Nerve

Question 1

Nerve fibers

Answer 1

• axons enveloped by a sheath cell called a Schwann cell

- small axons usually unmyelinated and thicker are myelinated and have Schmidt-Lanterman clefts and nodes of Ranvier

Question 2

unmyelinated fibers

Answer 2

-enclosed in a simple fold of a Schwann cell, some very thin can share a fold

Question 3

Myelinated fibers

Answer 3

• thicker axons
• Schwann cell wraps around axon multiple times
• squeezes out most of the cytoplasm except some places-schmidt-lanterman clefts
• nodes of Ranvier indicate end of one Schwann and the beginning of another, which is covered by interdigitating processes

Question 4

Nerves

Answer 4

• bundles of fibers that contain myelinated and unmyelinated axons and motor and sensory fibers
• surrounded by CT

Question 5

epineurium

Answer 5

• outermost layer
• binds bundles or fascicles together into nerves
• dense irregular to loose CT

Question 6

perineurium

Answer 6

• prominent layer, most visible
• modified fibroblasts (epithelioid myofibroblasts)- form tight junctions with each other and collagen fibers
• groups nerve fibers into bundles or fascicles
• selective diffusion (blood-nerve) barrier

Question 7

endoneurium

Answer 7

-delicate layer of reticular fibers produced by Schwann cells

Question 8

ganglia

Answer 8

• peripheral clusters of cell bodies of neurons that are surrounded by satellite cells
• sensory and autonomic can be easily distinguished at the level of the light microscope

Question 9

sensory ganglia

Answer 9

• contain cell bodies of psuedonunipolar neurons
• no synapses within ganglion
• numerous myelinated fibers
• neurons have a central nucleus and a regular ring of satellite cells-protective capsule
• single cell process

Question 10

pseudounipolar neuron

Answer 10

-oneish dendrite and cell body off to side of axon

Question 11

bipolar neuron

Answer 11

• 2 dendrites

- cell body in middle of axon

Question 12

multipolar

Answer 12

• multiple dendrites
• cell body at top
• one axon

Question 13

autonomic ganglia

Answer 13

• contain cell bodies of multipolar neurons
• synapses in ganglion
• numerous unmyelinated fibers
• neurons have an acentric nucleus and smaller cell bodies
• multiple cell processes, single axon

Question 14

specialized termini

Answer 14

• motor end plate
• free endings
• meissner’s corpuscles
• pacinian corpuscles
• muscle spindles

Question 15

motor end plate

Answer 15

• ending of motor neuron axons
• synaptic vesicles at expanded axonal terminus
• postsynaptic membrane has junctional folds and acetylcholine receptors

Question 16

sensory receptors

Answer 16

• externoreceptors
• enteroreceptors
• proprioreceptors
• free endings
• encapsulated endings

Question 17

free endings

Answer 17

• bare axons are important for sensations from the skin of hot, cold, itching, touch, and pain
• can go to a merkel cell?

Question 18

encapsulated endings

Answer 18

-meissners and pacinian corpuscles and muscle spindles

MERKEL??**

Question 19

Meissner’s Corpuscles

Answer 19

• dermal papillae of hairless skin
• 150 microns
• touch receptors responsive to low frequency stimuli

Question 20

Pacinian Corpuscles

Answer 20

• hypodermis and deeper dermis of skin
• 1mm or larger
• mechanoreceptors that respond to pressure and vibration
• formed from concentric layers of Schwann cells

Question 21

Muscle Spindles

Answer 21

• proprioceptor
• encapsulated receptors in skeletal muscle
• contain thin specialized muscle fibers called intrafusal fibers in a fluid filled space
• sensory nerve fibers exiting the capsule send signals about the extrafusal muscle fiber length and relay this information to the spinal cord where it plays a role in reflexed involved in maintaining posture and coordinating walking