MUSCULAR SYSTEMPau Junyent & Aurora Nieto

What are muscles? I contractile tissue found in animals over 650 muscles half the weight of the human body produce movement & body heat skeletal, smooth and cardiac ability to contract and conduct electrical

impulses voluntary (biceps) or involuntary(lungs) striated or smooth

What are muscles? II Rigor Mortis: stiffening body after death,

caused by calcium in the muscle contract & relax; NOT stretch made up of elastic tissue need: Oxygen and Blood Antagonist muscles: pair of muscles that do

opposite things from one another Elasticity: the ability to return to original shape Flexion: ability to bend a joint

Differences Different functions Appearance

- skeletal muscle: striated (striped)- cardiac muscle: striated but stripes

less organized. contain branches, allow

rapid communication- smooth muscle: composed of cells with dark nuclei; not striated

Smooth Muscle I Involuntary muscle Found in hollow parts of the body Stimulated by the nervous system Two groups: single-unit and multiunit Single-unit: rapid and simple contractions Multiunit: contractions depend on the nervous

system Found in: Walls, arteries, veins, urinary bladder,

lymphatic vessels, uterus, respiratory tract, iris, etc…

Structure and function the same for every all organs Said to be in charge of ‘housekeeping’ functions

Smooth Muscle II Contracts everything at once Cytoplasm is filled with myosin and actin

molecules Myosin: ATP-dependent motor protein Actin: Protein found in all eukaryote cells Contraction caused by sliding actin and

myosin filaments

Skeletal Muscle I Produce movement & supports the

skeleton Voluntary muscle Controlled by the nervous system Attached to bones by tendons Made up of muscle fibers (myoblasts) Cartilage: connective tissue found in joints

Skeletal Muscle II Two groups: Type I and type II Type I: red, presence of oxygen, for

endurance and slow fatigue Type II: white, absence of myoglobin,

reliance on glycolytic enzymes, used shortly, use oxidative and anaerobic metabolism, fast fatigue

Skeletal Muscle III – Categorized I Categorized not only by color but by

arragement of fascicles Parallel, convergent, pennate, sphinter Parallel muscles:

fascicles run parallel to the direction of the muscle

most skeletal muscle (triceps, biceps) Convergent muscles:

Fibers come out from a common point. Cover larges surfaces. Allow a lot of movement (pectoralis major)

Skeletal Muscle III – Categorized II Pennate muscles:

1 or more tendons run through the muscle the fascicles form a slanted angle to the

tendons greater amount of muscle fibers = more

tension (Rectus Femoris) Sphinter muscles (circular) :

arranged around an opening when muscle contracts, opening gets smaller. at the entrances and exits of passage ways

Most Important Skeletal Muscles Pectoralis Major:

Thick, fan-shaped muscle At the front (chest) of human body Flexes chest area

Gluteus Maximus: Largest and most superfcial of gluteal

muscles Shape and appearance of buttocks Flexes thigh joint

Differences (Tendon & Ligament) Ligaments:

connect bone to bone help to stabilize joints long, stringy collagen Slightly elastic Stretched to gradually increase flexibility.

Tendon: connects muscle to bone tough, flexible attached to the skeletal muscles intermediaries between the muscles

Cardiac Muscle I Involuntary or voluntary muscle Heart Send blood to all the body by using

contraction Cardiomyocytes have 1-4 nuclei Cordinated contractions Blood is sent to clean body from waste

products and keep the body active Highly resistant to fatigue

Cardiac Muscle II Needs a lot of calcium Largest number of mitochondria Cardiac muscles contract to squeeze

blood out Relaxes to fill the heart with blood

Muscle Regeneration Occurs when a muscle is stretched or torn

(muscle strain) Muscle breaks when the stress limit is

trespassed Provides more strength and larger size Regenerates when the body rest Regeneration will occur no matter how old Satellite cells fuse with the broken fibers

Video http://www.youtube.com/watch?v=ren_I

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