Nervous Tissue

Question 0

What is the CNS?

Answer 0

Central nervous system consisting of brain and spinal cord. Integrative and control centers of body

Question 1

Two cell types and functions of nervous tissue

Answer 1

Neurons - receptive, integrative, and motor function
Neuroglial cells - Support and protection of neurons
Derived from ectoderm

Question 2

What is PNS?

Answer 2

Peripheral nervous system consisting of cranial nerves and spinal nerves. Communication lines between the CNS and the rest of the body

Question 3

What are afferent neurons?

Answer 3

Sensory nerves, somatic and visceral fibers that conduct impulses from receptors to the CNS.

Question 4

What are efferent neurons?

Answer 4

Motor nerve fibers that conduct impulses from the CNS to the effectors (muscles and glands)

Question 5

Efferent neurons are subdivided into? What do they do?

Answer 5

Somatic - voluntary, conducts impulses from the CNS to skeletal
Autonomic - Visceral motor, conducts impulses from the CNS to cardiac muscles, smooth muscles, and glands

Question 6

Autonomic nervous system is subdivided to? Functions?

Answer 6

Sympathetic - mobilizes body systems during activity

Parasympathetic - Conserves energy, promotes house-keeping functions during rest

Question 7

T or F: There are cell bodies in the PNS

Answer 7

F, only in the CNS or peripheral ganglia

Question 8

Describe the general structure of a neuron

Answer 8

Cell body (perikaryon, soma), dendrites (receptive region), nucleus, nucleolus (enlarged), Nissl bodies, axon (axon hillock)

Question 9

What are nodes of Ranvier?

Answer 9

Spacing between neurilemma (myelin) and Schwann cell where saltatory signals are propagated

Question 10

What are Nissl bodies?

Answer 10

Aggregates of rough ER that stain dark purple in H&E

Question 11

T or F: Golgi is found in dendrites

Answer 11

F (only organelle not found in neuron extensions)

Question 12

What is a bipolar neuron?

Answer 12

One axon and one dendrite extension in line with cell body. Very rare, found in olfactory and retina.

Question 13

What is a unipolar neuron?

Answer 13

Two axons that extend from a common channel off the cell body. Sensor cell type found in dorsal root ganglia

Question 14

What is a multipolar neuron?

Answer 14

Most common. Motor neuron with dendrites off of cell body and a single axon.

Question 15

Where are pyramidal neurons found?

Answer 15

Hippocampus

Question 16

Function of sensory/afferent neurons?

Answer 16

Receive stimulus from internal and external environment and conduct to CNS

Question 17

Function of motor/efferent neurons

Answer 17

Conduct impulses from CNS to other neurons, muscles, glands

Question 18

What is the function of interneurons?

Answer 18

Connect other neurons in chain or sequence. Important in regulating activity within a network

Question 19

What three types of cytoskeleton are found in neurons?

Answer 19

Actin microfilaments - 6 nm diameter associated with plasma membrane, structural support
Neurofilaments - 10 nm diameter intermediate filaments in cytoplasm for structural support
Microtubules - 24 nm diameter found in cytoplasm, structural support and transport

Question 20

Describe axon transport

Answer 20

Anterograde transport to plus end of axon (kinesin active, dynein inactive)
Retrograde transport to negative end of axon (dynein active, kinesin inactive)

Question 21

Where is the MTOC for neurons located?

Answer 21

Cell body (negative end of microtubule)

Question 22

What is fast axonal transport?

Answer 22

20-40 cm/day, antero and retrograde, membrane bound vesicles and mitochondria

Question 23

What is slow axonal transport?

Answer 23

~1 mm per day, anterograde only!, cytoskeleton components and other soluble proteins

Question 24

What are synapses?

Answer 24

Sites of impulse transmission between pre and post synaptic cells

Question 25

Two types of synapses?

Answer 25

Electric and Chemical

Question 26

Define electrical synapses. Common?

Answer 26

Use gap junctions. Not common in mammals

Question 27

Describe chemical synapse structure

Answer 27

Axon terminal bouton where NT is packaged and released, post-synaptic apparatus containing receptors for NT, synaptic cleft is the gap between the pre and post synaptic membranes which the NT diffuses through

Question 28

Describe the function of the neuromuscular junction (motor endplate)??

Answer 28

Nerve stimulate release of NT into the cleft (ACh for example) stimulating change in the sarcolemma down the T tubules for fiber contraction. Enzymes in the cleft break down ACh to limit the twitch.

Question 29

What is myasthenia gravis?

Answer 29

Autoimmune disease against ACh receptor leading to muscle weakness (seen in eyelids first!)

Question 30

What is botulism?

Answer 30

Toxin from clostridium botulinum which blocks NT release most notably at the Neuromuscular junction

Question 31

Neurotoxins are common in what?

Answer 31

Snake, spider, insect venoms

Question 32

Function of oligodendrocyte

Answer 32

CNS myelin production and electrical insulation

Question 33

Function of microglial cells

Answer 33

CNS macrophage activity (part of MPS)

Question 34

Function of astrocyte

Answer 34

CNS structural support, BBB, ion homeostasis, NT uptake, growth factors

Question 35

Function of nervous satellite cell

Answer 35

Peripheral ganglia, structural support, growth factors

Question 36

Function of Schwann cells

Answer 36

Peripheral nerves, myelin production, electrical insulation

Question 37

T or F: Peripheral nerves can be made up of both sensory and motor neurons

Answer 37

T (dont typically specify until close to site of innervation)

Question 38

Describe packaging of a peripheral nerve

Answer 38

Axon surrounded by endoneurium, bundled into fasicles by perineurium, then bundles are bundled b epineurium

Question 39

Myelin formers in CNS? In PNS?

Answer 39

Oligodendrocytes. Schwann cells.

Question 40

Describe myelination in PNS

Answer 40

Can be done by Schwann cell which envelops the axon and rotates around in successive layers. Cytoplasm is forced out between membranes to form the sheath

Question 41

Describe unmyelinated axon in PNS

Answer 41

Schwann cell wraps around multiple axons in a bundle.

Question 42

Perineurial epitheloid cells are used to?

Answer 42

Establish BBB via tight junctions

Question 43

T or F: Oligodendrocytes myelinate multiple axons at many points

Answer 43

T

Question 44

What is a node of ranvier?

Answer 44

Space between Schwann cells where action potentials are propagated in saltatory transmission

Question 45

Loss of myelin leads to?

Answer 45

Lesser ability to conduct signal. Disorientation and muscle weakness

Question 46

Describe hereditary motor and sensory neuropathy Type I

Answer 46

Mutation in PMP-22 causes demyelination of PNS though loss of PMP-22 activity

Question 47

What is Charcot-Marie-Tooth syndrome Type I

Answer 47

Duplication of PMP-22 results in Schwann cell hyperplasia in PNS. Leads to constriction of nerves and loss of function

Question 48

What is Wallerian degeneration?

Answer 48

Damaged axon degrades down to last node before cell body. Cell body bloats and loss of Nissl bodies.

Question 49

T or F: PNS can regenerate

Answer 49

T

Question 50

PNS regeneration comes with what caveat?

Answer 50

Repair tends to not be as good as original, usually introduces more nodes leading to slower and weaker signals