Card Set Information
How does the nervous system carry out task? (3 Steps)
sense organs recieve information, spinal cord and brain process the info, brain and spinal cord command muscles and glands to carry out responses.
what are the two major subdivisions of the nervous system?
-central nervous system
-peripheral nervous system
What is in the central nervous system?
Brain and spinal cord - protected by the cranium and vetebral column
What is the PNS composed of?
How many sensory divisions are there and what are they?
somatic sensory division
visceral sensory division
What does afferent mean?
a signal coming towards the CNS, ex. like getting poked with a needle and feeling the pain.
What is somatic sensory division?
carries signals from skin, muscles, bones, joints.
What is visceral sensory division?
signals mainly from the viscera of the thoracic and abdominal cavities.
what is motor (efferent) division?
signals from the CNS carried to gland and muscle cells that carry out body responses.
How many motor divisions are there?
-somatic motor division
-visceral motor division
Define somatic motor divison
Carries signals to the skeletal muscles. (under voluntary control)
What is visceral motor division and what is another name for it?
carries signals to glands, cardiac muscles, and smooth muscle. (involuntary control). AKA - autonomic nervous system.
what are the divisions of the autonomic nervous system?
Sympathetic - arouse body for action "fight or flight"
Parasympathetic - calming effect "rest or relaxation"
What do neurons do?
carry out the communicative role of the nervous system
What are the properties of the nervous system?
What to sensory (afferent) neurons do?
detect stimuli such as light, heat, pressure, and chemicals then transport them back to the CNS. These neurons begin in almost every organ or the body and end in the CNS.
What do interneurons do?
they recieve the information from the sensory neurons, then decide what to do with it. All located in the CNS. Makes up about 90% of our neurons.
What do motor (efferent) neurons do?
send signals to muscle and gland cells, then response to body stimuli are carried out.
control center of a neuron
primary site for recieving signals from other neurons
what is found in synaptic vesicles?
what is neuroglia?
supporting cells that protect neurons and help them function
What is an effector?
organs that carry out responses.
Multipolar neurons and where there located
have one axon and multiple dendrites; brain and spinal cord
bipolar neurons and where there located
have one axon and one dendrite; nasal cavity, retina, and sensory neurons of the ear.
unipolar neurons and where there located
have only one single process leading away from the soma; are represented by neurons that carry signals to the spinal cord.
anaxonic neurons and where there located.
have multiple dendrites but no axon; brain, retina, and adrenal medulla
what is axonal transport
two way passage of proteins, organelles, etc along an axon
is movement away from the soma down the axon, in order to repair the axolemma or etc.
movement up the axon towards the soma; materials travel along microtubules of the cytoskeleton for recycling or disposing.
What are the two types of axonal transport?
Fast anterograde transport
moves contents to the neuron towards the distal end of the axon.
Fast retrograde transport
returns used synaptic vesicles and other materials to the soma and informs the soma of conditions. Some infections that enter this way are tetnas, herpes, rabies, and polio virus.
slow axonal transport
is always anterograde
supplies axon with enzymes, cytosketal componenets, replaces worn out structures.
reaches out to a nerve fiber and spirals around it (like electrical tape)
wrapping that insuates a neerve fiber from the extracellular fluid and speed up conduction in the nerve fiber
resemble cubiodal epithelium lining the internal cavities of the brain and spinal cord.
*produce cerebrospinal fluid, clear liquid that bathes the CNS and fills internal cavitites
*patches of cilia help to circulate CSF
small macrophages that deveop from white blood cells called monocytes. they wonder through the CNS probing tissue for debis.
the most abundant glial cells in the CNS and make up about 90% of the tissue in the brain.
what entire surface does astrocyte cover?
brain surface and nonsynaptic regions of the neurons in the gray matter of the CNS
Astrocytes have most abundant function of wat kind of cells?
What are the extentions of astrocytes called, and what do they do?
perivascular feet, forms a tight seal called the blood brain barrier.
Astrocytes convert what to what?
blood glucose to lactate and supply to neurons for nourishment.
how do astrocytes communicate?
electrically with neurons and may influence synaptic signaling between them
what do astrocytes regulate?
chemical compostion of tissue fluid. when recieve signals thet release neurotransmitters and potassium ions.
what do astrocytes from when neurons are damaged?
scar tissue. this can either be called astrocytosis or sclerosis
what types of glial cells only occur in the PNS
envelops nerve fibers of the PNS
surround the neurosomes in ganglia of the PNS, provide electrical insulation around the soma and regulate chemical environment.
what are tumors in adults composed of?
-tumors are called gliomas, which grow rapidly and are highly malignant
bc of BBB these tumors do not yeild to chemotherapy
What is the myelan sheath made of in the CNS
What is the mylean sheath made of in the PNS
production of mylean. begins at 14th week of fetal development and isnt complete until late adolensce
last wrapping of the coil, thick outermost layer. The nucleus is found here and most of the cytoplasm
comes after the basal lamina. it is a thin sheet of fibrous connective tissue.
What do the nerve fibers in the CNS dont have that is in the PNS
neurolemma or endoneurium
nodes of ranvier
gaps between the segments of mylean sheaths
mylean covered segments from one gap to the next
short section of nerve fibers btwn axon hillock and first glial cell
axon hillock and initial segment both play a role in initiating a nerve signal. this is where impulses begin.
in the PNS, the unmylenated nerve fibers envelope in what?
what does a schwanns cells plasma membran do for unmylenated nerve fibers?
folds once around each fiber and somewhat overlap the edges. AKA mesaxon
how many fibers can one oligodendrocyte mylenate?
several fibers with cytoplasmic reticulum