nervous system histology

Question 1

functional definition of nervous tissue

Answer 1

• enables body to respond to changes in internal and external environments
• controls and integrates functional activities of the organs and organ systems

Question 2

anatomical divisions of the nervous system

Answer 2

CNS = brain and spinal cord

PNS = all peripheral nerves outside CNS with associated ganglions and receptors

Question 3

functional divisions of the nervous system

Answer 3

sensorimotor = afferent; signal from periphery to CNS

motor = efferent; signal from CNS to periphery

• somatic = voluntary actions via skeletal muscle
• autonomic = control of internal organs via smooth muscle, cardiac muscle, and glandular epithelium

Question 4

structure of a nerve cell

Answer 4

dendrites: receive nerve impulses; contain microtubules and neurofilaments and free ribosomes

cell body: nucleus and site of protein production

Nissl body = stack of RER responsible for protein production

axon = single nerve fiber which transmits impulses to distal end; may have lipid-rich myelin sheath; contain microtubules and neurofilaments

Question 5

neuronal morpholgy

Answer 5

• sensory = pseudounipolar

- somatomotor, autonomic, interneurons = multipolar

Question 6

CNS supporting cells (neuroglia)

Answer 6

oligodendrocytes = produces myelin (fried egg)

astrocytes = scaffolding in brain tissue (star)

microglia = phagocytic cells (dark spots)

ependymal = produce CSF in ventricles and spinal canal (next to a space)

Question 7

PNS supporting cells

Answer 7

schwann cells = surround all axons; produce myelin for myelinated nerves

neurilemma = thin layers of schwann cells

Question 8

myelin histology

Answer 8

H&E = clear area surrounding axon

Osmium = dark ring

Question 9

neuronal histology

Answer 9

cross section:
- individual nerve fibers surrounded by endoneurium
- fascicle = bundle of nerve fibers surrounded by perineurium
- nerve = bundle of fascicles surrounded by epineurium
surrounding/between fascicles
longitudinal:
- long nerve fibers
- schwann cell nuclei (thin, long, wavy)

Question 10

white and gray matter of CNS

Answer 10

grey = cell bodies and supporting cells
white = myelinated nerve fibers

Question 11

myelin sheath function

Answer 11

allow faster transmission of a nerve impulse

Question 12

nerve impulse

Answer 12

propagation of axonal membrane depolarization toward the axon terminal as sodium channels open and allow influx

Question 13

synapse

Answer 13

site of transmission of an impulse from a neuron to another neuron, muscle cell (neuromuscular junction), or gland cell

Question 14

kinds of synpases

Answer 14

axodenderitic, axosomatic, axoaxonal; few or 1000s per neuron

Question 15

ganglia

Answer 15

PNS neuron cell bodies

• parasympathetic: located in organ being innervated
• sympathetic: located in chain ganglia/dorsal root ganglia

Question 16

ganglion cell histology

Answer 16

• large nucleus off to one side

- nucleolus and nissl bodies stain dark