Chapter 12

Question 1

What are the two major divisions of the nervous system?

Answer 1

CNS and PNS

Question 2

What are the two types of cells found in the nervous system?

Answer 2

Neurons and glial cells

Question 3

Define nucleus, ganglion, tract, and nerve.

Answer 3

Nucleus – localized cell bodies in CNS
Ganglion – localized cell bodies in PNS
Tract – bundle of axons in CNS
Nerve – bundle of axons in PNS

Question 4

The enteric nervous system is part of which division of the nervous system and is it under somatic or autonomic control?

Answer 4

PNS and under autonomic control

Question 5

List and define all parts of the neuron.

Answer 5

Cell body (soma) – contains nucleus and organelles
Dendrites – receive information at synapses
Axons – carry neural signal to synapse
Axon hillock – tapering of cell body to axon where neural signal initiates
Nodes of Ranvier – gaps in myelin covering along length of axon to speed up propagation
Axon terminal – at end of axon that makes connections with target cell at synapse

Question 6

Where are unipolar, bipolar, and multipolar neurons found?

Answer 6

Unipolar – not found in vertebrates
Bipolar – olfactory epithelium and retina
Multipolar – all other neurons

Question 7

List the 6 types of glial cells, where they are found, and functions of each.

Answer 7

Astrocyte – CNS – support
Microglia – CNS – immune surveillance and phagocytosis
Oligodendrocyte – CNS – produce myelin covering
Ependymal cell – CNS – create CSF and part of BBB
Satellite cell – PNS - support
Schwann cell – PNS – produce myelin covering

Question 8

Which part of the nervous system does multiple sclerosis and Guillain-Barre affect?

Answer 8

Multiple sclerosis – CNS
Guillain-Barre – PNS
Demyelination diseases

Question 9

What part of the neuron is where the action potential originates?

Answer 9

Axon hillock

Question 10

What is the relay center of the brain that receives incoming sensory information and sends it to the cerebral cortex for integration and processing?

Answer 10

Thalamus

Question 11

List the different types of gated channels and how they operate.

Answer 11

Ligand-gated – opens when signaling molecule (ligand) binds to receptor on membrane
Mechanically gated – opens in response to physical distortion of membrane
Voltage-gated – respond to change in electrical potential of the membrane
Leakage channels – randomly open and close

Question 12

What is the resting membrane potential, its value, and how is it restored?

Answer 12

When the neuron is at rest and ion channels are not open, at -70 mV, and restored by the Na+/K+ ATPase

Question 13

What are the threshold value and value of maximum depolarization?

Answer 13

-55 mV and +30 mV

Question 14

What happens to the action potential when a stronger stimulus is applied?

Answer 14

Increased frequency of action potentials

Question 15

What are the activation and inactivation gates in the voltage-gated sodium channels and their purpose?

Answer 15

Activation gate – opens when membrane passes -55 mV (threshold)
Inactivation gate – closes after specific period of time

Question 16

What is the difference between relative and absolute refractory periods?

Answer 16

Absolute refractory period cannot generate another action potential no matter how strong the stimulus is due to the presence of the inactivation gate of the voltage-gated sodium channels
Relative refractory period can regenerate another action potential but requires a larger stimulus

Question 17

What kind of propagation does unmyelinated axons undergo, and myelinated axons? How does the axon diameter affect the rate of conduction?

Answer 17

Unmyelinated – continuous conduction
Myelinated – salutatory conduction
Larger the diameter – faster the rate of conduction

Question 18

What are IPSPs and EPSPs and where do they summate in the neuron?

Answer 18

IPSPs – hyperpolarizing graded potentials
EPSPs – depolarizing graded potentials
Summate at axon hillock/initial segment

Question 19

What are the characteristics of the synapse and how do they relate to the NMJ?

Answer 19

Presynaptic element – motor neuron axon terminal
Neurotransmitter – acetylcholine
Synaptic cleft – space between cells that NT diffuse
Receptor proteins – nicotinic ACh receptors
Postsynaptic element – sarcolemma of muscle cell
NT elimination/re-uptake – eliminated by acetylcholinesterases

Question 20

List the different neurotransmitter systems, their neurotransmitter, receptor, whether it is excitatory or inhibitory.

Answer 20

Cholinergic – acetylcholine – nicotinic and muscarinic – excitatory
Amino acid NT group – glutamate, GABA, glycine – glutamatergic, GABAergic, glycinergic – glutamate excitatory; GABA and glycine inhibitory
Biogenic amine group – dopamine, norepinephrine, epinephrine – dopaminergic (D1 and D2), adrenergic – D1 excitatory, D2 inhibitory, norepi and epi excitatory
Neuropeptides – met-enkephalin, beta-endorphin - unspecified

Question 21

List the two types of receptors and how they function.

Answer 21

Ionotropic – ligand-gated ion channels
Metabotropic – G protein – 2nd messenger system

Question 22

What are the two 2nd messengers and what makes them?

Answer 22

cAMP – made by adenylate cyclase
inositol triphosphate (IP3) – made by phospholipase C

Question 23

What misfolded proteins are associated with AD and PD?

Answer 23

AD – beta-amyloid
PD – alpha-synuclein