Human Physiology Week 1 - Study Guide
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Questions and Answers

What is the main role of collagen in the extracellular matrix?

  • Provides hydration to the tissue
  • Promotes elasticity and stretchiness
  • Facilitates cell communication
  • Provides structure and strength (correct)
  • What is NOT a characteristic of the extracellular matrix?

  • It influences tissue structure and function.
  • It is secreted by cells.
  • It can fill spaces between cells.
  • It consists only of proteins. (correct)
  • Which tissue type primarily provides protection and serves as a barrier?

  • Epithelial Tissue (correct)
  • Connective Tissue
  • Nervous Tissue
  • Muscle Tissue
  • What effect does the presence of proteoglycans have on cartilage tissue?

    <p>Allows for cushioning in joints</p> Signup and view all the answers

    Which component serves as the 'glue' connecting cells to each other in the extracellular matrix?

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

    In which level of tissue organization do cells and their extracellular matrix compose a structure?

    <p>Tissue level</p> Signup and view all the answers

    What is the primary function of nervous tissue?

    <p>Facilitates sensation and signal transmission</p> Signup and view all the answers

    What is the primary role of fibroblasts in connective tissue?

    <p>Produce collagen and elastin</p> Signup and view all the answers

    Which of the following statements about elastin is true?

    <p>It offers elasticity to certain tissues.</p> Signup and view all the answers

    What tissue type is primarily responsible for lining organs and producing glandular secretions?

    <p>Epithelial Tissue</p> Signup and view all the answers

    Which type of muscle is involuntary and lines internal organs?

    <p>Smooth muscle</p> Signup and view all the answers

    What initiates oxidative stress in cells?

    <p>Reactive oxygen species production</p> Signup and view all the answers

    What primary role does loose connective tissue play in the body?

    <p>Fills spaces and supports blood vessels.</p> Signup and view all the answers

    Which of the following is NOT a mechanism of reversible cell injury?

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

    Which response is characterized by an increase in cell number due to hormonal stimulation?

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

    During which process do lysosomes release digestive enzymes in the cytoplasm?

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

    Which of the following is a response to excessive physical stress on cells?

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

    What is a key consequence of chronic cellular stress leading to hypertrophy?

    <p>Cell size increases without new cell formation</p> Signup and view all the answers

    What are antioxidants primarily responsible for in relation to reactive oxygen species (ROS)?

    <p>Neutralizing ROS to prevent damage</p> Signup and view all the answers

    Which condition is often associated with a down syndrome genetic alteration?

    <p>Chromosomal abnormality</p> Signup and view all the answers

    Which type of bone is characterized by irregular collagen structure and is considered weaker than mature bone?

    <p>Woven bone</p> Signup and view all the answers

    What is the primary non-mineralized component of the extracellular matrix in bone?

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

    During which phase of fracture healing does the soft callus form?

    <p>Soft callus formation</p> Signup and view all the answers

    Which cells are responsible for breaking down the extracellular matrix in bone?

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

    Which component is NOT correctly associated with mature bone?

    <p>Presence of fibroblasts</p> Signup and view all the answers

    What is the term used for the process of transforming cartilage into bone during fracture healing?

    <p>Endochondral ossification</p> Signup and view all the answers

    Which statement about cancellous bone is accurate?

    <p>It is directly in contact with bone marrow.</p> Signup and view all the answers

    What type of cell can become osteoblasts and is considered a bone precursor cell?

    <p>Osteoprogenitor cell</p> Signup and view all the answers

    Which feature is NOT characteristic of lamellar bone compared to woven bone?

    <p>Increased cellular activity</p> Signup and view all the answers

    Which of the following factors does NOT influence the duration of fracture healing?

    <p>Body temperature</p> Signup and view all the answers

    Study Notes

    Tissue Organization Hierarchy

    • Chemical level: Atoms combine to form molecules
    • Cellular level: Cells are composed of molecules
    • Tissue level: Cells AND extracellular matrix (ECM) they produce
    • System level: Composed of different tissue types, e.g., skin includes epithelial, connective, and nervous tissue

    Extracellular Matrix

    • Secreted by cells, influencing tissue structure and function
    • Examples:
      • Bone ECM makes it hard and rigid
      • Tendon ECM makes it stretchy

    Extracellular Matrix Components

    • Collagen: Provides structure and strength (triple helix structure)
    • Elastin: Provides elasticity (stretchiness)
    • Proteoglycans: Fill space, attract water, influence tissue softness (e.g., cushioning in cartilage)
    • Integrins: "Glue" connecting cells to cells and other ECM proteins

    Tissue Types and Functions

    • Epithelial: Protection (e.g., skin), lining organs (e.g., blood vessels), glandular secretions (e.g., mucus, sweat)
    • Connective: Filling spaces, structural support, energy storage
      • Connective Tissue Proper: Areolar tissue, filling spaces
      • Blood: Nutrient supply
      • Cartilage: Support, cushioning
      • Bone: Support, rigidity
      • Ligament: Connects bone to bone
      • Tendon: Connects muscle to bone
      • Adipose: Fat storage
    • Muscle: Contraction for movement
      • Skeletal: Voluntary control
      • Smooth: Lines organs, involuntary control
      • Cardiac: Heart muscle
    • Nervous: Transmission of electrical impulses for information

