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.
Attached to bones
for movement
Also acts as
source of blood
cells/storage of
minerals
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).
Joint
capsule
The elbow is a hinge joint that acts similarly to a door.
(Also called a synovial joint)
Antagonistic pair
Scapula
Arm flexed1. Biceps contracted
(Thick and short)
2. Pull up Radius
Arm extended1. Triceps contracted
(Thick and short)
3. Triceps relaxed
(Long and thin)
2. Pull down Ulna
Radius
Ulna
Look at the video
3. Biceps relaxed
(Long and thin)
11.2.3 Outline the functions of the structures in the
human elbow joint named in 11.2.2.
Joint Part
Cartilage
Synovial fluid
Joint capsule
Tendons
Ligaments
Biceps muscle
Triceps muscle
Humerus
Radius
Ulna
Function
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?
Yes
Yes
Type of
movements
Multiple angular motions
Rotational
Angular motion in one
direction
Possible
movements
Flexion, extension,
abduction, adduction,
circumduction, rotation
Ball that fits into
depression
Flexion and extension
Structure
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. Tendons
2. Muscle
3. Muscle bundle
4. 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.
Light band
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 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.
Task: Complete the
following table by
looking at the
diagram
Actin
H zone
A band
I band
M line


Myosin



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
troponin
tropomyosin
Rest
myosin
complex
ADP
Pi
actin
filament
myosin
filament
At rest, the actin-myosin binding site is
blocked by tropomyosin, held in place by
troponin
Myosin heads cannot bind to actin
filaments
Myosin is bound to ATP (ADP + Pi)
troponin
Ca2+
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
+
ADP
Pi
 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
 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/template
s/student_resources/shared_resources/animations/m
uscles/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?