NEUROBIOLOGY EXAM 3 NOTES

Arizona state university bio 467 neuro exam 3 latest 2021 Updated Version correct study guide download to score A+

NEUROBIOLOGY – EXAM 3 NOTES

VASCULATURE OF THE BRAIN

Anatomy • Layers covering the brain (from the outside in) o Skin → epicranial aponeurosis → periosteum → bone → 3 meninges layers ▪ 3 meninges layers • Dura mater – dense outer fibrous layer; thick supporting layer ▪ Arachnoid mater – spider-webby middle layer ▪ Pia mater – 1-cell layer thick lining of surface of brain; acts in blood-brain barrier • Blood supply to the brain o In general ▪ Middle ear infection is most common cause of brain abscess bc of these arteries ▪ Brain capillary bed surface area = size of tennis court ▪ 20% of oxygen taken in by lungs goes to brain o Cerebrovascular Complex ▪ Anterior Branches • L/R Internal Carotid aa.

• Anterior Cerebral a.
• Anterior Communicating a.
• Middle Cerebral a.

▪ Posterior Branches • L/V Vertebral aa.

• Posterior Inferior Cerebellar a. o Basilar a.

▪ Anterior/inferior/superior cerebellar aa.

• Posterior Cerebral a. – prone to blockage

because it has a sharp turn o Posterior Communicating a. Veins of the brain – drain from the ventricles of the brain o no valves • Random anatomic terms Landers mentions o Palpebral Fold – area where veins enter the orbit

Cerebrospinal Fluid – ultrafiltrate of blood • Important for the brain o Brain is <2% of body weight, but receives 20% of blood volume!

• If blood flow to brain stops for 10-15 sec – unconscious 1 / 3

• If blood flow to brain stops for 5 min – irreversible damage to brain cells

• Facts about CSF o Makeup - 50% less glucose than plasma, little protein and lymphocytes ▪ Sterile – no protein or cell populations o Total CSF volume = 130ml

• Pressure = 70-180 mmH2O
• Choroid Plexus makes 21 ml/hr (500ml/day)

▪ Replaces 3-4 times a day ▪ In lateral ventricle, supplied by Anterior Choroidal a. ▪ In 3 rd ventricle, supplied by Posterior Choroidal a.Circulation of CSF

• 1) Lateral Ventricle – bilateral, separated by the septum pellucidum o contains choroid plexus!! (which produces CSF) • 2) Interventricular Foramen of Monroe – drains CSF from lateral ventricles to 3 rd ventricle • 3) Third Ventricle – unilateral, located between thalamic hemispheres • 4) Cerebral Aqueduct of Sylvius – drains CSF from 3 rd ventricle to 4 th ventricle • 5) Fourth Ventricle – unilateral, located between pons and cerebellum o Also contains choroid plexus that makes CSF

• 6) Three options:

• Posterior Foramen of Magiende – drains 4

th ventricle posteriorly into subarachnoid space o Foramen of Luschka – drains 4 th ventricle laterally into subarachnoid space o Central Canal of Spinal Cord – drains 4 th ventricle into spinal column • 7) Subarachnoid Space – circulates CSF around outside of brain • 8) Arachnoid Granulations - extensions through dura that act as a one-way valve return of CSF • Two possible tracts from here… Superior Sagittal Sinus Inferior Sagittal Sinus

Right Transverse Sinus Straight Sinus

Sigmoid Sinus Left Transverse Sinus

Sigmoid Sinus Internal Jugular v. 2 / 3

Venous return

• Straight sinus – runs down the falx cerebri

CNS barriers – control transport of nutrients and wastes between 2 vascular interfaces to maintain microenvironment of CNS neurons • Blood-Brain Barrier – physical, metabolic, and transport properties of brain capillary endothelium o What does it block/control ▪ circulating macromolecules (glucose) ▪ ions ▪ toxins ▪ peripheral NT’s o How does it block ▪ Zona occludens – tight junctions in endothelial wall (no fenestrations) • Limits presence of fenestrations in capillary walls • Makes these capillaries unique from the rest of the body ▪ Lack of endocytic pits in capillaries • Blood-CSF Barrier – lining of choroidal capillaries o What does it block/control ▪ Allows ultrafiltrate of blood to leak out and form CSF ▪ Allows 2-way flow o How does it block ▪ Microvilli in choroidal epithelium ▪ Zona adherens – tight junctions in epithelial wall • Associated with specific enzyme carriers • Things not protected by these barriers (SNAP, MCL, P) o Subfornical area o Neurohypophysis o Area Postrema o Pineal body

• Median Eminence
• Choroid plexus of 4

th ventricle

• Lamina terminalis
• Posterior Commissure

CEREBELLUM

In general • Roles of the cerebellum o Maintain posture, balance, equilibrium, muscle tone o Consolidates received info and coordinates motor activity ▪ Controls timing, speed, and precision of movement ▪ Provides give and take between Primary Motor and Premotor Cortex – adjusts continuous movement to make it more precise • Input to cerebellum o Motor cortex, visual cortex, auditory cortex

• Vestibular system – which is in the temporal bone and for balance o Somatosensory cortex

• Random areas Landers mentions o Folia – small folds (like gyri) in the cerebellum o Vermis – worm-like midline structure

• Paravermal areas – on either side of the vermis, made up by parts of the anterior &posterior

lobes o Primary Fissure – divides the anterior and posterior lobes

• Cerebellar Tonsils – bilateral, on either side of the medulla
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