Disturbances in Homeostasis + Infection + 3 Lines of Defence

What is infection?

Invasion, multiplication, and damage caused by pathogens not normally in the body.

What types of pathogens exist?

Bacteria, viruses, fungi, parasites.

What can pathogens do to host cells?

Attack cells, stop cell function, produce waste, and trigger inflammation.

What is an example of pathogen waste?

White discharge in conjunctivitis or strep throat.

What is the body's 1st line of defence?

Skin, cilia, saliva (enzymes/antibodies), stomach acid.

What is the body's 2nd line of defence?

Phagocytes (neutrophils, NK cells), antimicrobial proteins, inflammatory response.

What is the body's 3rd line of defence?

Adaptive immune response (learns + remembers).

What are examples of non‑pathogen causes of inflammation?

Trauma, chemicals, foreign bodies, temperature extremes, allergies.

What is degeneration?

Cell death or functional loss in tissue.

Examples of degeneration conditions?

Osteoarthritis, osteoporosis, Alzheimer's, Parkinson's, emphysema, heart cell loss.

What is injury?

When external force exceeds tissue strength.

What is excess inflammation an example of?

Asthma, rheumatoid arthritis.

What is neoplasm?

Excessive abnormal tissue growth → cancer.

What are genetic disturbances?

Huntington's disease, cystic fibrosis.

What is excessive exposure?

Too much chemical/physical stress e.g. smoking, sunburn.

What is "too much" vascular disturbance?

Haemorrhage or haematoma.

What is "too little" vascular disturbance?

Arterial blockages reducing oxygen to heart/brain.