CBIO 2200 1nd EditionExam # 4 Study Guide Lectures: 15 - 17Lecture 15 (October 23)- Organization of the muscle fiber:o Muscle  fascicles  muscle fiber (cells)  myofibrils  thick and thin filaments (myofilaments) - Types of Mysium:o Epimysium – around the muscleo Periomysium – around fascicleso Endomysium – around individual muscle fibers/cells- Myoblasts: stem cells that fuse to make each muscle fiber- Satellite cells: stem cells or undifferentiated myoblasts; help repopulate muscle- Sarcolemma: plasma membrane of muscle- Sarcoplasm: cytoplasm of muscle cells- Myofibrils: long protein cords that occupy the sarcoplasm- Glycogen: storage form of glucose- Myoglobin: muscle form of hemoglobin; red pigment that stores oxygen in muscle- Sarcoplasmic Reticulum (SR): ER of muscles; goes around all myofibrils- Terminal cisternae: dilations of the sarcoplasmic reticulum- Transverse (T) tubules: tubular in-folding which penetrate through the cell and emerge on the other side- Triad: composed of the two terminal cisternae and one transverse tubule- What is each myofibril made up of?o A bundle of parallel protein microfilaments called myofilaments- Contractile proteins: do the work- Regulatory proteins: regulate muscle contraction- Tropomyosin: covers myosin binding sites on actin- Troponin: lays on top of tropomyosin; have calcium binding sites; when calcium binds, the troponin-tropomyosin complex roles away and reveals myosin binding sites- Titin: anchors myosin to Z discs and keeps muscles from overstretching- Sarcomere: the distance between two z discs- What is the most famous kind of linking protein?o Dysrophin- Denervation atrophy: muscle atrophies when a nerve signal is blocked from the muscle- What constitutes a motor unit?o One nerve fiber and all the muscle fibers innervated by it- Neuromuscular junction: where nerve meets the muscle- Schwann cell: myelin producing cellsLecture 16 (October 28) - Myasthenia Graviso Autoimmune diseaseo Women ages 20-40o Body produces antibodies that bind to ACh receptors and block ACh from bindingto themo Insufficient muscle contraction- Treatments for Myasthenia Gravis o Cholinesterase inhibitors: allow ACh to not be broken down; ACh may eventually be able to beat antibodieso Immunosuppressive agents: suppresses production of antibodieso Thymus removal (thymectomy): removes ability to make T cellso Plasmapheresis: remove blood; take out plasma (where the antibodies are), and put it back- Electrophysiology: study of electrical activity of cells- What is the mV for resting membrane potential?o 90- Depolarization: stimulated cell (sodium channels open)- Repolarization: sodium channels close and potassium channels open- Hyperpolarizatoin: potassium channels remain open after the potential reaches un-stimulated level- Major phases of contraction and relaxation:o Excitation – arrival of nerve signal, ACh releaseo Excitation-contraction coupling – release of calcium, links with troponino Contraction – hydrolyze of ATP, release of ADP and inorganic phosphate, power stroke, ATP binds to myosino Relaxation – myosin releases actin, nerve stimulation stops, ACh release stops, AChE breaks down ACh, tropomyosin re-blocks active site- Rigor Mortis: hardening of muscles and stiffening of body; lasts about 48 hrsLecture 17 (October 30)- What does the supply of ATP depend on?o Oxygeno Organic energy sources- Two main pathways of ATP synthesis o Anaerobic fermentation – makes 2 ATPo Aerobic respiration – makes 36 ATP- Two characteristics of Cardiac muscleo Striated like skeletal muscle, but myocytes/cardiocytes are shorter and thickero Intercalated discs- In smooth muscle, z discs are absent and replaced by dense bodies. Myocytes have a fusiform shape. Sarcoplasmic reticulum is scanty. There are no T tubules. Capable of mitosis and hyperplasia. Some lack nerve supply while others receive autonomic fibers. Involuntary excitation.- Types of paralysis:o Spastic paralysis – contraction without relaxation Tetanus (lockjaw)o Flaccid paralysis – muscles are limp and cannot contract Botulism – type of food poisoning  Botox- What do tension of muscle fibers depend on?o The fiber’s resting length at the time of stimulationo The frequency of stimulation- Myogram: recording of muscle contraction; recording of the mechanical event- 3 stages of a twitcho Latent period o Contraction phaseo Relaxation phase- Threshold: a certain amount of tension has to develop in order for muscle to contract- Strength of twitch depends on:o Starting lengtho Muscles fatigue after continual useo Warmer muscles contract more stronglyo Hydration level influences cross bridge formationo Increasing the frequency of stimulus increases tension output- Isometric muscle contraction: muscle develops tension but does not shorten; no movement- Isotonic muscle contraction: muscle is changing length; tension remains constant but there is