012 Muscular System[1]

8/4/2019 012 Muscular System[1]

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The Muscular System


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Muscle Tissues

Skeletal striated, multinucleate, voluntary,10-100 m

Smooth-found in walls of hollow visceralorgans; ex. stomach, bladder, respiratorypassages; visceral, nonstriated, involuntary;

discuss peristalsis

Cardiacin heart only, striated, involuntary,

intercalcated disks


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Muscle function: produce movement

maintain posture stabilize joints generate heat

Functional Characteristics: Excitability- respond to a stimulus Contractility- ability to shorten forcibly whenadequately stimulated

Extensibility- the ability to be stretchedElasticity- the ability of a muscle fiber to resume

its resting length after being stretched


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Skeletal Muscle Tissue


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Smooth Muscle Tissue


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Cardiac Muscle Tissue


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Gross Anatomy Skeletal Muscle


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bundle ofmuscle fibers

muscle fiber(cell)

myofibril

sarcomere

MuscleAnatomy


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Myofibril


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Sarcomere

Z

lines


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Sarcomere A band


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Sarcomere I bands


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Actin and Myosin Filaments

myosinactin


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Myosin (Thick) Filament


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Actin (Thin) Filament


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Sliding Filament Hypothesis


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No Calcium Ion

tropomyosin


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Calcium Ion Present

tropomyosin

myosin binding sites


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Actin & Myosin Interaction


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Biology 100

Human Biology

Motor Unit

spinal cord

motor neurons

muscle bundle

muscle fibers

neuromuscular junctions


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Neuromuscularjunctions

branching axonto motor unit

muscle fibers

S i l i f Sk l l M l


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Stimulation of Skeletal Muscle


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axon

plasmamembrane

myofibrils

sarcomere


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T tubules

sarcoplasmicreticulum


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plasma membrane

sarcoplasmic reticulum

T tubule

calcium

actin myosinhead

M l T it h


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stimulus

latent period

period ofcontraction

period ofrelaxation

Muscle Twitch


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Contraction Response


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Origin- fixed point of attachment; for biceps brachii O=clavicle and humerus

Insertion- moveable, usually crosses a joint; O= radius

Prime mover- - muscle group responsible for producingparticular movement

Antagonist- works opposite of prime mover

Synergist-reduces undesirable or unnecessary movementContraction of a muscle crossing 2 or more joints would

cause movement of all if synergists werent there tostabilize itEx. make a fist without bending wrist

Fixator- specialized synergist- helps maintain posture; ex.muscles of the back fix scapula


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biceps(flexor)

biceps(flexor)

triceps(extensor)

triceps(extensor)

AntagonisticMuscles


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Direction of muscle fibers- straight, transverseSize of muscles- maximus, minimus, longus, brevis

Location- frontalis, temporalis, occipitalis

# of origins- biceps, triceps, quadriceps

location of muscles origin and insertion-sternoclediomastoid- O= sternum and clavicle, I =

mastoid process of temporal bone

shape of muscle- deltoid- triangle shape, trapezius-

trapezoid shapeaction of muscle- adductor muscle (adducts, brings

in thigh)

Naming skeletal muscles:


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Frontalis

Orbicularis oris

Orbicularis oculi

Masseter

sternocledeomastoid

zygomaticus

aponerosa

temporalis

Frontal


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Sternoclediomastoid

Temporalis

Masseter

Obicularis oris

Obicularis oculi

C di M l Ti


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Cardiac Muscle Tissue


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Smooth Muscle Tissue


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Slow-Twitch Versus

Fast-TwitchMuscle Fibers


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ATP is Generated by:

1. creatine phosphate

ADP + creatine phosphatecreatine +ATP

2. lactic acid fermentationFrom stored glycogen via anaerobic glycolysis;

glucosepyruvic acid (no O2) lactic acidO2

3. aerobic respirationKrebsCO2 + H2O + ATP

Energy for muscle contraction:ATP is the only energy source

ATP(ATPase + H2O)ADP + Pi

Fast glycolitic: white muscle fibers low myoglobin


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Fast glycolitic: white muscle fibers, low myoglobin,anaerobic glycolysis, few mitochondria, fast twitchfibers, high glycogen stores, short bursts, fatigueseasily

Slow oxidative: red muscle, aerobic, high myoglobin,low glycogen stores, lots mitochondria, slow, tonic, longdistance

Fast glycolitic-oxidative: red pink, aerobic, fast,high myoglobin, intermediate amt. of mitochondria,intermediate glycogen, intermediate fatigue resistance

Ratio- red:white (all 3 types in body)

Ex. fish-long distance blue fin tuna- mostly red meat

quick bursts- yellow tail- more white meat


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Sprinter-anaerobic

respiration

Long distance

Runner-

aerobicrespiration


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Disuse- atrophyMuscles must be physically active if they are to remainhealthy

Cast- muscle strength can decrease at a rate of 5%/ day;can use e- stimulusAvoid muscle injuries:

-warm up muscles- walk fast 5 minutes

-then stretch- avoids pulls and tares

cramp- sustained spasm or tetanic contraction; may bedue to low blood sugar levels, electrolyte depletion,dehydration

how to care for cramp: RICEstrain- muscle pullspasm- ticshernia- protrusion of organ through body cavity wall may

be due to heavy wts.


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Isotonic and Isometric Contractions

Isotonic contraction Contraction with a change in length The muscle shortens and movement occurs.

Isometric contraction Contraction without any change in length The muscle does not shorten and there is no

movement produced even though the musclecontracts.

C


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Isotonic and Isometric Contractions

Isotonic

Isometric

012 Muscular System[1]

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