Lecture Notes - Chapter 4: Alteration of Cell and Tissue Biology

Overview

Cells Adaptations: Reversible changes that can occur in cells and tissues, which include:
- Atrophy: Cells shrink due to inactivity (common in elderly or bedridden patients).
- Hypertrophy: Cells grow larger (e.g., muscle growth from weightlifting).
- Hyperplasia: Increase in the number of cells.
- Metaplasia: One type of cell changes to another type (e.g., in smokers' respiratory systems).
- Dysplasia: Abnormal development of cells.

Ciliated Cells: Line the upper respiratory tract, push mucus out.
**Effects of Smoking: Results in dysplastic and metaplastic changes, loss of cilia, inability to expel mucus leading to chronic cough.
Reversible if Smoking Stops: Cells can revert back to ciliated form.

Definition: Decreased oxygen supply leading to cell injury.
Causes: Reduced blood supply, respiratory issues (e.g., COPD), carbon monoxide poisoning, anemia.
Anoxia: Total loss of oxygen.

Mechanism: Blood supply returns to tissue, causing inflammation and oxidative stress from free radicals.
Thrombus: Blood clot obstructs blood flow, leading to cell swelling and potential death.
Oxidative Stress: Caused by free radicals, leading to lipid peroxidation, protein alteration, and DNA damage.
Antioxidants: Counteract free radicals.

Environmental Toxins: Heavy metals, ethanol, and drugs can be harmful.
Infectious and Inflammatory Injuries: Immune responses cause additional damage:
- Phagocytes: Eat harmful substances and worn-out cells.
- Histamine: Attracts white blood cells to injury sites.
- Antibodies and Complement System: Fight infections and mediate inflammatory response.

Types: Water, proteins, lipids, carbohydrates.
Examples: Fatty liver in obesity or alcoholism, lysosomal storage diseases.
Origin: Endogenous (internal) or exogenous (external) substances.
Cell Death: Abnormal accumulations can lead to cellular stress and necrosis.

Apoptosis: Natural, programmed cell death; cells are broken down and cleaned up by phagocytes.
Necrosis: Pathological cell death due to injury; types include:
- Coagulative: Protein denaturation (e.g., heart tissue post-infarct).
- Liquefactive: Tissue liquefaction (common in brain infections).
- Caseous: Combination; cheesy substance in lungs (e.g., tuberculosis).
- Fatty: Chalky white appearance in fatty tissues.
- Gangrenous: Tissue death from hypoxia, can be dry or wet.

Algor Mortis: Cooling of the body post-death.
Rigor Mortis: Stiffening of the muscles due to lack of energy to release muscle contraction.
Livor Mortis: Blood pooling in lower parts of the body, causing discoloration.
Putrefaction: Decomposition of the body by bacteria.
Skeletonization: Final breakdown to skeleton, often assisted by insects or other organisms.

End of Chapter 4