Child development stages


Your Baby's Defenses

Journey into a baby`s body to witness the different defenses an infant has in place to ward off pathogens. From the skin, in through the mouth, and on into the bloodstream, a baby`s body is ready to defend against all types of unwanted guests.

Skin - Surface Barrier
Sensitive yet tough, skin protects the body from pathogens, injury, and water loss and also helps regulate body temperature. A key protein is kreatin, found in claws, horns, and tooth enamel.

Mucosa - Moist lining defense
Mucous membranes, which line body cavities exposed to the external environment (nostrils, genital areas, and anus) as well as the digestive tract and respiratory system, contain glands that secrete a protective fluid that blocks pathogens.

Inflammatory response
Tissues react to injury or invasion with a cascade of actions designed to isolate the damage and protect surrounding tissue. Blood vessels dilate and white blood cells mobilize as part of the body`s innate immune defense; we experience it as swelling, redness, pain, and plus.

Antibody-mediated immunity
Cells called B lymphocytes produce antibodies that designate specific pathogens circulating in the blod or lymph system as targets. Other white blood cells such as phagocytes then eliminate the intruder. The antibodies product enable the immune system to remember the foreign cell.

Passive immunity
A mother transfers temporary immunity to the fetus via the pacenta and to her newborn via antibodies in colostrum and breast milk. These "borrowed" immune factors degrade in a few months, however, and must be replaced with antibodies produced by the infant`s own immune system.

Cell-mediated immunity
When pathogens succeed in attacking cells in the body, T lymphocytes, which originate in bone marrow but mature in the thymus gland, coordinate the destruction of these foreign invaders. Like antibody-mediated immunity, this is part of the infant`s acquired, or adaptive, immune system.


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