A&P Test 2 Flashcards
Venous structures in the brain are called
sinuses
The walls of the sinuses in the brain are made up of the
dura mater
why are most subdural hematomas venous?
because the sinus’s are made of the dura mater and if something rips through the dura part of the wall then the venous structures rip too
our brain blood flow rate depends on what?
the brain’s metabolic demands
How does the brain prevent under profusion?
by vasodilating the blood flow pathways in the brain
How does the brain prevent over profusion?
by constricting the blood flow pathways in the brain
Why do we have a circular pathway in the brain?
it ensures collateral pathways if we have a blockage in a feed artery
Where do the internal carotid arteries enter into the circle of willis?
In the middle, one on each side
Where do the vertebral arteries connect with the circle of willis?
they come together to form one artery called the basilar artery
The vertebral arteries come together over what anatomical landmark to make the basilar artery?
at the base of the pons
Where does the basilar artery come into the circle of willis?
in the middle on the posterior side
What are the 3 large arteries that connect to the circle of willis?
Posterior cerebral artery
Middle cerebral artery
Anterior cerebral artery
Of these, which is the largest?
Posterior cerebral artery
Middle cerebral artery
Anterior cerebral artery
middle cerebral artery
The middle cerebral artery supplies what area of the brain?
The middle and lateral portions
Which part of the brain is supplied by the anterior cerebral artery?
the front and midline portions
Which part of the brain is supplied by the posterior cerebral artery?
Back and far lateral areas
What are the two parts of the anterior cerebral artery?
Early; Pre-communicating A1
Late; Post-communicating A2
Which part of the anterior cerebral artery touches the circle of willis?
Early; Pre-communicating A1
Which part of the anterior cerebral artery does not touch the circle of willis?
Late; Post-communicating A2
What is the small artery that attaches the two anterior cerebral artery?
anterior communicating artery
After the internal carotid’s touch the circle of willis, their names change to
middle cerebral artery
Which part of the posterior cerebral artery touches the circle of willis?
early; Pre-communicating part P1
Which part of the posterior cerebral artery does not touch the circle of willis?
Late; Post-communicating P2
Which artery connects the middle cerebral arterties to the posterior cerebral arteries?
The posterior communicating artery
Which artery supplies the front and top of the cerebellum
superior cerebellar artery
What artery does the superior cerebellar artery come from
the basilar artery
Which artery supplies the middle of the cerebellum
anteroinferior cerebellar artery
What artery does the anterioinferior cerebellar artery come from
the basilar artery
What supplies the back portion of the cerebellum?
posteriorinferior cerebellar artery
What artery does the posteriorinferior cerebellar artery come from
vertebral arteries
the anteriorinferior artery comes off of the basilar artery, right over the
middle of the pons
the posteriorinferior artery comes off of the vertebral arteries, right over the
brainstem
most epidural hematomas are a result of
trauma
subdural hematomas are a result of
tearing the dural walls like a bad wreck and you have whiplash
subarachnoid hemorrhage is the most messy, why?
because in the other types, the blood typically tends to aggregate into one place which can be solved by a drain or opening the skull there
Which type of bleed is associated with aneurysms and hemorrhagic strokes?
subarachnoid hemorrhages
subarachnoid hemorrhages are typically venous or arterial?
arterial
what is a cause of hemorrhagic strokes?
bad lifestyle choices, alcoholism, long term hypertension
When metabolism goes up in the brain, so should
blood flow
What is the top byproduct of metabolism that is involved in regulation of brain blood flow?
CO2
why does blood flow increase when metabolic demands increase?
CO2 is created as a metabolic byproduct (increased metabolism=increased CO2), and then leaks into the surrounding tissues, blood flow increases to get rid of that excess CO2 as well as replace any nutrients expended in metabolism
What is the number 1 regulator of brain blood flow?
