Cellular Function Spring 2026

Pathophysiology Basics & Cellular Function

What is Pathophysiology?

Pathophysiology refers to the continuum of health and illness, where health is defined as the perceived wholeness of body, mind, and spirit, and illness is characterized as a state resulting in suffering or distress.

Key Themes

  • Homeostasis
      - The balance maintained in body systems for optimal function.

Understanding Disease

  • Definition: Disease is a functional impairment of cells, tissues, organs, or organ systems.
  • Causes of Disease: Types of causes include:
      - Pathogen: A disease-causing microorganism (bacteria, viruses, fungi, etc.).
      - Multifactorial: Involves more than one cause.
      - Idiopathic: No known cause.
      - Nosocomial: Infection received in a healthcare environment.
      - Iatrogenic: Caused inadvertently by medical treatment.

Presenting Signs and Symptoms of Disease

  • Signs vs. Symptoms:
      - Signs: Objective findings (observable by others).
      - Symptoms: Subjective experiences reported by the patient.
  • Local vs. Systemic: Local effects are confined to one area, while systemic effects are throughout the body.
  • Acute vs. Chronic: Acute diseases develop quickly and have a short duration; chronic diseases develop slowly and are long-lasting.
  • Remissions vs. Exacerbations: Remission is the period where symptoms decrease or disappear, whereas exacerbation refers to a worsening of symptoms.
  • Asymptomatic: Detection of disease in a person without symptoms.

Diagnosis and Treatment

  • Diagnosis: A label assigned to a disease based on specific diagnostic criteria.
  • Prognosis: A prediction regarding how an individual will progress through the disease process, emphasizing the distinction between morbidity (disease state) and mortality (death).
  • Treatment: Care provided to patients that is informed by current research and knowledge in healthcare: it should:
      - Go beyond singular pieces of research (Evidence-Based Practice - EBP).
      - Encompass the entirety of knowledge, including practice by experts.
      - Consciously respect variations in human health.

Levels of Prevention

  • Primary Prevention: Efforts to prevent diseases from occurring entirely (e.g., vaccination).
  • Secondary Prevention: Involves early disease detection through screening, even prior to symptom manifestation.
  • Tertiary Prevention: Rehabilitation efforts aimed at preventing further complications and progressions of diseases, thus aiding patients in sustaining quality of life with existing conditions.

Review of Cellular Function

  • Cell Characteristics:
      - Cells are the basic unit of all living organisms, function as the smallest form of life, and can replicate independently, with over 200 types present in the human body.

Cellular Organelles

  1. Nucleus:
       - Acts as the control center of the cell, storing genetic code and including structures such as chromatin and nucleolus.
  2. Cytoplasm:
       - Substance where cellular work is conducted, comprising water, electrolytes, proteins, neutral fats, and glycogen; houses organelles.
  3. Ribosomes:
       - Locations of protein synthesis; can be free-floating or bound to rough endoplasmic reticulum (ER).
  4. Endoplasmic Reticulum (ER):
       - A tubular communication system that can be rough (producing membrane proteins and enzymes) or smooth (synthesizing lipids, regulating intracellular calcium, and detoxification).
  5. Golgi Apparatus:
       - Sorts, chemically modifies, and packages proteins for delivery.
  6. Lysosomes:
       - Contain enzymes that digest worn-out organelles and engulfed substances.
  7. Peroxisomes:
       - Manage free radicals and some metabolic processes.
  8. Mitochondria:
       - Organelles known as the powerhouse of the cell; they have their own DNA and ribosomes and produce energy via aerobic metabolism, mainly creating ATP.

Energy, Replication, Differentiation

  • Energy (ATP): Obtained by breaking down glucose, triglycerides, or proteins. Can be stored by synthesizing larger molecules.
      - Krebs Cycle: Central role in energy production, along with forms of respiration (aerobic and anaerobic).
  • Cell Proliferation: Refers to cell division and reproduction, involving:
      - Mitosis: Division resulting in two genetically identical daughter cells.
      - Meiosis: Special division occurring only in gametes (sperm and ova).
  • Cell Differentiation: The process through which cells develop specialized functions, with stem cells being less differentiated and capable of maturing into various cell types as necessary.

Plasma Membrane and Material Exchange

  • Plasma Membrane: A semipermeable lipid bilayer encapsulating the cell.
      - Selective Permeability: Only certain substances can pass through the membrane freely.
      - Substances with Free Passage: Includes enzymes, glucose, and electrolytes.
Exchanging Material
  1. Diffusion: Movement of solutes toward lower solute concentrations.
  2. Facilitated Diffusion: Passive transport of solutes using carrier molecules from a high to low concentration.
  3. Osmosis: Passive movement of water across the membrane toward higher solute concentrations (osmotic pressure).
  4. Active Transport: Movement against the concentration gradient, consuming energy (e.g., Na-K pump).
  5. Exocytosis: Expulsion of proteins from the cell via membrane fusion of vesicles containing the proteins.
  6. Endocytosis: Process of bringing substances into the cell, including:
       - Phagocytosis: Cell engulfs solid substances (cell eating).
       - Pinocytosis: Engulfs liquid substances (cell drinking).

Types of Tissues

  1. Epithelial Tissue
  2. Nervous Tissue
  3. Muscle Tissue
  4. Connective Tissue

Cellular Adaptation

  • Atrophy: Reduction in cell size; may result from decreased functional workload.
  • Hypertrophy: Growth in cell size, prompted by hormonal signals or increased workload.
  • Hyperplasia: An increase in cell number, also linked to hormonal changes or activity levels.
  • Metaplasia: Transformation of one cell type into another.
  • Dysplasia: Abnormal cell development resulting in alterations of size, shape, uniformity, and structure.
  • Anaplasia: Rapid and uncontrolled cell proliferation accompanied by loss of differentiation.

Cell Injury

  • Causes of Cellular Injury: Most diseases stem from cell injury due to factors such as ischemia, necrosis, free radicals, and others. Injury may be reversible if exposure to stressors is short-lived and not excessive.

Cell Death

  • Cell Death Mechanisms: Overwhelmed cellular damage leads to:
      - Apoptosis: Programmed cell death (cellular suicide).
      - Necrosis: Disorderly cell death associated with inflammatory responses.

Carcinogenesis

  • Cancer: Describes neoplasms (uncontrolled tissue growth) that invade and destroy; these can originate in one organ or spread from another.
      - Epithelial cells are most likely to transform into neoplasms.
      - Characteristics of Neoplasms:
        - Autonomy: Independent growth not regulated by normal cellular controls.
        - Anaplasia: Degree of differentiation observed in cancer cells indicates aggressiveness; more anaplasia means more malignancy.
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