HYS- CH4.1, 4.2 Cells Of Nervous System And Transmission Of Neural Impulses Flashcards
parts of neuron
cell body
dendrites - recieve inputs
axon hillock - integrates input
axon - transmits signal
what is myelin sheath created by
in CNS by oligodendrocytes (meaning branched off)
in PNS by schwann cells (one wraps around which leaves nodes of ranvier)
how do nodes of ranvier affect signal transduction
action potential skips to each node
how do action potentials cross synapse
chemical messengers neurotransmittetrs in vesicles, causes influx of calcium to let vesicles fuse with the membrane of cell
potassium and sodium leak
sodium leaks in
potassium leaks out
-70 mV
more potassium leaves so it becomes more negative
Na/K pump works to counter Na and K leak to not loose resting potential
depolarization
resting potential is rising above the resting potential closer to 0
(away from -70 mV)
activates Na+ voltage gated surge and membrane potential increases to 35 mV
at what membrane potential does an action potential occur?
-55 to -45 mV
hyperpolarization
membrane potential goes below resting potential and prevents generation of action potential (refractor period prevents backflow)
voltage gated sodium channels close and voltage gated potassium channes open and positive charge escapes the cell
what does PumpKin MEAN
P for potassium is K which is pumped “in”
Sodium must be pumped “out”
“in” is 2 letters which means 2 K+ IN and “out” has 3 letters which means 3 Na+ OUT
2 K+ in, 3 Na+ out
what is the threshold potential of a neuron
-50 mV is is the mem potential when an action potential is triggered
what triggers release of NT into synapse
influx of Ca2+
role of spinal cord in simple reflex art
to house interneurons between afferent and efferent neurons allowing for fast transmission (doesnt need the brain)
Afferent neurons - SENSORY neurons that carry nerve impulses from sensory stimuli TOWARDS the CNS
efferent neurons - are MOTOR neurons that carry neural impulses AWAY from the central nervous systme and towards MUSCLES to cause movement
simple reflex doesnt involve higher order – no brain involved
a nerve impulse originating from the optic nerve travels to the visual cortex in the occipital lobe and in this case accts as a
autonomic nerve, effector nerve, sensory nerve, motor nerve, affector nerve
sensory bc is transmits sensory info to the CNS (occipital lobe)
when the sympathetic nervous system transmits an impulse to the pancrease the primary hormone released is ….
epiphrine, norepinephrine, glucagon, insulin
glucagon
glucagon increases usable blood sugars which we need in a sympathetic response
where is the pituitary gland?
underside of the brain
