cells

Pathophysiology Basics & Cellular Function (NUR2063)

What is Pathophysiology?

  • Pathophysiology: The study of the changes in bodily functions due to disease or illness.

  • Continuum of Health and Illness:

    • Health: Defined as the perceived wholeness of body, mind, and spirit.

    • Illness: A state that results in suffering or distress.

Key Themes

  • Homeostasis: The body's ability to maintain stable internal conditions.

What is Disease?

  • Defined as a functional impairment of cells, tissues, organs, or organ systems.

  • Causes of Disease:

    • Pathogen: Disease-causing microorganism.

    • Multifactorial: Diseases with multiple causes.

    • Idiopathic: Diseases with no known cause.

    • Nosocomial: Diseases acquired in a healthcare environment.

    • Iatrogenic: Diseases caused inadvertently by medical treatment.

Presenting Signs and Symptoms of Disease

  • Differentiation:

    • Signs vs. Symptoms.

    • Local vs. Systemic signs.

    • Acute vs. Chronic diseases.

    • Remissions vs. Exacerbations.

    • Asymptomatic patients.

    • Subjective vs. Objective data interpretation.

  • Importance of integrating data and observations to identify the disease process being treated.

Diagnosis & Treatment

  • Diagnosis:

    • A label for a disease based on established diagnostic criteria.

  • Prognosis:

    • A prediction of the disease course, highlighting morbidity (complications) and mortality (death).

  • Treatment:

    • Involves comprehensive care informed by current research and expert practice.

    • Key characteristics of effective treatment include evidence-based practice (EBP), respect for patient variation, and holism in patient care.

Etiology and Pathogenesis

  • Etiology: Study of the causes or origins of disease.

  • Pathophysiology: Mechanisms of disease impact on body processes and functions.

  • Clinical Manifestations: Observable signs and reported symptoms during disease assessment.

Levels of Prevention

  • Primary Prevention:

    • Prevention of disease from occurring (e.g., vaccinations).

  • Secondary Prevention:

    • Early detection of disease through screening, even before symptoms appear (e.g., screening tests).

  • Tertiary Prevention:

    • Rehabilitation and preventive care to minimize complications and enhance quality of life in individuals with diseases.

    • Distinguish by:

    • Primary = Prevent

    • Secondary = Screen

    • Tertiary = Rehab

Review of Cellular Function

  • Cell:

    • Basic unit of life and structure of all living organisms.

    • Each cell can replicate independently.

    • The human body contains over 200 distinct cell types.

Cellular Anatomy and Organelles

  • Nucleus: The control center of the cell; contains genetic code (DNA).

  • Cytoplasm:

    • Composed of water, electrolytes, proteins, neutral fats, and glycogen.

    • Site for metabolic activities within cells.

  • Organelles:

    • Ribosomes: Site of protein synthesis; can be free or rough ER-attached.

    • Endoplasmic Reticulum (ER):

    • Rough ER: Synthesizes membrane proteins and enzymes.

    • Smooth ER: Synthesizes lipids, metabolizes carbohydrates, regulates calcium, and detoxifies drugs.

    • Golgi Apparatus: Modifies, sorts, and packages proteins.

    • Lysosomes: Digest waste materials and cellular debris.

    • Peroxisomes: Detoxify harmful substances; control free radicals.

    • Mitochondria: Site of ATP production through aerobic metabolism; contains its own DNA.

Energy, Replication, and Differentiation

  • Energy (ATP):

    • Derived from the breakdown of glucose, triglycerides, or proteins.

    • Energy storage occurs through the synthesis of larger molecules.

  • Cell Proliferation:

    • Process of cell division (Mitotic division produces two identical daughter cells; Meiosis occurs in gametes).

  • Cell Differentiation:

    • Specialization of cells (stem cells can differentiate into various cell types).

Cellular Exchange Mechanisms

  • Plasma Membrane: Semipermeable lipid bilayer regulating entry and exit of substances.

  • Selective Permeability: Allows specific substances to pass into or out of the cell while blocking others.

  • Substances with Free Passage Include:

    • Enzymes: Facilitate biochemical reactions.

    • Glucose: Provides primary energy source.

