lecture 1-2

• Pathology: the science of disease is a basic science and a branch of medicine.
• Leading causes of death in Canada 2022: 1st cancer, 2nd cardiovascular.
• Disability is equally important to death.
• DALY (disability-adjusted life year) = loss of one year of full health
• Life-expectancy is increasing linearly and increases 2.2 years/decade.
• Measles, mumps, rubella, polio have all dropped due to vaccinations.
• Many people think disease is mostly genetic but it is a minor reason in most cases.
• Major factors in disease are environmental, access to healthcare, and lifestyle.
• Diet and exercise have a major influence on disease.
• Manifestation of disease can be symptom, sign, lesion, sequel, or complication.
• If there is a lesion, it needs to be studied through biopsy.
• Pathologists take a sample of a lesion and study it through histopathology.
• Cytology is the branch of biology concerned with the structure and function of plant and animal cells.
• Epithelial tissues are thin tissues that cover all the exposed surfaces of the body.
• Connective tissues connect, support, bind, or separate other tissues or organs, typically having relatively few cells embedded in an amorphous matrix, often with collagen or other fibers, and including cartilaginous, fatty, and elastic tissues.
• Immunohistochemistry is a strategy for staining tissues and cells.
• Atrophy is a condition where cells are smaller and has fewer organelles, often due to lack of exercise, inadequate blood supply, inadequate hormonal stimulation, or inadequate nutrient supply.
• Hypertrophy is a condition where cells get bigger, often due to excess exercise or through drug use.
• Hyperplasia is a condition where the number of cells increase, often due to pathological hyperplasia or metaplasia.
• Metaplasia is a condition where one type of cell substitutes another, often due to irritation, causing loss of normal function.
• Dysplasia is a condition where a cell doesn’t look normal, often a prelude to cancer.
• Anaplasia is a condition where cancerous cells are present.
• Cell injury can be reversible but if it continues, it will lead to cell death.
• All disease involves cell injury and potentially cell death.
• Many different causes impair the ability of the cell to maintain homeostasis.
• Four common targets areas within the cell are the most vulnerable parts: mitochondria, plasma membrane, endoplasmic reticulum, and nucleus.
• Mitochondria decrease ATP production, which affects ion pumps when injured.
• The endoplasmic reticulum synthesizes proteins, so injury will affect many processes.
• The nucleus, which contains genetic material, will alter cell function when injured.
• All parts of the cell are interdependent.
• There is no distinct indicator of the boundary between reversible and lethal injury.
• Once there is irreversible cell injury, a sequence of events occurs.
• The extent of injury depends on the type of cell, duration, severity, adaptability, and health.
• Cell injury can be caused by hypoxia, which is inadequate oxygen reaching the tissue.
• Ischemia, a major cause of hypoxia, is inadequate blood supply.
• Hypoxia can be caused by a thrombus (blood clot) which can come loose (called an embolus) and travel elsewhere and cause a block, plaque (atherosclerosis), pressure on the outside, severe spams of the blood vessel.
• Tolerance to ischemia is highly variable, for example, the kidney is very resistant but neurons die immediately.
• Erythrocyte impairment can also cause hypoxia, which can be anemia or CO poisoning.
• Infarct is a complete block of blood supply, which can cause stroke (if in brain) and heart attack (if in heart).
• Physical injury can be mechanical, thermal, altered pressure, radiation, electrical, or chemical.