Skeletal Tissue and Bone Growth

Chapter 6: Skeletal Tissue

• Parathyroid hormone (PTH) increases blood calcium levels.
• PTH stimulates osteoclasts to break down bone and release calcium into the bloodstream.
• Osteoclasts break down bone tissue via resorption.
• Osteoblasts build bone tissue through formation.
• Osteocytes maintain bone matrix and communicate for bone maintenance.
• Skeletal system provides support, movement, protection, mineral storage, blood cell production, and energy storage.
• Intramembranous ossification forms bone directly from mesenchymal tissue in flat bones like the skull without a cartilage stage.
• Bones adapt to mechanical stresses, remodeling in response to stress, which is known as Wolff's Law.
• Bone thickness is increased with appositional bone growth, which adds new tissue to the surface.
• Periosteum is the outer layer of connective tissue surrounding bones with outer fibrous and inner osteogenic layers.
• Interstitial cartilage growth occurs within the cartilage, where chondrocytes divide and secrete new matrix.
• Haversian canals are central canals containing blood vessels.
• Volkmann's canals are perpendicular canals that connect Haversian canals.
• Canaliculi are small channels that allow osteocytes to communicate.

Chapter 7: Skeleton

• Skull bones connect with sutures (immovable joints) except for the mandible, which has a movable joint.
• Parts of the ethmoid bone include the cribriform plate, crista galli, perpendicular plate, ethmoidal labyrinths, and nasal conchae.
• The axial skeleton supports and protects the brain, spinal cord, and organs in the thorax.
• The appendicular skeleton facilitates movement through limbs and their girdles.
• Intervertebral discs serve as shock absorbers between vertebrae and allow movement of the spine.
• Spine regions include cervical, thoracic, lumbar, sacral, and coccygeal.

Chapter 8: Joints

• Bursae, fluid-filled sacs, reduce friction between moving structures like tendons and bones.
• Symphysis joints are cartilaginous joints that allow limited movement, such as the pubic symphysis.
• Menisci are C-shaped cartilage pads that improve joint stability and absorb shock in synovial joints.
• Interosseous fibrous joints are connected by a ligament or membrane, allowing slight movement (e.g., the joint between the radius and ulna).
• Synovial joints are freely movable joints with components like a synovial cavity, synovial fluid (lubricates), articular cartilage, and ligaments.
• Syndesmosis is a type of fibrous joint where bones are connected by a ligament or membrane (e.g., distal tibiofibular joint).
• Types of fibrous joints include sutures (immovable), syndesmoses (slightly movable), and gomphoses (peg-in-socket, e.g., teeth).

Chapter 9: Muscle Physiology/Muscle Tissue

• Tropomyosin covers actin filaments and blocks binding sites for myosin in the absence of calcium.
• Wave summation is the increase in muscle contraction strength due to repeated stimuli before the muscle can fully relax.
• Endomysium surrounds individual muscle fibers.
• Perimysium surrounds fascicles (bundles of muscle fibers).
• Epimysium surrounds the entire muscle.
• Myofibrils are rod-like structures in muscle fibers composed of sarcomeres and responsible for contraction.
• Isotonic muscle contractions change length, while isometric contractions maintain the same length
• A muscle twitch is a single contraction cycle with phases including latent, contraction, and relaxation.
• The neuromuscular junction includes motor end plate, nerve stimulus, and events at NMJ.
• The synapse between a motor neuron and a muscle fiber; acetylcholine is released, causing muscle contraction.
• Aerobic ATP generation requires oxygen and produces more ATP.
• Anaerobic ATP generation does not require oxygen and produces less ATP and lactic acid.
• Direct phosphorylation donates a phosphate to ADP from creatine phosphate to form ATP.
• The sliding filament model of muscle contraction describes actin filaments sliding over myosin, shortening the sarcomere and causing muscle contraction.
• Slow oxidative fibers provide endurance, low power, and high fatigue resistance.
• Fast oxidative fibers provide moderate power, endurance, and fatigue resistance.
• Fast glycolytic fibers provide high power, low endurance, and quick fatigue.

Chapter 10: Muscles

• Levers consist of a fulcrum (pivot point), effort (force applied), and load (resistance).
• The mechanical advantage of levers depends on the arrangement of their components.
• Agonists are the primary muscles responsible for movement, while antagonists oppose the action of the agonist.
• Rotator cuff muscles, including supraspinatus, infraspinatus, teres minor, and subscapularis, stabilize the shoulder joint.
• Hamstring muscles are biceps femoris, semitendinosus, and semimembranosus, which flex the knee and extend the hip.
• Muscles of facial expression, like the orbicularis oris and orbicularis oculi, control facial expressions like smiling and frowning.
• Muscles involved in plantarflexion include the gastrocnemius, soleus, and tibialis posterior.
• The triceps brachii is the primary muscle involved in extending the elbow.