Anatomy and Physiology Exam 3 Questions With Verified Answers

Sarcolemma - Answers muscle plasma membrane Sarcoplasm - Answers cytoplasm of a muscle cell Muscle cells respond to neural, stretch, or other signals by changing their _______. - Answers sarcolemma electrical potential (voltage) The electrical potential change is coupled to intracellular changes that result in ______. - Answers force generation (contraction) Contractility - Answers active shortening of muscle cell and generation of tension (force) Extensibility - Answers passive stretching of muscle cells Elasticity - Answers return of muscle cells to original resting length after being stretched Which muscle tissue(s) has cells w/ obvious stripes called striations - Answers skeletal, cardiac Which muscle tissue is voluntary and which is involuntary? - Answers voluntary-skeletal......involuntary-cardiac,smooth What muscle tissue contracts rapidly but tires easily? - Answers skeletal Cardiac muscle contracts at a rate set by the heart's ________. - Answers pacemaker Which muscle tissue is primarily found in the walls of hollow visceral organs? - Answers smooth Which muscle tissue forces food and other substances through internal body cavities? - Answers smooth What are the three connective tissue sheaths? - Answers endomysium, perimysium, epimysium What is a fine sheath of connective tissue composed of reticular fibers surrounding each muscle fiber? - Answers endomysium What is fibrous connective tissue that surrounds groups of muscle fibers called fascicles? - Answers perimysium What is an overcoat of dense regular connective tissue that surrounds the entire muscle? - Answers epimysium each muscle is served by ________. - Answers one nerve(bundle of nerve fibers), an atery, and one or more veins when muscles contract... - Answers the movable bone (insertion) moves toward the immovable bone (origin) How does a muscle attach to a bone directly? - Answers epimysium of the muscle is fused to the periosteum of a bone (less common) How does a muscle attach to a bone indirectly? - Answers connective tissue wrappings extend beyond the muscle as a tendon or aponeurosis that attaches to a bone (more common) What is a single muscle cell called? - Answers a myocyte or muscle fiber Myocyte size - Answers 10 to 100 micrometers in diamter and many 10s of cm long Each mature myocyte is created by fusion of multiple precursor cells called _________. - Answers myoblasts Sarcoplasm has numerous ________ and an oxygen-binding protein called _________. - Answers glycosomes, myoglobin Myocytes contain the usual organelles, as well as.... - Answers myofibrils, sarcoplasmic reticulum, T-tubules Densly packed rodlike contractile elements are called ________. - Answers myofibrils What is the smallest contractile unit of a muscle called? - Answers a sarcomere What is the region of a myofibril b/w two succesive Z-discs? - Answers a sarcomere What is a sarcomere composed of? - Answers thick and thin myofilaments made up of contractile proteins How long does a thick filament of a myofilament extend? A thin filament? - Answers thick: the entire length of an A-band thin:across the I band and part way into the A band What is a coin-shaped sheet of proteins (connectins) that anchors the thin filaments and connects myofibrils? - Answers Z-disc Where do elastic filaments stretch and what are they made of? - Answers from Z-disc through the thick filament to the M-line. a huge protein called titin. What are thick filaments composed of? - Answers 200-500 myosin protein molecules What protein has a rod-like tail and two golbular heads? - Answers myosin What is the primary contractice protein in thin filaments and what is it made out of? - Answers F-actin each F-actin strand is a double helical polymer of individual globular subunits called G-actin Each G-actin subunit contains an active site to which _______ attaches to during contraction. - Answers a myosin head What is a filamentous protein bound in the grooves of the F-actin helix that blocks the myosin binding site inrelaxed muscle? - Answers tropmyosin What is troponin and what does it do? - Answers a regulatory protein complex bound to F-actin and tropomyosin, and binds calcium ions Sarcolplasmic reticulum is a type of ________ that mostly runs ________ and surrounds each ________. - Answers elaborate, smooth ER longitudinally myofibril _________ of SR form perpendicular cross channgels. - Answers paired terminal cisternae The sarcoplasmic reticulum functions to regulate intracellular _________ levels. - Answers calcium Elongated tubes of sarcolemma called ________ penetrate into the cell's interior at each A band-I band junction - Answers T-tubules T tubules associate with the paired terminal cisternae to form _________. - Answers triad junctions T-tubules are part of the ________. - Answers sarcolemma The electrical impluses from T tubules signal for _________ from the adjacent terminal cisternae into the sarcoplasm (cytoplasm) - Answers Ca2+ The Ca2+ released by T-tubules binds to ____ - Answers troponin Calcium binding to troponin moves _____________ so that the myosin binding sites of F-actin are ___________ and muscle _________ occurs. - Answers tropomyosin exposed contraction "power stroke" is related to the __________ model of contraction. - Answers sliding filament in order to contract, a myocyte must: (1)(2)(3) - Answers 1.) be stimulated by a nerve ending 2.) propogatean electrical current, or action potential, along its sarcolemma 3.) have a transient rise in sarcoplasmic Ca++ concentration, which is the final trigger for contraction __________ is the linkage of the sarcoplasmic electrical signal to the contraction - Answers Excitiation-contraction coupling Skeletal muscles are stimulated by _______ of the somatic nervous system. - Answers motor neurons ________ of these neurons travel in nerves to muscle cells. - Answers axons ________ of motor neurons are in the brainstem or spinal cord. - Answers cell bodies Axons of motor neurons branch profusely as they enter muscles. Each axonal branch forms a _________ with a single myocyte. - Answers neuromuscular junction Each motor neuron and all the myocytes is innervates is called a _________. - Answers motor unit The total force of contraction of a muscle is the summation of all the active motor units. What is the called? - Answers spacial summation The neuromuscular junction is formed from _______ and _________. - Answers the axon terminal and the motor endplate of a myocyte. The axon terminal has small membranous sacs called _______ that contain the neurotransmitter _________. - Answers synaptic vesicles acetylcholine (ACh) Though very close, axon terminals and motor endplates are always separates by a space called the ____________. - Answers synaptic cleft Many pesticides contain inhibitors of acetylcholinesterase that bind to its active site and prevent it from degrading ACh, which can cause a ____________________. - Answers spastic rigid paralysis and suffocation. _________ is a spastic rigid paralysis caused by a toxin produced by clostridium bacteria. - Answers tetanus (lockjaw) ______ fromt he skin of poisonous frogs in central america blocks the action of ACh by preventing it from binding to its sarcolemma receptor, which causes ____________. - Answers Curare, flaccid paralysis with no loss of consciousness What is a transient plasma membrane electrical depolarization event? - Answers Action potential what is shortening of a muscle called? - Answers cross bridge cycling What is it called when myosin heads attache to actin filaments? - Answers Cross bridge formations What is it called when ATP attaches to myosin head and the cross bridge detaches? - Answers Cross bridge detachment What is it called when energy from hydrolysis of ATP cocks the myosin head back into the high energy state? - Answers cocking of the myosin head What kind of contraction occurs when the tension generated by the cross bridge exceeds the load and the muscle decreases in length? - Answers shortening (concentric contraction) What is it called when the load is greater than the muscle force generation and the muscle lengthens during the contractions? - Answers eccentric contraction Contraction ends when... - Answers the cross bridges become inactive, the tension declines, and relaxation is induced. The two types of muscle contraction are... - Answers 1.) Isometric contraction: increasing muscle tension (muscle doesnt shorten) 2.) Isotonic contraction: decreasing muscle length (muscle shortens) What is the response of a muscle to a single action potential stimulus called? - Answers a muscle twitch What ar ethe three phases of a muscle twitch? - Answers 1.) Latent period 2.) Period of contraction 3.) Period of relaxation