Central Nervous System: Nervous Tissue Flashcards
What are the cell types of the nervous system?
Neurons and glia
What is the afferent division of the CNS?
Sensory
What are the similarities and differences between somatic vs visceral sensations?
Both: Part of the sensory (afferent) division of the CNS
Somatic: conscious sensation (things you notice feeling); carries signals from receptors in the skin, muscles, bones, and joints to the CNS
Visceral: subconscious sensation; carries signals from the viscera of the thoracic and abdominal cavities (heart, lungs, stomach, urinary bladder, etc.) to the CNS
What is the efferent division of the CNS?
Motor
What are the similarities and differences between the somatic nervous system (SNS) vs. autonomic nervous system (ANS)?
Both: Part of the motor division of the CNS
SNS: Produces muscle contractions under voluntary control; also responsible for somatic reflexes (involuntary contractions)
ANS: under involuntary control; consists of sympathetic, parasympathetic, and enteric systems
What is a multipolar neuron?
Structure: A neuron with many dendrites, but only one axon.
Function: motor (CNS to periphery); integrative (neuron to neuron)
What is a bipolar neuron?
Structure: A neuron with one dendrite and one axon.
Function: special sense organs (cells that translate something physical or mechanical into electrical impulses sent to the brain)
What is a unipolar neuron?
Structure: A neuron with one long process that splits into dendrites and an axon. Also called “pseudounipolar”, because they start out as bipolar neurons in the embryo, but their two processes fuse into one neuron.
Function: sensory (periphery to CNS); often found in ganglia; usually serve as bridges for chemical and electrical signals
What is an anaxonic neuron?
A neuron with many dendrites, but no axon.
What are the functions of motor neurons (somatic and visceral)?
Conduct impulses from CNS or ganglia to effector cells (muscles or glands)
Somatic: send voluntary impulses to skeletal muscle
Visceral: sends involuntary impulses to smooth muscle, Purkinje fibers, and glands
What are interneurons?
Also called “intercalated neurons”; located between sensory and motor neurons and connect sensory and motor pathways in the CNS; ~90% of human neurons are interneurons.
What are oligodendrocytes?
Glial cells of the CNS that have multiple processes that spiral around nerve fibers, forming myelin sheaths around them. These sheaths insulate nerve fibers and speed up signal conduction.
What are Schwann cells
Glial cells of the PNS; form neurolemma around all PNS nerve fibers and the myelin around most of them; aid in regeneration of damaged nerve fibers.
What are Nodes of Ranvier?
Internodal segments between myelin sheaths on an axon.
What is the functional disadvantage of an unmyelinated nerve fiber? What is its anatomical advantage?
They conduct signals relatively slowly but occupy less space
What are the similarities and differences between chemical and electrical synapses?
Both: Junction between two cells that allows for the continuation of an action potential.
Chemical: Carry neurotransmitters across a synapse from one cell to another to allow for a continuation (or inhibition) of an action potential
Electrical: Gap junctions that articulate with one another on the pre- and post-synaptic membranes to allow for direct continuation of an action potential without the need for a neurotransmitter (less prevalent in humans)
