PATHOPHI

• Skeletal and Muscular Physiology:

  • From the 1st to the 8th week after conception, skeletal parts are already being formed
  • Osteoblast: bone forming
  • Osteoclast: breakdown
  • Osteocytes: mature bone cell
  • Ossification process:
  • Intramembranous: skull bones
  • Endochondral: rest of skeleton or bones
  • Cartilage conversion or replacement becomes bone (Hyaline cartilage to bony tissue)
  • Perichondrium surrounds hyaline cartilage forms periosteum
  • Osteoblast forms compact bones associated with diaphysis
  • Epiphytes: as cartilage grows after birth, 2nd ossification center is formed
• • Epiphysial plate: growth region
• Bone Growth:

  • Bone Remodelling
  • Childhood bone formation is greater than bone destruction
  • Osteoclasts can cause destruction or resorption
  • Calcium is a major storage site
  • Anything that can destroy bones can contribute calcium in blood
  • Hypernatremia: high sodium
• Bone Repair:

  • Once bone breaks, it forms a blood clot and is infection-prone
• Calcium Homeostasis:

  • Influential in many processes where calcium binds
  • Parathyroid hormone (PTH) influences calcium levels
  • Calcitonin inhibits osteoclast activity and the release of calcium
• Pathophysiology: Fracture

  • Greenstick: incomplete fracture causing the other side to bend
  • Transverse: straight line
  • Spiral: common twisting injury
  • Oblique: diagonal
  • Compression: bone is crushed
  • Comminuted: Bones into 3 or more pieces or fragments
  • Segmental: Floating bone
  • Healing process involves the inflammatory development of hematoma
• Muscular System Physiology:

  • General Properties of Muscle Tissue:
  • Contractility
  • Skeletal Muscle: contraction leads to movement
  • Smooth Muscle: increased pressure in hollow organs leads to contraction
  • Cardiac Muscle: contraction leads to pressure in the heart
  • Extensibility opposes contraction and leads to the lengthening of muscle
• Whole Skeletal Anatomy:

  • Epimysium surrounds skeletal muscle
  • Perimysium is in the middle
• Skeletal Muscle Fiber:

  • Cell membrane of muscle fibers is Sarcolemma
  • Transverse tubules contract muscle as a whole
  • Sarcoplasmic reticulum releases calcium for muscle contraction
• Cardiac Markers:

  • Used to measure if a patient is suspected to have a heart attack
  • Troponin is a cardiac indicator that remains elevated for 48 hours
• PARATHYROID HORMONE: Secreted by cells in the parathyroid gland o Essential for the maintenance of blood Ca levels within homeostatic limits.
• (CALCITROL)Assists PTH in the kidney tubules by preventing Ca removal through urine.
• CALCITROL - o PTH stimulates Calcitriol activation in the kidney-->PTH-induced increases in blood Ca levels.
• CALCITONIN - Secreted from C cells in the thyroid gland when blood Ca levels are too high. o Lowers blood Ca levels by inhibiting osteoclast activity
• Open fracture: compound fracture; bone pokes through the skin and can be seen, or a deep wound exposes the bone through the skin.
• Closed fracture: simple fracture; bone is broken but the skin is intact.
• Inflammatory stage: formation of hematoma at the fracture site and a small amount of bone in the distal fracture fragments is resorbed.
• Reparative stage: formation of callus; new blood vessels develop
• Remodeling stage: the callus that is originally cartilaginous becomes ossified and the bone is broken down and rebuilt.
• Two main aspects to muscle contraction: an electrical component and a mechanical component
• Contractability: ability of the muscle to shorten forcefully, or contract
• • Excitability: capacity of the muscle to respond to a stimulus.
• Elasticity: ability of the muscle to recoil to its original resting length after it has been stretched.
• Extensibility: muscle can be stretched beyond its normal resting length and still be able to contract.
• • Epimysium: forms a connective tissue sheath that surrounds each skeletal muscle.
• Perimysium: loose connective tissue serving as passageway for blood vessels and nerves
• Endomysium: separates the individual muscle fibers within each fascicle
• Electrical component structures: respond to and transmit electrical signals.
• Sarcolemma: cell membrane of muscle fibers
• Transverse tubules: carry impulses into the center of the muscle fiber
• Sarcoplasmic reticulum: the release of Ca is a “switch” for muscle contraction
• Mechanical component structures: general muscle property is due to two main structures in the muscle
• Myofibrils: extend the entire length of the muscle fiber; the protein filaments in this structure interact to shorten the muscle fiber during contraction
• Myofilaments: actin myofilaments (thin filaments) and myosin myofilaments (thick filaments)
• Actin Myofilaments: actin, tropomyosin, and troponin
• • Tropomyosin: in a relaxed muscle, it covers the attachment sites of the actin.
• Troponin: has subunits that anchors the troponin to the actin
• Myosin Myofilaments: composed of myosin molecules