PHCY 411 Exam 2 Pathophysiology Study Guide PDF

Unit 3-1: Muscles, Bones, and Joints Practice Test: 1. Know muscle types and function. a. Function of muscle cells: i. Contractility ii. Excitability iii. Extensibility iv. Elasticity b. Skeletal muscle: several sheaths of c...

Unit 3-1: Muscles, Bones, and Joints Practice Test: 1. Know muscle types and function. a. Function of muscle cells: i. Contractility ii. Excitability iii. Extensibility iv. Elasticity b. Skeletal muscle: several sheaths of connective tissue that hold the fibers together i. Voluntary ii. Fibers: striated, tubular, multinucleated iii. Located on skeleton iv. Epimysium: “outside of muscle” v. Perimysium: “around the muscle” vi. Endomysium: “within muscle” vii. Holds in parallel alignment viii. Continuous with tendons ix. When muscle fibers contract, pull is exerted on endomysium, then perimysium, then epimysium c. Smooth muscle: i. Involuntary ii. Fibers: non-striated, spindle-shaped, uninucleated iii. Covers internal organs d. Cardiac muscle: i. Involuntary ii. Fibers: striated, branched and uninucleated iii. Covers the heart 2. Know sarcomere structure and function. a. A bands (dark region): contains full length of the thick filament (myosin) and inner end of thin filaments (actin) i. H zone: center part of A band ii. M line: center of H zone; contains tiny rods that holds thick filaments together b. I bands (light region): regions on either side of the A band i. Z line: center of I band c. Sarcomeres: repeating segments i. Functional units of skeletal muscle tissue ii. Contractions  d. Myofibrils: long rods of muscle cells e. Sarcolemma: plasma membrane f. Sarcoplasm: cytoplasm g. Sarcoplasmic reticulum: ER that stores calcium 3. Know steps in muscle contraction and relaxation: Sliding filament theory, calcium regulation, neurogenic stimulation a. Sliding filament theory: sliding movement of myosin on an actin filament i. Steps: 1. ATP binds, causing myosin to detach 2. Myosin turns ATP to ADP; releasing P energy 3. Myosin extends and attaches to actin 4. ADP is released b. Regulation of contraction: i. Muscle activity initiated by excitation (EC Coupling) 1. Excitation-Contraction Coupling: depolarization of sarcolemma ii. Physical and chemical changes elevate calcium concentration iii. Motor end plate (axon terminals) release ACh to travel the ACh receptors iv. ACh binds to open sarcolemma Na+ channels (nicotinic ACh receptors - nAChRs) that initiates depolarization causing action potential (AP) to pass to sarcolemma to increase Ca2+, causing contraction v. Increase in intracellular Ca2+ activates actin-myosin machinery to induce contraction vi. Relaxation occurs and repolarization c. Calcium regulation and release: (Calcium Induce Calcium Release - CICR) i. Dihydropyridine (DHP) receptors: located on sarcolemma 1. Voltage gated Ca2+ channels when open will let in a spark of Ca2+ 2. Delivery too slow to induce contraction 3. Induce opening of ryanodine receptors ii. Ryanodine receptors (RyRs): located on SR of skeletal and cardiac muscles 1. Release a lot of Ca2+ from SR iii. Some Ca2+ are free, most are bound to calsequestrin iv. Free Ca2+ decreases due to contraction v. Troponin: Ca2+ dependent 1. Troponin C (TnC): Ca2+ sensor; 4 binding sites 2. Troponin I (TnI): links to actin; inhibits actin-myosin ATPase 3. Troponin T (TnT): binds to tropomyosin to block sites 4. When Ca2+ rise, troponin-tropomyosin allows myosin to bind to actin  5. Initiate the cross-bridge cycle. 6. When Ca2+ rise, troponin-tropomyosin blocks binding site d. Neurogenic stimulation: i. Resting membrane potential is 70 mV ii. Neurogenic signal sends AP to excite muscles to contract iii. Voltage-gated Na+ channels open and depolarization happens iv. Depolarization causes Ca2+ channels to open; Ca2+ goes into cell v. Na+ and Ca2+ channels will close and K+ channels open; causing repolarization vi. Resting membrane potential is re-established by Na+/K+ ATPase pump e. Depolarization i. Skeletal myofibers depolarize and repolarize very quickly ii. Once repolarization happens, a 2nd AP can induce another contraction