Muscle Contractions and Sliding Filament Theory

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Questions and Answers

What is the primary role of osteoblasts in bone tissue?

  • Serving as stem cells
  • Breaking down bone tissue
  • Facilitating bone growth (correct)
  • Maintaining bone matrix

Which of the following structures contains elastic cartilage?

  • Vertebrae
  • Sternum
  • Ear (correct)
  • Knee joint

What combination of components makes up the inorganic part of bone?

  • Osteocytes and osteoclasts
  • Collagen fibers and proteins
  • Bone cells and collagen fibers
  • Calcium phosphate salts (correct)

Which bone cell is responsible for maintaining the bone matrix?

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

What is the function of osteoclasts in the skeletal system?

<p>Breaking down bone tissue (C)</p> Signup and view all the answers

What occurs during an isometric contraction?

<p>Muscle length is unchanged (D)</p> Signup and view all the answers

What type of muscle contraction involves muscle length changing?

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

Which of the following is an example of an isotonic exercise?

<p>Doing bicep curls (D)</p> Signup and view all the answers

What initiates muscle contraction through the sliding filament model?

<p>Release of calcium ions (A)</p> Signup and view all the answers

During the power stroke in muscle contraction, what happens?

<p>Myosin heads pivot and pull actin filaments inward (B)</p> Signup and view all the answers

What is required for the sliding filament cycle to continue?

<p>Presence of calcium and ATP (D)</p> Signup and view all the answers

Which of the following activities primarily demonstrates an isometric contraction?

<p>Holding a push-up position (A)</p> Signup and view all the answers

What role does ATP play in muscle contraction?

<p>It helps myosin release actin and re-cock for another cycle (D)</p> Signup and view all the answers

Which of the following is NOT one of the bones making up the coxal bone?

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

What are the three fused bones that comprise the coxal bone?

<p>Ilium, Ischium, Pubis (B)</p> Signup and view all the answers

Which bones are located in the wrist area?

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

Which of the following correctly identifies a major region of the human skeletal system?

<p>Pelvis, Spine, Skull (C)</p> Signup and view all the answers

What is the function of the acetabulum in the pelvic structure?

<p>Forms the socket for the hip joint (B)</p> Signup and view all the answers

Which bone is classified as a facial bone?

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

Which of the following is NOT a cranial bone?

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

Which suture separates the parietal bones from the frontal bone?

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

What is the primary function of the vertebral body?

<p>Protect the spinal cord (C)</p> Signup and view all the answers

Which of the following pairs correctly match the types of vertebrae with their typical number in humans?

<p>7 cervical, 12 thoracic, 5 lumbar (D)</p> Signup and view all the answers

Which bone serves as the lower jaw in the human skull?

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

What is the name of the suture that joins the two parietal bones?

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

Which process of a vertebra projects posteriorly?

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

What type of joint is characterized as immobile?

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

Which joint type allows for the greatest range of motion?

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

Which of the following joints is slightly moveable?

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

What is the main characteristic of synovial joints?

<p>Covered with articular cartilage (C)</p> Signup and view all the answers

Which structure encloses the synovial joint and contains synovial fluid?

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

In what type of joint are the bone ends joined by cartilage?

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

What type of joint is the knee considered to be?

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

Which joint type is exemplified by skull sutures?

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

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Study Notes

Muscle Contractions

  • Isometric Contractions: Muscles maintain the same length while generating tension. Examples include:

    • Balancing on tiptoes
    • Holding a bench-press bar in the same position
    • Doing a plank exercise
    • Pushing against a concrete wall
  • Isotonic Contractions: Muscles change length while generating tension. Examples include:

    • Running up a hill
    • Doing bicep curls
    • Swimming freestyle
    • Pedalling a bicycle on a flat surface
  • During isometric contractions, muscle length remains unchanged, while in isotonic contractions, muscles may lengthen or shorten.

Sliding Filament Theory

  • Nerve Impulse: Signals from motor neurons release calcium ions (Ca²⁺) from the sarcoplasmic reticulum into muscle cells.
  • Calcium Binding: Calcium binds to troponin on actin filaments, moving tropomyosin and exposing binding sites.
  • Cross-Bridge Formation: Myosin heads attach to exposed sites on actin, forming cross-bridges.
  • Power Stroke: Myosin heads pivot, pulling actin filaments towards the sarcomere center, leading to muscle shortening.
  • ATP Binding: ATP binds to myosin, causing detachment from actin and re-cocking for another cycle.
  • This process repeats as long as calcium ions and ATP are available.

Bone Structure

  • Organic Components: Bone cells, proteins, collagen fibers.
  • Inorganic Components: Calcium phosphate salts.

Bone Cells Functions

  • Osteogenic cells: Stem cells involved in creating new bone.
  • Osteoblasts: Responsible for bone growth and forming the bone matrix.
  • Osteocytes: Maintain bone tissue and health.
  • Osteoclasts: Break down bone tissue.

Skull Anatomy

  • Facial Bones: Nasal bone, maxillary bone, mandible, zygomatic bone.
  • Cranial Bones: Frontal bone, parietal bone, occipital bone, temporal bone.

Skull Sutures Identification

  • Sagittal Suture: Between the two parietal bones.
  • Coronal Suture: Between frontal and parietal bones.
  • Lambdoid Suture: Between occipital and parietal bones.
  • Squamous Suture: Between temporal and parietal bones.

Vertebrae Components

  • Vertebra Structure:
    • Body
    • Spinous Process
    • Transverse Process
    • Vertebral Foramen

Coxal Bone

  • Formed from three fused bones: ilium, ischium, pubis.

Types of Joints

  • Fibrous Joints: Immobile, like skull sutures.
  • Cartilaginous Joints: Slightly movable, such as the pubic symphysis and joints between ribs and sternum.
  • Synovial Joints: Freely movable with joint cavities, like the knee joint, enclosed by a fluid-filled capsule.

Synovial Joint Components

  • Articular Capsule: Encloses the joint.
  • Articular Cartilage: Covers bone ends for smooth movement.
  • Synovial Membrane: Lines joint cavities, producing synovial fluid for lubrication.

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