Nervous System - Lec 1&2 Flashcards
what is involved in the PNS
cranial & spinal nerves
ganglia
enteric plexus
sensory receptors
cranial & spinal nerve
how many pairs of spinal nerves
31
how many pairs of cranial nerves
12
what is part of the ANS
heart mm
smooth mm
glands
what is part of somatic system
voluntary skeletal mm’s
SAIA =
sensory, afferent, input, ascending
- sensory converys input from sensory receptors all over the body from somatic senses into the CNS, traveling on ascending neurons
MEOD =
motor, efferent, output, descending
3 parts to a neuron
- cell body
- dendrites
- axon
what does the cell body include
nucleus
cytoskeleton
endoplasmic reticulum (sheath)
ribosomes (proteins produced)
nissl bodies
what do dendrites do
receiving / input end of a neuron - they receive communication
receive info from axon terminals via synapses - then towards cell body
have plastic capabilities
*ex) practicing something new, creating new connections and you get better at it)
what does the axon do
“the highway”
communicate everything from cell body to rest of the body
contains mitochondria, microtubules, neurofibrils
where is the next action potential triggered
initial segment (trigger zone)
what cells produce CSF
ependymal
where do Schwann cells create myelin
PNS
where do oligodendrocytes create myelin
CNS
can Schwann cells regenerate?
yes
oligodendrocytes DON’T
what two cells are in the PNS
Schwann Cells
Satellite Cells
(the two S cells)
what is Wallerian Degeneration
active process of degeneration of the distal end of an axon as a result of a nerve lesion
what is the “glue” that supports / maintains neuronal networks
neuroglia
what do astrocytes do
form a tight cinch around blood capillaries forming blood brain barrier to protect us from toxins
regulate ion concentrations
what forms neuronal synapses
astrocytes
what functions as phagocytes
microglial cells
why does is matter if myelin regenerates or not
w/o the sheath around nerve fibres the transmission of electrical signals slows down
regeneration helps restore efficiency of nerve signal transmission - vital for movement/sensation
regeneration aids in recovery after injuries /damage
what is the functional unit of the nervous system
neurons
can neuroglia divide
yes
neurons CANNOT
describe nervous system communication
neurons send signals to other neurons and to effectors (glands/mm cells)
what 3 ways does our nervous system adapt/change
sprouting of new dendrites
synthesis of new proteins
changes in synaptic contacts
inside of the cell is ____
negative
During resting membrane potential the cell is ___
polarized (not equal in molecular composition or structure between 2 sides)
build up of negative ions (anions) inside cytosol
build up of EQUAL amt positive ions (cations) in extracellular fluid OUTSIDE of cell
the rest of the cell is NEUTRAL
the higher the difference between + and - sides =
the HIGHER the resting membrane potential
grey matter has UNMYELINATED axons
white matter has MYELINATED axons
3 factors that produce RMP
- unequal distribution of ions
- inability of most anions to leave the cell
- electrogenic nature of Na+ and K+ + ATPases
sodium potassium pump, pumps __Na+ out of cell for every __K+ that enter cell
3 Na+ OUT, 2 K+ IN
graded potential = short distance
does not travel down axon
used for short term communication
what is the type of nerve conduction that occurs in unmyelinated axons and mm fibres
continuous conduction
nerve fibres that are the slowest at 2 meters per second
C fibres
at the presynaptic cleft, which voltage gated channels must open to stimulate the release of the vesicles full of neurotransmitters
Calcium (Ca2+)
Ionotophic receptor is made from how many types of proteins?
one
metabotrophic is made from more than one
process to remove neurotransmitters from the synaptic clelft
- enzyme degradation
- diffusion
- uptake cells
what cells offer structural support for the cell body of a neuron in PNS
Satellite cells
which functional class of neurons is responsible for integration?
interneurons
lipids in myelin make ____
white matter
what is a ganglion
cluster of cell bodies outside CNS
what is the plasma membrane of an axon called
axolemma
what are the nodes of ranvier
gaps in myelin sheath
bipolar = 1 dendrite, 1 axon
multipolar = several dendrites, 1 axon
graded potential = varies in size of amplitude, (doesn’t reach threshold)
action potential = threshold has been reached
what is the plasma membrane of the axon
axolemma
what channels open or close when a chemical stimulus comes into contact
ligand gated
what channels open or close in response to vibration/touch/pressure/stretching
mechanically gated
what is summation
when a graded potential joins another graded potential
- becomes stronger and lasts longer
where does saltatory conduction occur
in myelinated axons
B fibres =
mid size
partly myelinated
saltatory conduction
ANS
2 advantages for Gap junctions
faster communication
synchronization
3 types of regeneration
neuropraxia
axonotmesis
neurotmesis
what is a synapse
communication site
types of synapses
axodendritic
axosomatic
axoaxonic
EPSPs and IPSPs are involved w ____ synapses
chemical
which region of the brain does peception primarily occur
cerebral cortex
the greater the difference in charge across the membrane, the larger the membrane potential
RMP exists because of what
small buildup of negative ions in the cytosol along the inside of the membrane, and an equal buildup of positive ions in the extracellular fluid along the outside surface of the membrane
what 3 factors does the RMP arise from
- unequal distribution of ions in the ECF and cytosol
- inability of most anions to leave the cell
- electrogenic nature of the Na+ -K- ATPases
why does a stronger stimulus cause a larger graded potential than a weaker stimulus?
larger amplitude
which channels are open in the depolarizing stage vs hyperpolarizing
depolarizing = Voltage gated Na+ open
hyperpolarizing = Voltage gated K+ open
the flow of Na+ in during depolarizing stage changes the membrane potential from -55mV to ____
+30mV
at the peak of the impulse the inside of the membrane is 30 mV more positive than the outside
a nerve impulse either occurs completely or it does not occur at all
all-or-nothing principle
