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- Movement involves the muscle, nervous, skeletal and circulatory systems
- Exoskeleton
- Tendons connect muscles to bones
- Ligaments connect bones to bones
- Biceps and triceps work antagonistically
- Muscle fibres are made of protein and contain lots of mitochondria

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- Muscular system : contains all the ligaments, joints, muscles
- Nervous System: Contains the receptors, effectors and
- Skeletal system contains all the bones in the body

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- movement systems includes skeletal framework, muscles and nerves
- biceps and triceps for movements of forearm
- ligaments and tendons
-

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Myofibre
Antagonistic muscle Tricep and Bicep
ligament, joints

Exception to cell theory(multinucleate cell)

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skeletal system- provide a surface for muscle attachment and  facilitate the movement of an organism
muscular system- connect to bones and contract to provide the force required to produce movement
nervous system

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- Muscular system and skeletal system
- Muscle contraction and relaxation
- Ball and socket joint, hinge joint

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Skeletal System and muscular system

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Systems needed for movement
-muscular system
(flexor and extensor muscles)
-skeletal system
(knee joint and hip joint)
-nervous system

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Muscular, Skeletal and Nervous system

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Muscular system
- Muscle cells
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Skeletal system

Nervous system

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Muscles are composed of muscle fibres, which contain muscle cells
Muscle cells contain myofibrils which are composed of sarcomeres.
Muscle contractions are initiated when a synapse releases neurotransmitters to trigger an electrical impulse in the muscle cells.

This impulse causes the release of calcium ions from the store in the sarcoplasmic reticulum into the myofibrils and thus into the sarcomeres.
Sarcomeres consist of a thin protein known as actin and a thick protein known as myosin.
Both proteins overlap within the sarcomere.
When enough calcium ions are released, they bind to proteins on the actin called troponin. This causes the tropomyosin to shift slightly to expose the myosin binding sites on the actin.

Myosin heads store ATP, which is broken down to cause the them to attach to the binding sites on the actin. They then pull the actin protein towards the M line, which causes the actin and myosin to further overlap. This causes the sarcomeres to shorten.

The large number of sarcomeres present in the myofibrils causes them to shorten, which results in the muscle fibres contracting and evidently the entire muscle contraction.

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1. Calcium ions are released from the sarcoplasmic reticulum once a nerve impulse reaches
2. These Calcium ions bind with troponin and cause it to move which exposes the myosin binding site on actin
3. A cross bridge is formed between actin and myosin filaments caused by the breaking down of ATP
4.  ATP breaking down allows the myosin heads to change orientation
5. The changed myosin heads bind to the actin filament releasing ADP
6. The myosin heads then disconnect from the actin to their original shape to grab more ATP
7. This ATP is broken down into ADP and the energy released will be stored in the myosin head
8. When actin slides along the myosin, it causes muscle contraction as the sarcomere is shortened

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Explain muscle contraction.
- Muscles contain myofibrils which contain sarcomeres
- Muscles contract when myosin in the sarcomere binds with actin
- The sarcoplasmic reticulum produces calcium ions when a nerve impulse arrives
- Calcium ions bind with troponin, a protein present on actin, which causes it to expose the myosin binding site
- A cross-bridge is formed between actin and myosin, with energy being released
- Energy in the myosin head moves the head along the actin, causing to slide across
- ADP is released in the process, causing the myosin to disconnect from the actin to grab more ATP
- This ATP is broken down into ADP and Pi, with the remaining energy being stored in the myosin head
- As a result of this, the sarcomere is shortened, along with other sarcomeres, which causes the whole muscle to contract

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muscle contraction is initiated by the impulse from motor neuron.

muscle is composed of sarcomere, which contains actin and myosin.

action potential triggers calcium released from sarcoplasmic reticulum.

when muscle is relaxing, troponin covers the binding site on actin, to prevent myosin attaches to actin.

cacium ions bind with troponn. causing the troponin to remove from the actin, so that the bind site is exposed.

