PNB 2274 Exam 3 CHEN Flashcards
Dura matter
two fibrous layers of dense connective tissue, lymphatic system between the 2 layers with blood vessels and tissue fluids
arachnoid layer
transparent, epithelial cells, CSF in subarachnoid space
pia matter
follows brain’s underlying folds, accompanies branches of cerebral blood vessels
progressive hypoglycemia
low blood glucose; leads to confusion, unconsciousness, death
arteries in the brain
vertebral and internal carotid arteries
veins in the brain
internal jugular veins
anastomosis
vessels joined together
colateral circulation
provides alternative route for blood supply in the brain in the event of clot
circle of willis
two vertebral arteries meet to form the basilar artery which connects to the carotid artery to supply blood to the 3 cerebral arteries
anterior cerebral artery
supplies innerside of brain
middle cerebral artery
supplies outside of cerebral hemisphere, most likely to clot
posterior cerebral artery
supplies back of brain
blood brain barrier
complex that surrounds most blood vessels in the brain that separates the blood stream and the extracellular space in the brain
composition of the BBB
endothelium cells with tight junctions, astrocytes
astrocytes
glial cells that have end feet which completely surround blood vessels in the brain; maintains BBB and makes tight junctions stronger
function of BBB
limits paracellular solute flux, regulates composition and volume of brain interstitial fluid
Difference of brain interstitial fluid and plasma
interstitial fluid:
- low protein content due to tight junctions which results in a low buffering capacity
- low pH (7.33) due to higher partial pressure of CO2 because brain is highly metabolic
- low glucose concentration because it is transported into tissues of brain
- low potassium levels are needed to establish resting membrane potential
- low bicarbonate ions
plasma:
- higher pH (7.4) due to lower partial pressure of CO2; breathing affects plasma less than interstitial fluid
- higher protein content, better buffer capacity
neurovascular unit
capillaries, neurons, glial cells, endothelial cells, pericytes –> all play roll in contributing to tight junctions in BBB
critical role in maintaining local blood flow, homeostatic needs, optimizing local signal transduction
involved in many CNS pathologies (blood vessel related, bacterial/virus related, neurologically related, age related)
respiratory effects of carbon dioxide induced changes of medullary extracellular fluid pH in cats
- inhibition of exhalation increases buildup of CO2 in they system
- buildup increases CO2 partial pressure, magnifying pH change
- chemoreceptor responds to the pH change and activates phrenic nerve to contract the diaphragm
- activation of diaphragm increases breathing effort
Why do seizures often accompany brain injuries?
Hemorrhagic stroke: when a blood vessel in the brain bursts, the BBB is compromised, making the brain interstitial fluid more saturated with potassium and thus making the membrane more depolarized, bringing Ek closer to threshold. This allows action potentials to fire asynchronously and more often
Brain interstitial fluid vs CSF
- they are both located outside of the brain cells (extracellular)
- exchange through diffusion
Brain interstitial fluid
fluid that brain cells (neurons, astrocytes) are bathed in
Cerebrospinal fluid
liquid surrounding the brain and spinal cord that helps absorb the mechanical shock and maintain chemical stability
found within the brain ventricles, central canal of the spinal cord, subarachnoid space
the wastes generated by brain tissues can be removed as the cerebrospinal fluid continues to circulate
cerebrospinal fluid production
- produced by the choroid plexus in lateral and 3 ventricles
- intraventricular foramen connects the lateral ventricles, the cerebral aqueduct connects the 3rd and 4th ventricles - CSF leaves the 4th ventricle via paired lateral apertures or single median aperture
- flows through the subarachnoid space and into arachnoid villi and drains into dural venus sinuses
sleep experiment
during sleep, glial cells shrink because norepinephrine tells them to, which increases interstitial space to 60% and increases the CSF ability to flush out toxins
grey matter
darker, contains nerve cell bodies, dendrites
cerebral cortex and basal ganglia
white matter
axons, nerve fibers with myelin sheaths
commissural fibers, projection fibers, association fibers
commissural fibers
fibers that connect one cerebral hemisphere to the other
EX: corpus callosum
projection fibers
fibers that connect the cerebrum and other parts of the brain and / or spinal cord
EX: internal capsule
association fibers
fibers that connect areas of the cerebral cortex within the same hemisphere
EX: fornix
cerebrum
largest, higher brain functions
diencephalon
deep, center for homeostasis
thalamus, hypothalamus, epithalamus
cerebellum
impairs motor function on ipsilateral side of the brain/body
- adjusts postural muscles of body
- error correcting during movement
- motor learning and adaptation
