components of the nervous system Flashcards
(44 cards)
What are the 3 major functions of the nervous system?
Sensory: receptors
integration: interpretation of sensory information
motor: response to information processes through stimulation of effectors (muscle contraction, glandular secretion)
What are the 2 types of neural tissue?
Neuroglia: for support, regulation and protection of neurons
neurons: for processing, transfer, and storage of information
what are the CNS neuroglia?
-astrocytes
-oligodendrocytes
-micoglia
-ependymal cells
what are the PNS neuroglia?
Schwann cells (neurolemmocytes)
satellite cells
Where do most neoplasms arise from?
glial cells (astrocytes)
Glial cells are ______, ________ neurons and lack ________ and ________ ________
glial cells are smaller, outnumber neurons, and lack dendritic and axonal processes
True or False: Glial cells do not participate in neuronal signaling
TRUE
What are the functions of neuroglia (glial cells) ?
-mechanical support elements of neurons- are essential for neuron function
-insulation of neurons
-phagocytic defense mechanisms
-Modify electrical activity in the neuron
-Regulate metabolism in neurons
What are astrocytes?
Wrap around the nerve cell and support the cell. they hypertrophy when the cell is injured.
what are oligodendroglia?
Interposed btwn the neuron and blood vessels.
What are microglia?
Small cells which move along inflamed or damaged brain cells, their function is phagocytosis
What are ependymal cells?
line central canal of the spinal column and ventricular cavities; they are ciliated and combine w endothelial cells to form a choroid plexus, which secretes CSF
what do astrocytes do?
- Create a supportive framework for neurons (moat predominate glial cell)
-create BBB
-secrete chemicals for embryological neuron formation
-stimulate the formation of scar tissue secondary to CNS injury
What do oligodendrocytes do?
-create myelin sheath around axons of neurons in CNS. Myelinated axons transmit impulses faster than unmyelinated axons.
-do not regenerate after injury
-incapable of division
-capable of myelinating more than 1 axon
-fewer branches than astrocyte
what do the microglia do?
“brain macrophages”
phagocytize cellular wastes and pathogens
- smallest neuroglia
-transported to the site of neuronal injury/degeneration where they proliferate and develop into large macrophages that phagocytize neuronal debris
What do ependymal cells do?
Line central canal of spinal column and ventricular cavities
Ciliated and combine w endothelial cells to form choroid plexus, which secrete CSF.
Line the roof of all the ventricles (lateral ventricles are the 1st and 2nd) (third and fourth) and the central spinal canal
Form the cuboidal epithelium
Secrete CSF
what are satellite cells?
support group of cell bodies of neurons with ganglia of the PNS
What are Schwann cells?
Surround all axons of neurons in the PNS creating a neurilemma around them
neurilemma allows for potential regeneration of damaged axons
creates myelin sheath around most axons of PNS
What is Saltatory conduction?
impulses in myelinated axons travel from one node of Ranvier to another bypassing the area between the nodes and increasing the velocity of conduction.
What is a neuron?
structural unit of the nervous system
-receives and conducts stimuli
What does the neuron consist of?
cell body
axon- there is only one which carries impulses away from cell body
dendrites- extends from cell body, there may be 1 or many
what does the sensory/afferent branch of the neuron do?
receives sensory input
What does the motor/efferent branch do?
controls effector tissue (muscles/glands)
how much brain volume is blood?
5-10% 60-80mL
