module 11: human health and physiology ii 11.2 muscles and movement
TRANSCRIPT
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?