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Blood supply of brain and spinal cord, stroke, Neuron anatomy and physiology, Action and resting potential of neuron, neuron synapse, glai, visual pathway
where are the vessels in the brain
on the surface
where does blood enter the brain
through a hole in the skull
what is the hole in the skull where blood enters called/
foramina
what percentage of total body weight does the brain hold
2%
how much of the body blood supply does the brain receive
15-20%
what will happen if blood supply to the brain is stopped or altered
bain cells will die
What goes into brain by blood supply
oxygen, carbohydrates, amino acids, fats, hormones, vitamins
what goes out of the brain
carbon dioxide, ammonia, lactate, hormones
how many arteries supply the brain
2
which arteries supply the brain
internal carotid arteries and vertebral arteries
What do the right and left arteries form at the base of the brain?
the basilar artery
What do the basilar and blood supply of internal carotid arteries form?
the ring (circle of willis)
what is the circle of willis for?
the supply blood to brain even if other arteries or pathways are blocked
What is a brain attack?
a stroke
What causes a stroke?
when the blood supply of the brain is stopped or blocked
What can a stroke lead to?
paralysis or aphasia
What are the 2 major causes of strokes?
blockage or bleeding in the brain or neck
Where does blockage cause a stroke?
in the neck/brain
thrombosis
a blood clot in the brain or neck
embolism
blood clot from somewhere else that moved to brain/neck
stenosis
obstruction/narrowing of an artery in head/neck
hemorrhage stroke
bleeding of a blood vessel
symptoms of hemorrhage stroke
-sudden weakness/numbness in face/arm/leg on 1 side
-sudden dimness or loss of vision in one eye
-sudden difficulty speaking/understanding
-sudden severe headache
conditions linked to stroke
-high bp
-smoking
-heart disease
-diabetes
-transient ischemic attacks
Carotid
greek- kartosi= deep sleep
What is the eye in the visual pathway
the camera
what is the retina in the visual pathway
photographic film
what do the cornea and lens provide
focus
what adjust to light
iris
what is the retnia
layers of neurons
how are images displayed through retina?
focused images are inverted
structure of cornea
transparent, convex surface
what does the cornea hold
-no blood vessels
-aqueous humor
-tears
at resting membrane potential which ions cross the membrane easily?
K+
At resting potential which ions cannot cross the membrane easily?
Cl-, Na+
What ion cannot cross the resting potential membrane at all?
A-
What is the pump ratio for the cell mebrane
3 Na+ in/ 2K+ out
Which ions are more of on the inside of the membrane during resting potential K+ or Na+?
K+
When does action ptiental occur in a neuron?
When neuron send info down axon (away from cell body)
Depolarization current
explosion of electrical activity
what happens during a stimulus in a neuron?
resting potential decreases to 0mV (depolarization)
When is action potential fried?
When dp= -55mV
when is the threshold
-55mV
is the size of the action potential always the same, and why?
yes because of All or none principle
important ions in NS
K+, Na+, Cl-, Ca++, A-
when does action potential occur?
when diff ions cross membrane
What happens first when action potential occurs?
Na+ channel opens and rush into neuron ( makes more + and more depolarization)
What happens second when action potential occurs?
K+ channels open and rush out of neuron ( makes more - and less depolarization)
When does repolarization occur
when action potential goes back towards -70mV and beyond to stabilize
when does hyperpolarization occur?
when k+ stay open for to long and neuron goes beyond -70mV
What do Glia not do/ have
carry nerve impulses, resting potential, more than one processes, and chemical synapses
Can neurons work properly with out glia?
no
Astrocyte/ Astroglia
star shaped cells that provided nutrition and physical support, clean up, digest dead, and regulate extracellular space.
Microglia
digest dead neurons
Oligodendroglia
insulation (myelin) to neurons in CNS
Satellite cells
Support neurons in PNS
Schwann Cells
insulation( myelin) neurons in PNS
The similarities of neurons and other cells
-surrounded by cell membrane
-nuclei carries genes
-has cytoplasm and other organelles
-carry out basic cellular process
Diff of neurons from other cells
-dendrite ( info into cell)
-axon (infor out of cell)
how do you classify neurons?
by number of extensions
Bipolar Neurons
two processes extending from cell body
Pseudounipolar neurons
2 axons
1 axon goes to SPINAL cord;
1 axon goes to SKIN/MUSCLES
multipolar neurons
many processes (1 axon)
interneurons
send info between neurons
characteristics of axons
smooth, 1 per cell, myelin, further from cell body
characteristics of dendrites
rough, multipule, no myelin, near cell body
nucleolus in neuron
produce ribosomes= genetic info into proteins
nissi bodies in neuron
group ribosomes
er in neuron
transport materials through cytoplasm
Rough er: ribosomes protein synthesis
Golgi apparatus in neuron
package pesticides and proteins
microfilaments/ neurotubules in neuron
transport materials, structural support
oldest and longs cells in body
neurons
where can new neurons
hippocampus
synapses
where info flows between neurons
synaptic cleft
small gap between pre/post synaptic
presynaptic ending
neurotransmitter & organelles
postsynaptic
receptors
which way does and impulse travel on a axon to synaptic terminals?
down
what do electric impulses trigger?
migration vesicles
what does the vesicle membrane fuse with?
presynaptic membrane
what does the presynaptic membrane release?
neurotransmitter into synaptic cleft
Dale’s law (debunked)
1 neurotransmitter is made by a neuron
what do molecules that cross synaptic cleft bind with and what do they influence?
receptor sites and influence electrical response in postsynaptic
when does change in excitability happen
when neurotransmitter binds with receptor
when does continuation of “message” occur
with larger number of postsynaptic excitatory events
What arteries supply the spinal cord and brain?
the vertebral and internal carotid
where does the vertebral arteries come from
subclavian arteries
where does the internal carotid arteries come from?
common carotid arteries
What arteries supply the spinal cord
vertebral and 10 medullary
where do the medullary arteries come from
segmental branches of aorta
Medullary + vertebral arteries=
anterior and posterior spinal arteries
loss of posterior arteries in spinal cord =
loss of sensory function
loss of anterior arteries in spinal cord =
loss of motor deficits
at level of medulla vertebral arteries give off what?
branch of anterior spinal artery (10-12 count)
at level of pons right + left vertebral arteries =
midline basilar artery
basilar artery + internal cerebral artery =
posterior cerebral arteries
internal cerebral arteries + circle of willis =
posterior and anterior communicating arteries
anterior + middle cerebral arteries =
anterior circulation of forebrain
where do the anterior & middle cerebral arteries branch from?
circle of willis
branches from circle of willis support
cortex, basal ganglia, thalamus, internal capsule
Note 
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