Exam 2 Flashcards
poikilothermic
body temperature same as environment
homeothermic
warm blooded
better at heating than cooling
what is the sensor for hemeothermic
pre-optic area
what releases IL-1
leukocytes
what are leukocytes activated by
bacteria
virus
fungus
IL-1 does what
used during a fever
increases synthesis of prostaglandin
what does prostaglandin do
activates receptors in preoptic area
what does preoptic area activate
it activates the autonomic nervous system to raise body temperature
some bacteria grow less at higher temps
homeostasis involves what two types of behavior
reflexive (degrading fats) and overt (searching for food)
where to make lesion for rats to become obese
ventromedial hypothalamus
VMH
what is the normal role of the VMH
to stop eating behavior
where to make lesion for rat to stop eating
lateral hypothalamus
LH
what is the normal role of the lateral hypothalamus
to initiate eating behavior
also augments taste sensation, facilitates ingestion and swallowing, regulates ANS regulation of digestion
electrical stimulation of the LH produces what
stimulation-bound feeding
SBF
at high stimulation currents, LH stimulation supports what
brain-reward stimulation (via DA)
two signals for the onset and offset of hunger
a fast neural signal
a slow hormonal signal
what is believed to explain why someone has pain after having a limb removed
the touch fibers going into the substantia are always active to some degree, and even in the absence of pain there is a baseline of activity in touch fibers
what act as fast hunger-off signals
signals from stomach and from the mouth
food going straight into stomach
intragastrically
sham-fed
food never reaches stomach
what happens if an animal is sham-fed
they will eat more than animals that aren’t sham-fed, but they will still stop eating at some point
constant hedonic value
if starving, then shitty food is very pleasurable
if very full, really good food is still tempting
what causes bulimics to binge
a bulimic finds food equally pleasurable regardless of hunger state
stomach distension
a fast hunger off signal from the stomach
vagus nerve
connects stomach with VMH
what happens if you cut the vagus nerve
stomach distension no longer signals satiety
does the VMH receive fast or slow signals
fast
caloric content of food is a fast hunger off signal from the stomach via what nerve
splanchnic
blood is a fast or slow hunger off signal
slow
the original glucostatic theory
sites in brain (LH) have receptors that measure glucose levels in the blood that when no longer activated initiate LH activity and eating behavior
what is the problem with the original glucostatic model
diabetics have very high blood glucose level because they don’t have enough insulin but they’re always starving
hyperphagic
very hungry
diabetics show that it’s not _____ that is the slow hunger off signal, but it is _____
it’s not blood sugar
it is intracellular glucose
role of insulin
transfers glucose into cells
without it, glucose will not enter most cells
what is the problem with the glucostatic theory once we know that glucose needs to be inside the cells
most brain sites don’t need insulin to absorb glucose from the blood into the cells, so the diabetic’s brain should have plenty of glucose and therefore wouldn’t be hyperphagic
glucose receptors are not in the ___ but in the ___
not in the brain
in the liver
where does glucose need to be injected to satiate hunger
in liver or hepatic portal vein (directly to liver)
what happens when energy levels are high from high glucose levels
liver signals the brain via increased activity of inhibitory afferents from vagus nerve to LH to stop eating
what happens when energy levels are low from low glucose levels
liver signals the brain via decreased vagus nerve activity to initiate eating
LH is disinhibited
lipostatic theory
the brain indirectly measures fat by measuring free fatty acids
the two stages of lesioning the VMH
dynamic phase: lots of eating
static phase: eating curbs and a new constant but very high weight is set
how do you alter your weight set point
increasing the number of fat cells in body in early years, aka overfeeding
VMH lesion is altering what to make the rat gain weight
metabolism
insulin is released by what
islet cells of the pancreas
insulin increases the conversion of glucose to what
glycogen (happens in the liver; glycogen is stored form of glucose)
fats
insulin facilitates the transport of fats into where
adipose tissue
fats are stored as what
triglycerides
triglycerides are what
glycerol and fatty acids
order from which glucose is used in the body
blood stream
glycogen in muscles and liver
stored fat cells (breaks down into three fatty acids)
muscle
gluconeogenesis
getting glucose from muscle
glucagon is released by what
the islet cells of the pancreas
what does glucagon do
when blood glucose levels fall, its release causes glycogen to be broken down into glucose in the liver
