Science Lesson!:)Michelle Oh, Christine Kim

*the skin*The immune system

The Skin

Largest organ in the human body

Has many important jobs in the body

PROTECTS YOUR BODY

Forms a barrier that keeps harmful substances outside the body (protects body from injury)

The barrier also helps keep important substances in (Ex. water)

Maintains body Temperature

Blood vessels & Sweat glands

Become warm->Blood vessels enlarge->Amount of blood that flows through them increases->Heat moves from the body moves into the outside environment

Sweat glands produce perspiration when you become warm, and the perspiration evaporates from your skin, and your skin’s temperature goes down

Eliminates Wastes

Perspiration contains dissolved waste

Whenever you sweat or perspire, you are eliminating waste

Gathers Information

The nerves in your skin provide information about things such as pressure, pain, and temperature

Producing Vitamin D

Some skin cells produce vitamin D in the presence of sunlight

Parts of the Skin

Organized into two main layers: epidermis & dermis

Epidermis

Does not have nerves or blood vessels

Epidermis cell life cycle: start out deep in the epidermis->mature and move upward as new cells form beneath them->after two weeks they die and become part of the epidermal surface layer->another two weeks they are shed and replaced by dead cells below

Epidermis Function

Outer layer of skin

Dead cells on the surface provides protection

The shedding of dead cells carries away bacteria

Some cells produce fingernails

Other cells in the epidermis produces melanin

Dermis

Inner layer of skin

Contains nerves and blood vessels

Caring for your skin

Healthy Diet

Keeping your skin clean

Limiting sun exposure

Immunity: the body’s ability to destroy

pathogens before they can cause disease

Active Immunity

When a person’s immune system produces antibodies in response to the presence of pathogen (Ex. chicken pox)

Result from either getting the disease or being vaccinated

Immune Response

T and B cells help destroy pathogen

Vaccination

Process in which harmless antigens are delibarely introduces into a person’s body to produce active immunity

Can gain active immunity

Vaccine, used for vaccination, consisst of pathogens that have been weakened or killed but can still trigger the immune system to go into action

first line of defense

: THE SURFACE OF THE SKIN, BREATHING PASSAGES, STOMACH FUNCTION

trap & kill pathogens

Skin- exposed to oil and sweat <may fall w/ dead cells>

Breathing passages- come in w/ inhale ex.nose, pharnx, etc.

Mouth & stomach- some found in food

saliva breaks down food

Second line of defense

: INFLAMMATORY RESPONSE :FLUID & WHITE BLOOD CELLS LEAK TO TISSUES

White blood cell- disease fighters

Inflammation - blood vessels widen, white blood cells transfer -> swollen

Fever- helps fight infections

THIRD LINE OF DEFENSE

: IMMUNE RESPONSE: REACTS TO EACH KIND OF PATHOGENS

Lmphocytes: white blood cell (distinguish different kind fo pathogens)

(Continued)

LYMPHOCYTES:

T cells: identify the kinf of pathogen

Antigens: from or outside of the body?

B cells: produce proteins that destroy pathogen

AIDS

AIDS: Acquired Immuneodeficiency Syndrome

HIV (human immunodeficiency virus) : virus that cause AIDS

if fluids come in conctact, infection!

When you get sick

Antibiotics- helps when infected by bacteria

no medications for common cold - plenty of rest

over the counter medications-> comfortable

drink plenty of fluid

Passive immunity

: WHEN ANTIBODIES ARE GIVEN TO THE PERSON

babies need passive immunities before birth