- automating and optimizing behavior
cerebrocerebellum, vestibulocerebellum, spinocerebellum
neocortical composition layers 1-4
sensory receptors
neocortical composition layers 4-6
commander neurons
frontal lobe
motor, speech, memory, information, personality, emotion
primary motor cortex
sends signals to initiate contraction
Broca’s area
motor control of language, articulation, tongue control
orbitofrontal cortex
judgement, rewards and punishments in relation to a decision
olfactory bulb
smell response
temporal lobe
hearing, speech, language, smell, info retrieval
primary olfactory cortex
sense of smell
Wernicke’s area
language processing and understanding
primary auditory cortex
hearing
primary somatosensory cortex
senses touch, pain, temperature
parietal lobe
sensation, sensation memories, integration of sensation, proprioception (spacial awareness)
somatosensory association cortex
processes information from primary somatosensory cortex
primary gustatory cortex
processes taste along with the insular lobe
insular lobe
instinct and mood
occipital lobe
visual processing and visual memory storage
visual association area
interprets info from primary visual cortex
primary visual cortex
2D sketch
angular gyrus
language comprehension
arcuate fasiculus
white matter tract that connects broca’s area and wernicke’s area (association fibers)
damage to Broca’s area
unable to speak
damage to Wernicke’s area
speak nonsense / no understanding
damage to arcuate and fasiculus
- articulation and understanding is preserved
- speech contains paraphrasic errors
- understands they’re making mistakes
- trouble reading out loud or repeating
basal ganglia
structures in the cerebral hemisphere that receive input from the cortex and sends output signals through the thalamus to the cerebral cortex
- links complex motivational signals to motor function
- side loop for motor control: gets info from sensory motor cortex which modules muscle tone; prevents unwanted movement
huntington’s disease
unwanted movement
Direct pathway
excitatory; simple, fewer connections
- excitatory neuron from cerebral cortex synapses with an inhibitory neuron which inactivates in inhibitory neuron and excites the thalamus
- inhibits inhibition – overal is excitatory
Indirect pathway
inhibitory; more complicated connections
- an excitatory neuron synapses with an inhibitory neuron which inhibits an excitatory neuron in the subthalamic nucleus which excites the globus pallidus and inhibits the thalamus
- overal action is inhibited
Parkinsons disease
loss of substantia nigra cells (dopaminergic neurons of basal ganglia)
slow movement
USUALLY:
- inhibitory neuron from substantia nigra acts on the indirect pathway, overall effect is inhibitory
- excitatory neuron from substantia nigra acts on the direct pathway, overall effect is excitatory
basal ganglia structures
caudate nucleus, putamen, globus pallidus, claustrum, amygdaloid body
claustrum
processes visual information
amygdaloid body
emotion/mood
thalamus
relay center from motor control to cerebral cortex or sensory input to cortex; all conscious senses except for olfactory; GOOD FILTER
hypothalamus
command center for autonomic nervous system, endocrine system, regulates homeostatic systems, food and water intake, emotional behavior
NO BBB: secretes hormones in endocrine system
pineal gland
secretes melatonin to regulate circadian rhythm
brainstem
- bidirectional passageway for all tracts extending between the cerebrum and spinal cord
- autonomic and reflex centers
medulla, pons, midbrain
midbrain
motor movement, particularly movements of the eye, auditory and visual processing
tectum, red nucleus, reticular formation, substantia nigra
tectum
superior colliculus, inferior colliculus
superior colliculus
visual reflex center
inferior colliculus
auditory reflex center
pons
autonomic respiratory center, cranial nerve nuclei, reticular formation
SURVIVE AFTER CUT
medulla
center for cardiovascular regulation and respiratory rhythm generation
NO SURVIVAL AFTER BEING CUT
cerebrocerebellum
motor planning; lateral hemispheres
vestibulocerebellum
input from brainstem vestibular nuclei, eye and head movement and balance, flocculondar tube
spinocerebellum
motor execution
vermis, paravermis
vermis
trunk movement
paravermis
limb movement
two functional brain systems
reticular formation, limbic system
reticular formation
receives info from motor cortex, basal nuclei, cerebellum, cranial motor neurons; extends through brainstem and throughout brain
motor functions and sensory functions
motor functions of reticular formation
regulates muscle tone at rest, autonomic motor functions (respiratory, cardiovascular, vasomotor)
sensory functions of reticular formation
alert cerebrum (reticular activating system), pain modulation, habituation
limbic system
ring around diencephalon; emotional function and memory function
cingulate gyrus, hippocampus, parahippocampal gyrus, amygdala, olfactory bulbs, fornix, diencephalon nuclei
emotional function of limbic system
emotion and motivational aspects of behavior; provides emotional component to learning process (esp amygdala)
