Cell Biology Quiz for Physician Assistants
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Which of the following cell types is NOT classified as a prokaryote?

  • Protozoa (correct)
  • Cyanobacteria
  • Rickettsiae
  • Bacteria

    • Which of the following is a primary function of the plasma membrane?

  • To generate energy for the cell
  • To synthesize proteins
  • To control the movement of substances into and out of the cell (correct)
  • To store genetic information

    • What distinguishes eukaryotes from prokaryotes?

  • Eukaryotes lack a defined nucleus
  • Eukaryotes possess membrane-bound organelles (correct)
  • Eukaryotes are smaller in size than prokaryotes
  • Eukaryotes have a simpler cellular organization
  • Eukaryotes lack genetic material

    • What term describes the communication between cells?

    <p>Cellular crosstalk (C)</p> Signup and view all the answers

    What is the fundamental arrangement of lipids in the cell membrane?

    <p>A bilayer of phospholipid molecules with hydrophilic heads facing outwards (A)</p> Signup and view all the answers

    Why is it important to understand cellular biology in the context of studying to be a Physician Assistant?

    <p>To understand how diseases affect cellular function (D)</p> Signup and view all the answers

    Which of these is NOT a function of the cell membrane?

    <p>Generating energy for the cell (C)</p> Signup and view all the answers

    What is the main role of proteins in the cell membrane?

    <p>All of the above (D)</p> Signup and view all the answers

    What are microdomains?

    <p>Small, specialized regions within the cell membrane that have distinct lipid and protein compositions (D)</p> Signup and view all the answers

    What is the significance of the amphipathic nature of lipids in the cell membrane?

    <p>All of the above (D)</p> Signup and view all the answers

    Which of the following is NOT a primary cause of cellular injury?

    <p>Excessive ATP production (A)</p> Signup and view all the answers

    What is the primary consequence of decreased ATP production in a cell?

    <p>Cellular swelling (B)</p> Signup and view all the answers

    What is the main function of the sodium-potassium pump in a cell?

    <p>Maintaining the proper balance of ions inside and outside the cell (D)</p> Signup and view all the answers

    Which of the following is NOT a potential consequence of prolonged cellular injury?

    <p>Increased cellular proliferation (C)</p> Signup and view all the answers

    Which of the following cellular processes is characterized by programmed cell death?

    <p>Apoptosis (D)</p> Signup and view all the answers

    What is the primary function of the potassium-sodium antiport system?

    <p>To establish an electrical potential across the cell membrane (C)</p> Signup and view all the answers

    Which of the following is an example of endocytosis?

    <p>Ingestion of bacteria by a white blood cell (B)</p> Signup and view all the answers

    What is the key difference between pinocytosis and phagocytosis?

    <p>Pinocytosis involves the uptake of liquids, while phagocytosis involves the uptake of solids. (D)</p> Signup and view all the answers

    During exocytosis, what is the primary function of intracellular vesicles?

    <p>Transporting and releasing substances from the cell (A)</p> Signup and view all the answers

    What is the resting membrane potential in biological cells?

    <p>The electrical charge difference across the cell membrane when the cell is at rest (A)</p> Signup and view all the answers

    How are action potentials transmitted through the body?

    <p>By a series of conformational changes in membrane proteins, allowing for the movement of ions (D)</p> Signup and view all the answers

    Which of the following is NOT a primary type of tissue found in the body?

    <p>Vascular (A)</p> Signup and view all the answers

    What is the role of founder cells in tissue formation?

    <p>To act as precursors for various specialized cell types within the tissue (C)</p> Signup and view all the answers

    What metabolic process leads to the accumulation of purine catabolites like xanthine and hypoxanthine during ischemia?

    <p>Glycolysis (B)</p> Signup and view all the answers

    Which of the following is NOT a consequence of free radical damage to the cell?

    <p>Increased DNA synthesis (C)</p> Signup and view all the answers

    How does carbon monoxide (CO) produce hypoxic injury?

    <p>By reducing the oxygen-carrying capacity of blood (D)</p> Signup and view all the answers

    What is the mechanism by which lead poisoning can damage the body?

    <p>Interfering with normal reactions of various enzymes (C)</p> Signup and view all the answers

    What is the primary cause of reperfusion injury?

