BIOS 252 MIDTERM EXAM ESSAY QUESTION WITH ANSWERS

BIOS 252 MIDTERM EXAM ESSAY QUESTION WITH ANSWERS Chapter 10 & 11 1. Identify and describe intracellular structures (organelles, myofilaments, ect.) of a muscle cell. Contrast skeletal, cardiac and smooth. Epimysium – covers whole muscle belly; Perimysium – slightly thicker layer of connective tissue surrounds a bundle of cells called a fascicle; Endomysium – thin layer of tissue surrounding each cell; Muscle fiber – muscle cells are long, cylindrical & multinucleated; Sarcolemma – muscle cell membrane; T tubules – are investigations of the sarcolemma into the center of the cell; Myofibrils – muscel fibers filled with treads separated by SR; Myofilaments – are contractile proteins of muscle; Sarcoplasmic Reticulum (SR) – system of tubular sacs sotes Ca+2 in a relaxed muscle, release of Ca+2 triggers muscle contraction; Skeletal Muscle – attaches to bone, skin or fascia; striated, voluntary control of contraction, multinucleated; Cardiac – striated, involuntary control, uninucleated. 2. Describe all phases of twitch. Latent phase – the time that elapses between the generation of an action potential in a muscle cell and the start of the contraction of the muscle. Contraction phase – when the muscle contracts this starts after the latent phase ends with muscle tensions. Relaxation phase – starts after muscle tension and continues until muscle contraction has ended. 3. Outline the sequence of physiological events of a twitch starting at the motor neurons and ending with movement. 4. Describe a neuromuscular junction and identify all major components. Stimulus down axon terminal → Excitability on synaptic cleft (releases Ca++) → Ach moves down to synaptic end bulb and meets receptors, gated channel for Na+ → Sodium creates an action potential that travels across the sarcolemma( plasma membrane) → Action potential travels down the t-tubule which stimulates the SR to release Ca2+ → Ache starts the update of Ach and the action potential fade away 5. Describe the connective tissue “packaging” of muscle. 6. Describe the major functions of the three types of muscles and the differences between them. 7. Describe how skeletal muscles acting across synovial joints function as a lever system. Discriminate between 1st class, 2nd class and 3rd class levers in the human body(provide an example of each