Cell Growth and Death Mechanisms
36 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What characterizes paracrine signaling?

  • It binds to receptors on the same cell.
  • It acts on distant target cells.
  • It releases signals into extracellular fluid acting locally. (correct)
  • It transmits signals electrically along a nerve cell.

    • Which type of signaling requires direct contact between cells?

  • Endocrine signaling
  • Paracrine signaling
  • Contact-dependent signaling (correct)
  • Neuronal signaling

    • What type of cell death is characterized by an organized and controlled cellular process, usually beneficial to the organism?

  • Ischemia
  • Infarct
  • Necrosis
  • Apoptosis (correct)

    • What is the function of mitogens?

    <p>They stimulate cell division.</p> Signup and view all the answers

    Which of the following is NOT a feature of reversible injury?

    <p>Nuclear alterations</p> Signup and view all the answers

    Which phase of the cell cycle is primarily concerned with DNA replication?

    <p>S phase</p> Signup and view all the answers

    Which of the following describes the cellular injury that is not reversible?

    <p>Necrosis</p> Signup and view all the answers

    What can lead to decreased oxidative phosphorylation?

    <p>Cellular injury</p> Signup and view all the answers

    What term refers to the shrinkage and condensation of the nucleus during apoptosis?

    <p>Pyknosis</p> Signup and view all the answers

    What is a primary factor that differentiates reversible injury from irreversible injury?

    <p>Duration of the injury</p> Signup and view all the answers

    Which statement about growth factors is accurate?

    <p>They stimulate cell division.</p> Signup and view all the answers

    Which type of necrosis is characterized by the death of adipose tissue due to enzymatic digestion?

    <p>Fat necrosis</p> Signup and view all the answers

    Which of the following is NOT a function of signal molecules in cell signaling?

    <p>Conducting electrical impulses</p> Signup and view all the answers

    What indicates irreversible cell injury?

    <p>Severe alterations in organelles</p> Signup and view all the answers

    In terms of morphology, what is a common microscopic feature of necrosis?

    <p>Cell leakage</p> Signup and view all the answers

    Which cellular phase acts as a checkpoint for the cell to decide whether to proceed to DNA replication or not?

    <p>G1 phase</p> Signup and view all the answers

    What characterizes irreversible cell injury?

    <p>Inability to adapt and cell death</p> Signup and view all the answers

    Which type of cell death is characterized by a lack of inflammatory reaction?

    <p>Apoptosis</p> Signup and view all the answers

    Which morphological change is NOT associated with necrosis?

    <p>Cellular division</p> Signup and view all the answers

    What is a key feature of coagulative necrosis?

    <p>Preservation of tissue architecture</p> Signup and view all the answers

    In which condition is liquefactive necrosis commonly seen?

    <p>Brain infarcts</p> Signup and view all the answers

    Which type of necrosis involves multiple tissue planes?

    <p>Gangrenous necrosis</p> Signup and view all the answers

    Which of the following describes a significant indicator of necrosis?

    <p>Karyorrhexis</p> Signup and view all the answers

    What is a common outcome of necrosis?

    <p>Inflammatory response</p> Signup and view all the answers

    What type of necrosis is a localized area of coagulative necrosis called?

    <p>Infarct</p> Signup and view all the answers

    Which morphological change is particularly characteristic of necrotic cells?

    <p>Anucleate cells</p> Signup and view all the answers

    What is the characteristic appearance of caseous necrosis?

    <p>White and friable</p> Signup and view all the answers

    In which condition is fibrinoid necrosis most commonly observed?

    <p>Immune reactions involving blood vessels</p> Signup and view all the answers

    What does fat necrosis primarily result from?

    <p>Release of lipases in acute pancreatitis</p> Signup and view all the answers

    Which condition does NOT contribute to cellular injury due to oxygen deprivation?

    <p>Hypercapnia</p> Signup and view all the answers

    Which mechanism is a key factor in cellular injury?

    <p>Membrane permeability defects</p> Signup and view all the answers

    What is a defining characteristic of apoptosis?

    <p>Plasma membrane remains intact</p> Signup and view all the answers

    In which apoptotic pathway is the intrinsic pathway involved?

    <p>Both physiological and pathological situations</p> Signup and view all the answers

    Which of the following is a common feature of necrosis?

    <p>Disorganized cellular architecture and inflammation</p> Signup and view all the answers

    What is primarily damaged during cellular injury?

    <p>Mitochondria, cell membranes, and DNA</p> Signup and view all the answers

    Fat necrosis leads to the formation of which structure in the affected area?

    <p>Calcium soaps</p> Signup and view all the answers

    Study Notes

    Cell Growth/Proliferation, Necrosis/Apoptosis, Tissue Injury

    • The stability of a structure is directly related to the security of its foundation (Blake Higginbotham quote)
    • The lecture outlines cell growth/proliferation, cell injury/death (reversible/irreversible), cell injury mechanisms, and morphological features of cell death (necrosis/apoptosis).

    Lecture Outline

    • Cell Growth/Proliferation
    • Cell Injury/Death
      • Reversible injury
      • Irreversible injury
      • Mechanisms of cell injury
      • Mechanisms and morphological features of cell death
        • Necrosis
        • Apoptosis

    Lecture Objectives

    • Define and use relevant terms (pyknosis, karyorrhexis, karyolysis, ischemia, infarct) correctly.
    • Describe the morphological and biochemical features of apoptosis.
    • List examples of apoptosis in physiological and pathological conditions.
    • Describe the morphological and biochemical features of necrosis.
    • Compare necrosis and apoptosis in terms of critical features, common situations of occurrence, and mechanisms of development.
    • Compare the types of necrosis (coagulative, caseous, fat, liquefactive, and gangrenous) by gross and microscopic features, common sites/tissues involved, and common causes/mechanisms
    • Provide examples for each type

    Cell Cycle

    • The cell cycle includes the phases: M phase (mitosis), S phase (DNA replication), G1/G2 phases
    • Control/regulatory systems regulate DNA replication, mitosis, and cytokinesis.
    • Checkpoints occur in G1 and G2 to decide if a cell proceeds to the next phase.

