Muscular System Evelin Morales Period 5 (Names of all the muscles:…
Muscular System Evelin Morales Period 5
Major Functions of the muscular system
muscles are responsible for all types of body movement.
over 600 skeletal muscles, more than half of body weight.
change in body position.
also movement of substances within the body.
maintain body position.
stabilizing joints, body posture, regulate organ volume.
contraction produces heat; helps with homeostasis.
Names of all the muscles:
3 Types of muscle tissues and their major functions/ characteristics
striated- visible banding.
forms the hearts wall.
cells are long, cylindrical, branched, and has single central nucleus.
involuntary- cant consciously control.
joined to another cell at intercalated disc.
interconnected nature of cardiac muscle cells allows heart to circulate blood throughout body.
cells are spindle-shaped with single central nucleus.
has no striations, appears smooth.
found mainly in hollow walls of organs, such as the digestive tract, blood vessels urinary, and reproductive organs.
aka visceral muscles.
controls movement inside internal organs.
attached by tendons to bones.
striated- visible banding.
cells are long, cylindrical, parallel and multinucleated.
voluntary- subject to conscious control.
makes up about 40-50% of body weight ("red meat").
Connective Tissues of the Muscles:
Perimysium- around a fascicle.
Epimysium- covers the entire skeletal muscle.
Endomysium- around a single myocyte= muscle fiber= muscle cells.
Tendons- attach muscle to
Characteristics of Muscles
Contractility- ability to shorten when an adequate stimulus is received.
Irritability- ability of muscles and nerves to respond to stimulus by producing electrical signals or action potentials.
Main Structures of Skeletal Muscle
organ composed mainly of skeletal muscle cells and connective tissue.
across a joint.
Body- main part of the muscle.
Tendons- strong cords of fibrous connective tissue that attach muscles to bone.
Insertion- the end of a muscle attached to the bone that moves when a muscle contracts.
Origin- the end of a muscle that attaches to the bone that does not move when contraction of the muscle occurs.
Bursae- synovial- lined sacs contains synovial fluid; located between some tendons and underlying bones.
Ligaments- strong cords of fibrous connective tissue that attach bone to bone.
Muscles Produce Movement
Extension increases the angle between two bones.
Flexion decreases the angle between two bones.
Muscles can not push! They can only contract (pull together).
Physiology of muscle contraction
Ca++ binds to actin myofilament, exposing the myosin binding site.
Myosin head moves toward M-line.
Nerve impulse or actin potential travels down sarcolemma.
Myosin attaches to actin.
repeated many times powered by ATP.
Z lines get closer together.
Nerve Impulse/ Actin Potential
nerve impulse down to axon terminal. release Ach.
ach binds to motor end plate.
in sarcolemma= Na+= (sodium) channels open.
actin potential= electrical current or change.
Body Movement Terminology
refers to a movement that increases the angle between two body parts.
extension at the elbow is increasing the angle between the ulna and the humerus.
extension of the knee straightens the lower limb.
for example, abduction of the shoulder raises the arms out of the sides of the body.
is a movement away from the midline- just as abducting someone is to take them away.
flexion between the ulna and the humerus.
when the knee flexes, the ankle moves closer to the buttock, and the angle between the femur and tibia.
refers to a movement that decreases the angle between two body parts.
adduction of the hip squeezes the legs together.
is a movement towards the midline.
in fingers and toes, the midline used is not the midline of the body, but of the hand and foot respectively.
therefore, abducting the fingers spreads them out.
it is sometimes referred to as internal rotation.
is a ration movement towards the midline.
this is in the opposite direction to the movements.
is a rotating movement away from the midline
depression refers to a movement in an inferior direction.
refers to the movement in a superior direction (shoulder shrug).
refers to flexion at the ankle, so that the foot points more superiorly.
refers to extension at the ankle.
Structure of the skeletal muscle
each muscle is surrounded by a connective tissue sheath called the epimysium.
each skeletal muscle fiber is a single cylindrical muscle cell.
they are bundled together and wrapped in a connective tissue covering.
an individual skeletal muscle may be made up of hundreds, or even thousands, of muscle fibers
Nuclei pushed against sarcolemma.
actin filaments- thin filament.
myosin filaments thick filament.
Sarcoplasmic Reticulum- a modified ER found in Muscles that store and delivers Ca++ (CALCIUM) Ions.
during contraction, the thin filaments are pulled toward the center of each sarcomere, shortening the whole muscle.
Organizational Levels of the skeletal muscle
myofibrils are organelles within the muscle cell that contain thick and thin myofilaments.
the myofilaments are organized into sarcomeres, and they serve as the functional units of skeletal muscle.
they are packed within a fascicle.
the endomysium is the connective tissue surrounding individual muscle fibers.
light band (I Bands)
there are 2 types of myofilmaents
each filament consists of a rod- like tail which ends in 2 globular heads.
each myosin filament combines with about 200+ others to form a thicker filament.
2..Myosin- thick filaments found in the A Band .
Actin- composed of 2 thin, twisted strands of the fibrous protein Actin.
Active Sites- are scattered down the Actin Myofilaments at regular intervals.
Sarcomere consists of Myosin and Actin filaments.
dark band (A Band)
Sarcoplasm- muscle cell cytoplasm, which is specialized to contain a lot of Glycogen.
Sarcolemma- Muscle cell membrane.
Myoglobin- is similar to Hemoglobin and stores Oxygen in a muscle cell.