Nervous System

A nerve cell is microscopic, is conducts impulses, they are collected into macroscopic nerve bundles which carry electricle messages all over the body. Neurons and nerves are the Parenchymal tissue.

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• 1. Central Nervous System (CNS): Brain and Spinal cord
• 2. Peripheral Nervous System (PNS): Cranial Nerves, Spinal nerves, Plexus, Peripheral nerves. 9 cranial nerves carry impulses between bain, head, and neck, but the Vegus nerve (10th cranial nerve) carries msg to neck, chest and abdomen. There are 12 pairs of cranial nerves and 31 pairs of Spinal nerves.

Sensory nerves, which carry messages toward the brain.

Example is seeing, hearing, smelling

Motor nerves, which carry messages away from the brain to the muscle or organ.

• Part of the peripheral nerves that carry away from the CNS to the organs (glands, heart, blood vessels and involuntary muscles).
• There are two types: Sympathetic and Parasypathetic nerves. Sypathetic stimulates body in times of stress by increasing heart rate, increasing BP, releasing epinephrine, etc. Parasympathetic nerves balance the sympathetic by slowing down the HR + BP, stimulating paristalsis, increasing saliva, etc.

A plexus is a large network of nerves in peripheral nervous system

An exammple would ve the cervical, brachial and Lumbar plexus

Neurilemma surrounds the myelin sheath

A synapse is the space betweeen terminal end fibers and dendrites/organ where the neurotransmitters transfer. (An example of a neurotransmitter is Acetylcholine, norepinephrine, epinephrine, dopamine, serotonine, endorphons.) They can only transmit in one direction, away from the terminal end fiber. It takes longer to cross the synapse than thru the body.

A glial cell is the stromal tissue. Glia or neuroglia maintain the health of the nervous cells, they hold the nervous system together and help ward off infection and injury with phagocytosis (engulfing waste materials) Glial cells DO NOT transmit and impuls. But there are more glial cells than neurons and the can reproduce.

• 1. Astrocyte or astrogial cell (star-like): transports H20 and Salts between capillaries and neurons
• 2. Microglial cell: Phagocytes that protect neurons in response to inflammation.
• 3. Oligodendroglial cell (oligodendrocytes): (few dendrites) they from the Myelin Sheath.

Ganglia are small clusters of nerve cells outside of the brain and spinal cord

The threshold of exciteability is the lowest energy that will elict a nerve impulse

The all or nothing law is the magnitude of a nerve impulse doesn't depend on the magnitude of the stimulus initiating it.

• A chemical reaction is for an impuse in one neuron.
• An electrical impulse in one causes a response in the other.

• cerebrum-Lg part think memory. surface of brain is called the cerebral cortex, where the GYRI=raised/elevated folded areas and the SULCI=groves in brain. Ventricles are spaces or canals in cerebrum where the CSF (cerebrospinal fluid) protects brain.
• cerebellum-lower part of brain, judgement, voluntary movements, balance.
• Brain Stem=> Pons and Medulla Oblongata (L/R nerves, vasomotor ctr, heartrate, resiratory system)
• Diencephalon-highest part of the brain stem (about where thalamus is?)

• The Thalamus integrates and monitors impulses from the skin (pain) it is the sensory relay station.
• The Hypothalamus controls the bodies temp, sleep, appetite, sex desire, emotions (pleasure, sad, fear) and also regulates the release of hormones from the pituitary gland, and it monitors the parasympathetic and sympathtic nervous systems.

• Column of nervous tissue from the medulla oblongata to the 2nd lumbar w/in vertral column. The Cauda Equina (horses tail) is below the spinal cord, it is a fan of nerve fibers where the spinal cord ends.
• Gray matter=cell bodies, dendrites
• White matter=nerve tracts w/ myelin sheath
• (remember: afferent=towards, efferent=away)

• 1. Dura mater-(tough mother) outter layer, channels and contains blood.
• Subdural space
• 2. Arachnoid membrane-(spider-like) loosly attached
• Subarachnoid space- contains CSF, space for fluid
• 3. Pia mater-(pia=delicate) inner layer, it is rich in blood supply

• Congenital defect in lumbar spinal colum by imperfect union of vertebral parts (neural tube defects)
• Spina bifida occulta- cover w/skin only can see w/x-ray
• Spina bifida cystica-more severe protrusion

thin, slender

Leptomeningeal, pertaining to the pia and arachnoid because of their thin structure

spinal cord

poliomyelitis- inflammation in gray matter in spinal cord leading to paralysis

nerve

neuropathy- a disease or abnormalty in nervous system

pons

cerbellopontine- pertaining to the pons and cerebellum

nerve root (spinal nerves)

radiculopathy- condition in the nerve root that can lead to inflammation, pain, tingling, numbness or dificulty controling specific muscles

sheath (meninges)

intrathecal injection

excessive sensitivity to pain

• analgesia
• hypalgesia (decrease sensitivity to pain)

burning

causalgia- intesne burning pain

feeling, nervouse sensation

paresthesia-(par from para means abnormal) abnormal burning prickling sensation or feeling

seizure

• epilepsy
• narcolepsy- sudden uncontrolable stupor or sleep

word, phrase

dyslexia

weakness

hemiparesis- half L/R weakness

speech

aphasia- inability to speak

paralysis

• hemiplegia- L/R
• Paraplegia-Upper/Lower
• Quadriplegia-4 limbs paralyzed

eat, swollowing

dysphagia-difficulty swallowing

action

apraxia

strength

neurasthenia-nerve fatigue

to cut off, to cut short

syncopal- Faint, one strength is cut off

order, coordination

ataxia

process of cutting

nourishment