Skeletal System Functions and Structure
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Questions and Answers

Which of the following is NOT a primary function of the skeletal system, as described in the text?

  • Facilitating movement
  • Regulating body temperature (correct)
  • Protecting internal organs
  • Producing blood cells

    • What specific substance, stored within the bone matrix, does the text identify as essential for muscle contractions and nerve impulse transmission?

  • Sodium
  • Potassium
  • Calcium (correct)
  • Phosphorus

    • Which of these accurately describes the role of bones in movement?

  • They produce the impulses that cause muscles to contract and relax.
  • They directly generate the force needed for movement.
  • They function as levers, with joints serving as fulcrums. (correct)
  • They act solely as anchors for muscles.

    • In what part of the skeletal system is adipose tissue, which acts as a source of energy, primarily found?

    <p>Yellow marrow</p> Signup and view all the answers

    Besides calcium, which other mineral is specifically mentioned as being stored in the bone matrix?

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

    What is the primary function of cartilage, in the context of the skeletal system?

    <p>To provide flexibility and reduce friction at joints</p> Signup and view all the answers

    Which of the following sets of organs are correctly paired with their skeletal protectors?

    <p>Heart - ribcage, Lungs-ribcage, Brain - skull</p> Signup and view all the answers

    What percentage of total body calcium is estimated to be stored in the bones, as stated?

    <p>More than 98%</p> Signup and view all the answers

    Which of the following is the primary site of hematopoiesis in adults?

    <p>Red bone marrow</p> Signup and view all the answers

    Which of the following best describes the function of osteocytes?

    <p>Maintaining the protein and mineral content of the surrounding matrix.</p> Signup and view all the answers

    Which skeletal division includes the bones of the limbs and the pectoral and pelvic girdles?

    <p>Appendicular skeleton</p> Signup and view all the answers

    Which type of bone is predominantly found in the wrists and ankles?

    <p>Short bones</p> Signup and view all the answers

    What is the primary role of osteoclasts in bone remodeling?

    <p>Removing and recycling bone matrix through osteolysis.</p> Signup and view all the answers

    The roof of the skull, sternum, ribs, and scapulae primarily consist of what type of bones?

    <p>Flat bones</p> Signup and view all the answers

    What is the term for the basic structural unit of compact bone?

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

    Which of the following best describes sesamoid bones?

    <p>Small, flat bones that develop inside tendons.</p> Signup and view all the answers

    What are the channels that connect the central canals of adjacent osteons?

    <p>Perforating canals</p> Signup and view all the answers

    Which of the following distinguishes spongy bone from compact bone?

    <p>The presence of a matrix in a lattice-like network of trabeculae.</p> Signup and view all the answers

    What is the name of the long tubular shaft that forms the axis of a typical long bone?

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

    The ends of long bones are primarily made of which type of bone?

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

    What is the significance of trabeculae in spongy bone?

    <p>They provide strength along lines of stress and protect red bone marrow.</p> Signup and view all the answers

    What is the primary function of articular cartilage?

    <p>To reduce friction and absorb shock at joints.</p> Signup and view all the answers

    How does cartilage differ from bone?

    <p>Cartilage is avascular, relying on diffusion for nutrients, while bone is vascular.</p> Signup and view all the answers

    The epiphyseal plate is important for growth in the length of bones. What replaces it when the bone stops growing?

    <p>An epiphyseal line</p> Signup and view all the answers

    Which type of ossification does not use a cartilage model?

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

    What is the outermost covering of a bone primarily made of dense irregular tissue?

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

    During intramembranous ossification, what is the uncalcified matrix secreted by osteoblasts called?

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

    Which membrane lines the medullary cavity and other canals within the bone?

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

    What structural component do both compact and spongy bone have in common?

    <p>Osteocytes housed in lacunae</p> Signup and view all the answers

    Which of the following cells is NOT capable of mitosis?

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

    What is the name for the spongy bone found between two layers of compact bone in flat bones of the cranium?

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

    What type of fibers contribute to roughly one-third of the bone weight?

    <p>Collagen fibers</p> Signup and view all the answers

    What is another term for spongy bone?

