Nervous System:Along with the endocrine system, regulates and maintains homeostasis.
Neurons carry electrical signals to allow cell communication.
click
on this image for an audio message Use these web resources to supplement your studies of lecture notes and objectives.
Textbook (sample quizzes, labeling)-select a chapter number in pull down menu.
More online tutorials
The body
Nervous System:Along with the endocrine system, regulates and maintains homeostasis.
Neurons carry electrical signals to allow cell communication.
click
on this image for an audio message
I. Histology:
A. Neurons:
very long cells with membrane extensions
neurons carry information along their membrane extensions via electical signals
secrete neurotransmitters (chemical signals) to communicate with other cells
1) Cell body:
- contains the nucleus of the cell
- is the biosynthetic center of the cell, producing neurotransmitter chemicals
2) Dendrites: some neurons have one, most have many
They provide a large surface area for the reception of signals
from other neurons. carry signal towards cell body. Some are actually sensory
receptors.
3) Axon: efferent neuron will only have one
- conduct the impulse, action potential, away from cell body
-release neurotransmitter chemical that carries signal from axon to dendrite
of following neuron.
Signal always travels from dendrite to axon, which releases neurotransmitter
to carry the signal to next dendrite.
click
on this image for an audio message
Helpful
web link
A
web activity
B. Neuroglial cells
1) Neuroglial cells known as Schwann Cells (neurolemmocytes) wrap
around the axons of neurons in nerves. They form the myelin sheath, a whitish
fatty sheath that insulates
and aids repair. More importantly, It speeds the rate of the impulse.
a) white matter = myelinated cells (where fast conduction occurs)
b) gray matter = unmyelinated cells (where decisions are made)
2) Neuroglial cells in brain ventricles produce CSF (cerebrospinal fluid) that
acts to transport nutrients throughout the CNS
II. Organization of the Nervous System:
A. Structural
1) Central Nervous System: The CNS
These structures act as control centers to regulate many organ
functions.
It contains:
a) Brain
b) Spinal cord
2. Peripheral Nervous System: The PNS
These structures monitor sensory information (receptors) and
send it to CNS (sensory neurons), as well as carry signals
from CNS (motor neurons) to organs (effectors)
It contains:
a) Sensory receptors and Sensory/Afferent nerves (both spinal and cranial) :
to the CNS
b) Motor/Efferent nerves (both spinal and cranial) : away from the CNS
B. Functional
System determined by what effectors are stimulated.
1) Somatic Nervous system
voluntary control of skeletal muscle cells (effectors)
uses Acetylcholine for neurotransmitter to activate effectors
2) Autonomic Nervous system
Involuntary control of effectors that includes: smooth muscle (in blood vessels,
digestive and respiratory system); cardiac muscle (heart rate);, endocrine glands
(including adrenals that secrete adrenaline); sweat glands and digestive glands.
uses Epinephrine (adrenalin) as neurotransmitter to activate/inhibit effectors
a)sympathetic = “fight or flight” division
combined effect of many control control centers on many effectors that results
in: increased Heart rate;increased respiratory rate;increased blood glucose;
decreased urine output;decreased digestive activity including apetite.
b) parasympathetic = "rest and digest" division (also called "feed"
and "breed") that results in:decreased heart rate;decreased respiratory
rate; increased storage of energy; increased urine output; increased digestive
activity and absorption of nutrients.
click
on this image for an audio message
In the CNS:
Nuclei are clusters of cell bodies that provide control centers (gray)
Tracts are groups of myelinated neuron processes that carry information (white)
In the PNS:
ganglia are clusters of cell bodies that provide control centers (gray)
nerves are groups of myelinated neuron processes that carry information (white)
click
on this image for an audio message
Helpful
web link
More
IV Feedback loops control organ function.
click
on this image for an audio message
Consists of neurons that communicate (along membrane by electrical signals)
and between cells (by chemical signals by neurotransmitter). Components of feedback
loop are italicized.
1) Sensory receptors are usually dendrites of neurons that gather information, both internal and external stimuli, and send that signal towards CNS.
2) Signal sent to the CNS along axon of afferent or sensory neuron
3) The association neuron (of brain or spinal cord) acts as the control
center and integrates the information/sensory input, deciding what shouldbe
done regarding the stimulus.
4) The motor neuron carries the signal the effectors.
5. Effectors are organs and cells that cause a change in what triggered
the stimulus.
Signal always travels from dendrite to axon, which releases neurotransmitter
to carry the signal to next dendrite.
click
on this image for an audio message
--------------------------------------------------------------------------------
Professor Thomas M. Lancraft
Human Anatomy Courses
at St. Petersburg College
St. Petersburg/Gibbs Campus
10/2009