lecture11 vision init

2016-09-17-lecture01.md

@@ -577,6 +577,35 @@ They are the direct decendents of the mother stem cells that give rise to the ne
 
 Devasting diseases of astrocyte function include brain cancer with gliomas like glioblastomas typicaly being comprised of astrocytes gone wild. It is also thought that some childhoold epilepsies may originate from altered astrocyte function.
 
+blood brain barrier-- control entry of neurotransmitters and hormones into the brain
+
+areas of the brain without a blood-brain barrier (from Table 32-2 Basic Neurochemistry 6e):  
+
+Pituitary gland
+Median eminence
+Area postrema
+Preoptic recess
+Paraphysis
+Pineal gland
+Endothelium of the choroid plexus
+
+There is a positive relationship between lipid solubility and brain uptake of chemical compounds 
+
+- permeability of lipid soluble compounds is rapid (ethanol, nicotine, diazepam, THC)
+- polar molecules (e.g. glycine and catecholamines) enter slowly across BBB
+- gases and volatile anesthetics diffuse rapidly into the brain
+
+ blood—brain barrier permeability of CO2 greatly exceeds that of H+ thus pH of brain interstitial fluid reflect pCO2 rather than blood pH. Therefore a patient with metabolic acidosis may be brain alkalotic at teh same time.
+
+ glucose is primary energy substrate of the brain. Nearly all oxygen consumption for the brain. GLUT-1 glucose transporters highly enriched in brain capillary endothelial cells. Since glucose is a polar substrate, this transporter facilitates its transport across the BBB.
+
+Neutral L-amino acids enter the brain as rapidly as glucose (Phenylalanine, leucine, tyrosine, isoleucine, valine, tryptophan, methionine, histidine and l-dihydroxy- phenylalanine (l-DOPA))
+
+water enters rapidly through diffusion.
+
+<figure><img src="figs/Neurochemistry-fig32-1-BBB_5961e8a.jpg" height="100px"><figcaption></figcaption></figure>
+
+
 --
 
 ## Oligodendrocytes