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

    What is the primary mineral component of bone that gives it its hardness?

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

    What is the term for the passageways in bone matrix that allow mature bone cells to communicate and receive nutrients?

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

    What cells differentiate from monocytes and macrophages?

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

    What is the role of yellow bone marrow?

    <p>It stores fat as an energy source</p> Signup and view all the answers

    Where are the stem cells that produce osteoblasts found?

    <p>In the periosteum and endosteum</p> Signup and view all the answers

    During intramembranous ossification, what structure is formed from osteoid secreted around capillaries?

    <p>Trabecular matrix</p> Signup and view all the answers

    Which bones do NOT fully ossify at birth, allowing for deformation during passage through the birth canal?

    <p>Skull and clavicles</p> Signup and view all the answers

    What is the initial skeletal precursor replaced during endochondral ossification?

    <p>Hyaline cartilage</p> Signup and view all the answers

    What is the perichondrium?

    <p>A membrane that covers cartilage</p> Signup and view all the answers

    What causes the chondrocytes within the shaft to die during endochondral ossification?

    <p>Lack of nutrients due to impermeable matrix</p> Signup and view all the answers

    What is the periosteal bud composed of?

    <p>Fibroblasts, lymph vessels, and red marrow elements</p> Signup and view all the answers

    Which cells secrete osteoid during the formation of trabeculae?

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

    What process opens up the medullary cavity in the center of the diaphysis?

    <p>Osteoclast breakdown of spongy bone</p> Signup and view all the answers

    What characterizes the secondary ossification centers?

    <p>They form in the epiphyses.</p> Signup and view all the answers

    Which part of the epiphyseal plate contains small chondrocytes that secure the plate to the osseous tissue of the epiphysis?

    <p>Reserve zone</p> Signup and view all the answers

    What is the primary role of the chondrocytes in the proliferative zone?

    <p>To form new chondrocytes by mitosis</p> Signup and view all the answers

    What happens to most of the chondrocytes in the zone of calcified matrix?

    <p>They die due to a calcified matrix</p> Signup and view all the answers

    How does appositional growth lead to an increase in the diameter of bones?

    <p>By adding new osteons to the external bone surface</p> Signup and view all the answers

    What process is responsible for a bone when the matrix is resorbed on one surface and deposited on another?

    <p>Bone Modeling</p> Signup and view all the answers

    When does the process of bone modeling primarily take place?

    <p>During bone growth</p> Signup and view all the answers

    Which of the following is NOT a function of calcium ions in the human body?

    <p>Regulation of respiratory rate</p> Signup and view all the answers

    What is the primary effect of parathyroid hormone (PTH) on bone tissue?

    <p>Stimulates osteoclast activity, leading to increased calcium release</p> Signup and view all the answers

    Which hormone directly opposes the effects of parathyroid hormone (PTH) in regulating blood calcium levels?

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

    What is the effect of calcitonin on calcium absorption in the digestive tract?

    <p>Decreases the rate of calcium absorption</p> Signup and view all the answers

    In individuals with hypercalcemia, which bodily system is typically underactive?

    <p>The nervous system</p> Signup and view all the answers

    Which of the following best describes the effect of calcitriol on the kidneys?

    <p>Increases calcium reabsorption by the kidney tubules</p> Signup and view all the answers

    What condition is characterized by abnormally low levels of calcium in the blood?

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

    Which of the following bone disorders results from overactive osteoclasts?

    <p>Paget's disease</p> Signup and view all the answers

    Which condition is characterized by the deposition of bone around skeletal muscles and normally soft tissues?

    <p>Fibrodysplasia Ossificans Progressiva</p> Signup and view all the answers

    What is a key characteristic of Marfan syndrome, relating to bone structure?

    <p>Excessive cartilage formation leading to long limbs</p> Signup and view all the answers

    Which hormone promotes osteoblastic activity and the production of bone matrix and is reduced in women post-menopause?

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

    What is the primary cause of gigantism?

    <p>Overproduction of growth hormone before puberty</p> Signup and view all the answers

    What is a distinguishing feature of acromegaly in terms of bone growth?

