Difference Between Skeletal, Smooth & Cardiac Muscles скачать в хорошем качестве

Difference Between Skeletal, Smooth & Cardiac Muscles

Compare Skeletal, Smooth, and Cardiac Muscle with Dr. Faiza A clear, exam-oriented walkthrough of how skeletal, smooth, and cardiac muscles differ—histology, innervation, excitation–contraction coupling, action potentials, contraction speed, fatigue resistance, and functional significance. See triads vs dyads, T-tubule locations, dense bodies vs Z discs, troponin vs calmodulin–MLCK, and why cardiac muscle resists tetany while smooth muscle can sustain powerful tonic contractions. 🔬 Key Topics Covered: • Histology & Architecture: multinucleated striated cylindrical skeletal fibers; mononucleated non-striated spindle-shaped smooth fibers (multi-unit vs single-unit with gap junctions); branched striated cardiac fibers with intercalated discs (gap junctions, desmosomes) • Structural Markers: Z discs vs dense bodies; triads at A–I junction (skeletal) vs dyads at Z disc (cardiac); caveolae (smooth) • Sarcoplasmic Reticulum & T-Tubules: most developed in skeletal, least in smooth; T-tubules absent in smooth (caveolae instead) • Control & Innervation: voluntary somatic (skeletal) vs involuntary autonomic/hormonal (smooth, cardiac); myogenic activity in single-unit smooth and cardiac; neurogenic control in skeletal and multi-unit smooth • Action Potentials: brief Na⁺-driven AP (skeletal); smooth muscle spikes/plateau and slow waves; prolonged cardiac AP with plateau (Na⁺/Ca²⁺ influx, K⁺ currents) and long refractory period • Excitation–Contraction Coupling: skeletal—mechanical DHPR–RyR coupling; cardiac—Ca²⁺-induced Ca²⁺ release (L-type → RyR); smooth—Ca²⁺–calmodulin → MLCK phosphorylation of myosin • Mechanics: speed of contraction (fast/slow skeletal types vs slower smooth/cardiac), fatigue resistance (cardiac highest); length–tension in skeletal/cardiac; smooth muscle latch phenomenon and high force at large shortening • Modulators of Force: recruitment and frequency (skeletal), stretch/hormones/local metabolites (smooth), fiber length/Ca²⁺/autonomics (cardiac) 🎓 Learning Objectives: • Tabulate key structural and functional differences among skeletal, smooth, and cardiac muscle. • Explain EC-coupling pathways (mechanical, CICR, calmodulin–MLCK) across muscle types. • Interpret AP patterns (spike, plateau, slow waves) and link them to contraction profiles. • Predict how innervation, hormones, and stretch alter force in each tissue. 💡 Clinical Relevance: • Understand why cardiac muscle avoids tetany (long refractory period) and how smooth muscle sustains tone (latch). • Relate ANS/hormonal signals to organ functions (vascular tone, GI motility, bladder, uterus). • Connect structural differences (triad/dyad, dense bodies) to disease mechanisms and pharmacology. 📚 Learning Resources: Phone: +92 310 7990649 Email: [email protected] Website: https://www.medicoseacademics.com/ Facebook:   / medicoseacademics   Instagram:   / medicoseacademics   YouTube:    / @medicoseacademics   My personal stamp: Dr. Faiza | Medicose Academics Dr. Faiza Assistant Professor of Physiology MBBS (AIMC, lahore, Best Graduate) FCPS (Physiology) CHPE (Certificate in Health Professional Education) DHPE (Diploma in Health Professional Education) DHPE (Masters in Health Professional Education) MBA (Masters of Business Administration) MPH (Masters of Public Health) LinkedIn:   / faizaikram   Tags: Muscle Physiology, Skeletal vs Smooth vs Cardiac, Intercalated Discs, Gap Junctions, Triad vs Dyad, T-Tubules, Sarcoplasmic Reticulum, Dense Bodies, Troponin vs Calmodulin, MLCK, Caveolae, Cardiac Action Potential, Plateau Phase, Slow Waves, Excitation Contraction Coupling, Latch Mechanism, Autonomic Nervous System, Length Tension Relationship, Tetany vs Refractory Period, Medical Education