memory function of limbic system
hippocampus primarily
Kluver-Bucy Syndrome
results from bilateral destruction of amygdala
- decreased emotionality (disinhibited behavior)
- docility (loss of normal response to threats)
- hypersexuality
- hyperorality
- visual agnosia
Case of HM
removal of hippocampus to remove epilepsy:
- trouble forming new explicit long term memories
- working memory and procedure in tact
- better in muscle memory games (implicit memory)
Explicit memory
facts and events
hippocampus, parahippocampal region, medial temporal lobe
conscious
Implicit memory
perceptual and motor skills; reflex
amygdala, striatum, cerebellum
unconscious
Short term memory
increases neurotransmitter release
G-coupled receptor releases cAMP which activates protein kinase A, opens calcium channels, vesicular release releases neurotransmitters
Long term memory
alters gene expression, transcribes a new protein, and forms more synapses; requires repetition
repetition increases cAMP, which reaches protein kinase A and opens calcium channels –> starts activating and transcribing the gene and gene expression is altered. New protein is present which stimulates growth of axon through branching, forming new synapses and increasing synapse strength
left hemisphere
language, math, logic and reasoning
right hemisphere
spatial abilities, visual imagery, facial recognition, music
cranial nerves
some say marry money but my brother says big brains matter most;
on on on they traveled and found voldemort guarding very ancient horcruxes
cranial nerve I
olfactory
cranial nerve II
optic
cranial nerve III
oculomotor
cranial nerve IV
trochlear
cranial nerve V
trigeminal
cranial nerve VI
abducens
cranial nerve VII
facial
cranial nerve VIII
vestibulocochlear
cranial nerve IX
glossopharyngeal
cranial nerve X
vagal/vagus
cranial nerve XI
accessory
cranial nerve XII
hypoglossal
olfactory nerve
smell; sensory
optic nerve
vision; sensory
oculomotor nerve
4/6 eye muscles; pupil size, eye shape, eyelid
motor
trochlear
1/6 eye muscle; motor
trigeminal
pain, temperature, touch, chewing
3 branches: opthalamic, maxillary, mandible
greatest sensory function
sensory and motor
abducens
1/6 eye muscles; motor
facial
facial expression, taste, control of salivary glands, tears (THINK GIANA); sensory, motor, parasympathetic
vestibulocochlear
hearing and balance; sensory
glossopharyngeal
general taste sensation, 1/3 back of tongue, blood pH, gasses, swallowing, salivary gland
sensory, motor, parasympathetic
vagus
swallowing, speaking, visceral sensory, motor, autonomic
sensory, motor, parasympathetic
accessory
traps and sternocleidmastoid; motor
hypoglossal
tongue, pointed to weakened nerve; motor
spinal cord
information integration center
31 pairs of nerves exit intervertebral foramina
spinal meninges
3 layers, subarachnoid space has CSF, grey matter opposite than brain
somatic neurons
skeletal muscle/skin
visceral neurons
internal organs / smooth and cardiac muscle
ascending tracts
signals to brain
posterior column pathway, spinocerebellar, anterolateral pathway
descending tracts
commands to motor neurons
corticospinal pathway, medial and lateral pathways
spinocerebellar
position of body, spine to cerebellum
anterolateral pathway
pain, temperature, crude touch (sensory)
spinothalamic tract
corticospinal pathway
corticobulbar, corticospinal
corticobulbar pathway
cortex to brainstem, innervates face and neck
posterior column pathway
sensations of discriminative touch, vibrations, joint positions
fasiculus cuneatus
fasiculus gracilis
medial and lateral pathways
vestibulospinal
tectospinal
reticulospinal
rubrospinal
rubrospinal path
red nucleus, voluntary movement
tectospinal
head and eye movement (midbrain)
reticulospinal
locomotion, posture
sensory receptors
- respond to a particular modality of environmental stimuli
- transduce different forms of sensation to nerve impulses that are conducted to CNS
- perceptions of the world are created by the brain from AP sent from sensory receptors
special senses
vision, hearing, taste, smell, equilibrium
somatic senses
touch, temperature, pain, itch, proprioception
somatic stimuli
muscle length and tension, proprioception
visceral stimuli
blood pressure, distension of gastrointestinal tract, blood glucose concentration, internal body temperature, osmolarity of body fluids, lung inflation, pH of cerebrospinal fluid, pH and oxygen content of blood
meissner’s corpuscle
rapid mechanoreceptor; touch and pressure
merkle’s corpuscle
slow mechanoreceptor; touch and pressure
free nerve ending
slow; nociceptors, thermoreceptors, mechanoreceptors
pacinian corpuscle
rapid mechanoreceptor; vibration and deep pressure
ruffini corpuscle
slow mechanoreceptor; skin stretch
olfactory pathways form nose project through olfactory bulb to the
olfactory cortex
sensory pathways project to the
thalamus which relays info to cortical centers
equilibrium pathways project to the
cerebellum
thermoreceptors
temperature; in skin, muscle, liver, hypothalamus
why are there thermoreceptors in the liver?
