MIDTERM

Fundamental Concepts of Pathophysiology and Clinical Manifestations

• Definitions of Pathology:

  • Pathology: Derived from "pathos" (disease) and "logos" (study). It is the scientific study of diseases and abnormal variations in the body's physiological, anatomical, biochemical, or chemical states.

  • General Pathology: Focuses on the basic reactions of cells and tissues to abnormal stimuli that underlie all diseases.

  • Systemic Pathology: Examines the specific responses and alterations in specialized organs and tissues.

  • Pathogenesis: The specific mechanism or biological process through which pathological and clinical manifestations are produced in the body. It describes the sequence of events from the initial stimulus to the ultimate expression of the disease.

  • Etiology: The "root cause" of a scenario or disease. It identifies what started the change, such as injury, trauma, or severe emotional disturbance.

• Signs vs. Symptoms:

  • Symptoms: Subjective experiences declared by the patient. These are based on how the individual describes their experience (e.g., pain, nausea, emotional state). Symptoms for the same condition can vary significantly between patients.

  • Signs: Objective findings observed and measured by a healthcare provider. These fit specific criteria for diagnostic rules and are documented through clinical observation or measurement (e.g., fever, swelling, high blood pressure).

• Dysfunction vs. Disease:

  • Dysfunction: An altered physiological function without structural damage (e.g., functional bowel disorder).

  • Disease: A state involving both functional abnormalities and structural tissue damage (e.g., inflammatory bowel disease).

Cellular Adaptive Responses and Tissue Changes

• Mechanisms of Cellular Adaptation:

  • Hypertrophy: An increase in the physical size of individual cells, often leading to an increase in the size of the organ. Examples include skeletal muscle growth from exercise or pathological cardiac ventricular hypertrophy.

  • Hyperplasia: An increase in the number of cells in a tissue or organ. Examples include glandular proliferation during pregnancy or Benign Prostatic Hyperplasia ($BPH$). Hyperplasia may increase the risk of cancer.

  • Atrophy: A decrease in the size of an organ or tissue mass due to a decrease in cell size and function. Causes include aging, malnutrition, denervation (loss of nerve supply), or disuse.

  • Aplasia: The failure of cell production, leading to a loss of the ability to form cells.

  • Hypoplasia: A condition where there is a decreased number of cell production, though not as severe as aplasia.

  • Metaplasia: The replacement of one differentiated tissue type with another differentiated tissue type. A common example is the change of columnar epithelium to squamous epithelium in the esophagus due to chronic acid reflux or smoking.

  • Dysplasia: Disordered growth where cells lose their normal structure and function, often becoming a precursor to cancer (atypia).

Cell Injury and Death

• Stages of Cell Injury:

  • Reversible Injury: Damage that the cell can recover from if the stressor or stimulus is removed.

  • Irreversible Injury: Damage that results in cell death. Key markers include mitochondrial death (no $ATP$ production), plasma membrane damage (loss of integrity), and severe damage to nuclear genetic material.

• Types of Cell Death:

  • Apoptosis: Programmed, controlled cell death. The cell condenses, blebs into smaller components, and is consumed by macrophages without triggering an inflammatory response. This is a physiological necessity for tissue regulation.

  • Necrosis: Pathological, uncontrolled cell death caused by severe injury. It involves cell lysis (bursting), the release of cytokines, and an inflammatory response that can cause a domino effect of damage to surrounding tissues.

Homeostasis and Physiological Regulation

• Homeostasis: The constant regulation of the internal environment to maintain stability. Variables include temperature, blood sugar, $pH$, fluid balance, and ion concentrations ($Ca^{2+}$, $Na^+$, $K^+$).

  • Standard Values:

    • Base Temperature: $37^\circ C$.

    • Blood Pressure: $120/\text{week}$ (as noted in transcript, traditionally $120/80\,mmHg$).

    • Fasting Glucose: $4.8\text{ to }5.1\,mmol/L$.