ATP bind to the myosin, provide the energy to attach to actin.

myosin pull actin(slide cross) so that the  sarcomere is shorten.

myosin is disconnect from actin and attach to a new bind site.

the process is repeated and muscle is contracted

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Explain muscle contraction
-Depolarisation occurs along the muscle fibres
-Calcium ions are released by the sarcoplasmic reticulum
-these calcium ions would then bind to the troponin on the actin, exposing the binding sites of the actin for the myosin heads
-the myosin heads then form a cross-bridge with the actin elements
-atp binds to the myosin heads, causing them to change position from one actin binding site to the other
-this sliding mechanism continues along the actin, pulling the actin along the length of the myosin
-because the actin are attached to the Z line, as the actin are pulled along the length of the myosin, the z line also gets pulled thus shortening the sarcomere
-this causes the whole muscle to contract

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1. calcium ions are released from sarcoplasmic reticulum due to action potential
2.atp attaches to the myosin heads
3. myosin heads bind to actin filaments forming cross-bridge
4.

muscle contraction causes myosin filaments to pull the actin filaments towards the centre of the sarcomere

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1.  Depolarization causes the release of calcium ions
2. The calcium ions bind to troponin and reconfigure the complex, exposing the binding sites for the myosin heads.
3.The myosin heads will then bind onto the actin filaments creating cross-bridges
4. ATP will then bind onto the myosin head to break apart the cross bridge.
5. Hydrolysis of ATP causes the myosin heads to move forward binding to the next site and returning to the original position.
6. This causes the movement of the actin down in a sliding motion.

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Explain muscle contraction [8]
-Depolarisation causes sarcoplasmic reticulum to release calcium ions
-Calcium ions bind to troponin and exposes the binding sites of actin to the myosin heads
-A cross-bridge is formed between myosin heads and actin
-ATP binds to the myosin head causing the cross-bridge between actin and myosin to break
- Myosin heads bind to the new actin sites
-This movement causes the sliding action of myosin along actin
-The Z lines are now closer to the M line
-Sacromere becomes smaller in length

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Explain muscle contraction [8m]
- Muscle fibres compose of myofibrils
- These myofibrils consist of the sarcomere which contains actin and myosin filaments
- Muscle contraction occurs when the myosin filament head forms a cross bridge, attaching to a binding site on actin filaments. This is achieved when a neuron carrying an impulse causes the release of calcium ions from the sarcoplasmic reticulum. The calcium binds to troponin, a protein present on actin causing the movement of tropomyosin, exposing the binding sites on actin.
- Once ATP binds to the myosin head, it detaches from the binding site.
- The heads attach to binding sites at a different location, and the myosin slides along the actin.
- This movement causes the sarcomere to shorten.

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Neurotransmitter from the motor neurone binds to the receptors on the membrane of muscle fibre.

Depolarisation of the membrane of the muscle trigger release of Calcium ion from the sarcoplasmic reticulum to myofibre and bind to troponin on the actin of sarcomere.
This action displaces tropomyosin from the binding site of troponin.

Mitochondria at the myofibre produces ATP which binds to the myosin head of myosin that breaks down into ADP and Phosphate ion that allows the binding of myosin head onto the troponin's binding site forming a cross bridge.

Detachment of ADP and Phosphate ion from the myosin head pulls the actin towards the M line making actin slide past each other.

The myosin head detach from the actin's bind site b after another ATP binds to the myosin head. The ATP breaks down into ADP and Phosphate molecule and the energy will be stored in myosin head.

The sarcomere will be shortened as the actin is pulled towards the M line, making the entire muscle contract.

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- firstly, muscle contraction starts from an impulse from a motor neutron
- then ca2+ ions are released, which bind with proponin that dislocates it so that the binding sites are exposed
- Allowing the myosin head to attach to actin
- With every released from mitochondria, the myosin heads slides the actin
- The myosin heads disconnect to get more ATP

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Explain muscle contraction:
- An action potential occurs in the motor neurone, releasing calcium ions from the sarcoplasmic reticulum due to depolarisation
- The calcium ions proceed to the actin, where it binds to the troponin, exposing the myosin heads, forming a cross bridge that can be broken by ATP
-  ATP hydrolysis occurs that causes the myosin head to change position

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Explain muscle contraction
- It starts when an impulse occurs and causes a release of Ca2+ ions from the sarcoplasmic reticulum
- this is also called repolarization
- on the actin, the binding sites for the myosin heads are covered by troponin and tropomyosin
- The calcium ions then bind to troponin which results the myosin heads to be exposed

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muscle is composed of sarcomere, which contains actin and myosin.

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the muscle structure consists of myofibrils(contains contractile sarcomere), sarcoplasmic reticulum
- the arrival of action potential causes the release of ca2+
-ca2+ binds with troponin, which causes it to move on the actin
-ATP binds to myosin
-impulse travel across the sarcolemma
-actin and myosin bind to form a cross bridge
-myosin pulls the actin inward