CH. 13 Peripheral NS + Autonomic NS - Dr. Jones

sensory receptors

specialized to respond to changes in environment (stimuli)

sensation

awareness of stimulus

perception

interpreting meaning of stimulus

mechanoreceptors

respond to touch, pressure, vibration, and stretch

thermoreceptors

sensitive to change in temperature

photoreceptors

respond to light energy

ex.retina

chemoreceptors

respond to chemicals

eg. smell, taste, change in blood chemistry

nociceptors

sensitive to pain-causing stimuli (INTENSE stimulation)

eg. extreme cold/heat, excessive pressure, inflammatory chemicals

exteroceptors

respond to stimuli arising outside body

(most special sense organs)

-receptors for touch, pressure, pain, temp

interceptors

visceroceptors

-respond to stimuli arising in organs and blood vesels

proprioceptors

respond to stretch in skeletal muscles, tendons, joints, ligaments..

-inform brain of one’s movements

somatosensory system

part of sensory sytem serving body wall and limbs

-recieves inputs from Exteroceptors, Proprioceptors, and Interoceptors; input relayed TOWARD head, but processed along the way

adaption

change in sensitivity in presence of CONSTANT STIMULUS

inhibitory endogenous opioids

pain impulse blockage; protective action by body

eg. endorphins

visceral pain

stimulation of visceral organ receptors

-felt as vague aching, gnawing, burning

referred pain

pain from one body region percieved as coming from a diff. regionn

-visceral and somatic pain fibers travel along same nerves which cause brain to assume stimulus comes from common (somatic) region

nerve

- cordlike organ that is part of the peripheral nervous system

- classified as cranial or spinal

- consists of bundles of peripheral axons enclosed by of connective tissue

endoneurium

- layer of loose connective tissue that also encloses the fibers associated with Schwann Cells

perineurium

- coarser connective tissue wrapping

- binds groups of axons

epineurium

- tough fibrous sheath

- encloses all the fascicles to form the nerve

fascicles

groups of axons binded by perineurium are called...

mixed nerves

- contain both sensory and motor fibers and transmit impulses both to and from the central nervous system
- most are mixed (both sensory and motor)

ganglia

- collections of neuron cell bodies associated with nerves in the PNS

automatic nervous system

(Part of the Motor Division of the PNS)
Made up of the Sympathetic Division and the Parasympathetic Division

-maintains homeostasis

difference of automatic nervous system and somatic nervous system

-effectors

• Somatic NS : innervate skeletal muscles

• ANS: inervates cardiac muscle, smooth muscle, and glands

-number of neurons in charge of transmission

-neurotransmitters depend on target

parasympathetic division

promotes maintenance functions, conserves energy

sympathetic division

mobilizes body during activity

dual innervation

all visceral organs are served by both parasympathetic and sympathetic divisons

-conserve energy or mobilize for action

parasympathetic divison

rest-and-digest

-ppupils constricted

-direct digestion, diuresis, defecation

sympathetic division

fight or flight system

-excitement, emergency

-dilated pupils

-shunt blood to skeletal muscles and heart

-cause liver to release glucose for muscles

sympathetic division

increase heart and respiratory rates and inhibits digestion and elimination

parasympathetic division

decreases heart and respiratory rates and allows for digestion and discarding of wastes

nerves

bundle of axons in PNS