    • Electrolytes: Charged particles that conduct electricity in solution.

Types of Cellular Transport

  • Diffusion: Movement of solutes from an area of higher to lower concentration.

  • Facilitated Diffusion: Passive transport assisted by carrier molecules.

  • Osmosis: Passive transport of water across the membrane towards higher solute concentrations.

  • Active Transport: Requires energy (ATP) to move substances against their concentration gradient (e.g., Na-K pump).

  • Exocytosis: Active process for expelling materials from the cell.

  • Endocytosis: The intake of substances into the cell, which includes:

    • Phagocytosis: Engulfing solid materials (cell eating).

    • Pinocytosis: Engulfing liquids (cell drinking).

Cellular Adaptation

  • Atrophy: Decrease in cell size, often due to reduced workload.

  • Hypertrophy: Increase in cell size caused by functional demand or hormonal stimulation.

  • Hyperplasia: Increase in cell number in response to stimuli.

  • Metaplasia: Transformation of one cell type to another.

  • Dysplasia: Abnormal cell size, shape, or organization.

  • Anaplasia: Loss of differentiation and uncontrolled proliferation of cells.

Cell Injury and Death

  • Most diseases originate from cellular injury due to factors such as ischemia, necrosis, or free radicals. Injury may be reversible if the stressor is removed in time.

  • Causes of Cell Injury:

    • Physical agents (e.g., trauma), chemical agents (toxins), biological agents (viruses), radiation, and nutritional imbalances.

  • Cell Death:

    • Results when cellular damage is beyond repair. Two primary types:

    • Apoptosis: Programmed cell death intended for cell turnover.

    • Necrosis: Disorderly process leading to inflammation and tissue damage.

Carcinogenesis

  • Cancer: Refers to neoplasms that are invasive and destructively proliferative; may arise in one organ or spread from another site.

  • Characteristics of Neoplasms:

    • Autonomy and anaplasia (clearly abnormal growth patterns).

    • Malignancy correlates with the degree of anaplasia.

  • Steps in Carcinogenesis:

    • Initiation: DNA damage or mutation due to exposure to mutagens.

    • Promotion: Onset of uncontrolled cell growth.

    • Progression: Transition to a malignant state characterized by more significant changes in cell morphology and function.

Cancer Classification

  • Benign Tumors:

    • Localized, slow-growing, similar to tissue of origin; show minimal differentiation loss.

  • Malignant Tumors:

    • Invasive, aggressive, capable of metastasis, and poorly differentiated from the original tissue.

  • Classification by Stage and Grade:

    • Stage: Extent of neoplastic spread (TNM classification system: T denotes tumor size, N denotes nodal involvement, M denotes metastasis).

    • Higher numbers reflect greater extent of disease.

    • Grade: Abnormality of tumor cells as seen microscopically (graded I-IV).

    • Low Grade: Cells resemble normal tissue; higher differentiation equals better prognosis.

    • High Grade: Cells appear abnormal; lower differentiation equals poorer prognosis.

Examples of Cancer Types

  • Lung Cancer: Leading cause of cancer deaths globally; major risk factors include smoking and exposure to environmental toxins.

  • Colon Cancer: Most common gastrointestinal cancer, early detection is crucial.

  • Brain Cancer: Second most common cancer in children, primarily metastatic in adults.

  • Leukemias: Cancers of blood-forming organs;

    • Acute Lymphocytic Leukemia (ALL): Common in children.

    • Acute Myeloid Leukemia (AML): More prevalent in adults.

    • Chronic Lymphocytic Leukemia (CLL) and Chronic Myeloid Leukemia (CML): Gradual onset, typically found in adults.

  • Lymphomas: Malignant conditions affecting lymphocytes, with subtypes including Hodgkin Lymphoma (HL) and Non-Hodgkin Lymphoma (NHL).

Cancer Prevention Strategies

  • Prevention and early detection are paramount:

    • Avoid exposure to known carcinogens.

    • Regular health screening practices: e.g., Mammograms, Colonoscopies.

    • Adopt healthy lifestyle habits: Regular exercise, balanced diet, and vaccinations as appropriate.

    • Avoid tobacco and limit alcohol consumption (active smoking responsible for 90% of lung cancer cases).