    <p>Bones get thicker, especially in the face and hands</p> Signup and view all the answers

    Which of the following describes the effect of calcitonin on osteoblasts?

    <p>Calcitonin has no effect on osteoblasts</p> Signup and view all the answers

    Which of the following best describes osteogenesis imperfecta?

    <p>A genetic condition resulting in fragile bones due to defective collagen production.</p> Signup and view all the answers

    What is the primary function of osteoclasts during bone remodeling?

    <p>To resorb old or damaged bone.</p> Signup and view all the answers

    Which of the following is NOT a stage in bone fracture repair?

    <p>Cartilage calcification</p> Signup and view all the answers

    What is the role of collagen fibers in bone tissue?

    <p>To provide tensile strength.</p> Signup and view all the answers

    Which of the following best describes the initial response to a bone fracture?

    <p>Development of a blood clot or hematoma.</p> Signup and view all the answers

    How does mechanical stress affect bone tissue?

    <p>It stimulates the deposition of mineral salts and collagen fibers.</p> Signup and view all the answers

    Which nutrient is most essential for the proper absorption of calcium in the small intestine?

    <p>Vitamin D</p> Signup and view all the answers

    What is the primary function of calcitriol?

    <p>Stimulates the absorption of calcium and phosphate.</p> Signup and view all the answers

    Which hormone is responsible for the growth spurt during adolescence?

    <p>Sex Hormones</p> Signup and view all the answers

    Why is resistance training more effective than cardiovascular activities for increasing bone density?

    <p>Resistance training places greater mechanical stress on bones.</p> Signup and view all the answers

    What is the role of osteoblasts during bone remodeling?

    <p>To lay down new bone.</p> Signup and view all the answers

    Which nutrient is most associated with bone mineralization through its interaction with hydroxyapatite crystals?

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

    What determines the shape of bone after a fracture if not correctly reset?

    <p>The healing process will keep the bone in its deformed position.</p> Signup and view all the answers

    Which of the following is true regarding the effect of lack of mechanical stress on bone tissue?

    <p>It causes bones to lose mineral salts and collagen fibers.</p> Signup and view all the answers

    Which of the following is NOT a primary source of calcium?

    <p>Fatty Fish</p> Signup and view all the answers

    How do omega-3 fatty acids help with bone health?

    <p>They reduce inflammation and may enhance production of new bone tissue</p> Signup and view all the answers

    Study Notes

    Osseous Tissue and Bone Structure

    • Osseous tissue, or bone, is a hard, dense connective tissue forming most of the adult skeleton.
    • Cartilage provides flexibility and smooth surfaces for movement in areas with bone movement.
    • The skeletal system, comprised of bones and cartilage, supports the body, facilitates movement, protects internal organs, produces blood cells, and stores/releases minerals and fat.

    Functions of the Skeletal System

    • Support: Bones provide a framework for soft tissues and organs.
    • Movement: Bones act as levers, with joints as fulcrums. This allows for a range of movements.
    • Protection: Skeletal elements surround delicate tissues and organs. (e.g., ribs protect lungs, skull protects brain).

    Mineral, Energy Storage, and Hematopoiesis

    • Mineral Storage: Bone acts as a reservoir for calcium and phosphorus. These minerals are vital for body functions and can be released into the bloodstream. Over 98% of the body's calcium is in the bones.
    • Energy Storage: Yellow bone marrow (adipose tissue) stores triglycerides as an energy source.
    • Hematopoiesis: Red bone marrow, found in bone cavities, produces red blood cells, white blood cells, and platelets.

    Bone Classification

    • The adult skeleton has approximately 206 bones. It is divided into axial and appendicular skeletons.
    • Axial Skeleton: (80 bones) skull, hyoid, sternum, rib cage, vertebral column, sacrum, coccyx.
    • Appendicular Skeleton: (126 bones) limbs, pectoral girdle, pelvic girdle.
    • Bones are classified by shape:
      • Long Bones: Cylindrical, longer than wide (e.g., femur).
      • Short Bones: Cube-like, equal dimensions (e.g., carpals, tarsals).
      • Flat Bones: Thin, curved (e.g., skull, sternum).
      • Irregular Bones: Complex shapes (e.g., vertebrae, pelvis).
      • Sesamoid Bones: Small, flat, develop inside tendons (e.g., patella).