even if the muscle isn’t relaxed yet f. Relaxation i. After depolarization comes repolarization; relaxation ii. ACh no longer released iii. Ion movements across membranes must be reversed to allow relaxation iv. Re-establish Ca2+ gradients 1. SR have Ca2+ATPase (SERCA) pumps: pumps Ca2+ out of cytoplasm to SR to bound to calsequestrin 2. Sarcolemma have Na+/Ca2+ exchanger: exchange na+ for Ca2+; Ca2+ moved extracellularly; Na+/K+ATPase pump re-establishes Na+ gradient 4. Know structure and function of bones and cartilage. a. Bones: (osseo) i. Structural support: provides framework for attachment ii. Movement leverage: skeletal muscles use bones as leverage to move iii. Protection: underlying organs iv. Mineral storage: calcium and phosphate v. Blood-cell formation: produce RBCs, WBCs, and platelets vi. Energy storage: osteoblasts secrete osteocalcin that increases insulin sensitivity to increase glucose for increase fat storage vii. Types of tissues: 1. Bone connective tissue: extracellular matrix protein fibers contain calcium salts 2. Other connective tissues: blood, dense connective, and cartilage 3. Nervous tissue 4. Vascular tissue 5. Epithelial tissue  b. Cartilage: (chondro-) i. Location: 1. External ear 2. Nose 3. Articular cartilages 4. Costal cartilages 5. Larynx and epiglottis 6. Rings of trachea and bronchi 7. Intervertebral discs 8. Public symphysis 9. Articular discs ii. Abundant in embryo than adults iii. Forms most of skeleton to be replaced by bone during and childhood iv. Properties: 1. No nerves or blood vessels 2. Surrounded by dense irregular connective tissue (perichondrium); acts as girdle; growth and repair 3. Consists of water 4. Resilient tissue 5. Know osseous cell types and function a. Osteocytes: monitor and maintain protein and mineral content i. Occupy lacunae b. Osteoblasts: produce and secrete bone matrix or osteoid i. Inner and outer surfaces of bone ii. Osteogenesis iii. Becomes osteocyte when surrounded by bone matrix c. Osteogenic cells: stem cells that differentiate into osteoblasts i. Randomly dispersed ii. Most concentrated at innermost lining of periosteum d. Osteoclasts: resorption of bone or osteolysis i. WBCs ii. Secretes hydrochloric acid and lysosomal enzymes 6. Understand steps in ossification a. This is the formation of bone tissue i. Formation of bone collar around hyaline cartilage model ii. Cavitation of the hyaline cartilage iii. Invasion of internal cavities by the periosteal bud and spongy bone iv. Formation of medullary cavity; secondary ossification centers in epiphyses v. Ossification of epiphyses; hyaline cartilage remains only in epiphyseal plates and articular cartilage 7. Know structural and functional classification of joints a. Structural: i. Fibrous ii. Cartilaginous iii. Synovial b. Functional: i. Synarthroses: immovable; axial skeleton ii. Amphiarthroses: slightly movable; axial skeleton iii. Diarthroses: freely movable; appendicular skeleton (all synovial joints) 8. Know the anatomy of a synovial joint and how it plays a role in lubrication weeping a. Anatomy: i. Articular cartilage: ends of opposing bones are covered with hyaline cartilage to absorb compression ii. Joint cavity: space that holds a small amount of synovial fluid iii. Articular capsule: encloses joint cavity 1. Fibrous capsule: outer layer; dense irregular connective tissue that strengthen joint 2. Synovial membrane: inner layer; loose connective tissue lines joint capsule covering internal joint surfaces makes synovial fluid iv. Synovial fluid v. Reinforcing ligaments vi. Innervated: vii. Vascularized viii. Branches of major nerve and blood vessels feed synovial joints creating anatomical redundancies ix. Contains an articular discs (meniscus) that partly divides joint cavity b. Synovial joints: i. Subjective to compressive forces ii. Friction could overheat and destroy joint tissue c. Weeping lubrication i. Fluid is squeezed out as opposing cartilages touch ii. Cartilages ride on the slippery film iii. When pressure ceases, fluid rushes back in d. Lubricating devices allow joining bones to move across on another minimal friction