metabolism: if there is low glucose, thermal generation decreases and changes metabolic process
why are there thermoreceptors in the hypothalamus?
it is the thermoregulation center
mechanoreceptors
cell is twisted and receptors are activated
tactile
baroreceptors
proprioceptors
tactile receptors
touching skin
baroreceptors
carotid body, stretching is sensed and tells you how high of blood pressure
proprioceptors
tells you where body is, when cell is moved
nociceptors
tell you when body is damaged or inflamed – pain
chemoreceptors
general and special; ions and glucose with taste (conscious), pH regulation in brainstem (unconscious)
photoreceptors
transduce light into electrical signals
categories of sensory receptors
simple, complex
simple dendritic endings
free nerve endings, encapsulated nerve endings
free nerve endings
pain, temperature, smell
encapsulated
pressure and touch, wrapped around nerve endings
when pressure is applied, shape changes and channel gets closed; pressure gets redistributed and cells stop firing
complex sensory receptors
separate cell doing transduction work
rods and cones, hair cells, modified epithelial cells
hair cells
inner ear telling you loudness, senses balance
rods and cones
sight
exteroceptors
outside/ external stimuli
interoceptors
inside/ internal stimuli
proprioceptors
internal stimuli with movement
adquate/normal stimulus
the type/modality of stimulus that a receptor is most sensitive to
allows brain to perceive the stimulus accurately under normal conditions
receptor doesn’t matter HOW it’s activated, it is only giving info on one modality
sensory unit
one afferent neuron and all its receptors
receptive field
that part of body which when stimulated activates that afferent neuron
receptor potential
generated in transduction sites
amplitude correlates to stimulus intensity
stimulus intensity
how the body transmits action potentials and not lose info
- analog to digital conversion
- recruitment
analog to digital conversion
graded potential to action potential faster or slower
recruitment
strong stimulus recruits a neighbor sensory (afferent) neurons to fire action potentials
coding of stimulus type
modality, specificity of ascending pathway
specificity of ascending pathway
labeled line theory: trace the white matter tract because it tells you the type of info it’s sending
punctate distribution
point and spotted stimulation – less than 3mm apart, sticks feel like one poke
dorsal column
sensory pathway conveys sensations of fine touch, vibration, two point discrimination, and proprioception
- less divergence and convergence, less branching
lateral inhibition
primary neuron response is proportional to stimulus strength; B inhibits A and C
presynaptic inhibition
GABA from primary neuron activates calcium channels, therefore less vesicular release
tonic receptors
slowly adapting; produce constant rate of firing as long as stimulus is applied (may slowly decrease)
phasic receptors
rapidly adapting; burst of activity but quickly reduce firing rate if stimulus is maintained
sensory adaptation
neurons/body ceases to pay attention to constant stimuli
dorsal column tracts
Fasiculus Gracilis and fasiculus cuneatus and medial leminiscus
fasiculus gracilis and cuneatus
slender, myelinated sheaths, ascends ipsilaterally
synapses and crosses medulla
becomes nucleus gracilis and cuneatus when synapses and is no longer white matter fibers
medial lemniscus
ascending white matter tract from medulla to thalamus and synapses
anterolateral system tracts
spinothalamic, spinotectal, spinoreticular
spinothalamic
sharp pain
spinotectal
dual burning sensation
spinoreticular
dual burning sensation, limbic system, emotional pain
