Muscular System Lecture Exam with correct answers 2024.

the MOVABLE bone attachment - correct answer insertion Is each skeletal muscle considered an individual organ? - correct answer yes Each organ is composed of - correct answer muscle tissue blood vessels nerve fibers connective tissue a coat of dense regular connective tissue that surrounds the entire muscle organ, it continues at the ends of the muscle as the tendon - correct answer Epimysium a sheath of connective tissue that surrounds individual fascicles of the muscle - correct answer perimysium a sheath of connective tissue that surrounds individual muscle fibers - correct answer endomysium T/F: Each muscle fiber is a long cylindrical cell with multiple nuclei - correct answer True Do fibers generally span from the origin to the insertion of the muscle or from the insertion to the origin? - correct answer origin to the insertion Can some muscle fibers in the long muscles of the leg be more than a foot long? - correct answer Yes What is the longest muscle in the body? - correct answer Sartorius muscle long packets of actin and myosin filaments that cause the fiber to contract - correct answer myofibrils a specialized smoooth ER - correct answer sarcoplasmic reticulum extensions of the sarcolemma into the muscle fiber that conduct action potentials - correct answer t tubules -organelles that cause the contraction of muscle fibers -long cylinders of the proteins (myofilaments) that create the movement -make up most of the volume of muscles - correct answer myofibrils myofilaments are - correct answer proteins the arrangement of the myofilaments in the myofibrils in skeletal muscles create light and dark bands called - correct answer striations myofibrils are made up of proteins called - correct answer myofilaments what is the thick filament made of - correct answer myosin what is the thin filament made of - correct answer three proteins known as actin, tropomyosin and troponin What does each myosin molecule look like? - correct answer rod-like tail and two globular heads What does the myosin's rod-like tail do? - correct answer The tail anchors the protein to the thick filament What does the myosin's head do? - correct answer The head is used to bind actin filaments and creates the movement in muscle contraction What is the main protein of the thin filament? - correct answer actin Each globular unit has a specific active site called a - correct answer myosin binding site What happens at the myosin binding site? - correct answer myosin heads grab the actin protein and pull on it Tropomyosin and troponin are bound to actin and help to... - correct answer regulate muscle contraction a repeating pattern of thick and thin filaments in a myofibril - correct answer sarcomere definition of a sarcomere - correct answer the region of a myofibril between two Z-discs T/F: Sarcomeres are responsible for striations in muscle fibers. - correct answer True the dark band in striated muscle that contains the thick and thin filaments - correct answer A-band the light band in striated muscle that contains only thin filaments - correct answer I-bands the area of the sarcomere that only contains thick filaments in the middle of the A-band - correct answer H-zone the sheet of proteins in the center of the I-band that anchor the thin filaments and connect myofibrils together. Acts as the boundaries of the sarcomere - correct answer Z-disc the area of the A-band that contains desmin - correct answer M-line protein that anchors the thick filaments right down the middle of a sarcomere - correct answer desmin an elaborate smooth endoplasmic reticulum that runs the length of the muscle fiber and surrounds each myofibril - correct answer sarcoplasmic reticulum The sarcoplasmic reticulum is organized into paired areas called - correct answer terminal cisternae Terminal cisternae form channels that are ________________ to the muscle fiber - correct answer perpendicular The sarcoplasmic reticulum is responsible for storing what in the muscle fiber? - correct answer calcium This is essential for regulating the contraction of a muscle fiber - correct answer calcium extensions of the sarcolemma - correct answer t tubules Where do t tubules occur? - correct answer at the A band-I band junction What are t tubules responsible for? - correct answer conduction action potentials into the muscle fiber action potentials are - correct answer electrical signals the terminal cisternae run along next to the t tubules in the muscle fiber forming structures called - correct answer triads When a muscle contracts, the thin filaments are pulled past the thick filaments to shorten what? - correct answer the muscle fiber When a muscle contracts, it decreases the size of what zone and band? - correct answer It decreases the size of the H zone and I band nervous system ells that send signals to skeletal muscles to cause them to - correct answer contract Motor neurons have long extensions called - correct answer axons Axons start in the spinal cord and travel in nerves to reach - correct answer the muscle cells these open and allow calcium to enter the axon terminal - correct answer voltage-regulated calcium channels the neurotransmitter that signals muscle fibers to contract - correct answer acetylcholine chemicals that the nervous system uses to communicate - correct answer neurotransmitters This pulls tropomyosin off of the myosin binding sites on actin filaments - correct answer troponin a single motor neuron and all of the muscle fibers it stimulates to contract - correct answer motor unit T/F: When a motor neuron enters a muscle it branches and forms neuromuscular junctions with multiple muscle fibers - correct answer True Where are small motor units found? - correct answer in areas where fine motor control is required (fingers, eyes) Where are large motor units found? - correct answer in areas where large movements occur (abdominal muscles, quadriceps) __________ __________ in a motor unit are spread out in the muscle so that stimulation of one motor unit causes contraction of the entire muscle. - correct answer Muscle fibers This must stimulate a muscle for it to contract - correct answer a nerve this can control the strength and duration of a muscle contraction - correct answer frequency of nerve stimulation a single stimulus from a motor neuron to a muscle fiber results in a single contractile response called a - correct answer twitch a contraction in which the stimuli are too close together for the muscle fiber to relax is known as - correct answer tetanic contraction What are the two basic types of muscle contractions called? - correct answer -isotonic contractions -isometric contractions muscle contractions that happen while the length of the muscle changes are known as - correct answer isotonic contractions muscle contractions that happen when the length of the muscle does not change - correct answer isometric contractions In this type of contraction, the muscle changes in length to move a load. - correct answer isotonic contraction There are two types of isotonic contractions, they are known as... - correct answer -concentric contractions -eccentric contractions when the muscle shortens and does work it is known as a - correct answer concentric contraction when the muscle lengthens as it is contracting it is known as - correct answer eccentric contractions Only ______% of the energy released during muscle activity is used to contract the muscle. The remaining _____% is given off as heat. - correct answer 40% and 60% T/F: Muscle contraction is very efficient. - correct answer False; muscle contraction is very inefficient, you only use 40% of the energy you put in to do work. Is smooth muscle voluntarily or involuntarily controlled? - correct answer involuntarily alternating contractions and relaxations of smooth muscles that mix and propel substances through hollow organs is known as - correct answer peristalsis