also breaks down fats into fatty acids
can break down fatty acids into ketones
VMH activation inhibits what
secretion of insulin by the pancreas
when a VMH lesion disinhibits insulin release, what does this result in
excess insulin and excess fat storage, or not enough free fatty acids for energy
so even if an animal eats a lot, it can’t be used for energy
where is the fat signal monitored
the liver monitors free fatty acid levels
what happens when free fatty acid levels are high
the liver signals hunger (disinhibits LH)
when are fatty acid levels high
when there is little food in the body and fat is broken down for energy
VMH
stop eating behavior
stop hunger
LH
start eating behavior
start hunger
LH is disinhibited by
low glucose levels in liver
it is disinhibited via decreased activity of inhibitory vagus nerve inputs to LH
stimulation of the LH increases release of what
insulin
lesions of the LH result in what
decrease in insulin levels
breakdown of fat to FFAs
In summary, the stomach has receptors for ____ ____ and ____ ____, and sends a ____ ____ ____ signal via the ____ ____ to the ____
In summary, the stomach has receptors for stomach distension and caloric content, and sends a fast hunger off signal via the vagus nerve to the VMH
In summary, the liver has receptors for ____ and ____ ____ ____, and sends a ____ ____ ____ signal to the ____
In summary, the liver has receptors for glucose and free fatty acids, and sends a slow hunger on signal to the LH
bulimia includes higher than normal levels of ___ and lower than normal levels of ___
higher levels of NPY
lower levels of CCK
homonculus
a visual representation of how much of the sensory cortex is dedicated to each body part
the more ___ the larger the part of the map of sensory cortex that is dedicated to that body part
receptors in the area
the receptors for touch, pressure, and vibration are
dendrites of sensory neurons located within specialized end organs
what is the gold standard of end organs
pacinian corpuscle
what do end organs do
transmit specific stimuli to receptors, which transduce the stimuli to neural impulses
pacinian corpuscles
pressure
how is a pain stimulus transduced
free nerve endings of sensory neurons
end organs use what kind of ion channels for touch and pressure
mechanically gated
what kind of ion channels for pain
chemically gated
what chemical is released at beginning of pain transmission
endotoxins
these are released by dying or injured cells
what do endotoxins activated
chemically gated ion channels on free nerve endings of dendrites
how many pairs of spinal nerves
31
above the neck, cutaneous facial information reaches the brain via which cranial nerve
fifth
trigeminal
cervical
neck
thoracic
chest and upper back
lumbar
lower back
sacral
down to base of spinal cord, coccyx
all spinal nerves are mixed nerves which means what
they have both sensory and motor axons, and as you leave the spinal cord there are two subgroups
two subgroups of spinal nerves
dorsal and ventral
dorsal
input
sensory
ventral
output
motor
dermatome
a region of the skin innervated by an individual spinal nerve
therefore there are 31 dermatomes below the neck on each side of the body
why do dermatomes overlap
if a nerve gets cut, you can still get info from that area via other dermatomes
three types of sensory neurons
A-beta fibers
A-delta fibers
C-fibers
A-beta fibers
touch and pressure
thick and myelinated
fastest
A-delta fibers
pain
medium and myelinated
middle speed
C-fibers
pain
thin and unmyelinated
slow
is pain or touch transmitted faster
touch
A-beta fibers are thickest and myelinated
which fiber carries fast sharp pricking stabbing pain
A-delta
thicker than C-fiber and myelinated
which fiber carries slow throbbing burning aching pain
C-fibers
thin and unmyelinated
cutaneous info reaches brain via two ____ neural systems
ascending
what are the two ascending neural systems
dorsal column (medial lemniscus) anterolateral tract
is there a synapse for touch fibers
no
decussation
crossing over of the axon traveling to the other side of the brain towards thalamus
from spinal cord to brain for cutaneous information
no synapse of touch fibers
touch axons head to medulla
synapse in medulla in same side of body as original axon
next axons cross over to other side to thalamus
filtering of info in thalamus: either carries on to somatosensory cortex or it stops
when do you first feel the touch sensation
when the impulse reaches the somatosensory cortex AFTER it has gone through medulla and thalamus
axons leave in a tract from the medulla, what is this called
medial lemniscus
this is what crosses over to opposite side
after the medial lemniscus crosses over, it picks up axons of what
picks up axons of the trigeminal nerve carrying touch and pressure info from head and face
after the medial lemniscus crosses over and picks up axons of trigeminal nerve
heads to thalamus and synapses
from the thalamus, info is sent to what places
