Module 11:Human Health and

Physiology II

11.2 Muscles and Movement

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

Also acts as source of blood cells/storage of minerals

Attached to bones for movement

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

The elbow is a hinge joint that acts similarly to a door. (Also called a synovial joint)

Joint capsule

Antagonistic pair

Arm flexed- 1. Biceps contracted(Thick and short)

2. Pull up Radius

3. Triceps relaxed(Long and thin)

Arm extended-1. Triceps contracted(Thick and short)

2. Pull down Ulna

3. Biceps relaxed(Long and thin)

Scapula

Radius

Ulna

Look at the video

11.2.3 Outline the functions of the structures in the human elbow joint named in 11.2.2.

Joint Part Function

Cartilage

Synovial fluid

Joint capsule

Tendons

Ligaments

Biceps muscle

Triceps muscle

Humerus

Radius

Ulna

11.2.4 Compare the movements of the hip joint and the knee joint.

Hinge Joint: Knee joint Ball and socket: Hip joint

Both of these joints are also referred to as diarthrotic joints – joints that are freely movable

11.2.4 Compare the movements of the hip joint and the knee joint.

Task: Complete the following table using page 294 for reference,

Characteristic Hip joint Knee joint

Diarthrotic?

Type of movements

Possible movements

Structure

Yes Yes

Multiple angular motionsRotational

Angular motion in one direction

Flexion, extension, abduction, adduction, circumduction, rotation

Flexion and extension

Ball that fits into depression

Convex surface fits into concave surface

11.2.4 Compare the movements of the hip joint and the knee joint.

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

Striated (skeletal) muscle

1.Tendons2.Muscle3.Muscle bundle4.Muscle fibre (cell)

4.

Muscle cells are multi-nucleated and the plasma membrane is called the sarcolemma. Each cell is made up of multiple myofibrils. The sarcoplasmic reticulum is like the ER.

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

Myofibril

4.

Sarcomeres are repeating units of movement that make up myofibrils (from Z line to Z line). It’s made up of myosin and actin filmaents

Dark bandLight band

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

Myosin head

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

Actin Myosin

H zone

A band

I band

M line

Task: Complete the following table by looking at the diagram

What happens during muscle contraction?

Sarcomere before and after:

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 re-set myosin heads.

The Sliding Filament Theory of Muscle Contraction

1. Action potential arrives at the neuromuscular junction. Achetylcholine is released and binds to receptors on the sarcolemma. T tubules spread the action potential and the sarcoplasmic reticulum releases Ca2+ into the sarcoplasm

At rest, the actin-myosin binding site is blocked by tropomyosin, held in place by troponin

Myosin heads cannot bind to actin filamentsMyosin is bound to ATP (ADP + Pi)

actin filament

troponin

tropomyosin

myosin complex myosin

filament

ADPPi

Rest

Ca2+ (from sarcoplasmic reticulum) binds to troponin, changing its shape

As a result, tropomyosin is pulled out of the binding site and this exposes the myosin binding site on actin

Ca2+

troponin

Ca2+ activates ATPase, breaking down ATP to ADP + Pi

Myosin binds to actin to form crossbridge after the Pi is released

Energy provided moves the myosin head forward, pulling acting filament along in what is known as the power stroke. The ADP is released in the process

ADPPi

Ca2

+

Free ATP binds to head, changing myosin back to its original shape Actin-myosin cross bridge breaks (site if occupied by ATP) The head returns to original shape

With continued stimulation the cycle is repeated

If stimulation ceases, Ca2+ is pumped back into sarcoplasmic reticulum

Troponin and tropomyosin return to original positions

Muscle fibre is relaxed

Important points to note: The lengths of actin and myosin DO NOT change; they simply slide over each other The I band and H band disappear Myosin heads move towards the middle pulling actin towards the M line.

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 re-set myosin heads.

Task 1: Using the link, complete the assessments and make any necessary additions to your notes:http://brookscole.cengage.com/chemistry_d/templates/student_resources/shared_resources/animations/muscles/muscles.html

Task 2: Arrange the key events of the sliding filament theory into the correct order

11.2.8 Analyse electron micrographs to find the state of contraction of muscle fibres.

Which one is contracted and which one is relaxed? How do you know?