cavities caused by plaque forming bacteria hat eat sugars and produce acids.

Sebaceous Glands

glands associated with hair follicles that a greasy substance called sebum. This softens, lubricates and waterproofs the skin, plus kills bacteria.

Mammary glands

modified sweat glands that secrete milk for nursing mammals.

Nerves

control pathways composed groups of nerve cells wrapped by Connective tissue.

Neurons

functional nerve cells that transmit impulse

Dendrites

highly branched sensors that receive impulses.

Cell body

contains the nucleus and most of the cytoplasm.

Axon

long fiber (may be over 1 m long) ending with swelling called synaptic knobs that transmit impulses.

Neuroglial Cells

elper cells that insulate protect and feed the neurons. Some form coatinap around axons and dendrites called myelin sheaths

sensory neurons

connect sensory receptors to interneurons to effections (glands or muscles)

Interneurons

Make up the brain and spinal cord and lack or neurlemmas cannot be repaired.

white matter

carries message within the brain and spinal cord, has a myelin sheeth.

Gray matter

1. makes decisions has no myelin sheath

All the neurons you will ever have were produces in the embryo stage, counted 50,000 nerve cells die each day and are never replaced.

Learning

developing new circuits the more often a pathway is used the faster the response time.

Sensory memory

very short term retention of sensory input (<1 sec)

short term memory

simple storage of impulses for a few seconds to a few hours.(limited capacity)

Long term memory

permanent storage of information in the form of proteins, and in the cytoskeletons of dendrites. Different aspects of the same memory, are stored in different parts of the brain, and recombined by later thought.

Somatic Nervous System

1. controls skeletal muscles

a)Voluntary control

b) 1 motor neuron to each effector (motor unit)

c) acetycholine

Autonomic Nervous system

1. controls smooth muscle, cardiac muscle, and glands.

a) involuntary control

b) 2 motor neurons to each effector (1 from each antagonistic subsystems

Parasympathetic

acetycholine

Brain and spinal cord (sacrum)

Maintains homeostasis under normal conditions

Heart rate: slows down

sweat glands: turns off

pupils: contracts

sympathetic

norepinephrine
(thoradic and lumbar)

prepares the body for stress (fight or flight)

Heart rate: speeds it up

sweat glands: turns it on

pupils dilate

Central Nervous System-

consists of interneurons within the brain & spinal cord. Cannot be repaired. It is protected by 3 layers of connective tissue called the meninges plus a blood brain barrier around the blood vessels (allows glucose, selected ions, 02, CO2 to pass through, but restricts most other compounds, except for lipid soluble substances like caffeine, nicotine, alcohol, anesthetics, barbituates, and heroin.

spinal cord

1. dorsal nerve cord enclosed by the vertebral column

a) central canal- holds ceerbrospinal fluid

b) Inner gray matter- controls spinal reflexs

c) outer white matter- relays messages to and from the brain.

d) Meninges- 3 layers of connective tissue.

Brain

1. control center composed of 100 billion interneurons enclosed by the cranium (2% o f your body weight) although, it requires 20% of the oxygen supply and 67% of the blood glucose. Without oxygen consciousness is lost in about 5 seconds and permanent damage occurs within 4 minutes. Unless yo dro in cold water, it cools down the enzymes and slows the process.

a) Inner white matter- relays messages.

b) outer gray matter- makes decisions

c) meninges

Hindbrain

oldest part evolutionarily and the first part to become functional in the fetus. It controls man involuntary decisions.

Brain Stem

connects spinal cord to the rest of the brain- relay center.

a) medulla oblongata- controls heart rate, blood pressure, breathing, swallowing, vomiting, coughing, and sneezing.

b) Pons- helps with coordination

Reticular Formation

central core of the brain stem, connecting the spinal cord to the thalamus. It controls consciousness by censoring incoming information.

Reticular activating system(RAS)-

controls wakefulness. It is inhibited by a compoud called seratonin.

Cerebellum

involuntary control over skeletal muscles for balance, posture, muscle tone, and general coordination.

Midbrain

continuation of the brain stem, minor relay center.

Skeletal Muscle

(Voluntary Muscle) attached by tendons, bones of the skeleton, when it contracts, body parts move. Cylindrical and long.

Integumentary System

outerbody covering (5% body weight)

Epidermis

thin layer of stratified squamous pithelium composed of fibrous connective tissue (199+206) pancake shaped.

Stratum crneum

outer protective layer of dead cells filled with keratin (hard water proof protein) and melanin (black pigment to protect against UV Rays.)

Stratum Basala

Inner living layer that produces 4 things: a. keratinocytes(cells that produce keratin)b. Melanocytes (create and secrete melanin into kerotinocytes.) C. Vitamin D-(in sunlight) to harden bones and teeth.D) all skin outgrowths.

Dermis

Thick layer of areolan connetive tissue( 201) containing collagen fibers, skin outgrowths, blood vessels, nerves, and sensory receptors for heat, cold, pressure, and pain occur here. Blood vessels help control body temp. by dilating to release heat or constricting to conserve heat.