Peripheral Nervous System A

Question 1

Is the human brain useful by itself?

Answer 1

No. The human brain would be useless without its connections to the outside world

Question 2

What does the PNS provide?

Answer 2

PNS provides links from and to the world outside our body

Question 3

What are the four parts of the PNS

Answer 3

Sensory receptors
Transmission lines: nerves and their structure and repair
Motor endings and motor activity
Reflex activity

Question 4

What do sensory receptors respond to?

Answer 4

Specialized to respond to changes in the environment (stimuli)

Question 5

Define sensation

Answer 5

Awareness of stimulus

Question 6

Define perception

Answer 6

Interpretation of meaning of stimulus

Question 7

What are the three what’s to classify a receptor

Answer 7

Type of stimulus, body location, and structural complexity

Question 8

Define mechanoreceptors

Answer 8

Respond to touch, pressure, vibration and stretch

Question 9

Define thermoreceptors

Answer 9

Sensitive to changes in temperature

Question 10

Define photoreceptors

Answer 10

Respond to light energy ( example: retina)

Question 11

Define chemoreceptors

Answer 11

Respond to chemicals (smell, taste, changes in blood chemistry)

Question 12

Define nociceptors

Answer 12

Sensitive to pain-causing stimuli (extreme heat or cold, excessive pressure, inflammatory chemicals)

Question 13

What do exteroceptors do? 3 things

Answer 13

Respond to stimuli arising outside body

Receptors in skin for touch, pressure, pain, and temperature

Most special sense organs

Question 14

What do interoceptors (visceroceptors) do? 3 things

Answer 14

Respond to stimuli arising in internal viscera and blood vessels

Sensitive to chemical changes, tissue stretch, and temperature changes

Sometimes cause discomfort but usually person is unaware of their workings

Question 15

What do proprioceptors do? 2 things

Answer 15

Respond to stretch in skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles

Inform brain of ones movements

Question 15

What classifies a sensory receptor as a simple receptors of the general senses and where are they found

Answer 15

Modified dendritic endings of sensory neurons

Found throughout body and monitor most types of general sensory information

Question 16

What classifies a sensory receptor as a receptor for special senses and where are they located?

Answer 16

Vision, hearing, equilibrium, smell, and taste

All are housed in complex sense organs

Question 17

What are the general senses? (4 main senses)

Answer 17

Tactile sensations(touch, pressure, stretch, vibration)
Temperature
Pain
Muscle sense

No one-receptor-one-function relationship
Receptors can respond to multiple stimuli

Question 18

What are two types of nerve endings

Answer 18

Nonencapsulated (free) nerve endings

Encapsulated nerve endings

Question 19

Where are free nerve ending of sensory neurons located

Answer 19

Most body tissues; most dense in connective tissues (ligaments, tendons, dermis, joint capsules, periostea) and epithelia (epidermis, cornea, mucosae, and glands)

Question 20

What is the functional class of free nerve endings of sensory neurons?

Answer 20

Location: Exteroceptors, interoceptors, and proprioceptors

Question 21

Functional classes of free nerve endings of sensory neurons according to stimulus type

Answer 21

Thermoreceptors (warm and cool), chemoreceptors ( itch, ph, etc), mechanoreceptors ( pressure), nociceptors (pain)

Question 22

Where are the modified free nerve endings: tactile (merkel) discs located

Answer 22

Basal layer of epidermis

Question 23

Functional class of modified nerve endings according to locating

Answer 23

Exteroceptors

Question 24

Functional class of modified nerve ending according to stimulus type

Answer 24

Mechanoreceptors (light pressure); slowly adapting

Question 25

Location of hair follicle receptors

Answer 25

In and surrounding hair follicles

Question 26

Functional class of hair follicles according to location

Answer 26

Exteroceptors

Question 27

Functional class of hair follicles according to stimulus type

Answer 27

Mechanoreceptors (hair deflection); rapidly adapting

Question 28

Where are the tactile (Meissner’s) corpuscles located

Answer 28

Dermal papillae of hairless skin, particularly nipples, external genitalia, fingertips, soles of feet, eyelids

Question 29

What are the functional classes of tactile (Meissner’s) corpuscles according to location and stimulus type
L-
S-

Answer 29

L- Exteroceptors

S- mechanoreceptors ( light pressure, discriminative touch, vibration of low frequency); rapidly adapting

Question 30

Where are the lamellar ( pacinian) corpuscles located

Answer 30

Dermis and hypodermis; periostea, mesentery, tendons, ligaments, joint capsules; most abundant on fingers, soles of feet, external genitalia, nipples

Question 31

Where are the muscle spindles located

Answer 31

Skeletal muscles, particularly in the extremities

Question 32

What are the functional classes of muscle spindles according to location and stimulus type
L-
S-

Answer 32

L- proprioceptors

S- mechanoreceptors ( muscle stretch, length)

Question 33

Define the somatosensory system

Answer 33

Part of sensory system serving body wall and limbs

Question 34

Where does the somatosensory system receive its input from? ( three places)

Answer 34

Exteroceptors, proprioceptors, and interoceptors

Question 35

What are the three levels of neural integration in sensory systems

Answer 35

Receptor level: sensory receptors

Circuit level: processing in ascending pathways

Perceptual level: processing in cortical sensory areas

Question 36

What must happen for a sensation to occur

Answer 36

The stimulus must excite a receptor, and the AP must reach CNS