Understanding Infectious and Non-Infectious Diseases

Infectious Diseases

Definition

Temporary or permanent loss of health caused by microorganisms.

Types of Microorganisms

• Bacteria: Unicellular prokaryotic organisms that multiply and can destroy cells and tissues.
• Viruses: Not considered living organisms. They reproduce by entering cells and using their resources, causing damage.
• Protozoa: Single-celled eukaryotes. Some cause disease.
• Fungi: Unicellular and multicellular eukaryotes. Some can cause disease in weakened individuals.
• Parasites: Multicellular organisms that live at the expense of a host, weakening but not killing it.
• Prions: Misfolded proteins that accumulate and cause neuron degeneration.

Non-Infectious Diseases

Nonspecific Defenses

Mechanisms that prevent the entry of microorganisms:

• Skin: Acts as a barrier.
• Mucous Membranes: Produce mucus that traps and removes microorganisms.
• Inflammation: Prevents the entry of microorganisms. The affected area becomes red and swollen due to dilated capillaries, allowing white blood cells to attack foreign substances.

Specific Defenses

Act on specific microorganisms. White blood cells identify and attack microorganisms with antibodies or destroy them.

Other Health Conditions

Autoimmune Diseases

Occur when the immune system attacks the body's own cells (e.g., multiple sclerosis, lupus).

Allergies

Exaggerated immune responses to foreign substances.

Antibiotics

Treat bacterial infections (e.g., penicillin, cephalosporin). Antibiotic-resistant bacteria survive treatment and multiply, making them difficult to eliminate.

Malaria

Caused by a protozoan transmitted through the bite of an infected female Anopheles mosquito. The protozoan enters the bloodstream, travels to the liver, and multiplies.

Vaccines

Stimulate the immune system to produce antibodies against specific pathogens, preventing future infections.

AIDS

Caused by the retrovirus HIV, which destroys white blood cells, weakening the immune system and leading to opportunistic infections like pneumonia and tuberculosis. HIV is transmitted through bodily fluids (blood, semen, breast milk, vaginal fluids). Prevention includes condom use and needle exchange programs.

Tumors

Disorganized masses of tissue caused by excessive cell proliferation or the failure of aged cells to die.

Cancer

Occurs when tumor cells spread to nearby tissues and the circulatory or lymphatic system (metastasis).