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.
What type of neurons form from neuroblasts in the basal plate?
motor neurons
How does the development of sensory neurons explain why their cell bodies are located outside the CNS?
Sensory neurons develop from neural crest tissue, which is located outside the developing neural tube
What is the part of central nervous system?
Brain and spinal cord
- tract
What cells line the central cavity of the brain?
ependymal cells
What cells form myelin in the CNS?
oligodendrocytes
What cells form myelin in the PNS?
Schwann cells
What cells remove neurotransmitters in the CNS?
Astrocytes
What cells regulate ionic composition of the fluid around neurons in the CNS?
Astrocytes
What cells are the CNS phagocytes?
microglial cells
What can the symptoms of MS be relieved by?
- interferons
- steroid drugs
- implanting Schwann cells
What are examples of somatic sensory inputs/outputs?
- pain from skin
- a sound one hears
What are examples of visceral sensory inputs/outputs?
- taste
- stomachache
What are examples of somatic motor inputs/outputs?
- efferent innervation of the gluteus maximus
- efferent innervation of the masseter
What is an example of visceral motor input/output?
efferent innervation of a gland
What does the ANS regulate?
- cardiac muscles
- the digestive tract
- the bladder
What part of a neuron occupies the gray matter in the spinal cord?
motor neuron cell bodies
What is a ganglion?
A collection of neuron cell bodies
What is a synapse between a terminal bouton and a neuron cell body classified as?
axosomatic
What is myelin in the CNS produced by?
oligodendrocytes
What do afferent neurons of the PNS synapse with in the CNS?
neuron cell bodies in the gray matter
What is a monosynaptic reflex an example of?
serial processing
What are most nerves composed of?
axons of afferent and efferent neurons
What is the order of connective tissue coverings surrounding a nerve in order from superficial to deep?
1) Epineurium
2) Perineurium
3) Endoneurium
Where are the receptors of the general somatic senses located in the body? Name some of the senses.
1) Touch - dermis
2) Pressure - skin and deeper tissue
3) Pain - skin, joints, connective tissues
4) Temperature - skin and mucous membranes
Define interneuron.
mediator between sensory neurons and motor neurons
Distinguish gray matter from white matter of the CNS in terms of location and composition.
Gray Matter: found on the surface of the cerebral cortex & forms H-shaped region in spinal cord
- information processing like sensory, memory, emotion
White Matter: beneath the gray matter of the cerebral cortex and surrounds deep gray matter
- coordinates sensory and motor pathways
Name the neurons that are grouped together according to their structures and functions.
1) Sensory neurons - detect stimuli from the environment within the body
- transmit sensory information from sensory receptors
2) Motor neurons - long axons that extend from the CNS to muscles or glands
- transmit signals from the CNS to muscles or glands
3) Interneurons - form connections between other neurons
- integrate and process information received from sensory neurons or other interneurons
Describe the differences between neurons and neuroglia in terms of structure, function, and location.
Neurons:
- Structure: Cell body, dendrites (receive signals), axon (transmits signals), axon terminals (communicate with other cells).
- Function: Transmit electrical signals (action potentials) for communication in the nervous system.
- Location: Found throughout the nervous system, forming networks.
Neuroglia (Glial Cells):
Structure: Smaller than neurons, with processes that interact with neurons.
Function: Support neurons structurally and functionally, provide insulation (myelin), regulate environment, and participate in immune response.
Location: Distributed throughout the nervous system, outnumber neurons and occupy different regions depending on type.
Distinguish a nerve from a nerve fiber and a neuron.
Nerve: found throughout the body, including CNS and PNS & transmits signals between CNS and other parts of the body
Nerve Fiber: found within nerves and throughout the nervous system & conducts signals away from the neuron’s cell body to other neurons, muscles, or glands
Neuron: found in the brain, spinal cord, and peripheral nerves & responsible for sensory perception, motor control, cognition, and behavior
Define axon and dendrite.
Axon: long, slender projection of a neuron that typically conducts electrical impulses away from the neuron’s cell body
Dendrite: branching extension of a neuron that receive signals from other neurons or sensory receptors
From which blood cells do microglial cells originate?
white blood cells (monocytes)
What are the functions of microglial cells?
Resident immune cells, playing important roles in homeostasis and responding to injury
Describe the relationship between axons and Schwann cells in myelinated versus nonmyelinated nerve fibers.
Myelinated: axon is surrounded by layers of myelin sheath formed by Schwann cells in the PNS
Nonmyelinated: each Schwann cell partially envelops multiple axons but they do not form continuous layers of myelin around individual axons.
