Exam 3 Chapter 12 Flashcards
In which direction are afferent signals carried? What type of information do these signals contain?
Carry sensory information toward the central nervous system
What subdivision of the nervous system regulates contraction of the muscle tissue in the heart?
Visceral motor division of the peripheral nervous system
What type of sensation is pain from a pulled muscle?
general somatic sensory
What type of sensation is nausea?
general visceral sensory
What type of sensation is taste?
special visceral sensory sensation
Which type of neuron process receives stimuli?
dendrites
Describe how the electrical impulse from one neuron is passed to another neuron.
1) Electrical impulse in the presynaptic neuron reaches terminal bouton
2) Stimulates the release of chemical neurotransmitters from the neuron
3) Neurotransmitters diffuse across synaptic cleft and bind to receptor sites on the postsynaptic neuron to stimulate an electrical response in the postsynaptic neuron
TDLR: Electrical signal is passed by chemical messenger from one neuron to another
What is the structural type of most sensory neurons?
unipolar neurons
Which structural type of neuron is most abundant? Which neurons in the PNS are of this type?
multipolar neurons
- Motor neurons in the PNS
Which neuroglia make myelin in the CNS?
Oligodendrocytes
Which neuroglia make myelin in the PNS?
Schwann cells
Which neuroglia are common in regions where synapses occur?
Astrocytes
- regulate ionic and neurotransmitter levels in neural tissue
Do Schwann cells cover nonmyelinated axons in the PNS?
Yes
- numerous nonmyelinated axons are embedded in a SINGLE Schwann cell
Name the connective tissue wrapping that encloses a bundle of axons into a fascicle.
Perineurium
Where do synapses occur in the CNS?
Gray matter
Why is white matter white?
majority of nerve fibers in the region is myelinated
If there is no interneuron in a reflex arc, as in the stretch reflex, what functions as the integration center?
gray matter in the CNS at the synapse between the sensory neuron and motor neuron
If you touch a hot stove, you reflexively withdraw your hand. The sensation of pain comes after your hand has moved. Why does it take longer to feel pain than it does to move your hand?
The sensory impulse must be carried to the brain for processing the conscious sensation of pain
- processing takes longer than withdrawal reflex
What type of neuronal circuit contains multiple neurons synapsing on a single neuron, altering its potential to produce a nerve impulse?
Converging circuit
Both peripheral nerves and white matter of the spinal cord have axonal processes. Why is it possible to regain function after an injury to a peripheral nerve, but not after an injury to the spinal cord?
Peripheral injury = axons can regrow within regeneration tubes formed by surviving Schwann cells.
Spinal cord = neuroglia do not guide regrowing axons and secrete inhibitory chemicals that block neural regrowth.
Explain how the loss of myelination in the CNS can cause the signs and symptoms typical for multiple sclerosis.
Myelin insulates nerve signal and increases the speed of impulse conduction. Loss of myelin in the CNS interferes with the duction of nerve signals. All the symptoms described for MS indicate disruption of neural processing.