    <p>The generation of xanthine oxidase during ischemia (E)</p> Signup and view all the answers

    Which of the following is a characteristic of a stochastic effect caused by ionizing radiation?

    <p>It can lead to cell generation or hereditary effects. (E)</p> Signup and view all the answers

    What is the primary consequence of hypothermia on cellular function?

    <p>Slowed cellular metabolic processes. (E)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of an infectious injury?

    <p>Directly inhibiting DNA replication (E)</p> Signup and view all the answers

    Which of the following is an example of an injurious nutritional imbalance?

    <p>Deficiency in essential nutrients like vitamins and minerals (D)</p> Signup and view all the answers

    Which of the following statements accurately describes the mechanism by which phagocytic cells and inflammatory substances contribute to cellular injury?

    <p>They cause membrane alterations and damage both injured and uninjured cells. (B)</p> Signup and view all the answers

    Which of the following statements is true regarding the Extracellular Matrix?

    <p>All of the above statements are true. (D)</p> Signup and view all the answers

    What is the primary function of proteases in the proteolytic cascade?

    <p>To break down proteins for physiological regulation. (D)</p> Signup and view all the answers

    What is the primary function of the Cytoskeleton?

    <p>To maintain the shape of the cell, organize its internal components, and facilitate movement. (C)</p> Signup and view all the answers

    Which of the following is NOT a major type of cell junction?

    <p>Synapses (C)</p> Signup and view all the answers

    Which of the following statements is true regarding the role of carbohydrates in the plasma membrane?

    <p>Carbohydrates play a crucial role in intercellular recognition, essential for tissue formation. (C)</p> Signup and view all the answers

    Which of the following molecules bind to receptors on the cell membrane?

    <p>Ligands (B)</p> Signup and view all the answers

    Which of the following are examples of cell-adhesion molecules?

    <p>Integrins, cadherins, selectins, and Immunoglobulin superfamily CAMs (D)</p> Signup and view all the answers

    What is the process by which proteins are modified after translation, and what is its potential link to disease development?

    <p>Post-translational modification; it can lead to misfolded proteins and protein aggregation, which can contribute to disease. (A)</p> Signup and view all the answers

    Which of these is NOT a function of plasma membrane receptors?

    <p>Synthesize new proteins within the cell. (C)</p> Signup and view all the answers

    Which of the following statements accurately describes the function of the Cytoplasm?

    <p>The Cytoplasm is the site of various metabolic processes, protein synthesis, and waste elimination within the cell. (A)</p> Signup and view all the answers

    Which of the following is NOT a major cascade involved in the Proteolytic Cascade?

    <p>Hormonal cascade (D)</p> Signup and view all the answers

    What is the primary function of the Golgi apparatus in a cell?

    <p>To modify, sort, and package proteins and lipids. (B)</p> Signup and view all the answers

    Which type of cell junction is responsible for preventing the passage of most substances between cells?

    <p>Tight Junctions (B)</p> Signup and view all the answers

    Which of the following is NOT a function of the Extracellular Matrix?

    <p>To replicate genetic material within the cell. (A)</p> Signup and view all the answers

    What is the primary difference between free and bound ribosomes?

    <p>Free ribosomes produce proteins that remain within the cytoplasm, while bound ribosomes produce proteins that are secreted out of the cell. (C)</p> Signup and view all the answers

    Which of the following is an example of a disease that can result from abnormal function of a protease?

    <p>Cancer (B)</p> Signup and view all the answers

    Study Notes

    PHYA 501 PA Foundations II

    • Course covers physiology and pathophysiology.
    • Course instructor is Mary Minto, MHS, PA-C.
    • Course is offered at the University of Saint Joseph.

    Significance of Cells

    • All body functions depend on the integrity of the cells.
    • Understanding cellular biology is necessary to understand disease.
    • Functions of cells: movement, conductivity, metabolic absorption, secretion, excretion, respiration, reproduction, cellular communication (crosstalk).

    Back to the Basics

    • Prokaryotes:
      • Nucleus (single, circular chromosome).
      • Examples are cyanobacteria, bacteria, and rickettsiae.
    • Eukaryotes:
      • Complex cellular organization.
      • Membrane-bound organelles.
      • Well-defined nucleus.
      • Examples are higher animals, plants, fungi, and protozoa.

