Cell Biology: Cellular Processes

Cellular Processes and Organization

• Selective Permeability: Cell membranes allow the passage of some substances while blocking others, varying by cell type.
• Substances with Free Passage: Enzymes, glucose, and electrolytes readily cross membranes due to their dissolved nature in water. Enzymes are vital for chemical reactions in the body.
• Diffusion: Movement of solutes from higher to lower concentrations.
• Facilitated Diffusion: Movement of solutes from higher to lower concentrations using a carrier molecule.
• Osmosis: Passive movement of water across a membrane from lower to higher solute concentration, influencing cell function through processes like lysis or crenation.
• Active Transport: Movement of substances against their concentration gradient, requiring energy.
• Endocytosis: Bringing substances into a cell, encompassing phagocytosis and pinocytosis.
• Hypotonic: Solution with a lower solute concentration than another solution.
• Hypertonic: Solution with a higher solute concentration than another solution.
• Energy Source: The body breaks down glucose, triglycerides, or proteins to create energy (ATP) when other sources are unavailable.
• Energy Storage: Building larger molecules stores energy.
• Cell Proliferation: Cells divide and produce new cells through mitosis (prophase, metaphase, anaphase, telophase) and meiosis.
• Differentiation: Cells specialize and mature, stemming from less differentiated precursor cells (stem cells).
• Tissue Types:
• Epithelial: Barrier tissue, tightly packed cells (squamous, cuboidal, columnar)
• Connective: Supports and connects tissues, cells suspended in an extracellular matrix (e.g., loose, dense).
• Muscle: Enables movement, consists of fibers with contractile proteins (actin, myosin).
• Nervous: Senses, processes, and responds to stimuli, composed of neurons and neuroglia.

Cell Adaptation and Injury

• Atrophy: Decreasing cell size and function due to decreased workload or use.
• Hypertrophy: Increasing cell size and function due to increased workload.
• Hyperplasia: Increasing tissue size due to increased cell proliferation (compensatory or hormonal). Normal (liver regeneration, menstruation) vs. abnormal (endometrial, cancer).
• Metaplasia: Abnormal cell replacement (not always cancerous).
• Dysplasia: Abnormal cell development, potentially cancerous.
• Cell Injury Causes: Physical, chemical, biological agents, radiation, and nutritional imbalances.
• Cell Injury Consequences: Ischemia (lack of blood flow), necrosis (cell death), and damage caused by free radicals; may be reversible if balanced by cell renewal.
• Necrosis (types):
• Coagulative: Interruption of blood flow
• Liquefactive: Specific situations, e.g., bacterial infections.
• Caseous: Tuberculosis-like appearance.
• Fatty: Specific to fat tissue.
• Gangrene: Type of necrosis caused by severe hypoxic injury.
• Dry: Coagulative, often in extremities.
• Wet: More serious, with toxin release and bacterial invasion.
• Neoplasm: Unregulated and uncontrolled cell growth. Can originate in or spread to other sites (primary vs. secondary).

Cancer Types and Development

• Carcinogenesis (Stages):
• Initiation: Exposure to a cancer-causing agent.
• Promotion: Uncontrolled growth initiated.
• Progression: Permanent malignant changes and metastasis.
• Primary vs. Secondary Cancers: Primary is where cancer originates, secondary (metastasis) is where it spreads.
• Anaplasia: Undifferentiated cells in a primitive state.
• Benign Cancers: Slow, localized growth, resemble surrounding host tissue.
• Malignant Cancers: Rapid growth, metastasis, undifferentiated.
• Host Factors: Age, immune function, gender, socioeconomic status, weight, and prior cancer or chemotherapy.
• Cancer Detection Warning Signs: Changes in elimination habits, persistent sores, abnormal bleeding/discharge, lumps, indigestion, changes in moles, nagging cough/hoarseness.
• Cancer Complications: Cachexia, fatigue, infection, pain, anemia, leukopenia, thrombocytopenia.
• Diagnosis Procedures: Biopsy, tumor markers, imaging.
• Cancer Classification:
• Staging (TNM): Based on tumor size, lymph node involvement, and metastasis.
• Grading (I-IV): Based on tumor differentiation (how much it resembles normal tissue).
• Cancer Treatment: Palliative (comfort), prophylactic (prevention).

Genetic Disorders

• Karyotype: Visual representation of chromosomes.
• Phenotype: How genetic material manifests.
• Alleles: Different forms of a gene.
• Autosomal Dominant Disorders: Single gene, 50% chance of inheritance from affected parent. Examples: Marfan Syndrome, Neurofibromatosis.
• Marfan Syndrome: Genetic disorder affecting connective tissue, characterized by long extremities, cardiovascular problems, and ocular issues.
• Neurofibromatosis: Genetic disorder causing nervous system tumors and bone defects (type 1), or auditory nerve tumors (type 2).
• Autosomal Recessive Disorders: Both parents must carry the mutated gene. Examples: Phenylketonuria (PKU), Tay-Sachs.
• Phenylketonuria (PKU): Difficulty metabolizing phenylalanine, causing neurological damage. Treated with a strict diet.
• Tay-Sachs: Deficiency in an enzyme needed to break down lipids, leading to progressive neurological deterioration.
• Fragile X Syndrome: Trinucleotide repeat disorder, causing learning disabilities and behavioral challenges.
• Multifactorial Inheritance Disorders: Interaction of environmental and genetic factors. Example: Cleft lip and palate.
• Cleft Lip and Palate: Abnormal facial development, typically needing surgery and speech therapy.
• Chromosomal Disorders: Abnormal number or structure of chromosomes.
• Down Syndrome (Trisomy 21): Intellectual disabilities, characteristic physical features, increased risk of certain health problems.
• Turner Syndrome (Monosomy X): Short stature, reproductive issues, unique physical characteristics.
• Klinefelter Syndrome (Polysomy X): Male reproductive issues, physical characteristics.