Ch 13 - Peripheral Nervous System

Question 1

Function of the Peripheral Nervous System (PNS)

Answer 1

The PNS links the CNS to the outside world, nerves extend from every area of the body to provide the brain with sensory input & allows for motor output to reach effector organs

Question 2

Subdivisions of the PNS

Answer 2

1) Afferent division - carry impulses from the body TO the CNS
2) Efferent division - carry impulses from the CNS to the effector organs

Effector organs are either somatic (skeletal muscle) or autonomic (cardiac muscle, smooth muscle, glands)

Question 3

Classification Categories of Sensory Receptors

Answer 3

1) Stimulus type - change in environment that activates the receptor
2) Location - either location inside the body or the location of the source of the stimulus
3) Receptor structure - nonencapsulated vs encapsulated

Question 4

Classification of Sensory Receptors by Stimulus Type

Answer 4

1) Mechanoreceptors - respond to mechanical force
2) Thermoreceptors - respond to temperature changes
3) Photoreceptors - respond to light
4) Chemoreceptors - respond to chemicals in solution
5) Nociceptors - respond to damaging stimuli (pain)

Question 5

Classification of Sensory Receptors by Location

Answer 5

1) Exteroceptor - mostly found at or near body surface (sensitive to stimuli that arise outside of body)
2) Interoceptor - found deeper in the body (sensative to stimuli deep in body)
3) Proprioceptors - found in skeletal muscle, tendons, joints, ligaments (respondss to body movement/position)

Question 6

Sensory receptor that causes pain sensation/responds to damaging stimuli

Answer 6

Nociceptor

Question 7

Sensory receptor found in muscles, tendons, joints, and ligaments

Answer 7

Proprioceptors

Question 8

Anatomy of Sensory Receptors

Answer 8

Mostly composed of Nerve Endings - which are modified dendritic endings of sensory neurons (2 types)

1) Non-encapsulated (free) nerve endings
2) Encapsulated nerve endings

Question 9

Sensations allowed by non-encapsulated (free) nerve endings

Answer 9

1) Pain/temperature nociceptors/thermoreceptors) - within epithelia and connective tissue
2) Itch (chemoreceptors) - histamine release activates free nerve endings
3) Light pressure (mechanoreceptors) - Merkel cells in the integument
4) Light touch specifically for hair (mechanoreceptors) - free nerve endings wrap around hair follicle, respond to change in position of the hair/follicle

Overall, free nerve endings will be much more important for small, slight stimuli

Question 10

Encapsulated Mechanoreceptors

Answer 10

1) Tactile corpuscles - found in dermal papillae of hairless skin (light touch sensation)
2) Lamellar corpuscles - found deep in dermis (stimulated by onset of deep pressure)
3) Bulbous corpuscles - in dermis, subcutaneous tissue and joint capsules (deep, continuous pressure)
4) Muscle spindles - proprioreceptors found in tissue wrapped around skeletal muscle (muscle stretch, prevent damage)
5) Tendon organs - proprioreceptors found in tendons (reflex that relaxes skeletal muscle to prevent damage)
6) Joint kinesthetic receptor - proprioceptor monitoring stretch in joints (joint position)