    • Hemoglobin $A1c$: approximately $5.1\text{ to }5.5\%$.

• Feedback Systems:

  • Negative Feedback: The primary mechanism for homeostasis. If a level drops or rises, the body pushes the pathway in the opposite direction to normalize it (e.g., insulin/glucagon blood sugar regulation).

  • Positive Feedback: A mechanism where a stimulus is reinforced until a specific outcome is reached (e.g., childbirth contractions).

Traditional Chinese Medicine (TCM) Etiology and Syndrome Differentiation

• The Three Groupings of Etiology:

  1. External Pathogenic Invasion: Wind, cold, damp, heat, dryness, and summer heat entering the body through the defensive layer ($Wei\,Qi$).

  2. Emotional Disturbances: Internal causes such as grief, anger, or shame that disturb the flow of $Qi$ and blood.

  3. Miscellaneous: Includes physical trauma (injury/accidents), diet, lifestyle, and toxins.

• Emotions and Organ Systems:

  • Grief: Can be a primary etiology for physical symptoms like shoulder pain.

  • Shame: A mixed emotion that disturbs the Heart, weakens the Kidneys (leading to worthlessness), and affects the Spleen (leading to overthinking). It causes $Qi$ to become stagnant or to sink.

• TCM Patterns Related to Cellular Changes:

  • Hypertrophy: Often associated with Liver Yang Rising or Blood Stasis (Wiry, forceful pulse; red/purple tongue).

  • Hyperplasia: Linked to Phlegm accumulation or Dampness (Slippery pulse; swollen tongue with greasy coat).

  • Atrophy: Viewed as a deficiency state of Essence ($Jing$) or Blood.

  • Necrosis: Interpreted as severe Blood Stasis and Toxic Heat.

Inflammation: The Vascular and Cellular Response

• Acute Inflammation: A protective vascular response to injury designed to eliminate the cause, remove debris, and initiate repair. Dominant cells are neutrophils.

• Cardinal Signs of Inflammation:

  1. Rubor: Redness (caused by vasodilation/increased blood flow).

  2. Calor: Heat (caused by increased blood flow).

  3. Tumor: Swelling/Mass (caused by increased permeability and fluid leakage).

  4. Dolor: Pain (caused by nociceptor irritation and chemical mediators).

  5. Loss of Function: Occurs in extreme scenarios due to swelling and pain.

• Chemical Mediators: Histamine (first responder), prostaglandins, leukotrienes, cytokines, and the complement system.

• Systemic Effects: Fever, increased white blood cell count (leukocytosis), and sepsis.

• Chronic Inflammation: Persistent injury lasting months to years. Dominant cells are macrophages and lymphocytes. Can result in fibrosis (scarring) and tissue destruction.

Sepsis and Septic Shock

• Sepsis: A life-threatening systemic inflammatory response to an infection that has entered the blood. In TCM, this is viewed as Toxic Heat entering the deeper $Yin$ or $Xue$ (blood) levels.

• Septic Shock: The stage where the systemic response causes critical organ impairment, hypotension (low blood pressure), and oxygen deprivation.

• Sepsis Symptoms ($S.E.P.S.I.S$ acronym):

  • S: Shivering, fever, or feeling very cold.

  • E: Extreme pain or discomfort.

  • P: Pale, discolored, or clammy skin.

  • S: Sleepiness, confusion, or disorientation.

  • I: "I feel like I might die" (subjective perception).

  • S: Shortness of breath.

Hemodynamic Disorders

• Hyperemia and Congestion:

  • Hyperemia: Active increase in blood volume to a tissue (e.g., exercise or inflammation).

  • Congestion: Passive impaired outflow of blood (e.g., congestive heart failure, localized venous obstruction like $DVT$).

• Hemorrhage: Escape of blood from vessels into tissue spaces.

  • Petechiae: Smallest pinpoint hemorrhages.

