Chapter 13 - Nervous System

Question 1

Neurobiology

Answer 1

study of nervous system (includes neuroanatomy and neurophysiology)

Question 2

Nervous System Functions

Answer 2

1. Sensory
2. Perception
3. Integration
4. Motor Planning

Question 3

Two Main Divisions of the Nervous System

Answer 3

1. Central Nervous System (CNS) - brain and spinal cord

2. Peripheral Nervous System (PNS) - nerves and ganglia

Question 4

Sensory (Afferent) Division

Answer 4

• from receptors to CNS
• Somatic = signals from skin, muscle, bones, and joints
• Visceral = signals from thoracic and abdominal cavities

Question 5

Motor (Efferent) Division

Answer 5

• from CNS to glands and muscles
• Somatic = signal to skeletal muscle
• Visceral = signal to glands, cardiac and smooth muscle
  
  • Sympathetic = arouse the body
  • Parasympathetic = energy intake and conservation

Question 6

Nerve Cell

Answer 6

neuron

Question 7

Fundamental Physiological Properties of Neurons

Answer 7

1. Excitability - can respond to stimuli
2. Conductivity - can send signals to distant locations quickly
3. Secretion - can release chemical messengers (neurotransmitters)

Question 8

Functional Classes of Neurons

Answer 8

1. Sensory (Afferent)
2. Interneurons (Association Neurons)
3. Motor (Efferent)

Question 9

Sensory (Afferent) Neurons

Answer 9

detect stimuli

Question 10

Interneurons (Association Neurons)

Answer 10

receive signals from other neurons and make decisions about response

Question 11

Motor (Efferent) Neurons

Answer 11

send signals to muscles to provide response

Question 12

Structure of a Neuron

Answer 12

• Neurosoma (soma or cell body) - control center
• Nissl Bodies - contain compartmentalized rough ER
• Dendrites - receive signals
• Axon - generates action potentials (signals)
  
  • Synaptic Knob (terminal knob) - ending of axon branch that communicates with another cell

Question 13

Multipolar Neuron

Answer 13

two or more dendrites, one axon (most common in brain & spinal cord)

Question 14

Bipolar Neuron

Answer 14

one dendrite, one axon (olfactory cells, retina, & inner ear)

Question 15

Unipolar Neuron

Answer 15

single process (to spinal cord)

Question 16

Anaxonic Neuron

Answer 16

many dendrites, NO axon (brain, retina, & medulla)

Question 17

Neuroglia

Answer 17

• “glial cells”
• outnumber neurons 10 to 1
• support cells (protect and aid in function)
• glia means “glue” (bind neurons together)

Question 18

Types of Neuroglia

Answer 18

CNS:
1. Oligodendrocytes
2. Ependymal Cells
3. Microglia
4. Astrocytes
PNS:
1. Schwann Cells
2. Satellite Cells

Question 19

Oligodendrocytes

Answer 19

• neuroglia of CNS

- myelinate to assist conduction

Question 20

Ependymal Cells

Answer 20

• neuroglia of CNS

- secrete and circulate cerebrospinal fluid

Question 21

Microglia

Answer 21

• neuroglia of CNS

- help in defense and disposal

Question 22

Astrocytes

Answer 22

• neuroglia of CNS

- provide support and nourishment

Question 23

Schwann Cells

Answer 23

• neuroglia of PNS

- myelinate to assist conduction

Question 24

Satellite Cells

Answer 24

• neuroglia of PNS

- provide electrical insulation and regulate the chemical environment of the neurons

Question 25

Myelin

Answer 25

- analogous to insulation on a wire - Oligodendrocytes make fatty white matter of CNS - Internodes = fiber segments covered by myelin - Nodes of Ranvier = fiber segments with gaps in myelin - Neurilemma = outermost coiled layer of a Schwann Cell

Question 26

Unmyelinated Nerve Fibers

Answer 26

unmyelinated PNS axons are surrounded by Schwann cells, but the Schwann cells do not coil densely around these axons

Question 27

Signal conduction speed depends on two factors:

Answer 27

1. diameter of fiber (larger is faster) | 2. presence of myelin (myelinated is faster)

Question 28

Nerve Regeneration

Answer 28

- if a cell body remains intact, cut nerve fibers can regenerate - Schwann cells secrete nerve growth factors - Schwann cells and endoneurium produce regeneration tube to direct regrowth - CNS neurons cannot regenerate

Question 29

Synapses

Answer 29

- meeting point of neuron and other cell - presynaptic neuron to postsynaptic neuron - chemical or electrical

Question 30

Chemical Synapses

Answer 30

presynaptic neuron releases neurotransmitter to postsynaptic cell

Question 31

Neurotransmitters

Answer 31

- messenger molecules - some are excitatory, some are inhibitory - Acetylcholine (NMJ) - Norepinephrine (sympathetic) - Glutamine & Aspartate (excitatory) - GABA & Glycine (inhibitory) - Dopamine, Seratonin, Histamine

Question 32

Structures at a Synapse

Answer 32

- synaptic knob of presynaptic nerve - contains synaptic vesicles (packets of neurotransmitters) - synaptic cleft - neurotransmitter receptors on postsynaptic cell

Question 33

Electrical Synapse

Answer 33

- connects neurons, neuroglia, cardiac and single unit smooth muscle cells - adjacent cells joined by gap junctions - ions diffuse from cell to cell - quick transmission - no integration or decision-making