    Bone Structure

    • Long Bones: Designed for force transmission, rich blood supply.

      • Diaphysis: Long, tubular shaft, primarily compact bone.
      • Epiphyses: Ends of bone, primarily spongy bone (trabecular bone).
        • Articular Cartilage: Covers epiphyses for smooth articulation.
      • Metaphysis: Region connecting diaphysis to epiphyses. Epiphyseal plate is the growth plate.
      • Medullary Cavity: Shaft cavity containing bone marrow. Yellow marrow (fat) replaces red marrow during aging.
      • Membranes:
        • Periosteum: External covering of bone (blood vessels/nerves).
        • Endosteum: Internal lining, site of bone growth/repair.

    • Compact Bone:

      • Osteon: Basic functional unit.
      • Central Canal (Haversian Canal): Contains blood vessels, nerves, etc.
      • Perforating Canals (Volkmann's Canals): Connect central canals.
      • Lamellae: Concentric rings of bone matrix.
      • Lacunae: Spaces containing osteocytes.
      • Canaliculi: Channels connecting lacunae to central canal.

    • Spongy Bone: Lattice-like network of trabeculae (matrix spikes). Provides strength & allows lightness. Red marrow fills spaces.

    Bone Cells and Tissue

    • Organic Osteoid: Collagen fibers (strong, flexible).
    • Inorganic Hydroxyapatites: Mineral salts (calcium phosphate). Combining organic and inorganic components strengthen bone more than concrete and steel-reinforced concrete.
    • Cells:
      • Osteogenic Cells: Stem cells, produce osteoblasts.
      • Osteoblasts: Immature bone cells, synthesize bone matrix.
      • Osteocytes: Mature bone cells, maintain matrix.
      • Osteoclasts: Bone-resorbing cells (remove & recycle).

    Bone Formation and Development

    • Cartilage Template: Bones develop using a cartilage template, crucial for fetal skeletal development.
    • Intramembranous Ossification: Direct formation from mesenchymal tissue (flat bones, mandible).
    • Endochondral Ossification: Bone replacing hyaline cartilage model (most bones).

    How Bones Grow in Length and Width

    • Longitudinal Growth: Occurs at epiphyseal plates (growth plates).
    • Appositional Growth: Occurs at periosteal surface; remodeling also contributes.

    Bone Remodeling/Fractures and Repair

    • Bone Repair: Steps in fracture healing include hematoma formation, fibrocartilage callus formation, bony callus formation.
    • Modeling: Matrix resorption and deposition in bone growth.

    Exercise, Nutrition, and Hormones and Bone Tissue

    • Exercise: Stimulates bone deposition.
    • Nutrition: Calcium and Vitamin D are critical. Other nutrients (Vitamin K, Magnesium, Fluoride, Omega-3s) are also important.
    • Hormones: Growth hormone, thyroxine, sex hormones, calcitriol, PTH and Calcitonin influence bone growth, maintenance, and remodeling.

    Calcium Homeostasis and Disorders

    • Calcium Homeostasis: The body tightly regulates blood calcium levels through interactions between the skeleton, kidneys, and digestive system.
    • Hypocalcemia: Low calcium causes problems in multiple systems.
    • Hypercalcemia: High calcium disrupts the nervous system.

    Bone Disorders

    • Pituitary growth failure (dwarfism), Achondroplasia: Results from abnormal growth hormone production & hyaline cartilage development.
    • Marfan syndrome, Gigantism, Acromegaly: Genetic/hormonal disorders affecting bone growth.
    • Fibrodysplasia Ossificans Progressiva (FOP), Paget's disease, Osteoporosis, Osteogenesis Imperfecta (OI): Bone disorders resulting from genetic mutations, overactive osteoclasts, or bone resorption exceeding formation.

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    Description

    Test your knowledge on the functions and structures of the skeletal system. This quiz covers various aspects, from mineral storage to the role of cartilage and the division of the skeleton. It's an essential assessment for students studying anatomy and physiology.

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