CO2
we need as much cerebral bloodflow as it takes to
remove the CO2 that’s being produced
Once all of the CO2 is removed from the cerebral blood flow, then blood flow
doesn’t increase anymore, it just curtails
What is the range of systemic blood pressure (map) that is required for brain blood flow? autoregulation
50-150
If our cerebral metabolism hasn’t changed, but our blood pressure is increased, than the brain blood flow should
stay about the same because the vessels constrict to prevent over profusion
Systemic blood pressure is used to drive
brain blood flow
if there was no autoregulation, what would we see on a graph of brain blood flow and blood pressure?
a linear line with low blood flow arising from low blood pressure
If we have under profusion of the brain we would have
cell death
If we have over profusion of the brain we would have
bursting of aneurysms
More recently they have thought that autoregulation would cut off after the map drops below
60-70
after about a map of 50, the brain vessels can’t constrict anymore so we would see
a reduction in brain blood flow
what is the point when the blood vessels in the brain cannot dilate any further?
the lower limit autoregulation LLA
what is the point when the blood vessels in the brain cannot constrict any further?
the upper limit autoregularion ULA
if we have a patient who has prolonged HTN, what happens to their lower and upper limits?
the system adapts, and the LLA and ULA will shift to the right
How do the brain vessels adapt to squeeze tighter than the upper limit when exposed to prolong HTN?
The vessels harden
atherosclerosis
What will happen when the lower limit is raised d/t atherosclerosis and the patient’s map drops to 50
The brain tissue will now be under perfused
What is a way that the body adapts to a clot in the vessels?
collateral blood flow
often times when someone is trying to get a handle on cardiovascular health then they look at
the ability of the blood vessels to dilate
Collateral blood flow is something that we are
born with
HTN and diabetes zap the ability to _______ in the blood vessels
dilate.
this gives them more serious strokes and MI’s
Anesthetic drugs takes some of our _____ ofline
autoregulation
in an anesthetic that affects autoregulation just a little, you would expect the middle line on the graph to be
slightly sloped
in An anesthetic that affects autoregulation a lot, you would expect the middle line on the graph to be
steeper
Most of the textbooks say that anesthetics don’t effect autoregulation, but we know that isn’t really true, and they are simply taking into account the
Error bar that arises from variability from testing humans
the wider the error bar, they say the data is
statistically insignificant, and therefore cannot prove that the anesthetic takes autoregulation offline, even if the graph clearly shows that it does
an action protentional moves down an axon d/t
fast Na+ channels
What is in the axon wall that helps reset the cell after depolarization?
Na+/K+ pumps and voltage gated K+ channels
When the action potential reaches the end of the neuron, it opens up a second set of voltage gated ion channels specific for
Ca++
What is another name for the voltage gated Ca++ channel?
P-Type voltage gated Ca++ channels
When Ca++ floods into the cell after an action potential, what does it do?
It binds to VP2 ACh storage vesicles and pushes it to the cell wall for exocytosis
What is the difference between a VP2 ACh storage vesicles and a VP1 ACh storage vesicle?
VP2 ACh storage vesicles are at the cell wall, ready to be spilled out into the synapse.
VP1 ACh storage vesicles are either not full or not low enough to the synapse
What does VP2 stand for in a ACh storage vesicles?
Vesicle pool
What shuts off the ACh dumping into the synapse after an action potential?
Ca++ pumps using ATP
Na+/K+ pumps
K+ channel
Ca++ sensitive K+ channels
all of these remove + charges
What is found on the target skeletal muscle that ACh binds to?
nACH receptor
nACh receptors function as cylinders that open when 2 ACh molecules bind to it at the same time, and this allows what movement of ions?
Na+ floods, some Ca++ comes in, and a tiny but of K+ goes out
Why is it that in a healthy muscle cell, an endplate potential will always trigger an action potential?
because we have way way way more ACh receptors and ACh neurotransmitters
What is an endplate potential?
localized depolarization that happens in the muscle d/t ACh receptors opening up
Endplate potentials in a healthy muscle is always going to be enough to trigger an
an action potential by opening fast sodium channels, which results in a muscle contraction
What is the bare minimum end plate potential that is required to create an action potential in the post synaptic cell?
500,000 receptors activated
