Lecture #9 - Nervous System

Question 1

Basic divisions of the nervous system:

Describe the central nervous system (CNS)

Answer 1

• composed of the brain and spinal cord
• integrating and command center of the NS

Question 2

Basic divisions of the nervous system:

Describe the peripheral nervous system (PNS)

Answer 2

• made of nerves extending from brain and spinal cord (cranial and spinal nerves)
• link all regions of body to CNS
• contain ganglia (clusters of neuronal cell bodies)

Question 3

Basic divisions of the nervous system:

Name the senses found in the somatic sensory. What are their functions?

Answer 3

• general somatic senses: receptors spread throughout body; touch, pain, pressure, temperature, vibration
• proprioceptive senses: detect stretch in tendons/muscles; sensor body position
• special somatic senses: hearing, balance, vision

Question 4

Basic divisions of the nervous system:

Name the senses found in the visceral sensory. What are their function?

Answer 4

• general visceral senses:
  pain, nausea, hunger, temperature, stretch
  felt in digestive and urinary tracts, and reproductive organs
• special visceral senses: taste, smell

Question 5

Basic divisions of the nervous system:

Describe the visceral motor

Answer 5

• controls function of visceral organs
• regulates contraction of smooth and cardiac muscle
• makes up autonomic/involuntary NS

Question 6

Basic divisions of the nervous system:

Describe the somatic motor

Answer 6

• general somatic motor: signals contraction of skeletal muscle
• under voluntary control

Question 7

What are the special characteristics of a neuron? Describe them

Answer 7

• Longevity: can live and function for a lifetime
• Do not divide: fetal neurons lose their ability to undergo mitosis (exception: neural stem cells)
• High metabolic rate: require abundance oxygen and glucose (neurons die after 5 minutes without oxygen)

Question 8

Neuron Processes

Describe the cell body (soma)

Answer 8

• size varies
• most neuronal cell bodies located in CNS
• neuronal cell bodies in PNS are called ganglia

Question 9

Neuron Processes

Describe the dendrites

Answer 9

• branch from cell body
• transmit electrical signals TOWARD cell body
• function as receptive sites for receiving signals from other neurons

Question 10

Neuron Processes

Describe the axons

Answer 10

• neuron has only one
• impulse generator and conductor
• transmit impulses AWAY from cell body

Question 11

Neuron Processes

Describe the action potential

Answer 11

• generated at initial segment of axon
• conducted along axon to terminal boutons
• neurotransmitters: released from vesicles at the terminal boutons

Question 12

Neuron Processes

Describe the synapse

Answer 12

• site at which neurons communicate
• most information passed through chemical messengers
• presynaptic neuron: conduct signal toward a synapse
• postsynaptic neuron: transmit electrical activity away from synapse

Question 13

Classification of Neurons

Describe this structural classification: multipolar

Answer 13

• contain more than 2 processes (numerous dendrites to one axon)

Question 14

Classification of Neurons

Describe this structural classification: bipolar

Answer 14

• contain 2 processes
  (rare, found in some special sensory organs)

Question 15

Classification of Neurons

Describe this structural classification: unipolar

Answer 15

• contain one single short process

Question 16

Name the different types of neuroglia in the central nervous system (CNS)

Answer 16

AMEO
- astrocytes
- microglia
- ependymal cells
- oligodendrocytes

Question 17

Neuroglia in the CNS

Describe astrocytes

Answer 17

• most abundant glial cell type
• regulates neurotransmitter levels
• signals increases blood flow to active brain regions
• controls ionic environment around neurons

(star-shaped)

Question 18

Neuroglia in the CNS

Describe microglia

Answer 18

• smallest and least abundant glial cell
• phagocytic (macrophage of CNS)
• engulf invading microorganisms and dead neurons

Question 19

Neuroglia in the CNS

Describe ependymal cells

Answer 19

• line central cavity of brain and spinal cord
• ciliated: helps circulate cerebrospinal fluid

Question 20

Neuroglia in the CNS

Describe oligodendrocytes

Answer 20

• wrap their cell processes around axons in CNS
• produce myelin sheath in CNS

Question 21

Name the different types of neuroglia in the peripheral nervous system (PNS)

Answer 21

SaSc
- satellite cells
- schwann cells

Question 22

Neuroglia in the PNS

Describe satellite cells

Answer 22

• surround neuron cell bodies with ganglia

Question 23

Neuroglia in the PNS

Describe schwann cells

Answer 23

• surround axons in PNS
• form myelin sheath in PNS

Question 24

Myelin Sheaths in the CNS

Describe gray matter

Answer 24

• surrounds hollow central cavities in CNS
• site where neuron cell bodies cluster
• where synapses occur

Question 25

Myelin Sheaths in the CNS Describe white matter

Answer 25

- made of myelinated axons - consists of axons passing between specific regions of CNS

Question 26

Gross Anatomy of the Nervous System Describe nerves

Answer 26

- cabe-like organ in PNS - made of numerous axons wrapped in CT - axon is surrounded by schwann cells - contain myelinated and nonmyelinated sensory and motor axons

Question 27

Gross Anatomy of the Nervous System Describe endoneurium

Answer 27

- layer of delicate CT surrounding the axon

Question 28

Gross Anatomy of the Nervous System Describe perineurium

Answer 28

- CT that wraps a nerve fascicle (nerve fascicle - groups of axons bound into bundles)

Question 29

Gross Anatomy of the Nervous System Describe epineurium

Answer 29

- whole nerve is surrounded by tough fibrous sheath

Question 30

Neuronal Circuits Describe diverging circuit

Answer 30

- one presynaptic neuron synapses with several other neurons (divergence)

Question 31

Neuronal Circuits Describe converging circuit

Answer 31

- many presynaptic neurons synapses on a single post synaptic neuron (convergence)

Question 32

Neuronal Circuits Describe reverberating circuit

Answer 32

- circuit that receives feedback via a collateral axon from a neuron in the circuit

Question 33

What is the most common type of synapse that is between axon terminals of one neuron and dendrites of another?

Answer 33

axodendritic

Question 34

What type of synapse is between the axons and neuronal cell bodies?

Answer 34

axosomatic

Question 35

What is located on the presynaptic side that contains membrane-bound sacs with neurotransmitters and has mitochondria that are abundant in axon terminals?

Answer 35

synaptic vesicles

Question 36

What separates the plasma membrane of two neurons?

Answer 36

synaptic cleft