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The Nervous System
Transcript of The Nervous System
hold nervous tissue together
help other neurons in several functions The Nervous System Nancy Alvarado
Allyson Metz General functions of Nervous System 1. Composed of: *neural tissue *blood vessels *connective tissue 2. Dendrites: (short branch extension of nerve cell) receive the input. 3. Axon: nerve fiber
they carry the information away from the cell in "bioelectric signal" form, called NERVE IMPULSES.
NERVES would be bundles of axons. Neurological Cells:
and nourish neurons
. sometimes they can send and
reiceve messages. Organs of the nervous system Group one: Group two: Central nervous system
*brain & spinal cord Peripheral nervous system (PNS)
*nerves (cranial and spinal) these provide 3 general functions:
(1)sensory,(2) integrative, and (3)motor. Nerve Cells (neurons): react to physical and chemical changes in surroundings. Neural cells: two types. synapse: small space between neuron and cell. COMMUNICATION. at ends of peripheral neurons.
gather information by detecting inside &outside body changes
moniter external environmental factors
convert and transduce information into nerve impulses, then transmit it to the Central NS.
detect changes in internal and external body conditions 3. Motor Impulses stimulate effectors to respond. Somatic:
voluntary activities Autonomic:
involuntary actions 1. sensory receptors: 2. create sensations, add memory, produce thoughts... STRUCTURE OF A NEURON Every neuron has a cell body, dendrites, and an axon. CELL BODY contains granular cytoplasm, mitochondria, lysosomes, golgi apparatus, and microtubules
neurofibrils extend into axons and support them
chromatophilic substance consist of rough ER and is found is cytoplasm. DENDRITES provide receptor surfaces
where processes from other neurons communicate. AXON one axon arises from the cell body
and may be enclosed in
myelin sheatin and neuralemma. unmyelinated nerve tissure appears gray 1. the gray matter in the brain and spinal cord contain anmytelinated axons and neuron cell bodies. Dendrites: Axon: Classification of Neurons
and Neurologlial cells Structural differences in Neurons 1. Bipolar neurons
2 processes: one axon & one dendrite
found in specialized parts of eyes, nose, ears. 2. unipolar neurons:
1 process: axon that divides into 2 parts
found outside brain and spinal cord 3. Multipolar neurons:
many processes: one axon, the rest are dendrites
found in brain and spinal cord Functional differences in neurons 1. sensory neurons: conducts nerve impulses from receptors in peripheral body parts into brain/spinal cord. 2. interneuron: transmits nerve impulses between neurons in brain/spinal cord 3. motor neuron: conducts nerve impulses from the brain or spinal cord out to effectors (muscles/glands) Neuroglial cells types: CNS:
between neurons and blood vessels
functions: structural support, form scar tissue, transport substances between blood vessels and neurons, communicate, take extra ions. oligodendrocytes:
few cellular processes than astrocytes
these are in rows along axons
functions: form myalin in brain/spinal cord, make nerve growth factors microglia:
small cells with few cellular processes.
immune protection ependyma
cubodial &columnar cells in inner lining of brain and spinal cord
form layer where substances diffuse between fluid of the brain and spinal cord and cerebrospinal fluid. PNS: schwann cells:
has abundant, lipid-rich membranes that wrap around axons of peripheral neurons
speed neurotransmission satellite cells:
small cubodial cells
surround cell bodies of neurons in ganglia
support ganglia in the PNS THE SYNAPSE: when nerve impulses pass from one neuron to another: presympatic neuron:
brings impulse to synapse and stimulates or inhibits a postsypnatic neuron. synaptic cleft (the gap)
a narrow space seperating two cells; connected functionally.not physically. synaptic transmission:
process where impulse in presynaptic neuron signals postsypnotic cell. cont. the graded impulse from the dendrite triggers action potential that travels along the axon to synapse
axons have synaptic knobs on ends that secrete neurotransmitters, these are released when nerve impulse reaches end of axon.
neurotransmitter can be excitatory or inhibatory CELL MEMBRANE POTENTIAL membrane is usually polarized because the ions are not equally distributed
channels in membranes control distributions