Cells of the Nervous System Flashcards
Neurons
receive information and transmit it to other cells.
Glia
serve many functions in the nervous system
outnumber neurons in the cerebral cortex, but neurons outnumber glia in several other brain areas such as cerebellum
Santiago Ramón y Cajal
detailed drawings of the nervous system are still considered definitive today
used Golgi’s methods but applied them to infant brains, in which the cells are smaller and therefore easier to examine on a single slide
demonstrated that nerve cells remain separate instead of merging into one another.
Camillo Golgi
stain nerve cells with silver salts
membrane
surface of a cell structure that separates the inside of the cell from the outside environment
Most chem- icals cannot cross the membrane, but protein channels in the membrane permit a controlled flow of water, oxygen, sodium, potassium, calcium, chloride, and other important chemicals
nucleus
the structure that contains the chromosomes
mitochondrion
the structure that performs metabolic activities, providing the energy that the cell uses for all activities.
Ribosomes
the sites within a cell that synthesize new protein molecules. Proteins provide building materials for the cell and facilitate chemical reactions.
Some ribosomes float freely within the cell, but others are attached to the endoplasmic reticulum,
endoplasmic reticulum
a network of thin tubes that trans- port newly synthesized proteins to other locations
motor neuron
soma in the spinal cord, receives excitation through its dendrites and conducts impulses along its axon to a muscle
sensory neuron
spe- cialized at one end to be highly sensitive to a particular type of stimulation, such as light, sound, or touch
Tiny branches lead directly from the receptors into the axon, and the cell’s soma is located on a little stalk off the main trunk
Dendrites
branching fibers that get narrower near their ends
surface is lined with specialized synaptic receptors, at which the dendrite receives information from other neurons
greater the surface area of a dendrite, the more information it can receive
dendritic spines
short outgrowths that increase the surface area available for synapses
cell body, or soma
contains the nucleus, ribosomes, and mitochondria
axon
thin fiber of constant diameter.
conveys an impulse toward other neurons, an organ, or a muscle
can have many branches, but there is only one axon
myelin sheath
insulating material of an axon
nodes of Ranvier
interruptions in the myelin sheath on an axon
presynaptic terminal
also known as an end bulb or bouton (French for “button”).
At that point the axon releases chemicals that cross through the junction between that neuron and another cell.
afferent axon
brings information into a structure
efferent axon
carries information away from a structure
interneuron or intrinsic neuron
a cell’s dendrites and axon are entirely contained within a single structure
eg, in thalamus
Types of Glial Cells
astrocytes
microglia
Oligodendrocytes
Radial glia
astrocytes
star shaped, wrap around the synapses of functionally related axons,
shields it from chemicals circulating in the surround
by taking up the ions and transmitters released by axons and then releasing them back, an astrocyte helps synchronize closely related neurons, enabling their axons to send messages in waves
dilate the blood vessels to bring more nutrients into brain areas that have heightened activity
microglia
act as part of the immune system, removing viruses and fungi from the brain