Anatomy Nervous System
tract
Bundle of nerve processes inside the CNS
neurotransmitters
Chemicals released by neurons that stimulate other neurons, muscles, or glands
ganglion
Collection of nerve cell bodies found outside the CNS
efferent neuron
Neuron that conducts impulses away from the CNS to muscles and glands
afferent neuron
Neuron that conducts impulses toward the CNS from the body periphery
proprioceptors
Sensory receptors found in muscle and tendons that detect their degree of stretch
cutaneous sense organs
Sensory receptors found in the skin, which are specialized to detect temperature, pressure changes, and pain
schwann cells
Specialized cells that myelinate the fibers of neurons found in the PNS
neurilemma
a layer of cells that covers the axons of peripheral neurons; concerned with nerve regeneration
central nervous system (CNS)
a major subdivision of the nervous system that interprets incoming information and issues orders
peripheral nervous system (PNS)
a major subdivision of the nervous system that serves as communication lines, linking all parts of the body to the CNS
sensory nerves
also described as afferent nerves
motor nerves
also described as efferent nerves
stimuli
changes, occurring within or outside the body, that affect nervous system functioning
ganglia
clusters of cell bodies located in the peripheral nervous system
nuclei
clusters of cell bodies located within the CNS
dendrite
conducts electrical currents toward the cell body
nodes of ranvier
gaps in the myelin sheath
axon
generally conducts impulses away from the cell body
microglia
glial cells that engage in phagocytosis of pathogens and damaged tissue
schwann cells
glial cells that form the myelin sheath in the peripheral nervous system
myelin sheath
increases the speed of impulse transmission
depolarization
inside of the neuron becomes positively charged
synapse
junction or point of close contact between neurons
cell body
location of the nucleus
myelin sheath
makes white matter
neurons
nerve cells that transmit information as electrical signals
neuroglia (glia)
nerve tissue that is called nerve glue; composed of astrocytes, microgla, oligodendrocytes, and ependymal cells
motor nerves
nerves that carry out the plans made by the CNS
sensory nerves
nerves that gather information from the environment and carry it to the CNS
central nervous system (CNS)
nervous system subdivision that is composed of the brain and spinal cord
peripheral nervous system (PNS)
nervous system subdivision that is composed of the cranial and spinal nerves
association neuron (or interneuron)
neuron, serving as part of the conduction pathway between sensory and motor neurons
axon terminal
part of the axon where the neurotransmitters are stored
cell body
part of the neuron that contains the nucleus; dendrites bring information to this structure , and the axon carries information away from this structure
axon
part of the neuron that transmits information away from the cell body
axon terminal
releases neurotransmitters
nodes of Ranvier
short segments of the axonal membrane that are not covered by the myelin sheath; allows for salutatory conduction of the nerve impulse
somatic nervous system
subdivision of the PNS that controls voluntary activities such as the activation of skeletal muscles
autonomic nervous system
subdivision of the PNS that regulates the activity of the heart and smooth muscle, and of glands, it is also called involuntary nervous system
action potential
the changes in electrical charge across the membrane during depolarization and repolarization also called the nerve impulse
repolarization
the depolarized cell returns to the resting state
depolarization
the fist phase of the action potential caused by an inward movement of sodium (Na+)
refractory period
the inability of a depolarized neuron to accept a stimulus until it has repolarized
resting membrane potential (RMP)
the inside of the unstimulated neuron is negative this electrical charge is caused by the outward leak of potassium
peripheral nervous system
the part of the nervous system consisting of nerves that connect the brain and the spinal cord with the rest of the body
central nervous system (CNS)
the part of the nervous system that contains the brain and spinal cord
integrative function
the process and interpretation of information by the cells of the CNS; the decision-making capability
repolarization
the second phase of the action potential that is caused by the outward movement of potassium (K+)
astrocyte
this common type of glial cell supports and protects the neurons; the cell helps form the blood-brain barrier
dendrites
tree-like part of the neuron that receives information from another neuron and transmits that information toward the cell body
ependymal cell
type of glial cell that lines internal cavities of the brain and produces cerebrospinal fluid
myelin sheath
white, fatty material that surrounds the axon; it increases the rate at which the electrical signal travels along the axon
