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Functions of nervous system (5)
- Initiate/reguate movement of body parts
- regulate secretions of glands
- gather information about external/internal environment
- maintain an appropriate state of consciousness
- stimulate thirst, hunger, fear, rage and sexual behaviors appropriate for survival
3 basic functions of nervous system
- sensation (monitors change/events inside and out--stimuli and receptors)
- integration (processing and interpretation of sensory info to determine response)
- Reaction (motor output, activation of muscles or glands)
changes inside or outside the body monitored by nervous receptors
usually dendrites, the cells of the nervous system that monitor stimuli
nervous vs. endocrine system
- similarities: both monitor stimuli and reast so as to maintain homeostasis
- differences: NS is rapid and fast-acting, and the effects do not always perservere
- ES acts slower via blood-borne chemical signals (hormones) and the effects are longer-lasting
Order of nervous function
- Sensory (afferent) division -- inputs sensation
- Peripheral nervous system
- (central nervous system) -- brain and spinal cord
- Motor (efferent) division
- .....Somatic nervous system (voluntary, skeletal)
- .....Autonomic nervous system (involuntary--cardiac, smooth, gland)
- ..........Sympathetic (fight or flight)
- ..........Parasympathetic (slow and steady, homeostastis)
Impulse classification in nervous system
- Sensory (afferent) system (toward CNS)
- Integrating function (all inside CNS)
- Motor (efferent) system (away from CNS)
sensory--toward CNS. Body outside CNS.
- motor, away from CNS. Carry info from CNS to peripheral muscle, glands and/or other neurons. Body inside CNS
- Comes in 2 parts (somatic, automatic)
somatic motor neuron
1 efferent neuron, away from CNS
autonomic motor neuron
2 neurons (pre-ganglionic, post-ganglionic)
- helper-cells to nerves, structurally and functionally maintain.
- maintain myelin sheath, repair damage, metabolic support.
- 50x more neuroglia than nerves. Can divide
functional unit of the nervous system. Initates and conducts. Needs lots of oxygen, can't reproduce. Can regerate if the body is okay.
3 parts of a neuron
- Cell body (soma or perikaryon)
Neuron cell body or soma
control center of neuron. Synthesizes enzymes and other molecules essential to normal function. Contain Nissl bodies (rough ER), golgi bodies, mitochondria, but no mitosis stuff.
Rough ER in neuron cell body
groups of nerve bodies in the CNS (same as ganglia in PNS)
groups of nerve cell bodies outside brain in PNS (same as nuclei in CNS)
an arm-like extension emanating from every neuron. 2 kinds in a neuron: Axon and dendrite.
recieve stimuli, or impulses, from other neurons and conduct this stimulation to cell body. Ends of dendrites are receptors (modified). Lots of branches into cell body.
- conducts nerve impulses away from the cell body toward another neuron of an effector (single, long process, has neurofibrils but no nissl bodies).
- Long process goes to neuron or effector organs (DO something)
"neck" leading into axon
Telodendrion synaptic knobs
terminal bulb of axon tendrils
axon plasma membrane
Tracts or Fasciculi
Bundles of nerve processes in CNS (like nerves, in PNS)
Bundle of nerve processes in PNS (like tracts or fasciculi in CNS)
Function is to increase speed of impulse conduction along the axon and to insulate the nerve process. Neuroglia cell wrapped around axon or dendrite many times--myelinate fiber.
myelin sheath in CNS (like Schwann cells in PNS)
myelin sheath in PNS (like oligodendrocytes in CNS)