Panda Essay

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PHYSIOLOGY 2 The Brain and Cranial Nerves Brain Development Brain Organization Protective Coverings Brain Blood Flow Production and Flow of CSF Parts of the Brain Cranial Nerves The human brain contains 100 billion neurons and 10 trillion neuroglia. The human brain, compared to all other animals’ brains, is marked by the highest ratio of brain to body size - thought to directly correlate with our higher level of intelligence. Most of the expansion is manifest in man’s large cerebral cortex. Especially expanded are the frontal lobes which are associated with higher (executive) functions such as self-control, planning, reasoning, and abstract thought. Brain Development During the first 3 weeks of gestation, the human embryo's neural tube flexes as it grows, forming the three primary brain vesicles called the forebrain, midbrain, and hindbrain. The 1st and 3rd vesicles further divide forming 5 secondary brain vesicles in a process called encephalization. The major parts of the adult brain are directly derived from the 2o brain vesicles The brain grows at an amazing rate during development; at times, as many as 50,000 neurons are added each second. At birth, the neonatal brain looks very much like that of an adult and almost all the neurons the brain will ever have are already present. Brain Organization * The brain stem is the continuation of the spinal cord and consists of the medulla oblongata, pons and midbrain. * The cerebellum is the second largest part of the brain. * The diencephalon gives rise to the thalamus & hypothalamus. * The cerebrum is the newest (evolutionarily) and largest part of the brain as a whole. It is in the cerebral cortex that perception, thought, imagination, judgment, and decision making occur. Protective Coverings The cranial meninges are continuous with the spinal meninges and mirror their

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