  • Purpura: Medium-sized hemorrhages.

  • Ecchymosis: Large bruises.

  • Hematoma: A localized swelling or mass of clotted blood.

• Thrombosis: Formation of a blood clot within a vessel. Influenced by Virchow's Triad:

  1. Endothelial injury.

  2. Stasis or turbulent blood flow.

  3. Hypercoagulability (blood composition changes).

• Embolism: A detached mass (thrombus, fat, air, amniotic fluid) that travels through the blood and blocks a vessel. A Pulmonary Embolism ($PE$) blocks blood flow to the lungs and is fatal if untreated.

Systemic Shock and Edema

• Shock Categories:

  • Hypovolemic: Caused by loss of blood or fluid volume (e.g., hemorrhage, severe vomiting/diarrhea).

  • Cardiogenic: Failure of the heart to pump effectively (e.g., after a myocardial infarction).

  • Neurogenic: Triggered by nerve cord injury.

  • Anaphylactic: Severe allergic reaction causing system-wide vasodilation.

  • Septic: Result of dysregulated immune response to infection.

• Edema: Accumulation of fluid in extracellular spaces. Regulated by Starling Forces:

  • Hydrostatic Pressure: Pushes fluid out of vessels.

  • Oncotic (Osmotic) Pressure: Pulls fluid back into vessels using plasma proteins.

Cancer: Neoplasia and Characteristics

• Tumor Types:

  • Benign: Localized, slow-growing, encapsulated, well-differentiated, non-invasive.

  • Malignant: Invasive, rapid-growing, poorly differentiated, capable of metastasis.

• Hallmarks of Cancer: Sustained proliferation, evading apoptosis, stimulating angiogenesis (new blood vessel growth), and evading the immune system.

• Genetic Basis:

  • Oncogenes: Genes that promote tumor growth when activated.

  • Tumor Suppressor Genes: Genes that inhibit growth; mutations cause loss of function (e.g., $BRCA1$ and $BRCA2$).

• Staging ($TNM$ System): Evaluates Tumor size, lymph Node involvement, and Metastasis. Stages range from $1$ to $4$.

Genetic Disorders and Inheritance

• DNA Basics: 46 total chromosomes ($23$ pairs: $22$ autosomal, $1$ sex pair). Nucleotides: Adenine ($A$), Thymine ($T$), Cytosine ($C$), Guanine ($G$).

• Inheritance Patterns:

  • Autosomal Dominant: Only one affected allele needed to express the disorder (e.g., Marfan syndrome, Huntington's). $50\%$ chance of inheritance if one parent is affected.

  • Autosomal Recessive: Two affected alleles needed (e.g., Cystic Fibrosis, Sickle Cell Disease). $25\%$ chance if both parents are carriers.

  • X-Linked Recessive: Often passed from carrier mothers to sons (e.g., Hemophilia, Duchenne Muscular Dystrophy). Males are affected more frequently because they only have one $X$ chromosome.

• Chromosomal Abnormalities:

  • Down Syndrome: Trisomy $21$ (three copies of chromosome $21$).

  • Turner Syndrome: Missing one $X$ chromosome ($45\,X$).

  • Klinefelter Syndrome: Extra $X$ chromosome ($47\,XXY$).

Questions & Discussion

• Fat Cells: Discussion on whether weight gain is hypertrophy or hyperplasia. It is both; existing fat cells increase in size (hypertrophy), but new fat cells can also be created (hyperplasia).

• Shame in TCM: Question regarding which organ relates to shame. It is a mixed emotion disturbing the Heart, Kidneys (willpower/worthlessness), and Spleen (thought).

• Fertility and TCM: Discussion on preparing for conception through three cycles ($3$ months) to improve the health of egg and sperm, ensuring strong prenatal $Jing$ for the child.

• Sepsis Identification: Question on whether sepsis is always systemic. It starts locally but becomes life-threateningly systemic once it enters the blood stream.