chemoreceptors, 
nociceptors, 
mechanoreceptors, 
photoreceptors, 
thermoreceptors

Question 11

What are the classifications of receptors by location or stimulous origin?

Answer 11

Exteroceptors,
interoceptors,
proprioceptors

(external stimuli, visceral sensation, position/movement)

Question 12

Chemoreceptor

Answer 12

O2, pH, various organic molecules like glucose

Question 13

Nociceptor

Answer 13

Pain (tissue damage interpreted as pain) somatic and visceral

Fyi. Activated by thermoreceptors, then heat/cold are perceived as pain.

Question 14

Mechanoreceptor

Answer 14

Pressure, vibration, gravity, acceleration, sound, stretch and most cutaneous. Includes baroreceptors/bp/stretch and distention.

Question 15

Photoreceptor

Answer 15

light photons

Question 16

Thermoreceptor

Answer 16

Heat - present in skin and hypothalamus

Question 17

Receptor distribution?

Answer 17

General senses = throughout body (somatic and visceral) Special senses = localized in the head.

Question 18

What is different about receptors for smell vs. other special sense receptors?

Answer 18

Receptors for smell are neurons. Other senses use non-neural receptor cells that synapse onto sensory neurons.