    Cell Growth/ Proliferation: Cellular Requirements

    • Cellular requirements for growth and proliferation include nutrients and chemical signals from other cells.
    • Signal molecules are either soluble proteins, proteins bound to the surface of other cells, or proteins bound to the extracellular matrix (ECM).
    • Signal molecules stimulate or inhibit cellular function.

    Cell Signaling

    • Endocrine: Hormones secreted into the bloodstream are distributed throughout the body.

    • Paracrine: Paracrine signals are released into the extracellular fluid and affect nearby cells.

    • Synaptic: Neuronal signals are transmitted electrically along a nerve axon; this causes neurotransmitter release to adjacent target cells

    • Contact-dependent: A cell-surface-bound signal molecule binds to a receptor protein on an adjacent cell.

    Cell Growth/Proliferation: Signal Molecules Categories

    • Stimulatory signal molecules are classified into three major categories:
      • Survival factors: Suppress apoptosis
      • Mitogens: Stimulate cell division
      • Growth factors: Stimulate cell growth

    Cell Injury/Cell Death - Reversible vs. Irreversible

    • Cell death is the consequence of cell injury.
    • Reversible vs. irreversible injury
      • Stress
      • Injurious stimulus
      • Adaptive response
      • Ability/Inability to adapt
      • Reversible cell injury vs. cell death (e.g., necrosis, apoptosis)

    Reversible Cell Injury

    • Hallmarks: Decreased oxidative phosphorylation (ATP formation), Na+/K+ ATPase pump abnormalities, membrane alterations, changes in intracellular ion concentration, cellular swelling, alterations in intracellular organelles, defects in protein synthesis, cytoskeletal damage, DNA damage.

    • Light microscopic features: Cellular swelling due to energy-dependent ion pump failure, fatty change, abnormal processing of fatty acids.

    • Ultrastructural features: Plasma membrane blebbing, loss of microvilli, mitochondrial swelling, dilation of ER, detachment of polysomes, myelin figures, nuclear alterations.

    Irreversible Cell Injury

    • Cell can no longer adapt, resulting in cell death.
    • Characterized by severe mitochondrial damage and loss of membrane integrity.

    Cell Injury/Cell Death: Two Types

    • Necrosis:
      • Unregulated cell death, leakage of lysosomal enzymes into cytoplasm, inflammatory reaction, and a pathological process.
    • Apoptosis:
      • Programmed cell death, nuclear dissolution, no inflammatory reaction, and serves many normal cellular functions.

    Necrosis: Morphologic Changes

    • Increased eosinophilia, glassy appearance, vacuolated appearance, myelin figures, dilated mitochondria with amorphous densities
    • Nuclear changes:
      • Karyolysis (fading/loss of basophilia)
      • Pyknosis (nuclear shrinking; increased basophilia)
      • Karyorrhexis (nuclear fragmentation)

    Patterns of Tissue Necrosis

    • Coagulative necrosis: Preservation of tissue architecture for a few days; blocked proteolysis of dead cells. Seen in ischemia due to vessel obstruction (e.g., infarcts).
    • Liquefactive necrosis: Tissue converted to a liquid viscous mass; common in bacterial infections (abscesses) and brain infarcts.
    • Caseous necrosis: Area of necrosis appears white, friable, and cheese-like; a characteristic feature of tuberculous infection.
    • Fibrinoid necrosis: Deposition of immune complexes, blood vessels, pink amorphous area of necrosis.
    • Fat necrosis: Focal area of fat destruction, common in acute pancreatitis, formation of calcium soaps.
    • Gangrenous necrosis: Often coagulative, involving multiple tissue planes and necrosis of a limb due to blood supply loss.

    Cell Injury: Causes

    • Oxygen deprivation: Hypoxia (deficiency of oxygen), ischemia (reduced blood flow), inadequate blood oxygenation, decreased oxygen-carrying capacity, decreased blood volume.
    • Physical agents: Mechanical trauma, extremes of temperature (burns, deep cold), radiation, electric shock.
    • Chemical agents and drugs: Normal ions in high concentrations, poisons, pollutants, insecticides, herbicides, alcohol, therapeutic drugs.
    • Infectious agents
    • Immunologic reactions: Autoimmune reactions, reactions to microbes.
    • Genetic defects: Defects in functional proteins, accumulation of misfolded proteins, DNA damage
    • Nutritional imbalances: Protein-calorie deficiencies, vitamin deficiencies, nutritional excess

    Mechanisms of Cell Injury

    • Cellular response depends on injury type, duration, and severity.
    • Consequences depend on injured cell type, state, and adaptability
    • Key cellular components frequently damaged include mitochondria, cell membranes, proteins synthesis/packaging, and DNA
    • Key mechanisms include decrease in ATP, mitochondrial damage, loss of calcium homeostasis, oxygen-derived free radicals (oxidative stress), defects in membrane permeability, and abnormal proteins.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Necrosis-Apoptosis Lecture Notes PDF

    Description

    This quiz focuses on cell growth, proliferation, and the mechanisms of cell injury and death, including necrosis and apoptosis. It covers definitions and characteristics of these processes, ensuring an understanding of their comparative aspects and implications in health and disease.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser