Test 1: The Brain, protection and blood supply Flashcards
how much does the brain weigh?
about 3 pounds
all functions of the brain occur within ..
about 100 billion neurons
what are the functions of the brain?
Register sensation Integrate sensory information Stimulate response/ actions Physiological regulation/ homeostasis Higher executive functioning – planning, memory, behavior, Intellect
what is the frontal lobe associated with?
higher functions, planning, reasoning, and abstract thought
do humans have a larger frontal lobe than animals?
heck ya
what are the major regions of the brain?
cerebrum, cerebellum, diencephalon,
brain stem
cerebrum
largest region of the brain
Diencephalon
thalamus and hypothalamus
Brain stem
midbrain, pons medulla oblongata
dura mater
has two layers- durable, tough, they actually separate( this creates a sinus)
arachnoid
covers the brain non vascular, spidery layers are in the sub arachnoid space( where cerebral spinal fluid circulates)
Pia Mater
inner most layer, delicate, very tightly adheres to the brain
sinus
Blood goes through and comes back to the heart
what is the order of the protective covering of the brain
Pia mater, arachnoid, dura mater
PAD
extensions of dura mater
form hard, non- compliant membranes that divide the intracranial vault.
dural layers
- external periosteal layer
- internal meningeal layer
dural extensions
falx cerebri
falx cerebelli
tetorium cerebelli
falx cerebri
descends vertically in longitudinal fissure.
it separated L/R cerebral hemispheres
falx cerebelli
small triangular process.
it separated cerebellar hemispheres
tentorium cerebelli
looks like a tent
falx
sickle shaped (blade shaped)
what is the clinical importance of the tentorium cerebella?
brain tumors identified as supratentorial (above the tentorium) and infratentorial (below the tentorium)
Swelling: the brain can get partly pushed down and herniate through the tentorium, which becomes life-threatening
what percent of body weight is the brain?
2%
what percent of the body’s blood supply does the brain receive?
about 20%
the brain consumes _ % of total _ and _ even at resting
20% of total O2 and glucose
what does the brain use as its primary source of energy?
glucose
what is the normal cardiac output?
5L per minute (think of it as a fist is the size of your heart)
carotid arteries
R and L, internal and external
provide oxygenated blood
vertebral arteries
close to the vertebral column
provide oxygenated blood
cerebral arterial circle
circle of freaking willis. this is known as anastomosis- provides alternative routes of circulation
anastomosis
provides alternative routes of circulation
stinosis
a closing
internal jugular
dats a big vein
blood brain barriers
We need to protect the CNS and don’t want everything in the blood to get through
tight junctions
controling permeability
endothelial cells
inner lining of the blood vessels, these do not leak, that is why they have tight junctions, vascular
Blood cerebrospinal fluid barrier
produces CSF
arachnoid matter
controls what can move in and out. it is an avascular membrane enveloping the brain
Choroid plexuses
where CSF is made
Lipophilic
dissolves in lipids and fats
astrocytes
clamp around structures in the brain and support the function of the bbb.
In Parkinson’s they don’t work properly
what does not work properly in Parkinson’s?
astrocytes
what gets through the bbb?
o2 and co2 because they are lipophilic, alcohol, caffeine, drugs
What does not get through bbb
no glucose because it is water soluble
what is the hallmark feature of the blood brain barrier?
tight junctions
what are the costs of tight junctions?
active transport of glucose and difficulty treating disease
CSF
Clear fluid: (about 125 ml) O2, protein content is much lower than blood
There should be no blood in the csf
what are the basic functions of cerebral spinal fluid?
Mechanical: shock absorbent medium, buoyancy
Homeostatic function: pulmonary ventilation and cerebral blood flow (pH). Transport system (hypothalamic hormones)
Circulation: exchange of nutrients/ waste between blood and nervous tissue
ependymal cells
produce csf
ventricle
fluid filled space
choroid plexuses
network of capillaries lining ventricle walls
where are tight junctions?
they are in the surrounding cells, not the capillaries themselves
how much CSF is circulating?
about 125- 150 mL
how much CSF are we producing?
about 20 mL an hour and the same amount is being reabsorbed in the blood stream
lateral ventricles
2 largest ventricles .R and L, horn shaped structures
third ventricles
Cavity between R/L thalamus. Communicates with lateral ventricles via opening at anterior end of third ventricle.
fourth ventricles
Between brain stem and cerebellum. Narrows caudally to form the central canal of the spinal cord.
describe the flow of csf
It is produced in the lateral ventricle It is going to travel down into the interventricular foramen and then goes to the third ventricle. Then it is connected to the fourth ventricle via the cerebral aqueduct . Then it goes over the surface of the brain and spinal chord
arachnoid villi
: location or route through which CSF travels back into Venus circulation
arachnoid granulation
cluster of arachnoid villi
hydrocephalus
: CSF accumulation due to impaired CSF flow, absorption, and/or overproduction
Physiology: elevated intracranial pressure, potentially leading to brain damage and other complications
Some times confused with dimentia
