Topic 11: Human Health and Physiology

11.2 Muscles and Movement

11.2.1 State the role of bones,

ligaments, muscles, tendons and nerves

in human movement

11.2.2 Label a diagram of the human elbow joint, including cartilage, synovial fluid, joint capsule, named bones, and antagonistic muscles

11.2.3 Outline the functions of the

structures of the human elbow joint

11.2.4 Compare the movement of the hip joint and the knee joint

11.2.5 Describe the structure of striated muscle fibers, including the myofibrils with light and dark bands, mitochondria, the sarcoplasmic reticulum, nuclei and the sarcolemma.

11.2.6 Draw and label a diagram to

show the structure of a sarcomere,

including the Z lines, actin filaments,

myosin filaments with heads, and

resultant light and dark bands

11.2.7 Explain how skeletal muscle contracts including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross- bridges, the sliding of actin and myosin filaments and the use of ATP to break cross-bridges and break myosin heads 11.2. 8 Analyze electron micrographs to find the state of contraction of muscle fibers

11.2.1 State the role of bones, ligaments, muscles, tendons and nerves in human movement

How do muscles move?• Signals move along a neuron and cause a muscle to contract • Muscles are connected to the bones by tendons • The contraction causes the bones to moves • The bone is moved back to the original position by an “opposing”

muscle The musculoskeletal system consists of various organs and tissues which have different roles • Bones – provide support and

anchorage (the lever)• Ligaments – connect bones together • Tendons – attach bone to muscle • Nerves – sense stimuli and provide the

impulse to make muscles contract

11.2.2 Label a diagram of the human elbow joint, including cartilage, synovial fluid, joint capsule, named bones, and

antagonistic muscles 11.2.3 Outline the functions of the structures of the human

elbow joint

A. Humerus (upper arm) bone - Origin for the biceps tendon

B. Synovial membrane - Encloses the joint capsule and produces synovial fluid.

C. Synovial fluid - reduces friction and absorbs pressure

D. Ulna - the lever in the flexion and extension of the arm.

E. Cartilage (red) - living tissue that reduces the friction at joints.

F. Ligaments (blue) - connect bone to bone and produce stability at the joint.

11.2.2 Label a diagram of the human elbow joint, including cartilage, synovial fluid, joint capsule, named bones, and

antagonistic muscles11.2.3 Outline the functions of the structures of the human

elbow joint

Biceps (flexor) muscle provides force for an arm flexion (bending). • The scapula and humerus are the

origin for the bicep• Radius is the insertion for the

bicep

Triceps muscle is the extensor whose contraction straightens the arm.• The scapula and humerus are the

origin for the tricep• The ulna is the insertion

11.2.4 Compare the movement of the hip joint and the knee joint

11.2.4 Compare the movement of the hip joint and the knee joint

Similarities:• Both are synovial joints • Both involve moving leg • Both required for walking

Differences:

11.2.5 Describe the structure of striated muscle fibers, including the myofibrils with light and dark bands,

mitochondria, the sarcoplasmic reticulum, nuclei and the sarcolemma.

Skeletal muscles (2) consist of bundles of muscle fibers (3).

At each end of the muscle is the tendon (1)

A muscle fiber is a long, multi-nucleus cell (4 and the image below)

There are many parallel protein structures inside called myofibrils.

Myofibrils are wrapped in a membrane called the sarcolemma and “floating” in cytoplasm (sarcoplasm)

Within the sarcoplasm is the internal membrane called the sarcoplasmic reticulum

11.2.5 Describe the structure of striated muscle fibers, including the myofibrils with light and dark bands,

mitochondria, the sarcoplasmic reticulum, nuclei and the sarcolemma.

The function of the sarcoplasmic reticulum is to store and release Ca+ ions into the sarcoplasm to start the muscle contraction

In the cytoplasm are many mitochondria to provide ATP

Myofibrils contain two types of protein myofilaments (myosin and actin) • Myosin proteins are called the thick filaments • Actin proteins are called thin filaments

The sarcomere is the structural unit of the muscle and runs from Z line to Z line

11.2.6 Draw and label a diagram to show the structure of a sarcomere, including the Z lines, actin filaments, myosin filaments with heads, and resultant light and dark bands

Under a microscope a sarcomere appears to look like:

light section →dark section→ intermediate section →dark section → light section

The thin filaments (actin) are attached to the Z line

Hank…HELP!!!

11.2.7 Explain how skeletal muscle contracts including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross-

bridges, the sliding of actin and myosin filaments and the use of ATP to break cross-bridges and break myosin heads

The steps of a muscle contraction

1.First, a myofibril is stimulated by the arrival of an action potential from a motor neuron.

This triggers the release of Ca+ ions from the sarcoplasmic reticulum and surround the actin molecule

Ca+

actin

11.2.7 Explain how skeletal muscle contracts including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross-

bridges, the sliding of actin and myosin filaments and the use of ATP to break cross-bridges and break myosin heads

2.Ca+ ions react with troponin which triggers the removal of a “blocking” molecule, tropomyosin

3.The binding site is now exposed

4.Each myosin head (with ADP and P attached) attach to the binding site of the actin molecule forming the cross-bridge. The P is removed at this point

Cross-bridge

tropomyosin Exposed binding site

myosin head

11.2.7 Explain how skeletal muscle contracts including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross-

bridges, the sliding of actin and myosin filaments and the use of ATP to break cross-bridges and break myosin heads

5. The ADP molecule is released from the myosin creating the “power stroke” and the actin filament is pushed along

6. A fresh molecule of ATP binds to the myosin head and releases from the actin filament (breaking the cross-bridge)

This process is repeated many times per second to shorten the muscle by 50%

11.2.8 Analyze electron micrographs to find the state of contraction of muscle fibers

In a contracted muscle, the distance between Z-bands become shorter

Remember, a sarcomere is defined as Z-Band to Z-Band.