primary or secondary somatosensory area
primary somatosensory area
receives only ipsilateral information
secondary somatosensory area
receives touch and pressure info from both sides of the body (mostly face)
relationship between pressure and generator potential for A-beta
greater pressure means greater generator potential in dendrites of A-beta neurons
with continued pressure, there is adaptation
the stronger the stimulus, the _____ the ____ ____ of a neuron
the higher the firing rate
pain info comes in through ____ region of the spinal cord and synapses in ____ ____
dorsal region
dorsal horn
where do pain axons release neurotransmitter
onto the next axons on the opposite side of spinal cord
what system has A-delta and C-fibers
anterolateral system
it must split for us to tell the difference
nociceptors
respond to injury
the free nerve endings of A-delta and C-fibers
tissue injury releases what
histamine and other endotoxins that act upon chemically gated ion channels
pain fibers conduct to terminals in ___ ___ of spinal cord in layers ___ and ___. ___ ___ is released here
dorsal horn
1 and 5
Substance P
3 pathways that comprise the anterolateral system
spinothalamic tract
spinomesencephalic tract
spinoreticular tract
spinothalamic tract
thalamus
fast pain
C-fiber
spinomesencephalic tract
limbic, emotion
slow pain
A-delta
spinoreticular tract
reticular formation, medulla
alert and awake
pay attention to throbbing slow pain
A-delta
which tract/tracts are affective/motivational aspect of pain
spinomesencephalic
spinoreticular
slow, emotion aspect of pain
which tract/tracts are sensory/discriminative aspect of pain
spinothalamic
fast pain, where the pain is
neuralgia
inflammation of peripheral nerves
causalgia
gunshot
interneurons are where in the dorsal horn
layers 2 and 3
the substantia gelatinosa
why do A-beta fibers interact with A-delta and C-fibers via interneurons
to inhibit pain transmission
“closing the gate”
what happens if you lose A-beta inhibition
pain transmission is disinhibited
chronic pain
narcotic analgesics
in layers 2 and 3 of dorsal horn
tell spinal cord to block pain info
____ induces releases of ____ ____ from opioid interneurons in ____ ____. These ____ inhibit release of ____ ____, causing ____
Serotonin induces releases of opioid peptides from opioid interneurons in dorsal horn. These opioids inhibit release of Substance P, causing analgesia
Axon of ____ synapses onto axon of ____ ____ that is releasing ____ ____. ____ sends axons down into spinal cord into layers ____ and ____ of ____ ____ (____ ____) to activate ____.
Axon of interneuron synapses onto axon of pain fiber that is releasing substance P. Midbrain sends axons down into spinal cord into layers two and three of dorsal horn (substancia gelatinosa) to activate interneurons.
____ and ____ are two major ____ brain sites. They don’t ____ pain info, but they send out pain ____ signals through ____ ____. This means they send ____ down to ____ pain.
PAG and NRM are two major analgesic brain sites. They don’t receive pain info, but they send out pain suppressing signals through descending inhibition. This means they send axons down to inhibit pain.
When activated, the ____ releases our own internal ____, ____ (which is like morphine), which activates ____ ____. Opiate drugs activate the ____ and ____.
When activated, the interneuron releases our own internal opiate, enkephalin (which is like morphine), which activates opiate receptors. Opiate drugs activate the PAG and NRM.
____ bind onto the ____ of pain axons. There are opiate ____ on the axon ____ of the ____ axons, ____ substance P release.
Endorphins bind onto the terminal of pain axons. There are opiate receptors on the axon terminals of the pain axons, suppressing substance P release.
The more you activate ____ and ____, the more you ____ the ____ system. You can never completely do this because ___________
The more you activate PAG and NRM, the more you suppress the anterolateral system. You can never completely do this because this stuff only happens in two layers of the dorsal horn.
opiate narcotics
naturally occurring pain-relievers from poppy
morphine and codeine
two synthetic drugs with morphine-like actions
heroin
demerol
applying morphine to where produces analgesia
PAG
NRM
dorsal horn
analgesia
inability to feel pain
transduction
stimuli from the environment are converted into electrical signals (EPSP/IPSP) by the receptor
tinnitus
loud sounds have killed off hair cells in ear, remaining ones are damaged
always hear ringing
light produces IPSP or EPSP
IPSP
darkness produces IPSP or EPSP
EPSP
hair cells produce IPSP or EPSP
EPSP
only when action potential reaches ____ do we feel stimulus
cortex
receptors convert stimuli in environment into ____ ____ on sensory neuron
generator potentials
Before the sensory neuron, generator potentials are ____ ____. After the sensory neuron, they are ____ ____ ____.
