Pathophysiology and Disease Mechanisms: Key Concepts
Causative Organisms of Common Diseases
- Tuberculosis: Caused by Mycobacterium tuberculosis, a slow-growing, acid-fast bacterium affecting the lungs and other organs.
- AIDS: Caused by the Human Immunodeficiency Virus (HIV), which attacks CD4 T-cells, compromising the immune system.
- Syphilis: Caused by Treponema pallidum, a spirochete bacterium transmitted primarily through sexual contact.
- Gonorrhea: Caused by Neisseria gonorrhoeae, a Gram-negative diplococcus infecting mucous membranes.
Definitions of Medical Conditions
Mental and Endocrine Disorders
- Schizophrenia: A chronic mental disorder involving disturbances in thinking, perception, emotions, and behavior.
- Hypothyroidism: A condition resulting from decreased production of thyroid hormones (T3 and T4), leading to a reduced metabolic rate.
Infectious and Systemic Disorders
- Meningitis: Inflammation of the meninges (protective membranes of the brain and spinal cord) due to infection.
- Gonorrhea: A sexually transmitted infection (STI) affecting the genital tract, rectum, and throat.
- Osteoporosis: A skeletal disorder characterized by decreased bone mass and increased fragility.
- Inflammatory Bowel Disease (IBD): Chronic inflammatory disorders of the gastrointestinal tract, including Crohn’s disease and ulcerative colitis.
- Jaundice: Yellow discoloration of the skin and sclera due to elevated bilirubin levels.
- Gout: A metabolic disorder caused by uric acid crystal deposition in joints.
Tumors and Genetics
- Benign Tumor: A non-cancerous growth that remains localized.
- Malignant Tumor: A cancerous growth that invades surrounding tissues and metastasizes.
- Oncogene: A mutated gene that promotes uncontrolled cell growth, leading to cancer.
Acid-Base and Cellular Disorders
- Acidosis: Blood pH below 7.35 due to increased acid or decreased bicarbonate.
- Alkalosis: Blood pH above 7.45 due to decreased acid or increased bicarbonate.
- Atrophy: Decrease in cell or organ size due to loss of cell substance.
- Hypertrophy: Increase in cell size leading to organ enlargement.
- Hyperplasia: Increase in the number of cells in a tissue.
- Metaplasia: Reversible replacement of one mature cell type with another.
- Dysplasia: Abnormal, precancerous growth and maturation of cells.
Cardiovascular Disorders
Congestive Heart Failure (CHF)
CHF occurs when the heart cannot pump sufficient blood to meet metabolic needs. It is often triggered by hypertension, myocardial infarction, or valve disease, leading to fluid accumulation in the lungs and tissues.
Cellular Damage Mechanisms
- Cell Membrane Damage: Often caused by ATP depletion, free radicals, or calcium influx, leading to increased permeability and cell death.
- Mitochondrial Damage: Hypoxia or toxins impair oxidative phosphorylation, reducing ATP production and triggering apoptosis or necrosis.
Arthritis Comparison
- Rheumatoid Arthritis: An autoimmune disease affecting small joints symmetrically.
- Osteoarthritis: A degenerative joint disease affecting weight-bearing joints, characterized by cartilage destruction and osteophyte formation.
Infectious Diseases
- Syphilis: A chronic STI caused by Treponema pallidum, progressing through primary, secondary, latent, and tertiary stages.
- Leprosy (Hansen’s Disease): Caused by Mycobacterium leprae, affecting skin and peripheral nerves, leading to sensory loss and deformities.
- Hepatitis: Liver inflammation caused by viruses, alcohol, or toxins, potentially leading to cirrhosis or liver failure.
Thyroid and Metabolic Disorders
- Hypothyroidism: Low T3/T4 levels causing fatigue and weight gain.
- Hyperthyroidism: Excess T3/T4 levels causing weight loss and tachycardia.
- Diabetes Mellitus: Persistent hyperglycemia due to insulin deficiency or resistance.
Anemia and Hematological Disorders
- Deficiency Anemia: Caused by lack of iron, B12, or folic acid.
- Thalassemia: Inherited disorder with decreased hemoglobin chain synthesis.
- Hemophilia: Hereditary bleeding disorder due to clotting factor deficiency.
- Megaloblastic Anemia: Large, abnormal RBCs due to impaired DNA synthesis (B12/Folate deficiency).
- Iron Deficiency Anemia: Microcytic, hypochromic RBCs due to low iron stores.
Neurological Disorders
- Stroke: Sudden loss of brain function due to interrupted blood supply.
- Parkinson’s Disease: Neurodegeneration of the substantia nigra leading to dopamine deficiency and motor impairment.
- Alzheimer’s Disease: Progressive cognitive decline due to beta-amyloid plaques and neurofibrillary tangles.
- Epilepsy: Recurrent seizures caused by abnormal electrical activity in the brain.
Inflammation and Wound Healing
- Inflammation: A protective response involving vasodilation, increased vascular permeability, and leukocyte migration.
- Wound Healing: A process involving hemostasis, inflammation, proliferation (granulation tissue), and maturation (scarring).
Feedback Systems
- Negative Feedback: Reverses a stimulus to maintain homeostasis (e.g., temperature regulation).
- Positive Feedback: Amplifies a stimulus to complete a process (e.g., childbirth).