    Cellular Injury and Adaptation

    • Factors influencing reversal: Mechanism of injury, duration, severity
    • Free Radical Theory: Reactive oxygen species (ROS) with unpaired electron react with molecules, forming toxic chemicals
      • Normal part of metabolism, continuously formed
      • Oxidative stress: Excess ROS production causing cell injury and death, implicated in lifestyle diseases
      • Stimuli: Excessive exercise, radiation, tobacco smoke, heat
    • Antioxidants: Neutralize ROS, preventing DNA and cell damage
      • Endogenous: Glutathione, peroxidase, catalase
      • Exogenous: Vitamin C, E, beta-carotene
    • Exercise, Free Radicals, Antioxidants: Exercise increases ROS acutely, impairing muscle force production, but also stimulates endogenous antioxidant adaptation
      • Excessive exercise: Significant oxidative stress, relative to individual fitness
    • Genetic Alterations: Cause cellular injury/death
      • Chromosomal abnormalities: Down's syndrome
      • Gene mutations: Sickle cell anemia
      • Multiple gene mutations: Type II diabetes, obesity
    • Cellular Responses to Stress:
      • Decreased stress tolerance (atrophy)
      • Maintenance
      • Increased stress tolerance: Hypertrophy (cell size increase), Hyperplasia (cell number increase), Injury, Death
    • Mechanical Stressors: Overstretch, compression, friction

    Reversible Cell Injury

    • Increased sodium and calcium influx into cell
    • Cellular swelling
    • Impaired organelle function, decreasing ATP production and leading to acidosis
    • Reversal occurs if: Nucleus remains intact, energy source restored, toxic injury neutralized
    • Cell returns to normal function

    Chronic Cellular Stress Responses

    • Atrophy: Reduction in cell/organ size (e.g., bone loss, muscle wasting, brain cell loss)
    • Hypertrophy: Increase in cell size (e.g., left ventricular hypertrophy due to exercise or hypertension)
    • Hyperplasia: Increase in cell number (e.g., callus formation, thickened uterine wall lining)
    • Metaplasia: Change in cell type (e.g., ciliated epithelium to squamous epithelium in smokers)
    • Dysplasia: Increase in cell numbers AND loss of morphology AND loss of tissue organization (e.g., chronically injured areas)

    Irreversible Cell Injury

    • Cell death: Apoptosis (genetically mediated, programmed, no inflammation), Necrosis (active degradation of dead cells with inflammation)
    • Necrosis:
      • Nuclear and mitochondrial damage
      • Lysosomal enzyme release, self-digestion of dead tissue
      • Release of cellular contents into ECF and circulation (e.g., CK elevations in myocardial infarction)
      • Requires removal for repair/regeneration
      • Can cause gangrene formation

    Bone Structure

    • Cortical bone (compact bone): Tough outer layer, majority of bone, covered by periosteum with blood vessels
    • Cancellous bone (trabecular/spongy bone): Spongy, mesh plates, in contact with bone marrow

    Cellular Components of Bone

    • Osteoblasts: Immature bone cells, secrete ECM, become osteocytes or bone lining cells, can undergo apoptosis
    • Osteocytes: Mature bone cells, maintain ECM, respond to mechanical loading and hormones
    • Osteoclasts: Break down ECM, release minerals into bloodstream, create space for new ECM formation
    • Bone lining cells:

    Non-cellular Component of Bone (ECM)

    • Non-mineralized: Osteoid, primarily collagen
    • Mineralized: Hydroxyapatite

    Bone Classifications Based on Maturity

    • Immature bone (woven bone): Primary bone, found in fracture repair and fetal growth, weaker than mature bone due to irregular collagen and less mineral content
    • Mature bone (lamellar bone): Secondary bone, formed by remodeling from woven bone, stronger due to osteon structure, adapted to stressors, more mineral content

    Fracture Repair

    • Regeneration and remodeling, no scar, return to optimal functioning possible
    • Duration depends on: Fracture site, type, treatment, soft tissue involvement, individual factors (age, immunocompetency, nutrition)
    • Phases:
      • Hematoma formation (clotting, growth factor release, lasts about a week)
      • Inflammation (granulation tissue forms, fibrosis, neovascularization)
      • Soft callus formation (osteoclasts clear necrotic bone, periosteum/endosteum regenerate, cartilage and bony spicules form, immobilizes fracture)
      • Hard callus formation (fibrocartilage, endochondral ossification)
      • Remodeling (woven bone replaced by lamellar bone, excessive callus resorbed, bone remodels based on mechanical stresses - Wolff's Law)

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    Description

    Explore the intricate hierarchy of tissue organization, starting from the atomic level to the systematic level. Understand the significance of the extracellular matrix components and their role in various tissue types. This quiz covers essential concepts crucial for studying anatomy and physiology.

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