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what is the difference between nervous and endocrine system?
- nervous system is fast, short acting
- endocrine system is slower, but longer lasting
- nervous system is the most complex system in the body
what are the functions of the nervous system?
- monitors the body's internal and external environments
- integrates sensory information
- coordinates voluntary and involuntary responses
what is the difference of CNS and PNS?
- CNS integrates and coordinates input and output
- PNS serves as connection between the CNS and organs
what are the functional divisons of the peripheral nervous system?
- afferent division: sensory receptors and neurons that send information to CNS
- efferent division: neurons that send info to effectors which are the muscles and glands
- -SNS (somatic)
- -ANS (automatic)
what are the different parts of the neuron?
- dendrites receive signals
- axons carry signals to the next cell
- axon terminals synapse with the next cell
- cell bodies contain mitochondria, free and fixed ribosomes, and rough ER
what are the structural classifications of neurons?
- multipolar: 2 or more dendrites and one axon (most common)
- unipolar: hae cell body off to one side
- bipolar: one dendrite and one axon withthe cell body in the middle
what are the functional classification of neurons?
- sensory (afferent neurons) receive information from sensory receptors (somatic vs. visceral receptors)
- motor (efferent) carry information to peripheral targets called effectors (somatic vs. visceral)
- interneurons (association neurons) function as links between sensory and motor processes
- -located entirely in CNS and serve higher functions such as memory, planning and learning
whare the different neuroglial cells in the CNS?
- astrocytes: large, numerous neuroglia that maintain blood-brain barrier
- microglia: smallest and least numerous; phagocytic cells
- ependymal cells: line the fluid filled central canal of the spinal cord and ventricles of the brain (this lining is involved in producing and circulating cerebrospinal fluid)
- oligodendrocytes: insulating membranous wrapping around axons (myelin)
small gaps between myelinated axons
nodes of ranvier
difference between gray and white matter of the CNS?
- gray matter is regions of CNS composed of cell bodies
- white matter is myelinated axons
what are the different neuroglial cells in the PNS?
- satelite cells surround and support neuron cell bodies; similar in function to astrocytes
- schwann cells cover every axon in the PNS and produce insulating myelin; surface of the cell is called neurilemma
describe the orgnization of the nervous system
- neurons of the nervous system tend to group together in organized bundles
- cell bodies of neurons are clustered together into ganglia in PNS and nuclei/centers in CNS
- axons of neurons are bundled together to form nerves in PNS and tracts/pathways in CNS
why is a cell polarized?
excessive positive charge on the outside and negative charges on the inside (difference is called a membrane potential)
what are the types of stimuli and how does it open gated channels?
- types of stimuli
- -cellular exposure to chemicals
- -mechanical changes
- -temperature changes
- -changes in ECF ion concentration
- stimuli alter membrane permeability to Na+ or K+ or alter activity of the Na+/K+exchange pump
difference between chemically and voltage-gated ion channels
- chemical binds and gate opens
- membrane voltage changes and activation gate opens
how does sodium channel gating work?
- activation gate closed
- depolarization happens when activation gate open and inactivation gate open
- inactivation closed
gave examples of influx and efflux
- opening Na+ channels lets Na+2 in; move membrane toward OmV (depolarization)
- opening K+channels results in efflux of K+that moves membrane away from 0mv (hyperpolarization)
what are graded potentials
- local changes in the membrane that fade over distance
- all cells experience graded potentials when stimulated
- graded potentials by themselves cannot trigger activation of large neurons and muscle fibers
what is the purpose of graded potential?w
- det. whehter or not an action potential will occur
- some are excitatory (depolarizing) white others are inhibitory (hyperpolarizing)
- a threshold level of depolarization ned to be reached for action potential to occur?
what are action potential?
change in the membrane that travels the entire length of neurons
Generation of action potential
- depolarization to threshold (-60)
- activation of sodium channels and rapid depolarization (10)
- inactivation of sodium channels and activation of potassium channels (30)
- closing of potassium channels (90)
- return to resting potential
what is propagation?
local changes in the membrane in one site result in the activation of voltage gated channels in the next adjacent site
what are the two types of propagation?
- saltagtaory propagation: occurs in myelinated axons and is much faster than continous conduction
- continuous propagation or conduction occurs in unmyelinated fibers and is relatively slow