Muscular System My muscles move my body like

Muscular System My muscles move my body like strings move a puppet.

Muscles �From latin word MUS (little mouse) �For contraction or shortening �Responsible for essentially all body movement (machine of the body)

My muscles are important because they… Hold my organs in place � Hold my bones together so that I can move � Help me chew my food � Open and close my eyelids � Pump my blood � Allow me to run and play � Help me to smile! �

Function of Muscles � Produce movement • Muscle pulls tendons to move the skeleton � Maintain posture and body position • Continuous muscle contraction � Support soft tissue • Support weight of visceral organs � Guard entrances and exits • Encircle openings to digestive and urinary tracts. Control swallowing, defecation and urination � Stabilizing Joints � Maintain body temperature • Energy from contraction is converted to heat

Did you know? ? ? It takes more muscles to frown than to smile?

What are muscles made of? Stretchy, elastic cells and fibers

TYPES OF MUSCLES

SKELETAL MUSCLE FIBERS Striated/Voluntary � attached to the body skeleton � Cigar-shaped, multinucleate cells and the largest muscle fiber type � they are often activated by reflexes � Can contract rapidly and with great force but tires easily � Soft and surprisingly fragile but can exert tremendous power because of bundles of connective tissues

BUNDLES OF MUSCLE FIBERS Endomysium - delicate connective tissue that encloses the muscle fiber Perimysium - a coarse fibrous membrane that wraps the endomysium that contains the muscle fibers

BUNDLES OF MUSCLE FIBERS Fascicle - bundle of fibers formed from perimysium Epimysium - an overcoat that binds many fascicles that covers the entitre muscle fiber

BUNDLES OF MUSCLE FIBERS epimysium epi = upon perimysium peri = around endomysium end = within

Tendons/Aponeuroses �Bended epimysia that are strong which attach muscles directly to bones, cartilages or connective tissues. �Anchor the muscles and provides durability and conserving space. �Tough collagenic fibers that can cross rough bony projections which would tear the more delicate muscle tissue.

Why do I need tendons? Tendons attach my muscles to my bone helping my body move. Feel your tendon right above your heel in the back of your leg. This is the thickest tendon in your body.

SMOOTH MUSCLE FIBERS Visceral/Nonstriated/Involuntary �Located at the walls of the hollow visceral organs �Single nucleus and spindleshaped that are arranged in sheet or layers �Contraction is much more slower than the two muscle types

Peristalsis �A wavelike motion that keeps food moving through the small intestine

Contraction �The circular and longitudinal layers alternately contract and relax to change the size and shape of the organ.

CARDIAC MUSCLES Cardiac/Striated/Involuntary �Found in the heart �Moderated by small amount of soft connective tissues and arranged in spiral or 8 shaped bundles �It contracts fairly rate by the hearts “in house” pacemaker but sometimes by the nervous system

One way to keep my muscles strong… �Eat foods from the meat group every day. They are high in protein which helps to build strong muscles.

Another way to keep strong muscles… Exercise every day.

MICROSCOPIC ANATOMY of Skeletal Muscle

Sarcolemma �Seen beneath the plasma membrane of muscle fibers that contains the nuclei of the skeletal muscle �Also called as muscle disk

Myofibrils or Fibrils �A long ribbon like organelle that pushed the nuclei aside �Serve as a microscopic composition of the muscle fibers

Light I and Dark A bands �Gives the muscle cell as a whole its striped appearance

Z Disc Midline dark area interruption within the light I band H Zone A lighter central interruption in the dark A band

M Line �Located at the center of the H zone contains tiny protein rods that hold adjacent thick filaments together

Sarcomere �Chains of tiny contractile units in the myofibril which are ligned end-to-end along the length of the myobrils

Myofilaments Myosin Filaments (thick Filaments) - Made up of bundled molecules of protein called myosin - contains ATPase enzymes which splits ATP to generate the power for muscle contraction Myosin head (Cross Bridges)

Myofilaments Actin Filaments (Thin Filaments) - composed of actin proteins - contain some regulatory proteins that play a role in allowing (preventing) myosin head-binding to actin

Sarcoplastic Reticulum (SR) - Stores calcium and releases it on demand when muscle fibers is stimulated to contract

Thankz!