12 pairs that emerge from the brain
31 pairs that protrude from the spinal cord
conveys input into the CNS from receptors
Sensory (afferent) division
transmit impulses from CNS to effector organs
Motor (efferent) division
voluntary with concious control of skeletal muscles
involuntary that regulates smooth and cardiac muscles and glands
branches of the Autonomic Nervous System (ANS)
extensive network of neurons in the GI tract
Enternic Nervous System (ENS)
Enteric Nervous System (ENS)
sensory, integrative, and motor
sensory receptors monitor changes called stimuli, then sends info to brain and spinal cord
Nervous system processes and interprets sensory input and decides whether action is needed (integration)
stimulates effectors through spinal and cranial nerves which makes muscles contract and glands secrete
Neurons
metabolic center of neurons and contains a nucleus surrounded by cytoplasm and organelles
cell body
nuclei
ganglion
receiving or input portions on neurons
dendrites
dendrites
proprogates nerve impulses away from the cell bodies toward another neuro, muscle fiber, or gland
Axon
triggered zone of axon
Axon
axoplasm
axolemma
axon collaterals
synapse
axon terminals or telodendria
synaptic end bulbs or varicosities
neurotransmitters that can excite or inhibit other neurons, muscle fibers, or glands
most neuron in brain and spinal cord with several dendrites and on axon; motor neuron
found in special senses with one main dendrite and one axon
found in ganglia of spinal cord and cranial nerves with one axon and dendrites that are fused to one uninterrupted process
Unipolar Neurons
stimulus activates receptor, action potential is created in the axon and send TOWARDS CNS thru cranial or spinal nerves
unipolar structerd with receptors in dendrites or located as receptors that are separate cells
action potential (AWAY) from CNS to effectors in the PNS through cranial or spinal nerves; multipolar structure
processes incoming sensory info and creates a motor reponse by activating motor neurons
mulipolar structure locates in the CNS between sensory and motor nerves
not electrically excitable supporting cells in CNS and PNS that can multiply and divide and makes up half the volum of nervous system
neuroglia in CNS
processes contact capillaries, neurons, and thin membrane around the brain and spinal cord called pia matter
long branches, in white matter
have short branches, in gray matter
Astrocytes
Astrocytes
Astrocytes
helps maintain chemical environment for nerve impulses-serves as an conduit for substance between neurons and capillaries
neuroglia of CNS
Oligodendrocytes
multi-layered covering lipid and protein that covers axons
Myelin Sheath
neuroglia of CNS
Microglial Cells (microgalia)
Neuroglia of CNS
Ependymal Cells
Ependymal cells
neurogalia of PNS
Schwann Cells
Schwann Cells
neuroglia of PNS
Satellite Cells
Satellite Cell
contains neurtransmitter, do NOT have ion channels
Metabotropic receptors
cotains a neurostramitter binding site and an ion channel
Ionotropic receptors
affects AP propagation because larger the axon, the faster the propagation due to large surface area
affects AP propagation due to AP travels faster along myelinated axons
affects AP proganation bc AP travels at slower speeds at cooler temps
Saltatory Conduction
AP generated by myelinated axon, electric current flow through extracellar fluid from one node to the next causing the next node to depolarize and an AP at second node
Salatory Conduction
produce myelin
gaps in myelin sheath found at intervals in the rapid impulse conduction fround in myelinated axons
Nodes of Ranvier
clusters of cell bodies in the CNS
collection of cell bodies outside of the CNS in the PNS
bundle of nerve fibers in the CNS
bundle of nerve fibers in PNS
collection of myelinated fibers (tract)
composed of unmyelinated axons, dendrites, cell bodies, axon terminals, and neuroglia
like voltage stored in a battery where the flow of charged particles occurs
cell that has a membrane potential
nerve impulse
negative membrane potential become less negative, reaches zero, then becomes more postive
Depolarizing Phase
membrane potential is restored to the resting value of -70mv
Repolarizing Phase
after repolarizing phase, the membrane potential becomes more negative that the resting level-occurs when K+ channels remain open
when depolarizing reaches the level of -55mv and AP occurs
the AP is formed from a threshold stimulus, it either occurs completely or not at all
time after an AP begins when an excitable cell cannot produce another AP in reponse to a normal threshold stimulus
restores ionic distribution back to resting conditions
Sodium-Potassium pump
one-way to transfer info from a presynaptic neuron to a postsynaptic neuron
Chemical synapse
main cation in cystol is K+ w/ phosphates and amino acids being main anions
causes negativity of resting membrane potential
causes of negativity of resting membrane potential
causes of negativity of resting membrane potential
arise mainly in dendrites and cell bodies
arises at trigger zone and propagate along axon
ligand-gated or mechanically gated ion channels
voltage-gated Na+ and K+
decremental (not propagated); permit communicatio over short distances
Propagated and this permits communication over longer distances
depending on strength of stimulus, varies form less than 1mv to more than 50mv
all or none, about 100mv
typically longer, ranging from several milliseconds to several mins
shorter, ranging from 0.5 to 2 milliseconds
maybe hyperpolarizing or depolarizing
allows consists of depolarizinf phase followed by repolarizing phase and return to resting membrane potential
Not present; summation can occur
Present; summation cannot occur
gated channel that randomly opens and closes; located in nearly all cells, dendrites, cell bodies axons of all types of neurons
gated channels that open in response to binding of ligand stimulus; located in dendrites and cell bodies of interneurons and motor neurons, pain receptors
open in resposne to mechanical stimulus such as touch, pressure, vibration or tissue stretching; located in dendrites of some sensory neurons, touch, pain, and pressure receptors
open in response to voltage stimulus (change in membrane potential); located in axons of all types of neurons
voltage-gated Ca++ channels..synaptic vessicles..neurotransmitter..synaptic cleft..neurotransmitter receptors..postsynaptic potential
AP conducted thru membrane of adjacent cells thru gap junctions that connect the cystol of the 2 cells, ions flow from one cell to the next , the AP passes from cell to cell
Electrical Synapse
presynaptic neuron converts an electrical impulse into a neurtransmitter which then is converted nack to an electrical signal by the postsynaptic neuron
Chemical synapse
stimuli occur at different locations of the postsynaptic membrane at the same time
due to stimuli that occurs at the same loaction of the postsynaptic memebrane at different times
Chromatolysis (PNS neuron repair)
Wallerian Degeneration (PNS Neuron Repair)
formed when Schwann cells on either side of injured area multiply by mitosis and grow toward each other
Regeneration tube (PNS Neuron repair)
Continuous conduction
unmyelinated axons and muscle fibers
Continuous Conduction