    Basic Cellular Components

    • Diagram of a cell and its components was displayed.
      • Plasma membrane
      • Nucleus
      • Smooth endoplasmic reticulum
      • Rough endoplasmic reticulum
      • Golgi apparatus
      • Lysosome
      • Mitochondrion
      • Ribosomes
      • Cytoplasm
      • Microfilaments
      • Cilia, etc. (All identified parts shown).

    Plasma Membranes- Function

    • Encloses the cell.
    • Controls the composition of the enclosed compartment.
    • Creates a barrier.
    • Maintains polarity with selective transport.
    • Provides cell-to-cell recognition.
    • Allows cell-to-cell adhesion.
    • Provides cellular mobility and shape.
    • Functions like molecular glue for cells and organelles.

    Plasma Membranes- Composition

    • Bilayer of lipids and proteins, not uniformly distributed.
    • Can separate into discrete units (microdomains).
    • Areas within the plasma membrane differ in protein and lipid composition.
    • Caveolae are cave-like indentations.
      • Functions:
        • Storage area for receptors.
        • Route for transport into the cell.
        • Initiate info relay of extracellular chemical messengers into the cell.

    Plasma Membranes- Composition (Lipids)

    • Solid-gel phase, fluid-liquid crystalline phase, liquid-ordered phase.
    • Phases change in response to temperature and pressure.
    • Amphipathic lipids (hydrophilic and hydrophobic ends). - Control movement of hydrophilic substances and water. - Allow lipid-philic substances to move freely (oxygen, and CO2).

    Plasma Membranes- Composition (Proteins)

    • Proteins are major "workhorses" of the cell.
      • Functions: receptors, transporters, enzymes, surface markers, adhesion molecules, catalysts.
    • Proteins made from amino acids (polypeptides).
    • Post-translational modifications.
    • Proteins are made by ribosomes.
    • Travel to various locations in membranes.
    • Folding and unfolding can lead to disease.
    • Include integral, peripheral, and transmembrane proteins.
    • Cell-adhesion molecules (integrins, cadherins, selectins, immunoglobulin superfamily CAMs).

    Plasma Membrane Proteins (Cellular Receptors)

    • Protein molecules on plasma membrane, cytoplasm, or nucleus.
    • Usually attached to integral proteins.
    • Proteins bind ligands (hormones, neurotransmitters, antigens, infectious agents, drugs).
    • Plasma membrane receptors determine which ligands bind, how the cell responds to the binding, and open/close ion channels.

    Plasma Membranes—Composition (Proteases)

    • Proteases are enzymes tethered to the cell membrane.
    • Involved in the proteolytic cascade (orderly sequence of protein degradation).
    • Play roles in regulation, initiating, amplification, and propagation.
    • Four major cascades (caspase-mediated apoptosis, blood coagulation cascade, matrix metalloproteinase cascade, complement cascade).
    • Drug interventions are based on protease actions.
    • Abnormal protease function is linked to diseases (cancer, autoimmunity, neurodegenerative disorders).

    Plasma Membranes—Composition (Carbohydrates)

    • Oligosaccharides are contained within the plasma membrane, bound to membrane proteins and lipids.
    • Function in intercellular recognition (needed for tissue formations).
    • Abnormal surface carbohydrate markers are implicated in tumor cells.

    Extracellular Matrix

    • Meshwork of fibrous proteins, embedded in a water-gel-like carbohydrate.
    • Secreted from cells to envelope themselves.
    • Includes macromolecules and basal lamina.
      • Functions:
        • Glues cells together.
        • Pathway for diffusion of nutrients, water, and other water-soluble things.
        • Involved in regulating cell behaviors.

    Cell Junctions

    • Specialized areas of cell membranes (junctional complexes, desmosomes, tight junctions, gap junctions).
    • Hold cells together.
    • Allow movement of small molecules between cells.
    • Permeability of junctions dependent on calcium concentration.

    Cytoplasm

    • Fills the space between the nucleus and the plasma membrane.
      • Structure:
        • Cytoplasmic matrix.
        • Cytosol.
        • Cytoplasmic organelles.
      • Functions:
        • Synthesis and transport.
        • Elimination of wastes.
        • Metabolic processes.
        • Maintenance.
        • Motility.
        • Storage.

