Anatomy And Physiology

Homeostatic imbalance is the disturbance of homeostasis. Some of these imbalances include the following: Cerebrovascular Accident (CVA) –  commonly known as a stroke  Concussion – Bruise to the brain Contusion – Brain injury that causes tissue damage Cerebral Edema – Brain swelling Alzheimer's Disease – A chronic and progressive disorder of the brain that is most common cause of degeneration dementia. Multiple sclerosis – A disease of the central nervous system due to a damaged myelin sheath. Poliomyelitis –  infectious viral disease that effects the central system and can cause temporary to permanent paralysis. Paralysis – Lack of movement in certain muscles caused by damaged gray matter. Paraplegia – condition in which a person cannot move their legs consciously, but reflexes are still functional. Quadriplegia – Brain or spinal cord damage leading to immobility.

Astrocytes- form barrier between capillaries and neurons, star-shaped Microglia- dispose of debris, spider- like phagocytes Ependymal Cells- line cavities of the brain and spinal cord, produced and circulate CSF Oligodendrocytes- branched cells that wrap CNS nerve fibers Schwann Cells- surround fibers of the PNS Satellite Cells- surround neuron cell bodies with ganglia

The brain is made up of four major parts: the cerebrum, the cerebellum, the brainstem, and the diencephalon A neuron is a single unit which helps transmit messages. The can have one or more axons along which the message is passed and is speedened by the myelin sheath surrounding it. The message runs from the dendrites to the axon terminals. 

Action Potential The change of electrical conditions by the passage of an impulse along the membrane of a muscle or nerve cell. Resting State- The charge of the cell is -70 mv. The sodium and potassium channels are closed. Depolarization- The sodium permeability increases, sodium gates open and potassium gates are closed. The charge becomes more positive (-55 to -50 mV) Repolarization- The sodium gates close while the potassium gates open. Potassium exits the cell and internal negativity is restored, the charge is +30 mV Hyperpolarization- The potassium gates remain open causing excessive efflux of potassium which causes hyperpolarization, the charge becomes -75 mV  Na+/K+ pump-  Restores the restating electrical conditions of the neuron