Before the sensory neuron, generator potentials are graded potentials. After the sensory neuron, they are all-or-none action potentials.
a receptor that is sensitive to a particular environmental stimulus is
a stimulus-gated ion channel
A stimulus alters the ____ of the ion channel on the ____. It is usually an ____ ion channel. It usually ____ the ____ of the ____ channel and produces ____.
A stimulus alters the permeability of the ion channel on the receptor. It is usually an Na+ ion channel. It usually increases the permeability of the Na+ channel and produces depolarization.
generator potential
the change in membrane potential on the receptor
Generator Potential
bigger stimulus =
longer stimulus =
bigger stimulus = bigger generator potential
longer stimulus = will end early sometimes due to adaptaion
Action Potential
bigger stimulus =
longer stimulus =
bigger stimulus = more action potentials closer together
longer stimulus = more action potentials closer together but get further apart as stimulus goes on
The generator potential spreads ____ using ____ properties. It is ____ and ____. The ____ of the generator potential is ____ to the ____ of the ____. ____ generator potentials are needed to produce an ____ ____ at the ____ ____.
The generator potential spreads passively using cable properties. It is graded and decremental. The magnitude of the generator potential is proportional to the strength of the stimulus. Many generator potentials are needed to produce an axon potential at the sensory neuron.
The greater the ____ of the summated generator potentials, the greater the ____ of the action potentials.
The greater the magnitude of the summated generator potentials, the greater the frequency of the action potentials.
why does adaptation occur for touch
the end organ gets physically distorted when it’s touched and fluid sloshes around… dendrites start moving around, opens mechanically-gated ion channels. after a while the sloshing stops and end organ accepts its new shape
the two forms of coding of sensory info
anatomical and functional
anatomical coding
different modes of stimuli (visual, taste, etc) travel via sensory neurons to different areas of the brain
anatomical coding: law of specific nerve energies
Johannes Muller
“the nature of a sensory message is determined by the specific sensory pathways that are activated”
functional coding
within a different kind of stimulus, different intensities are determined by the frequency of action potentials arriving at the location (loudness, brightness)
frequency for hearing
pitch
amplitude for hearing
loudness
wave form shape for hearing
timbre
Sensory information contains both a ____ aspect (via ____ to ____ ____) and a ____ aspect (via ____ ____)
Sensory information contains both a discriminative aspect (via thalamus to sensory cortex) and a motivational aspect (via reticular formation)
how can you increase the ability of the brain to distinguish between two stimuli arriving in the sensory cortex
stimulate reticular formation
prosopagnosia
inability to recognize familiar faces
damage to parts of brain involved in high-level interpretation of sensory input
blindsight
a case of agnosia–missing last part of sensory info
all sensory systems work up until the conscious awareness part
true/false
sensory receptors always consist of mechanically gated ion channels
false
true/false
the generator potential is an all-or-none neural impulse
false
true/false
c-fibers are involved in transmitting touch and pressure
false
true/false
for the most part, medium diameter/moderately myelinated pain fibers carry sharp pain
true
true/false
touch fibers first synapse in the spinal cord
false
true/false
morphine acts to alleviate pain in the spinal cord as well as the brain
true
neurons involved in suppressing pain within the substantia gelantinosa via descending inhibition probably originate in the
periaqueductal gray
PAG
true/false
according to the opponent process theory of motivation, removal of stimuli in the environment associated with drug use increases the A process
false
a person suffering from chronic pain who is treated with the removal of the thalamus is most likely to say
the pain bothers me just as much but i can’t describe the pain
the pacinian corpuscle is capable of adaptation
true/false
true
a gunshot to the back of the head is most likely to disrupt
vision
the reticular formation is considered the active relay station of the brain
true/false
false
methods of eliminating a conditioned response
extinction
counter conditioning
touch receptors contain ion channels most sensitive to
mechanical deformation
the sensation of hue is associated with changes in
frequency of light
