Ch. 11 Nerve Tissue

Question 1

• efferent of motor nerves

- afferent or sensory

Answer 1

• away from CNS to salivary glands, ms, etc

- to CNS (receive from nose, eyes)

Question 2

• somatic nervous sys

- autonomic nervous sys

Answer 2

• provides sensory and motor innerve to all parts except viscera, smooth ms, glands
• provides efferent invol motor innerv to smooth ms, heart, and glands. also provides afferent sensory innerv fr viscera (pain and autonomic reflex)

Question 3

Supporting cells

Answer 3

• in cns: neuroglia

- in pns: schwann cells and satellite cells

Question 4

• sensory neurons
  1. somatic afferent fibers
  2. visceral afferent fibers
• motor neurons
• interneurons

Answer 4

1. convey pain, temp, touch, and pressure from body surface
2. transmit impulses of pain and other sensations from mucous membranes, glands and blood vessels

• convey impulse from cns to effector cells
• form communicating and integrating network bet sensory and motor neurons

Question 5

• multipolar
• bipolar
• unipolar

Answer 5

• one axon and 2 or more dendrites (motor neurons/ interneurons)
• one axon and one dendrite (retina of eye)
• have one process, the axon (sensory neurons)

Question 6

Cell body or perikaryon

Answer 6

• like a protein-producing cell
• have much rER as a NISSL body stacks and free ribosomes
• also has mitochondria, Golgi, lysosomes, microtubules, neurofilaments, transport vesicles, inclusions
• neurons do not dived, but subcellular components turn over regularly

Question 7

1. axodendritic
2. axosomatic
3. axoaxonic

Answer 7

1. axons and dentrites
2. axons and cell body
3. axons and axons

*Boutons en passant, an axon makes several button-like contacts w/ the receptor portion of the neuron

Question 8

synaptic transmission

Answer 8

1. presynaptic membrane depolarization induces…
2. brief opening of calcium channels
3. calcium influx promotes exocytosis of synaptic vesicles with…
4. release of neurotransmitter
5. neurotransmitter reacts w/ receptors and…
   - causing Na channels to open in that membrane, allowing Na to enter the neuron, causing others to open, generating a nerve impulse.
6. promotes postsynaptic membrane depolarization

Question 9

-excitatory synapse

Answer 9

• release of acetylcholine, glutamine and serotonin. opening Cation channels for Na influx leading to action potention and generate impulse.
• release of GABA or glycine, opening anion channels for CL influx. causing action potential to become more difficult.

Question 10

Acetylcholine (Ach)

Answer 10

• serves neurotransmitter bet axons and effectors or striated muscle in the ANS
• are called Cholinergic neurons or receptors
• 2 classes:
  1. muscarinic Ach receptor
  2. Nicotinic Ach Receptor

Question 11

Catecholamines

Answer 11

• Norepinephrine (NE), Epinephrine (EPI), Dopamine (DA)
• Adrenergic neurons
• EPI secreted by CNS and adrenal medulla during Fight-or-flight

Question 12

Serotonin, GABA, Glutamate, Aspartate and Glycine

Answer 12

-other neurotransmitters

• High-affinity reuptake: removal of neurotransmitter following its release into the synaptic cleft
• needed to limit the duration of stimulation or inhibition of postsyn membrane

Question 13

-myelin sheath

Answer 13

• is a thin layer of Schwann cell cytoplasm called the sheath of Schwann or neurilemma
• contains the nucleus and most of organelles of Schwann cells

Question 14

internodal segment

Answer 14

-the myelin between 2 sequential nodes of Ranvier

Question 15

satellite cell

Answer 15

• analogous to schwann but doesn’t make myelin
• small cuboidal cells that surrounds the neuronal cell body of ganglia
• help est and maintain a controlled micro-environment around the neuronal body in the ganglion
• electrical insulation
• pathway for metabolic exchange

Question 16

Neuroglia:

1. oligodendrocytes
2. astrocytes
3. microglia
4. ependymal cells

Answer 16

1. small cells forming and maintaining myelin in the CNS. aligned in rows between axons, fewer processes
2. provide physical and metabolic support for the neurons of the CNS
   - protoplasmic: gray
   - fibrous: white
3. inconspicuous cells w/ small, dark, elongated nuclei that possess phagocytotic properties
4. column-shaped cells line brain ventricles and canal of spinal cord, containing cilia and microvilli to absorb cerebrospinal fluid.
   - the modified ependymal cells and associated capillaries are called choroid plexus.

Question 17

Saltatory or Discontinuous Conduction

Answer 17

• nerve impulse jumping from node to node

- conduction is faster on axons of greater diameter and myelinated

Question 18

origin of nerve tiss

• CNS
• PNS

Answer 18

• from neuroectodermal cells of neural tube

- from neural crest

Question 19

Connective tiss components of peripheral nerve

1. endoneurium
2. perineurium
3. epineurium

Answer 19

1. loose conn tiss surrounding each individ nerve fiber
2. specialized conn tiss surrounding each nerve fascicle
3. dense, irregular conn tiss that surrounds a peripheral nerve and fills the spaces between nerve fascicles.

Question 20

31 segments of spinal nerves

Answer 20

8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal

Question 21

1. white matter

2. gray matter

Answer 21

1. peripheral substance contains myelinated and unmyelinated axons
2. surrounding central canal. containing neuronal cell bodies and dendrites. synapses only occur here.

*cell bodies of efferent neurons are on ventral horn of gray matter

Question 22

Classification of receptors

1. extereceptors
2. enteroreceptors
3. propioceptors

Answer 22

1. from external environ (temp, touch, smell, sound or vision)
2. from within the body (degree of filing of stretch of bladder)
3. from within the body, providing sensation of body position and muscle tone and movement

Question 23

Classifications of autonomic nervous system

Answer 23

1. sympathetic
2. parasympathetic
3. enteric division

1 and 2 supply the same organs but are antagonistic

Question 24

Organization of CNS

• gray matter
• white matter

Answer 24

1. is the site of synapses, forming an outer covering or cortex. nuclei seen in the deep portions of cerebrum and cerebellum.
2. many of the axons going to, or coming from a specific location are grouped into bundles called TRACTS

Question 25

- Neuropil - Brain stem - Nuclei

Answer 25

- the meshwork of axonal, dendritic and glial processes associated with the gray matter - is not clearly separated into regions of gray and white matter - appear as islands surrounded by more or less distinct tracts of white matter

Question 26

conn tiss of CNS

Answer 26

1. dura mater-outermost, thick sheet of dense conn tiss., continuous w/ periosteum of skull. 2. arachnoid-delicate sheet - contains trabeculae of loose conn. tiss fibers containing elongated fibroblast 3. pia mater-delicate. rests on brain surface and spinal cord, continuous w/ perivascular conn tiss sheath of blood vessels of brain and spinal cord *all covered by thin, squamous epithelial layer

Question 27

Wallerian/Antegrade degeneration

Answer 27

- degeneration of axon distal to a site of injury - in PNS, in a few days - in CNS, several weeks

Question 28

Chromatolysis

Answer 28

- loss of Nissl substance from the cell body | - the changes in cell body are proportional to the amt of axoplasm lost by the injury

Question 29

- scar formation | - regeneration

Answer 29

- in PNS, connective tiss and Schwann cells form scar tiss and the gap bet the ends of a severed or crushed nerve - Schwann cells divide and develop cellular bands that bridge a newly formed scar. the bridges serve as guides for regenerating axons to grow across the scar - if the axonal sprouts do not rest contact w/ the bridge of Schwann cells, the sprouts grow in a disorganized manner, and the muscle remains atrophic