Health and Disease Overview

Defining Health and Disease

• Health is defined by the World Health Organisation (WHO) as complete physical, mental, and social well-being, not simply the absence of disease.
• Homeostasis is the body's dynamic equilibrium, maintained through feedback and regulation.
• All body systems must function normally and in balance for health.

Characteristics of Disease

• Signs: Observable objective manifestations (e.g., swelling, redness).
• Symptoms: Subjective experiences (e.g., pain, weakness).
• Pathology: The study of disease.
• Pathologist: A physician specializing in disease diagnosis via cell/tissue analysis.
• Clinician: The healthcare provider responsible for patient care.

Disorders and Syndromes

• A disorder is an abnormal bodily condition, often with a common cause (genetic, biochemical, structural).
• Syndromes are specific types of disorders, like Down syndrome (trisomy 21).

Medical Imaging Techniques

• Chest X-rays: Inexpensive, readily available; limited soft tissue detail.
• Mammography: Detects breast cancer early, some discomfort/radiation exposure.
• CT Scan: Detailed cross-sectional images for diagnostics and treatments, higher radiation exposure.
• MRI: Excellent soft tissue detail, no ionizing radiation.
• Ultrasound: Non-invasive, inexpensive, operator dependent quality.
• PET Scan: Identifies metabolically active tissues (e.g., cancer), uses ionizing radiation.

Cytology

• Cytology is examining cells.
• Benign cells are distinct from cancerous cells (malignant).

Fine Needle Aspiration (FNA)

• FNA is using a needle to obtain cells from a suspicious area for microscopic diagnosis.

The Course of Disease

• Acute: Short-term illness.
• Terminal: Illness leading to death.
• Chronic: Long-term illness.
• Remission: Disease symptoms lessen or disappear.
• Exacerbation: Disease severity increases.
• Relapse: Disease returns after remission.
• Complication: New problem arising from an existing disease.
• Sequela: Consequences of a previous disease or injury.

Describing the Occurrence of Disease

• Mortality: Number of deaths.
• Morbidity: Incidence of a disease.
• Incidence: Count of new cases.
• Prevalence: Percentage of cases in a population.
• Epidemiology: Study of disease distribution and control.
• Etiology: Cause of a disease.
• Pathogenesis: How a disease progresses.
• Idiopathic: Disease with unknown cause.

Chief Causes of Disease (Etiology)

• Hereditary: Diseases passed from one generation to the next (e.g., sickle cell anemia).
• Congenital: Birth defects, often genetic.
• Degenerative: Degeneration of cells/tissues over time.
• Inflammatory: Uncontrolled inflammation.
• Autoimmune: Immune system attacks healthy tissue.
• Neoplastic: Uncontrolled cell growth
• Metabolic: Related to the body's processes, e.g. T1DM
• Traumatic: Injury or wound
• Nutritional: Deficiency or excess of nutrients.