Human Nervous System

central nervous system

brain and spinal cord

Peripheral nervous system

nerves outside the brain and spinal cord

The brain

made up of 100 billion neurons, 1 trillion neuroglia

cranium

cranial bones

cranial meninges

tough fluid filled membrane covering the brain

dura mater

outer layer

arachnoid

middle cobweb-like membrane

pia mater

inner layer

cerebrospinal fluid

circulates thru subarachnoid space and the ventricles of the brain

ventricles

cavities in the brain filled with cerebrospinal fluid

Brain stem

consists of medulla oblongata, pons, and midbrain

medulla oblongata

controls involuntary activities

diencephalon

consists of thalamus and hypothalamus

thalamus

relay center between sensory impulses and cerebrum

hypothalamus

maintains homeostasis: body temp, blood pressure, sleep, hunger and thirst

cerebellum

2nd largest portion of the brain

arbor vitae

white matter tracts spread thru cerebellum

cerebrum

largest portion of the brain - 15 billion neurons

cerebral cortex

thin outer layer of gray matter

convolutions (gyri)

folds that increase the surface of the cortex

corpus callosum

connects the 2 cerebral hemispheres

sulcus

shallow grooves

fissures

deep grooves that separate the cerebrum into distinct lobes

reflex

an involuntary response such as sneeze, blink or hiccup

reflex arc

receptor, sensory neuron, integration center, motor neuron, effector

spinal nerves

31 pairs that stem from spinal cord

cranial nerves

12 pairs that stem from brain

somatic nervous system

controls voluntary activities

-serves skeletal muscles

autonomic nervous system

controls involuntary activities

-serves internal organs

sympathetic division

inhibits down activity

-decreases heart rate

parasympathetic

stimulate up activity

-increases heart rate

stroke

a blockage or rupture of a blood vessel in the brain causing death of brain cells

parkinson's

a slowly progressive degenerative disorder of the nervous system characterized by muscle tremors caused by a low dopamine levels

meningitis

an inflammation of membrane surrounding brain and spinal cord

alzheimer's

a progressive loss of mental function characterized by degeneration of brain tissue, including loss of nerve cells and the development

Epilepsy

seizures caused by periodic disturbances of the brain's electrical activity resulting in some degree of temporary brain dysfunction

multiple sclerosis

destruction of myelin causing scarring of brain tissue

cerebral palsy

birth disorder affecting motor functions, crippling disorder with no cure

polio

viral disease causing paralysis / prevented by vaccine

stimulants

speeds up the body's activities

depressants

slows down body's activities

psychedelics

mind altering effects

spinal cord

extensions of the brain stem that runs down the spinal canal