Neuroanatomy Week 3 - PNS Flashcards
What do sensory receptors respond to?
pain, temperature, touch, and pressure.
Where are sensory receptors found?
throughout the whole body
What are sensory receptors?
- transducers,
- Stimulate chemical stimuli to create action potentials
What are the 2 categories of afferent neurons?
- Somatic
- Visceral
Afferent neurons
What are somatic afferent neurons associated with?
the skin, bones,
muscles,
and connective tissue
that makes up most of the
mass of the body (soma)
What are visceral afferent neurons associated with?
for the internal organs of the circulatory, respiratory, alimentary, excretory,
and reproductive systems.
Where are somatic efferent neurons (motor neurons) found?
ventral grayhorns of the spinal
cord
and motor nuclei of cranial nerves.
How are the fibers of peripheral nerves (except the very small ones)
arranged?
in bundles or fascicles
What is the entire PNS nerve is surrounded by?
epineurium
What do epineurial collagen fibres help with?
-stretching the nerve
- flexion of joints and movements
What is the perinerium?
The perineurium is a sheath that surrounds small bundle of fibers (fascile) in a nerve
What is another name for endoneurium?
Henle’s sheath or intrafascicular connective tissue
What is the endoneurium?
connective tissue sheath that directly surrounds individual Schwann cell–axon units
What is a neurolemma?
- outermost layer of Schwann cells
- surrounds the axon of the neuron.
- thin sheath around a nerve fiber
The cytoplasm (axoplasm) of an axon contains what 4 organelles?
- neurofilaments,
- microtubules,
- smooth endoplasmic reticulum,
- mitochondria.
What is an axolemma?
Plasma membrane around the nerve cell is called axolemma
The axolemma is responsible for maintaining the membrane potential of the axon, and contains ion channels through which ions can flow rapidly.