THE MUSCULAR SYSTEM

Types of Muscle Smooth – elongated, spindle-shaped, and flat; one nucleus; no ________; found in walls of hollow internal _____, blood ______, eye; in________; contracts ______; prolonged contractions; doesn’t easily _______ Smooth muscle video (2:53)

Types of Muscle Cardiac – striated, cylindrical, and branched; one nucleus; interlock at ______ disks (allow synchronized _____; specialized _____); found only in the _____; involuntary; extremely resistant to fatigue (enormous # of m________ and myoglobin); pacemaker cells (_____- generate their own impulse; discovered by Theodor Engelmann) Red arrow? Blue arrow? Yellow arrow?

Types of Muscle Skeletal muscle video (3:33) Skeletal – striated, cylindrical; multi________; voluntary; can be involuntary (r_____); made of slow- and fast-twitch fibers Slow-twitch = ______, endurance, _____ contractions, lots of blood, energy source is _____, duration is hours; contain lots of myoglobin (oxygen and iron-binding protein) Fast-twitch = ______, quick bursts, less blood, energy source is _____ and ___________, duration is up to 30 min; nerves run throughout the muscle (innervated); not as much ________ Fast twitch energy: ATP and glycogen Skeletal muscle video (3:33)

General Functions of Muscle Stabilizes ________ Allows us to remain _____ Produces _____ (body, breathing, digestion, circulation, birth, excretion) Contraction produces ______ (helps maintain body _____)

Muscle Anatomy (skeletal) muscle  fascicle  muscle fiber  myofibril  actin(thin)/myosin(thick); sarcomere _____ _____ _____ _____ _____ _____

Sliding Filament Theory Sliding filament theory – when a myofibril contracts, the _____ filaments slide past the _____ filaments, causing the myofibril, and therefore the muscle fiber, to _____ and _____

Events at Neuromuscular Junction 1. Nerve impulse reaches _____ terminal (AT) 2. Ca2+ protein channels _____ and Ca2+ floods AT 3. Ca2+ causes synaptic _____ in AT to release ACh 4. ACh diffuses across _____ _____ and binds with protein receptors in the _____ of muscle fiber 5. ACh binds to sodium-potassium pump in the sarcolemma, causing the pump to allow the simultaneous passage of Na+ ions _____ and K+ ions _____ _____ the muscle fiber 6. When stimulus _____, the enzyme acetylcholinesterase _____ _____ ACh and the process ends

Events at Neuromuscular Junction NMJ Animation (3:15) What’s the purpose of the junctional folds? Why are they found only at the NMJ of the sarcolemma?

Neuromuscular Junction

Generation of ATP Working muscles generate _____ in three ways: 1. Direct phosphorylation of ADP by creatine _____ (anaerobic; only in muscle fibers) CP supplies exhausted in ~ 20 seconds 2. Lactic acid _____ (anaerobic) 3. Aerobic respiration (generates the most ATP)

Muscular System Terms Prime mover – muscle that provides the major _____ for producing a specific movement Synergists – assist ____ ____ by providing more _____ and preventing unnecessary movements They enable us to have smooth, fluid movements Antagonists – muscles that _____ the movement of a ____ ____

Muscular System Terms Isotonic contraction – muscle contraction that causes _____ Isometric contraction – muscle contraction that causes ____ _____

Muscular System Terms Tone – continuous, partial _____ of a muscle Hypertrophy – _____ in tissue size without cell _____ Increase in muscle mass due to forceful _____ Atrophy – the _____ ____ of tissue due to lack of _____

Muscular System Terms Origin – point of _____ of a muscle; the end that does not _____ Insertion – point of _____ of a muscle; the end that does _____

Muscular System Terms Latent period and contraction & relaxation phases Latent – muscle prepares for _____ Contraction – ____ and ____ bind together; muscle _____ Relaxation – actin and myosin _____; contraction _____

Muscular System Terms Summation, tetanus, & fatigue Summation – occurs when a skeletal muscle is _____ a second time before _____ is complete; contractions after second and subsequent stimuli progressively _____ Tetanus – occurs if the stimulus is _____ at a sufficiently high rate; the muscle will not _____ between each stimulus but will remain _____ Fatigue – occurs if a muscle is not allowed to _____; muscle _____ even though _____ continues to be administered; muscle has depleted _____ supply; serves as a protective mechanism against _____ to sarcolemma and sarcoplasmic reticulum

Summation, Tetanus and Fatigue

Muscular System Terms All-or-none law – muscle fibers either _____ maximally or ____ at ____ Oxygen debt (EPOC) – occurs during the recovery period; even though muscles are _____, _____ rate is still high – Why, you ask? Good question! 1. _____ levels (and therefore ____ levels) in cells must be replenished to pre-exercise levels 2. Assists in the metabolism of _____ in _____ cells 3. Many cells and tissues throughout the body are still _____ after _____ (e.g. sweat glands, muscles, nerves)

Muscle Nomenclature Muscles are named according to a number of characteristics. This system of nomenclature makes learning their names and functions easier. The characteristics are: _________ (gluteus maximus) _________ (deltoid) ___________ ___ _________ (rectus abdominis) _____________ (frontalis)

Effects of Aging Muscle deteriorates and replaced by _______ Mitochondria break down  decrease of ________ Water content in tendons decreases = stiffness/pain Less blood flow (oxygen) to muscle cells = less ________ respiration = less production of ______