physiology: neurophysiology Flashcards
what makes up the neuron?
Cell body dendrites axon hillock axon saltatory conduction (nodes of ranvier) if myelinated
what is an action potential do?
change in permeability of membrane
the resting state?
before AP begins
neg. on the inside
pos. on outside
membrane is polarized at -90 millivolts (mV) membrane potential
depolarization stage?
depole >ascending phase
influx of sodium by fac. diff makes inside more positive; -90 mV is immediately neutralized
threshold occurs at -55 mV & -50 mV
when Calcium is released?
it releases NT!!
repolarization stage?
occurs at 10,000 of a second
na+ channels begin to close and K+ channels open wider
rapid diffusion (efflux) of K+ to exterior- re-establishes normal negative resting membrane potential
Repole> descending phase
voltage-gated sodium channels?
two gates - one outside called activation gate
one inside called inactivation gate
at -70 to -50 mV activation gate flips open; na+ ions pour in. the inactivation gate will then slowly close; this will not open again until membrane potential is at or nearly at resting membrane potential.
Axodendritic synapses?
MC synapse from axon to dendrite
what are gap junctions?
tunnels to connect cytosol of 2 cells
chemical synapses?
close together but do not touch
synpatic cleft is space bwn- need NT
synaptic delay of 0.5 m/sec
one way transmission- only synaptic end bulbs of presynaptic neurons release NT
NE ttransmitter?
brain stem, hypothalamus, etc. excitatory
glutamate NT
CNS, cerebral cortex excitatory
nitric oxide NT?
brain excitatory
ACH ??
inhibitory; motor cortex
dopamine?
inhibitory; substantia nigra
Glycine?
inhibitory; spinal cord
GABA?
inhibitory; spinal cord, cerebellum, basal ganglia
serotonin?
inhibitory; brain stem
what is summation?
1,000-10,000 synapses recieved in CNS
spatial summation is?
buildup of NT released- several presynaptic bulbs
temporal summation is?
NT releases- single presynaptic bulb; fires 2x or more
rapid succession of AP with only a few synapses
what are pain receptors?
nociceptors- free nerve endings; sense pain, tickle, itch, temp.
located greatest number: tongue, lip, genitalia, finger tips
least in number: upper arm, buttock, trunk
mechanoreceptors sense?
pressure- end bulbs of krause
corpuscles of ruffini- pressure, temp, 2-5 degrees perception
both are encapsulated
merkels discs?
general touch, hair follicles- not encapsulated
meissners corpuscles?
fine touch, nonhairy skin, encapsulated
pacinians corpuscles?
pressure, vibration, encapsulated “phasic receptor”
muscle spindles?
detect stretch- dynamic & staic only in skeletal muscle
GTO?
load or weight
golgi tendon reflex?
prevents excessive tension in a muscle
Sympathetic has what affect on the body??
flight or fight BV-vasoconstricts HR- increases rate Lung- deep breaths Bronchi- dilates bronchi Eyes- dilates GI- decreases digestion & secretion recpetors- Adrenergic PREgang.- ACH- short POSTgang.- EPI/NE- long
Parasympathetic has what affect on the body?
Rest & digest BV- little to no effect Muscle- yes Heart- decreases rate Lung- shallow breaths Bronchi- constricts GI- Increases secretions & bowel movement Receptors- Cholinergic PREgang.- ACH- long POSTgang.- ACH- short
what is absolute refractory?
NO A-P available
what is Relative Refractory?
A-P available with increase in potential
Influx of sodium means?
depolarization
efflux of potassium means?
repolarization
Somatosensory area is?
postcentral gyrus in the parietal lobe
Visual sensory area is in?
occipital lobe, striate cortex, calcarine fissure
Auditory sensory area is in?
superior temporal lobe, Heschl’s gyrus
Gustatory (taste) sensory area is in?
base of postcentral gryus
Olfactory sensory area is in?
medial temporal lobe
wernickes is?
the recepetive portion of language in the Superior Temporal Lobe
Motor area is in?
Precentral gyrus in the frontal lobe
premotor area is in?
skilled movements- anterior to motor cortex
Brocas area is in?
Expressive portion of language- inferior posterior frontal lobe.
where does Coordination of muscle contractions take place? clinical?
Cerebellum- SIN Staccato/Slurred speech Intention tremor Nystagmus
where is Crude sensation relayed?
Thalamus- main relay bwn cortex & spinal cord
What does the hypothalamus control?
ANS & endocrine system body temp., food intake, thirst rage & aggression maintains waking state & sleep releases somatstatin- inc. insulin & glucagon
what does the Limbic system do?
emotional aspects of behavior related to survival
including the: Fornix, Hippocampus, cingulate gyrus, Amygdala, Parahippocampal gyrus & parts of the thalamus
what does the superior colliculi do?
coordinates the eyeball movement in response to visual stimuli
located in the midbrain
what does the inferior collicul do?
coordinates head & trunk to auditory stimuli
Located in the midbrain
CN III,IV
EAR
where is breathing associated with? Pons or medulla?
Pons
Pneumotaxic & apneustic centers located here
CN V, VI, VII, VIII
which area functions in consciousness & arousal?
Medulla- reticular formation
Vital reflex centers regulate HB, breathing, & BV diameter
Coordinates- swallowing, vomiting, coughing, sneezing, & hiccuping.
Vestibular nuclei- maintain equilibrium
CN VIII, IX, X, XI, XII