List the hierarchy of a Muscle:

Muscle Tissue --> Muscle Fiber Bundle --> Single Muscle Fiber (One cell) --> Myofibrils --> Sacromeres made of Actin and Myosin.

Describe the Structure of a Muscle Fiber:

Contain Mitochondria for respiration, Myofibrils made of Sarcomeres which are surrounded by Sacroplasmic Reticulum.

What are they two proteins involved in Sliding Filament Theory:

Myosin (thick fibers) and Actin (thin Fibers).

Describe the structure of Myosin:

Myosin is a protein with many 'Heads' on it which it uses to bind to Actin to cause Actin to contract.

Describe the structure of Actin:

Actin is a protein which resembles a double helix of diamonds, is surrounded by two proteins called Tropomyosin and Troponin which block Myosin from binding to Actin. Actin is the fiber which contracts.

What is the membrane that surrounds a sarcomere and how is it involved in muscle contraction:

This is the Sarcoplasmic Reticulum and it is capable of pumping Ca2+ ions from the Sarcomere into itself to maintain a high concentration gradient.

What sets off a muscle contraction:

An action potential from a Motor Neuron.

What happens when an action potential arrives at the Sarcomere:

The SR will release Ca2+ ions into the sarcomere, which bind to Troponin which alters the shape of Tropmyosin, allowing Myosin to bind to Actin, release ADP+Pi using that energy to bend, contracting the actin.

Once the Myosin has done its Power Stroke, what happens:

The Myosin contains ATPase which is used to Hydrolyse an ATP molecule to ADP+Pi, which binds to the Myosin again, causing Myosin to release actin and return to its original state ready to go again.

If no Action Potential is maintained what happens after the power stroke:

The Ca2+ ions will be pumped into the Sarcoplasmic Reticulum and the muscle will relax.

Fast Twitch Muscle Fibers:

These are designed to cause very quick, short contractions (eyes, Sprinting), they contain a lot of Myosin, ATPase and respire Anaerobically, thus do not have much Myoglobin (appearing white), few blood vessels and Mitrochondria and glycogen stores .

Why are fast twitch muscle fibers only able to produce short term contractions?

This is because they respire anaerobically and thus build up a large amount of Lactic Acid quickly and cannot produce a large amount of ATP over time (but can do very quickly for short time). They fatigue quickly.

These are muscles that straighten a joint when contracted.

These are muscles which bend a joint when contracted.

The location where two bones meet, there are many types of joints (Ball and Socket, Hinge joint etc).

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Muscle Contraction

Skeletal Muscle Contraction Sliding Filament Theory

Question	Answer
List the hierarchy of a Muscle:	Muscle Tissue --> Muscle Fiber Bundle --> Single Muscle Fiber (One cell) --> Myofibrils --> Sacromeres made of Actin and Myosin.
Describe the Structure of a Muscle Fiber:	Contain Mitochondria for respiration, Myofibrils made of Sarcomeres which are surrounded by Sacroplasmic Reticulum.
What are they two proteins involved in Sliding Filament Theory:	Myosin (thick fibers) and Actin (thin Fibers).
Describe the structure of Myosin:	Myosin is a protein with many 'Heads' on it which it uses to bind to Actin to cause Actin to contract.
Describe the structure of Actin:	Actin is a protein which resembles a double helix of diamonds, is surrounded by two proteins called Tropomyosin and Troponin which block Myosin from binding to Actin. Actin is the fiber which contracts.
Tendons:	Attach muscles to bones.
Ligaments:	Attach bones to other bones.
What is the membrane that surrounds a sarcomere and how is it involved in muscle contraction:	This is the Sarcoplasmic Reticulum and it is capable of pumping Ca2+ ions from the Sarcomere into itself to maintain a high concentration gradient.
What sets off a muscle contraction:	An action potential from a Motor Neuron.
What happens when an action potential arrives at the Sarcomere:	The SR will release Ca2+ ions into the sarcomere, which bind to Troponin which alters the shape of Tropmyosin, allowing Myosin to bind to Actin, release ADP+Pi using that energy to bend, contracting the actin.
Once the Myosin has done its Power Stroke, what happens:	The Myosin contains ATPase which is used to Hydrolyse an ATP molecule to ADP+Pi, which binds to the Myosin again, causing Myosin to release actin and return to its original state ready to go again.
If no Action Potential is maintained what happens after the power stroke:	The Ca2+ ions will be pumped into the Sarcoplasmic Reticulum and the muscle will relax.
Fast Twitch Muscle Fibers:	These are designed to cause very quick, short contractions (eyes, Sprinting), they contain a lot of Myosin, ATPase and respire Anaerobically, thus do not have much Myoglobin (appearing white), few blood vessels and Mitrochondria and glycogen stores .
Why are fast twitch muscle fibers only able to produce short term contractions?	This is because they respire anaerobically and thus build up a large amount of Lactic Acid quickly and cannot produce a large amount of ATP over time (but can do very quickly for short time). They fatigue quickly.
What are the two types of Antagonistic Muscles	Extensors and Flexors.
Extensors:	These are muscles that straighten a joint when contracted.
Flexors:	These are muscles which bend a joint when contracted.
Joints:	The location where two bones meet, there are many types of joints (Ball and Socket, Hinge joint etc).
Ligaments:	Join bones to bones.
Tendons:	Join muscles to bones.

Created by: mjwilson1988

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