    Cytoplasmic/Intracellular Organelles (Cytosol)

    • Structure: gelatinous, semi-liquid portion of the cytoplasm.
    • Represents 55% of the total cell volume.
    • Functions: intermediary metabolism involving enzymatic biochemical reactions, ribosomal protein synthesis, storage.

    Cytoplasmic/Intracellular Organelles (Cytoskeleton)

    • “Bones and muscles" of the cell.
    • Maintains the cell's shape and internal organization.
    • Permits movement of substances within the cell and movement of external projections.
    • Internal skeleton = microtubules and microfilaments.
      • Microtubules.
      • Centrioles.
      • Microfilaments: Actin.
      • Cell-to-cell junctions.
      • Mechanotransduction.

    Intracellular Organelles (Ribosomes)

    • Structure: Ribonucleic acid (RNA) protein complexes made and secreted by the nucleus.
      • Free ribosomes.
      • Attached ribosomes.
    • Function: Synthesize proteins.

    Intracellular Organelles (Endoplasmic Reticulum)

    • Structure: Network of tubular or saclike channels.
      • Smooth ER.
      • Rough ER.
    • Function: Site of protein synthesis.
    • Senses cellular stress and may respond with misfolding of proteins.

    Intracellular Organelles (Golgi Complex)

    • Structure: Flattened, smooth membranes located near the nucleus.
    • Receives proteins from the endoplasmic reticulum (transport vesicles).
    • Transports vesicles congregate at the cisternae of the Golgi apparatus.
      • Functions:
        • Refining plant and directs traffic.
        • Processes, secretes, and releases substances.
        • Packages substances into clathrin-coated vesicles.

    Intracellular Organelles (Lysosomes)

    • Structure: Saclike structures that originate from Golgi.
      • Primary lysosomes (resting).
      • Secondary lysosomes (active, very acidic, bound to a vesicle).
      • Autolysosomes (digests debris).
    • Functions:
      • Intracellular digestion system (hydrolases: 40 digestive enzymes).
      • Role in autophagy.
      • Residual bodies exported from vacuoles = products that cannot be digested.

    Intracellular Organelles (Peroxisomes)

    • Structure: Membrane-bound organelles containing oxidative enzymes (catalase and urate oxidase).
    • Functions: Major sites of oxygen utilization, detoxify compounds and fatty acids by using H2O2, breaking down substances into harmless products like phenols, formic acid, formaldehyde, alcohol, and synthesis of specialized phospholipids for nerve cell myelination.

    Intracellular Organelles (Mitochondria)

    • Structure: Surrounded by a double membrane.
      • Outer membrane (smooth and permeable).
      • Inner membrane (very selective, contains enzymes for oxidative phosphorylation).
      • Cristae (increase surface area).
      • Matrix (inner portion, involved in metabolism).
    • Functions:
      • Responsible for cellular respiration and energy production.
      • Participates in oxidative phosphorylation.
      • Determining cell death (release of cytochrome C).

    Intracellular Organelles (Vaults)

    • Structure: Bigger than ribosomes, shaped as octagonal barrels.
    • Thousands present in cells.
    • Function: Hypothesized to be cells' "trucks" that carry messenger RNA (mRNA) from the nucleus to ribosomes.
    • Nuclear envelope has similarly shaped pores.

    Intracellular Organelles (Nucleus)

    • Structure:
      • Nuclear envelope.
      • Nucleolus.
      • Deoxyribonucleic acid (DNA).
      • DNA replication, repair, and transcription.
      • Histone proteins.
    • Functions:
      • Cell division & control of genetic information.
      • DNA repair and transcription.

    Cellular Methods of Transport and Communication

    • Communication between cells is required to maintain homeostasis, regulate growth and division, and coordinate cell function.
    • Three main ways cells communicate:
      1. Signal molecule binds to a plasma membrane receptor.
      2. Signal molecule enters the cell and binds to receptor proteins inside the target cell.
      3. Cells connect via protein channels (gap junctions) and coordinate activities directly.

    Categorizing Cellular Communication

    • Contact-dependent signalling.
    • Paracrine signalling.
    • Autocrine signalling.
    • Hormonal signalling.
    • Neurohormone secretion.
    • Neurotransmitter secretion.

