Nervous System

• Aids in response (reaction) to an outside force (stimulus)

• Critical for survival• Involves the 5 senses• Function: sends messages How does the Nervous System compare to the Endocrine System?

Neuron:• Nerve cell (specialized)/

Most in brain and spinal cord• Little regeneration• Axon (long arm) Covered by myelin (fat) Carry messages AWAY to the

dendrites of the next neuron• Dendrites (short arms) Pick up messages from the axon

of the other neuron• Synapse (space between

neurons)• Neurotransmitters released Acetylcholine Dopamine Cholinesterase shuts off

acetylcholine

Transmission of a Message:

• Polarized Nerve (resting potential): Na+ outside K+ inside

• Depolarized Nerve (action potential): Na+ moves inside K+ moves outside Imbalance of ions and acetylcholine released into synapse Contraction of muscle

• Repolarized Nerve: Action terminated

• Nerve: a bunch of neurons• Nerves send messages to muscles to move

• Multiple Sclerosis: An autoimmune disease Myelin eaten away WBC and T cells attack myelin Progressive disease Symptoms include: tingling,

paralysis, loss of equilibrium,

blurry vision, headaches, muscle

spasms, numbness No cure Connection to chicken pox virus?

• Myasthenia Gravis: Low amount of acetylcholine produced at neuromuscular

junction Symptoms: weak, tired, facial muscles fatigued

• Poison Gas (Curare): WW 2 stockpiles of nerve gas Interfered with production of cholinesterase Acetylcholine would continue to be released at the neuromuscular

junction Diaphragm with muscle spasms Resulting death

Action Pathway:

Sensory Neuron

(in sense organ): carries message to --

Association Neuron

(in brain or spinal cord) -- connects to --

Motor Neuron

(in muscle or gland) to carry out action

• Reflex Action: Involuntary, rapid, no brain

involvement

Central Nervous System• Includes brain and spinal cord• “Command Centers”• Interpret incoming information and issue instructions

• Brain: (3 lbs.)

Cerebrum: Consist of 2 hemispheres Grooves called sulci Ridges called gyri Conscious thought, learning, emotional response, higher intellectual reasoning Broca’s Area (speech) Corpus Callosum: connects right and left hemispheres

White Matter Gray Matter Parkinson’s Disease: tremors, problems with muscular

movement, lack of dopamine (neurotransmitter)

Thalmus: Relay station Crude recognition of whether

a sensation is pleasant or unpleasant

Hypothalmus: Controls body temperature,

H2O balance, metabolism, emotions, drives

Influence on pituitary gland and pineal gland

Limbic System (thirst, appetite, pain, pleasurecenter

Medulla Oblongata: Part of the brain stem Connects with the spinal cord Controls blood pressure, breathing, swallowing, vomiting

Cerebellum: Controls balance and equilibrium Controls body movements

Protection of the CNS:

• Meninges: Covering over brain tissue/spinal cord Meningitis: infection of meninges Encephalitis: brain swelling

• Cerebrospinal Fluid (CSF): Fluid in brain and spinal cord Acts as cushion

• Blood Brain Barrier: Composed of capillaries Prevents certain substances from entering brain tissue Glucose, essential amino acids, H2O cross barrier

Brain Abnormalities:• Concussion: Bruised brain; dizzy• Contusion: brain tissue damaged• CVA (stroke): 3rd leading cause of death in the U.S.• TIA: (5-50 min.); temporary numbness, impaired speech; a “warning”• Alzheimer’s Disease: progressive degeneration of the brain;

protein deposits; no cure; cause unknown; possibly genetic

• Spinal Cord (17” long) Enclosed in the vertebrae Covered by meninges and contain CSF Involved with reflexes

Peripheral Nervous System (outside CNS)• Somatic Nervous System

(Controls skeletal muscles) voluntary

• Autonomic Nervous System(Controls smooth and cardiac muscles) involuntary

Sympathetic Nervous System (for physical activity/stress) Parasympathetic Nervous System (helps to “unwind”)