Sliding Filament Theory - fr

What is the sliding filament theory?

An explanation of how the muscle contracts, by the sliding past each other of proteins in the muscle, pulling the sarcomere/contracting

What is a myofibril

An organelle, a thread like contractile unit

Makes up 80% of muscle

What is a sarcoplasm?

The cytoplasm of the muscle, containing organelles, glycogen, mitochondria etc

What is a sarcolemma?

The outer membrane of a muscle cell - still has phospholipid bilayer

• main purpose is to control the action potential for contractions function

• Contains ion channels controlling action potential

• Transmits neural activity

• Maintains internal environment

What is fasciculus?

A bundle of muscle cells surrounded by perimysium

What is the Endomysium?

Delicate sheath surrounding individual muscle fibre (cell)

Connective tissue

Its the end bro just at the smallest point, no more ygm

What makes up an individual muscle fibre?

• surrounded by endomysium

• myofibrils

• Sarcoplasm

• Multinucleated

• Sarcoplasmic Reticulum

• Mitochondria

• Myofilaments & T tubules (on muscle fibre/myofibril)

What is the Epimysium?

Outer layer of dense connective tissue surrounding entire muscle

Think epic #sobig its the outside

What is the perimysium?

Thick layer of connective tissue surrounding groups of muscle fibres

Think piri seasoning needs to go deeper than just sit on tip

What is a fascicle?

Bundles of muscle fibres

What terms do we use to describe sarcomeres in more detail?

Bands, discs and lines

When looking at muscle underr a microscope what do we see?

Mainly myosin (thickest) and actin

What proteins do we find in the sarcomere?

Myosin

Actin

Troponin

Tropomyosin

Myosin role

Creates movement

Mysoin structure

2 Heads - contain ATP enzyme, ATP attaches to head, breaks down into ADP

Hinge Region

2 Tails

Troponin and Tropomysin

Sit between actin, decide whether ectin will contract

What causes muscle contraction

At the sarcomeres: The heads of mysoin attach to actin filaments, form cross bridges and walk down the filament, forming Z

Neural stimulus: Somatic nervous system releases acetyl colene to stimulate muscle fibres and create action potential, this triggers calcium release in muscle cells

ATP must be available for energy, to make myosin move

Neuromucular junction - the end of a peripheral motor neuron meets a muscle fibre

Describe the process of excitation step - by - step

Neuron Signal is sent by the brain through the spinal chord through to the nerve endings

1 - An action potential rises at the Axon Terminal

2 - This causes the Na+ channels to open, Na+ enters through Na+ channels

3 - This causes Ca2+ channels to open, Ca2+ enters Ca2+ channels

4 - The Ca2+ allows the vesicles to move (vesicles contain neurotransmitter acetylcholene)

5 - Via exocytosis, neurotransmitters released across synaptic cleft

6 - Acetylcholene binds to ligand gated receptors on post-synaptic cell

7 - this causes Na+ to enter myofibril which increses the positive charge AKA excitation AKA depolarisation

8 - this excitation travels across sarcolemma (muscle membrane) into T-tubule

9 -

Describe the sliding filament theory step-by-step

1 - The depolarisation goes into T-tubule, into the sarcoplasmic reticulum

2 - this triggers the release of Ca2+

3 - The calcium binds to the troponin, causing it to change shape and move the tropomyosin off the binding site

4 - this allows the binding heads on myosin to bind to the binding sites on actin

5 - ATP allows the binding heads to relax, bind, pull (pulling it closer)

What is it called when the binding heads of myosin are attached to the binding sites of actin?

Cross - bridge

What is the z-line? M line? A band? I band?