    Signal Transduction

    • What happens after signalling cell sends message to target cell?
    • Message used to convey instruction to interior organelles.
    • How?
    • Ligands (extracellular signalling messenger)—bind and have two options.
      • Open/close channels to regulate ion movement
        • Transfer to intracellular messenger (second messenger).
        • Bunch of events in cell.
    • Two options for second messenger system
      • Cyclic adenosine monophosphate (cAMP)
      • Calcium (Ca2+)

    Cellular Transport

    • Solutes = dissolved stuff (electrolytes and non-electrolytes such as oxygen, carbon dioxide, glucose, urea, creatinine).

    Cellular Methods of Transport- Passive Transport

    • Occurs when water and small electrically uncharged molecules move through pores.
    • Does not require energy.
      • Types of passive transport:
        • Diffusion.
        • Passive mediated transport (facilitated diffusion).
        • Filtration (hydrostatic pressure).

    Passive Transport-Diffusion

    • Solute moves from an area of greater concentration to one of lesser concentration.
    • Influenced by electrical charge, size, and lipid solubility.

    Passive Transport- Hydrostatic and Oncotic Pressures

    • Filtration = movement of water/solutes through membrane due to a pushing force (hydrostatic pressure).
    • Osmosis = movement of water from an area of high water concentration to low water concentration due to pulling force (oncotic pressure).
    • Tonicity = osmolarity of a solution= concentration of molecules per weight of water.

    Mediated Transport

    • Integral proteins allow movement of inorganic anions, cations, and large, uncharged compounds across membrane.
    • Binding of specific solute → conformational change → allows solute to cross cell membrane.
      • Active or passive transport
        • Passive mediated transport = facilitated diffusion = no energy needed; molecules move down concentration gradient.
        • Active mediated transport = activated transport.

    Mediated Transport (Transport Carrier Protein/Channel Protein/Ion Channel)

    Active Transport

    • Transport by vesicle formation.
      • Endocytosis—taking in:
        • Internalizing process (section of plasma membrane enfolds substances; vesicles inside cell).
        • Pinocytosis (ingestion of extracellular fluid).
        • Phagocytosis (engulfing large molecules).
    • Exocytosis—expelling:
      • Discharge/secretion of material from intracellular vesicles (ex: expelling/secretion into extracellular matrix).

    Endocytosis and Exocytosis

    Transport of Electrical Impulses

    • Resting membrane potential: difference in voltage across plasma membrane (inside is more negative than outside).
    • Established through movement of ions across cell membrane.
    • Action potentials: example of how electrical impulses are transported through the body.

    Primary Types of Tissues in the Body

    • Cells with common structure and function organized into tissues (epithelial, connective, muscle, neural).
      • Founder cells.
      • Chemotaxis.
      • Contact guidance.
      • Stem cells.
      • Self-renewal.
      • Multipotency.

    Tissue Formation

    • Mitosis of founder cells (most basic precursor cells).
    • Held in place by specialized junctions and macromolecules.
    • May form sheets (example: epithelial cell sheets).
    • Migration of specialized cells.
    • Chemotaxis, contact guidance.
    • Stem cells: cells that can develop into many different cell types early in their development and growth; serve as internal repair and maintenance system.
      • Examples: epithelial lining of intestine, stomach, and skin.

    Epithelial Tissue

    • Covers most internal and external body surfaces.
    • Categorized by number and arrangement of cell layers (simple, stratified, pseudostratified).
    • Categorized by cell shape (squamous, cuboidal, columnar).
    • Structure varies based on location and function (cilia and microvilli).
    • Functions: protection, absorption, secretion, and excretion.

    Connective Tissue

    • Structure: Abundant extracellular matrix, ground substance, fibers (collagenous, elastic, and reticular).
    • Loose and dense connective tissue.
    • Function: Framework for forming organs, binding tissues and organs, supporting tissues and organs in their locations, storing excess nutrients.

    Muscle Tissue

    • Structure: Composed of myocytes (long, thin cells).
    • Three kinds of muscle tissue (smooth, skeletal, and cardiac).
    • Function: Contraction, enabling both voluntary and involuntary movement.

