Chapter 12 - Nervous Tissue

Question 0

What is the anatomical subdivision of the nervous tissue?

Answer 0

1. Central nervous system (CNS) - brain and spinal cord.

2. Peripheral nervous system (PNS) - nerves and ganglia.

Question 1

What are the basics of the nervous tissue?

Answer 1

1. Sense organs and sensory nerve endings receive information and transmit messages to the CNS.
2. The CNS processes the information and determines a response.
3. The CNS sends a response to muscles and gland cells.

Question 2

What makes up the Peripheral Nervous System (PNS)?

Answer 2

a. Nerves- a bundle of axons wrapped with CT.

b. Ganglia- swellings in a nerve where soma are concentrated.

Question 3

What are the functional PNS divisions?

Answer 3

1. Sensory (afferent) division- carries signals from receptors to the CNS.
2. Motor (efferent) division- carries signals from the CNS to gland and muscle cells (effectors).

Question 4

What are the divisions that make up the Sensory division?

Answer 4

a. Somatic sensory division- carries signals from the receptors in the skin, muscles, bones, and joints.
b. Visceral sensory division- carries signals from the viscera of the thorax and abdomen.

Question 5

What are the divisions that make up the Motor division?

Answer 5

a. Somatic motor division- carries signals to skeletal muscles.
b. Autonomic nervous system (ANS)- carries signals to glands, heart, and smooth muscles.

Question 6

What makes up the Autonomic Nervous System?

Answer 6

i. Sympathetic division- arouses the body to action (fight-or-flight).
ii. Parasympathetic division- has a calming effect (resting-and-digesting).

Question 7

What are the universal properties of neurons?

Answer 7

1. Excitability- they respond to environmental changes (stimuli).
2. Conductivity- they respond by producing electrical signals that are transmitted to other cells.
3. Secretion- neuron releases a neurotransmitter to stimulate the next cell.

Question 8

What are the functional classes of neurons?

Answer 8

1. Sensory (afferent) neurons- detect stimuli and transmit information to the CNS.
2. Interneurons (association neurons)- carry out the integrative function of the nervous system and also interconnect sensory and motor pathways.
3. Motor (efferent) neurons- send signals to muscles and gland cells.

Question 9

What is the structure of the motor neuron?

Answer 9

a. Soma (cell body)- control center containing the nucleus and organelles.
b. Dendrites- branched processes arising from the soma, they receive signals.
c. Axon hillock- mound in soma from which the axon originates.
d. Axon (nerve fiber)- a process that branches on the distal end and may have axon collaterals, they conduct signals.

Question 10

What are the variations of neuron structure?

Answer 10

a. Multipolar neurons- one axon and multiple dendrites.
b. Bipolar neurons- one axon and one dendrite.
c. Unipolar neurons- one process that branches like a T, in which a sensory signal travels toward the soma and bypasses it on the way to the spinal cord.
d. Anaxonic neurons- multiple dendrites but no axon.

Question 11

What are the types of neuralgia?

Answer 11

1. Oligodendrocytes- cells with processes that form myelin which insulate the axons in the brain and spinal cord.
2. Ependymal cells- cuboidal cells lining the cavities of the brain and spinal cord that secrete and circulate CSF.
3. Microglia- macrophages that phagocytize and destroy unwanted materials.
4. Astrocytes
5. Schwann cells- envelop axons of the PNS forming a myelin sheath.
6. Satellite cells- surround somas in ganglias of the PNS providing insulation.