Brain 2: brain blood flow, CFS brainstem Flashcards
How are glucose and oxygen used in the brain
Neurons use glucose and oxygen to make ATP in the brain
how many % is the brain’s weight (out of total body) and how many % of energy/oxygen does it consume
Brain is 2% of total body weight but consumes 20% of all the oxygen and glucose
How long does it take for neuronal function to be impaired or permanently damaged
interruption in blood flow for 1-2 minutes to be impaired and total deprivation of oxygen for about 4 minutes causes permanent injury
how does brain store glucose
No glucose is stored in the brain so the supply of glucose must be continous
what does a low level of glucose in the blood to the brain cause
mental confusion
dizziness
convulsions
loss of consciousness
how many % of cardio output goes to brain
15%
what is blood brain barrier
Tight junctions that seal together endothelial cells of capillaries in the brain and thick basement layer that surrounds the capillaries
What type of neuroglia at blood brain barrier and what does it do?
Astrocytes - their processes press up against the capillaries and secrete chemicals that maintain the permeability characteristics of tight junctions
What can cross the blood brain barrier
- Some water-soluble substances cross by active transport (ie glucose)
- Creatinine, urea, ions cross slowly
- lipid-soluble substances (O2, Carbon dioxide, alcohol, most anesthetic agents)
What can not cross the blood brain barrier
Proteins and most antibiotic drugs do not cross
What can break down the blood brain barrier
Trauma, certain toxins and inflammation
What is Cerebral spinal fluid
Clear colourless lipids, mainly water and protects brain and spinal cord from chemical and physical injuries
what does cerebral spinal fluid carry
carries small amount of O2, glucose, proteins, lactic acid, urea, cations, anions and some WBCs needed to neurons and neuroglia
Where does cerebral fluid circulate through
The cavities in the brain and spinal cord and around the brain and spinal cord in the subarachoid space
What is the total volume of cerebral spinal fluid?
80-150 ml in adult
what are ventricles in the brain
cavities within the brain filled with CSF
2 lateral ventricles (1 in each hemisphere of the cerebrum, Septum pellucidum)
Third ventricle
Fourth ventricle
What is a thin membrane that separates that the lateral ventricles
Septum pelluciadum
Functions of ventricles
- Mechanical protection
- shock absorbing medium that protects brain and spinal cord from jolts
- fluid also keeps brain floating in the cranial cavity - Homeostatic function - the pH of CSF affects pulmonary ventilation and cerebral blood flow
- Circulation - minor exchange of nutrients and waste products between blood and nervous tissue
Where is CSF formed
In the Choroid plexuses, networks of blood capillaries in the walls of the ventricles
what is difference between Blood brain barrier and blood-CSF barrier
BBB=tight junctions of brain capillary endothelial cells
Blood-CSF barrier=tight junctions of ependymal cells
What does Blood CSF barrier do
to protect brain and spinal cord from harmful blood borne substances
Circulation of CSF
CSF formed in Choroid plexus ->lateral ventricles ->Interventricular foramina ->Third ventricle ->Cerebral aquaduct -> Forth ventricle -> 2 lateral apertures and 1 median aperture -> central canal subarachoid space ->Arachoid villi ->superior sagittal sinus ->Straight sinus ->Sigmoid sinus -> internal jugular
brain stem contains
Medulla Oblongata
Pons
Midbrain
Where and what is in Medulla Oblongata
Starts at the foremen magnum and goes to pons
Mede up of sensory (ascending) tracts and motor/(descending) tract
Pyramids
what is pyramids
bulges of white matter of the anterior part of the medulla
formed by the corticospinal tracts
What is dicussation of pyramids
Crossing of axons in pyramids
90% of axons cross here
explains why each side of brain controls the opposite side of body
nuclei in medulla
- Cardiovascular center (regulates the heart beats and the diameter of BVs)
- Medullary rhythmicity area of the respiratory center (adjusts the basic rhythm of breathing along with areas in the pons)
- vomiting center (causes vomiting)
- deglutition center (causes swallowing)
Others causes sneezing, coughing, hiccupping
what and where is olive
just lateral to each pyramid
inferior olivary nucleus
- within the olive, receives input from cerebral cortex, red nucleus (midbrain), spinal cord
- it provides instructions that the cerebellum uses to make adjustments to mm activity as you learn new motor skills
gracile nucleus and cuneate nucleus
are associated with sensations of touch, pressure, vibration and conscious proprioception.
Gracile (leg), Cuneate (arm)
gustatory nucleus
from tongue to brain, receives gustatory input from taste buds of tongue
cochlear nuclei
part of the auditory pathway from inner ear to brain
receives auditory input from cochlea of the inner ear
Vestibular nuclei
equilibrium pathway from inner ear to brain
Cranial nerves in medulla
VIII vestibular cochlear nerves IX glossopharyngral nerves X vagus nerves XI accessory nerves XII hypoglossal nerves
Injury to Medulla
hard blow to the back of head/upper neck
can be fatal
damage to medullary rhythmicity area is really bad
alcohol overdose also suppresses the medullary rhythmicity area and may result in death
Where and what is pons
consists of nuclei and tracts
is a bridge that connects parts of brain with each other
relays signals for voluntary movements from cerebral cortex to cerebellum
pontine nucleus
pons’ nuclei
pneumotaxic area: Rhythm of breathing
apneustic area: inhale/exhale
These 2 areas along with the medullary rhythmicity area help control breathing
pons’nuclei associated with cranial nerves
V trigeminal nerves
VI abducens nerves
VII facial nerves
VIII vestibulocochlear nerves (balance and equilibrium)
associated with sensations of touch, pressure, vibration and conscious proprioception
gracile nucleus and cuneate nucleus
from tongue to brain
gustatory nucleus
part of the auditory pathway from inner ear to brain
cochlear nuclei
equilibrium pathway from inner ear to brain
vestibular nuclei