    Neural Tissue

    • Structure: Composed of specialized cells called neurons.
    • Neurons have synapses, cell bodies, axons, and dendrites.
    • Function: Receive and transmit electrical impulses rapidly across junctions (synapses).
    • Neurotransmitters (chemical messengers).

    Differentiate the Functions and Actions of the Sympathetic and Parasympathetic Systems

    • Nervous system:
      • CNS.
      • PNS:
        • Autonomic NS (Involuntary system).
        • Somatic NS (Voluntary system).
    • Sympathetic NS: Mobilize energy stores (fight or flight).
      • Preganglionic neurons release acetylcholine (ACh).
    • Parasympathetic NS: Conserve and restore energy; bradycardia, bronchiolar/pupillary constriction, increased secretions, peristalsis.
      • Preganglionic neurons release acetylcholine (ACh).

    Autonomic Nervous System

    • Coordinates and maintains a steady-state.
    • Composed of two neuron systems: Preganglionic and postganglionic.
    • Sympathetic and parasympathetic divisions

    Cellular Adaptation

    • Reversible, structural, or functional response to normal or adverse conditions
    • Cells' response to protect themselves from injury or maintain homeostasis.
    • Adapted cell is not a normal cell, but not injured either.
      • Types: hypertrophy, hyperplasia, metaplasia, and dysplasia.

    Cellular Adaptation—Atrophy

    • Physiologic (early development, e.g., thymus).
    • Pathologic (decreased workload, use, pressure, blood supply, nutrition, hormonal stimulation, nervous stimulation).
    • Mechanisms: Decreased protein synthesis, increased protein catabolism, autophagy.

    Cellular Adaptation—Hypertrophy

    • Caused by increased work demand or hormones (trigger signals: mechanical, trophic).
    • Physiologic (heart enlarges; e.g., occurs in response to postnatal requirements, moderate exercise training, pregnancy, early phase of volume/pressure increases).
    • Pathologic (likely occurs if physiologic response is prolonged; related to restriction in myocyte growth).

    Cellular Adaptation—Hyperplasia

    • Caused by increased rate of cellular division → increased number of cells (often occurs with hypertrophy).
    • Compensatory (allows organs to regenerate; example: liver).
    • Hormonal (example: implantation of fertilized ovum→ hormonal stimulation of the uterus).
    • Pathologic (abnormal proliferation of normal cells).
    • Example: endometrial hyperplasia (imbalance between estrogen and progesterone).

    Cellular Adaptation- Dysplasia & Metaplasia

    • Dysplasia: refers to abnormal changes in size, shape, and organization of mature cells (atypical hyperplasia)- does not indicate cancer.
    • Metaplasia: reversible replacement of one mature cell type by another less mature cell type; reprogramming of stem cells.
      • Example: normal bronchial columnar ciliated epithelial cells are replaced by stratified squamous epithelial cells.

    Mechanisms of Cellular Injury and Death

    • Leads to injury of tissues and organs.
    • Injured cells may recover (reversible injury) or die (irreversible injury).
    • Causes cell stress (acute or chronic; reversible or irreversible).
    • Can involve necrosis, apoptosis, autophagy, accumulation, or pathologic calcification.
    • Four Biochemical Themes:
      1. Adenosine triphosphate (ATP) depletion.
      2. Oxygen and oxygen-derived free radicals.
      3. Intracellular calcium and loss of calcium steady state.
      4. Defects in membrane permeability.

    Cellular Injury (Hypoxic Injury)

    • Hypoxic injury: lack of oxygen.
    • Ischemia: decreased blood flow.
    • Anoxia: sudden cessation of oxygen supply.
      • Cellular responses: ATP decrease, Na+/K+ pump failure, sodium-calcium exchange failure, cellular swelling

    Cellular Injury (Reperfusion Injury)

    • Restoration of oxygen.
    • Formation of xanthine oxidase.
    • Anaerobic metabolism, buildup of purine (xanthine and hypoxanthine) catabolites.
    • Massive amounts of superoxide and hydrogen peroxide build up.
    • Membrane damage, calcium overload, opening of mitochondrial membrane.
    • Massive escape of ATP & solutes = cell death.

