5/9/19 1 14 - Brain Brain Development • CNS forms from the neural tube • Ventricles form from hollow tube called neurocoel
5/9/19 2 Neurocoel Ventricles and central canal • Neurocoel – D u r in g d e v e lo p m e n t – E x p a n d s a n d F o ld s – B e c o m e s v e n tr ic le s a n d c e n tr a l c a n a l • Ventricles – L in e d b y c ilia te d e p e n d y m a • Circuates CSF Cranial Meninges • Dura mater • Arachnoid mater – Subarachnoid space • C S F • Pia mater Cerebrospinal Fluid (CSF) • Located in – Subarachnoid space – Ventricles – Central canal • Functions – Protects from chemical & physical injury – Nourishment of adjacent nervous tissue – Waste removal – O 2 /CO 2 exchange
5/9/19 3 CSF • volume: 150 ml – r e p la c e d ~ 8 h o u r s • ~500 ml produced per day • Produced by filtration at choroid plexuses – choroid plexus • capillaries covered by ependymal cells • located on walls of ventricles CSF • circulated by – C ilia te d e p e n d y m a l c e lls ( e p e n d y m o c y te s ) – P r e s s u r e d if f e r e n c e s in th e s y s te m • reabsorbed at arachnoid granulations (arachnoid villi) Hydrocephalus • Normally, – formation rate = reabsorption rate • If CSF reabsorption is blocked, à hydrocephalus
5/9/19 4 Blood Brain Barrier • series of elements – 1- tight junctions between brain capillary cells – 2- astrocytes influence capillary permeability – 3- molecular weight and solubility of molecule • blood brain barrier is incomplete in some areas: – hypothalamus/pineal gland/ neurohypophysis – capillaries of choroid plexus (blood-CSF barrier) Brain Stem regions • Midbrain –green • Pons -blue • medulla oblongata – orange medulla oblongata • runs from foramen magnum to pons • contains – ascending & descending tracts – nuclei responsible for vital functions • S e e n e x t s lid e
5/9/19 5 medulla oblongata nuclei • What is a nucleus? • autonomic nuclei – reticular formation – alertness – cardiovascular reflex centers: • heart rate, strength of beat, blood flow – respiratory rhythmicity centers: respiratory rate • centers coordinating reflexes of the throat – swallowing/coughing/sneezing/hiccuping/vomiting • site of crossover of sensory/motor information pons • pneumotaxic & apneustic centers – adjust respiration: • rate • depth • contains tracts processing info for cerebellum • ascending, descending, & transverse tracts midbrain • cerebral peduncles –bundles of fibers – descending (motor) fibers – fibers to cerebellum • corpora quadrigemina – nuclei which process • visual stimuli • auditory stimuli
5/9/19 6 corpora quadrigemina (4 colliculi, pl) •
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- Spring '18
- Mark Bolke