week 4 (intro to neurons) Flashcards
Epicure gives rise to
dorsal musculature
Epaxial musculature
extensor muscles of vertebral column
Hyperemia gives rise to
ventral musculature
Hypaxial musculature
flexor muscle of anterior body wall
superficial group of epaxial musculature:
spinalis, longissimus, and Iliocostalis
hypaxial musculature
oblique muscles of body wall- compress abdomen, and rectus muscles of body wall- flex vertebral column
neuroglia
support for neurons
division of nervous system
central nervous system and peripheral nervous system.
PNS division
afferent and efferent division
afferent division
carries sensory information from PNS sensory receptors to CNS
Efferent division
carries motor commands from cns to pns muscles and glands
Receptors of afferent division
detect changes or respond to stimuli, complex sensory organs (eyes and ears)
effectors of afferent division
respond to efferent signals, cells and organs
somantic nervous system
controls voluntary and involuntary reflexes skeletal muscle contractions.
autonomic nervous system
controls subconscious actions, contraction of smooth muscle nd cardiac muscle and glandular secretion.
parasympathetic division
relaxing effect
cytoplasm of cell body
perikaryon
Nucleolus production
RNA
dendrites
highly branched and receive information from other neurons
axon
carries electrical signal (action potential) to target
Axoplasm
cytoplasm of axon
Axolemma
specialized cell membrane
Collaterals
branches of a single axon
Telodendria
fine extensions of distal axon
Axon terminals aka synaptic terminals
tips of telodendria. communication with other cells
Neuromuscular junction
synapse between neuron and muscle
Neuroglandular junction
synapse between neuron and gland
endomembrane system
holds and stores product until release
Presynaptic cell
neuron that sends message
Postsynaptic cell
cell that receives message
synaptic cleft
small gap that separates the cell membrane of the presynaptic cell and that of the postsynaptic cell
Multipolar neurons
common in CNS (includes all skeletal muscle motor neurons)
Visceral sensory Neurons
monitor internal environment
Somatic sensory neurons
monitor effects of external environment
Ganglioin
nerve center
Introceptors
monitor internal systems
Exteroceptors
external senses
Proprioceptors
monitor position and movement (skeletal muscles and joints)
Preganglionic fibers
CNS to ganglion
Postganlionic fibers
ganglion to the effectors
Interneurons
between sensory and motor neurons, responsible for distribution of sensory information and coordination of motor activity
SAME
S is for sensory A is for afferent M is for Motor E is for Efferent afferent(in) brings to and efferent(effro-out) brings out
White matter
regions of CNS with many myelinated nerves
Grey matter
unmyelianted areas of CNS
PNS
soma in ganglia
Schwann cells
wrapped around an axon forming a myelin sheath
action potential
electrical impulse produced by graded potential
Synaptic activity
Neurotransmitter release at presynaptic membrane
electrical gradients
separate charges of positive and negative ions
electrochemical gradients
can oppose or reinforce chemical gradient
Assoicate Negative with
iNside
Associate pOsitive with
Outside
Resting membrane potential
-70mV
chemically gated channels
open or close when bind specific chemicals at a binding site
Voltage gated channels
respond to changes in membrane potential
excitable membrane
a membrane that can generate and propagate an action potential
Mechanically gated channels
respond to physical distortion of membrane , important in sensory receptors
Graded Potential
any stimulus that can open a gated channel
depolarization occurs when
membrane potential moving from -70m
v toward a less negative value.
The stronger the stimulus the greater the
change in the membrane potential and the larger the area affected.
Repolarization
when stimulus is removed, membrane potential returns to normal
Hyperpolarization
increasing the negativity of the resting potential resulting of opening of a potassium channel. Positive ions move out cell.
Action potential
a graded depolarization large enough to change resting membrane potential to threshold level of voltage gated sodium channels
All-or-none principle
Once it reaches threshold it will happen
Four steps in generation of action potential
- depolarization to threshold
- Activation of Na+ channels
- Inactivation of Na+ channels and activation of K+ channels
- Return to normal permeability
Refractory Period
From beginning of action potential to return to resting site
Absolute Refractory Period
sodium channels open or inactivated. No action potential possible
Relative Refractory Period
Membrane potential almost normal, very large stimulus can initiate action potential
Propagation
action potentials generate in axon hillock and moves along entire length of axon
Two methods of propagating action potentials
Continuous propagation and Saltatory Propagation
Continuous Propagation
unmyelinated axons
1 segment of axon at a time
Saltatory progation
myelinated axons
faster and uses less energy.
current jumps from node t node
Type A fibers
myelinated, large diameter, high speeds.
140 m/sec
Type B fibers
Myelinated, medium diameter, medium speed
18 m/sec
Type C Fibers
unmyelinated, small diameter, slow speed.
1 m/sec
Electrical synapses
direct physical contact between cells, locked together at gap junction.
Chemical synapses
signal transmitted across a gap by chemical neurotransmitters