    Cellular Injury (Free Radicals and Reactive Oxygen Species ROS)

    • Free radicals (or ROS) = electrically uncharged atom or group of atoms with an unpaired electron; results in membrane damage.
      • Types of damage:
        • Lipid peroxidation.
        • Alteration of proteins.
        • Alteration of DNA.
    • Mechanisms for inactivation of free radicals
      • Mitochondrial oxidative stress.

    Cellular Injury (Chemical Injury)

    • Direct toxicity to cell.
    • Damage/destruction of plasma membrane.
    • Reactive free radicals and lipid peroxidation.

    Cellular Injury (Lead, Carbon Monoxide)

    • Lead: binds to enzymes (anemia), blocks release of glutamate (neurologic disorders).
    • Carbon monoxide: reduces oxygen-carrying capacity, promotes tissue hypoxia.

    Cellular Injury (Asphyxial, Infectious, Immunologic & Inflammatory)

    • Asphyxial injuries= failure of cells to receive or use oxygen.
    • Infectious injuries: invasion, destruction, toxin production, hypersensitivity reactions.
    • Immunologic & Inflammatory injuries: phagocytic cells, immune and inflammatory substances (histamine, antibodies, lymphokines, complement cascade, proteases), cause membrane alterations; infection and damage to normal (uninjured/uninfected) cells

    Cellular Injury (Injurious Genetic & Epigenetic Factors, Nutritional Imbalances)

    Cellular Injury (Temperature Extremes & Climate Change)

    • Hypothermic injury: slows cellular metabolic processes (slows Na+/K+-ATPase pump); produces reactive oxygen species.
    • Hyperthermic injury: May affect pulmonary responses to hypoxia or increase carbon dioxide; e.g., overheating, sudden infant death syndrome.

    Cellular Injury (Ionizing Radiation)

    • Any form of radiation capable of removing electrons from atoms; e.g., X-rays, Gamma rays, alpha, beta particles.
    • Deterministic effects (occur above a threshold dose).
    • Stochastic effects (cell generation, heredity effects, & cancer; unrelated to threshold).
    • Bystander effects: cells outside the field of radiation are affected by the radiation; results in genomic instability.

    Manifestations of Cellular Injury (Cellular Accumulation)

    • Cellular accumulation (infiltrations): excessive amounts of normal or abnormal substances (water, proteins, lipids, carbohydrates) causing harm to the cell.
      • Endogenous: by-products of abnormal metabolism; e.g., abnormal proteins, lipids, and other materials
      • Exogenous: infectious agents or minerals.

    Cellular Infiltrations (Water, Lipids, Proteins, Pigments, Calcium, Urate, Glycogen)

    Manifestations of Cellular Injury (Cont'd)

    Cellular Death (Necrosis, Apoptosis, Autophagy).

    • Necrosis and apoptosis.

    Cellular Death (Necrosis)

    • Sum of cellular changes after local cell death and the process of autodigestion (autolysis).

      • Necrosis processes
        1. Cell death and progression to necrosis.
        2. Karyolysis.
        3. Pyknosis.
        4. Karyorrhexis.

    • Types of necrosis

      • Coagulative necrosis
        • Hypoxia leads to protein denaturation; changes in albumin.
        • Kidney, heart, & adrenal glands.
      • Liquefactive necrosis
        • Ischemia; death of neurons & glial cells in the brain.
        • Hydrolytic enzymes create a liquid-filled cyst or form pus

    Cellular Death (Necrosis Cont'd)

    Cellular Death (Apoptosis)

    • Programmed cellular death.
      • Normal and pathologic cells involved.
    • Characterized by the “dropping off” of cellular fragments (apoptotic bodies).
    • Dysregulated apoptosis
      • Excessive rate of apoptosis → Neurodegenerative diseases, ischemic injury.
      • Insufficient rate of apoptosis → Cancer & autoimmune disorders.

    Cellular Death (Autophagy)

    • Self-destructive "recycling" process.
    • Survival mechanism: cannibalizes cells with bad organelles or abnormal proteins and reuses good stuff; e.g., metabolic stress conditions.

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    Test your knowledge of cell biology concepts essential for Physician Assistants. This quiz covers prokaryotes vs. eukaryotes, functions of the plasma membrane, and cellular injury. It is designed to reinforce the fundamental principles of cellular biology needed in the healthcare field.

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