The peripheral nervous system

what are sensory receptors?

specialized to respond to changes in their environment called stimuli

What are non-encapsulated dendritic endings?

free nerve endings that detect temperature, pain, itch, light touch, are located at the base of hair follicles

What are encapsulated dendritic endings?

dendrites enclosed in a connective tissue capsule and detect discriminatiory touch, initial, continuous, and deep pressure, and stretch of muscles, tendons and joint capsules

What are mechanoreceptors?

stimulated by mechanical force, such as touch, pressure, vibration, and stretch

What are thermoreceptors?

detects changes in temperature

What are photo receptors?

detect light

What are chemoreceptors?

stimulated by chemicals, such as odours, tastes, or chemical components of body fluids

What are nocireceptors?

respond to painful stimuli

what are exteroreceptors?

located at or near the body surface and detect stimuli from outside the body, such as touch, pressure, pain, skin temperature receptors, and most of the special senses

What are interoreceptors?

associated with internal organs and vessels, monitor chemical changes, stretch, or temperature

what is proprioreceptors?

found within skeletal muscles, joints, and associated connective tissues and relay information about body movements

What does the perception of pain do for the body?

protects the body from damage and is stimulated by extremes of pressure and temperature

what is the pain threshold?

the stimulus intensity at which we begin to perceive pain

What is the pain tolerance?

genetically determined trait with learned aspects that varies from person to person

What is visceral pain?

stimulation of receptors within internal organs from stimuli such as extreme stretch, schemia, chemical irritation, and muscle spasms

What is reffered pain?

pain that feels as though it is located on an area different than the affected body region

What are peripheral nerves?

eihter cranial or spinal, classified according to the direction in which they transmit impulses

What are mixed nerves?

contain both sensory and motro fibres. most nerves are mixed

What do sensory nerves do?

carry impulses towards the CNS

What do motor neurons do?

carry impulses away from the CNS

What is the structure of a nerve?

bundle of myelinated and unmyelinated peripheral axons enclosed by connective tissue

What is endoneurium in the nerves?

The connective tissue sheath that wraps around the individual nerve fiber.

What is the perineurium?

connective tissue wrapping that bundles groups of fibres into fascicles

What is epineurium?

bundles all fascicles into a nerve

What are nerve plexuses?

network of interweaving anterior rami of spinal nerves

what are dermatomes?

areas of skin innervated by cutaneous branches of a spinal nerve, most overlap, so destruction of a single spinal nerve wont cause complete numbness

what are synapses en passant?

junctions between autonomic motor endings and visceral effectors and release either acetylcholine or epinephrine

What are refelxes?

rapid, predictable motor responses to a stimulus and occur over highly specific neural pathways called relfex arcs

what are somatic reflexes?

activate skeletal muscles

What are autonomic reflexes?

involve smooth muscle, cardiac muscle and/or glands

What is a reflex arc?

The passage of information in a reflex (from receptor to effector)

what is a stretch reflex?

causes contraction of a muscle that has been stretched

do damaged CNS nerves regenerate?

almost never do to oligodendricytes

Can damaged PNS nerves regenerate?

if the cell bodies remain intact yes do to schwann cells

What is chromatolysis?

breakdown of nissl bodies after nerve damage

What is wallerian degeneration?

breakdown of the distal portion of the axon and myelin sheath

What does a regeneration tube do for a nerve?

makes nerves grow at a rate of 1mm per day