chapter 13: Peripheral Nervous system and Reflexes

Question 1

What are sensory receptors?

Answer 1

specialized receptors that respond to environmental stimuli

Question 2

What is sensation?

Answer 2

awareness of a stimulus

Question 3

What is perception?

Answer 3

interpretation of the meaning of that stimulus (in brain)

Question 4

What are the 5 types of classification of receptors by stimulus type?

Answer 4

MECHANOreceptors - touch, pressure, stretch
THERMOreceptors - temperatuere (hot/cold)
PHOTOreceptors - light
CHEMOreceptors - chemicals
NOCICEPTORS - pain

Question 5

What are the 3 types of receptor classifications by location?

Answer 5

exteroreceptors - sense changes outside the body

interoreceptors - sense changes inside the body (visceral)

proprioreceptors - located in skeletal muscles and joints

Question 6

What do poprioreceptors do?

Answer 6

provide information on body position

ex muscle spindles

Question 7

Where are complex receptors found?

Answer 7

in special sense organs

ex. eye, ear

Question 8

what are the two types of simple receptors?

Answer 8

receptors with….

• ***unencapsulated (free) dendritic endings
• thermoreceptors
• nociceptors
• merkel disks (light touch)
• hair follicle receptors (light touch)

****encapsulated dendritic endings
(all are mechanoreceptors)
- meissner's corpuscles (light pressure)
- pacinian corpuscles (deep pressure)
- ruffini endings (deep, cont pressure)
- muscle spindles (muscle stretch)
- Golgi tendon organ (stretch in tendons)

Question 9

What are the three levels of integration of sensory input?

Answer 9

1) receptor level
2) circuit level - ascending pathways
3) perceptual level - neuronal circuits in the cerebral cortex

Question 10

Describe the processing of a stimulus at a receptor level.

Answer 10

receptor responds to changes in E

• receptor TRANSDUCES E to changes in membrane potential.
• these changes called GRADED POTENTIALS
• these potentials are INTEGRATED at sensory neuron
• if it reaches threshold, AP (GENERATOR POTENTIAL) is generated and transmitted to CNS

Question 11

How is the intensity of a stimulus coded for?

Answer 11

in frequency

Question 12

What happens to some receptors if they are exposed to the same constant stimulus?

Answer 12

they adapt to reduce the sensitivity

Question 13

What are tonic receptors? do they tend to adapt?

Answer 13

tonic receptors generate impulses constantly and respond to inhibitory and excitatory stimuli. (ex equilibrium receptors in ear, nociceptors)

DO NOT usually adapt

Question 14

What are phasic receptors? do they tend to adapt?

Answer 14

phasic receptors only generate impulses when they are stimulated by a change in the environment. (ex pacinian and meissner’s corpuscles)

FAST ADAPTING

Question 15

How many neurons typically make up the chain that ascend from sensation to the brain? What are the they called?

Answer 15

3

1st, 2nd, and 3rd order sensory neurons

Question 16

explain what 1st, 2nd, and 3rd order neurons do and where they tend to be located.

Answer 16

1ST order:
- receptor to the top of the spinal cord

2ND order:
- connect to the thalamus

3RD order:
- connect to the cerebrum or cerebellum

Question 17

What are the three types of sensory circuits?

Answer 17

Spinothalamic

Dorsal-medial meniscal

Spinocerebeller tracts

Question 18

What do spinothalamic circuits do?

Answer 18

They are nonspecific ascending pathways:

• carry general information from pain, temp, coarse touch to cerebral cortex for analysis.

(the emotional aspects of perception - pain, pleasure)

Question 19

What do dorsal-medial lemniscal circuits do?

Answer 19

specific ascending pathways that:

• carry discriminative information on: fine touch, vibration, pressure, conscious proprioception (joint and limb position) to cerebrum

Question 20

What do spinocerebellar circuits do?

Answer 20

transmit to cerebellum for coordination of skeletal muscles

no role in conscious sensation