Introduction to the Immune System

A network defending the body from pathogens

A system digesting food into nutrients

A group regulating body temperature daily

A pathway transporting oxygen to tissues

A microorganism that can cause disease

A nonliving mineral in body fluids

A harmless protein used for energy

A large organ that stores vitamins

Bone marrow in long bones

Spleen near the stomach

Thymus above the heart

Lymph nodes in the neck

They filter lymph and activate immune responses

They store bile and release digestive enzymes

They pump oxygenated blood to all tissues

They secrete hormones controlling metabolism

Unbroken skin covering body surfaces

Dilated blood capillary networks

Contracting skeletal muscle fibers

Cartilage around major joints

Sweep trapped particles toward the throat

Digest pathogens within alveoli

Produce antibodies against invaders

Increase oxygen diffusion across lungs

Cilia beating with sticky mucus

Alveolar macrophage phagocytosis

Surfactant reducing surface tension

Hemoglobin binding carbon dioxide

Antibacterial enzymes breaking down microbes

High salt concentrations dehydrating cells

Strong acids dissolving bacterial walls

Large antibodies neutralizing toxins

Denaturing microbial proteins rapidly

Increasing nutrient absorption rate

Thickening intestinal mucus layers

Stimulating alveolar gas exchange

Skin blocks entry; mucus traps and moves debris

Skin secretes antibodies; mucus forms scar tissue

Skin digests pathogens; mucus hardens into keratin

Skin raises pH; mucus lowers blood pressure