Muscles Flashcards
What is the role of Calcium?
What is the role of ATP?
Moves/changes the position/shape of the troponin/protein/tropomyosin uncovering the binding site allowing cross bridges to form.
Energy source enables formation of actomyosin cross bridges and movement of myosin head
Sliding filament theory
Explain
Nerve impulse reaches muscle fibre
AP travels across memb and deep into interior down transverse tubules
Adj sarc rect memb temporarily permeable to Ca
Ca into sarcoplasm of myofibrils
Ca binds to topin in actin
Changes shape displaces tropomyosin blocking binding site
Ca activates myosin hydrolyse ATP
Myosin moves toward binding site of actin using energy from hydrolysis
Cross bridges form
Myosin heads bind +tilt pulling actin past
Myosin detach and reattach
Muscle contracts
Stream AP stops
Sarc rect stops releasing Ca
Ca pumped back into sarc rect
How does the muscle cell contract?
Myosin head changes shape
Works like a ratchet
Moving actin and myosin filaments past each other
What is the role of phosphocreatine?
Can quickly synthesise ATP from ADP anaerobically
Vertebrate Skeletal Muscle
What can’t move without?
What does it provide main source of power for?
Three properties of skeletal muscle?
What are these?
What does voluntary mean?
Leavers and joints
Human locomotion
1) excitability-receive and respond to stimuli
2) extensibility-can stretch and contract
3) elasticity-can return to original shape
Can contract when we want
Antagonistic Muscle What can muscle only do and not do? How do muscles usually act? What does contraction of a muscle move? What does the second muscle do? What's an example?
Pull or contract can't push In a group Bone of a joint Returns to original position Bicep and tricep when one bend the other stretched out
3 types of muscle?
A little info about each
Cardiac- myogenic and doesn’t tire
Smooth- involuntary
Skeletal- attached to bones
Muscle Structure
What is a muscle composed of?
How are they bonded together?
What are they then?
What does it have an extensive supply of?
What spread throughout muscle fibres?(2)
What do stretch receptors monitor?(2)
What do ends of muscle have? What do they form and what do they attach?
What are tendons not? But what do they contain?
Muscle fibres
By sheath of connective tissue
Bundled further
Nerves and blood
Motor nerve endings and an extensive network of stretch receptors
Degree of stretch and how quickly muscles are changing length
Collagen and connective tissue form tendons attach muscle to bones
Not contractile but have stretch receptors
Fibres Structures
What does each fibre have?
What are there numerous of within each muscle? What do these show?
What do myofibrils contain?(2) their names?
What is packed between?
What do they have little of? What do they have more of?
What does this have a network of and what does this contain?
What’s the name of its membrane?
What are transverse tubules?
Are fibres long or short? And what do they contain many of?
Motor neurone end plates Myofibrils cross striations Proteins actin and myosin Mitochondria Cytoplasm sarcoplasm Sarcoplasmic reticulum large amounts Ca2+ Sarcolemma Long tubular indentations running at right angles Long and nucleus
Muscle tissue to micro filaments?
What are the microfilaments?
Muscle tissue > muscle fibres > myofibrils > microfilaments
Actin/myosin
Striations What is the sarcomere? What is the z line? What is the H line? What does the dark band consist of? What does the H zone consist of? What is in the light band? What is the I band? What is the A band? How does it appear when viewed under a light microscope? What do you view it under to see it more clearly?
Distance between 2 z lines Protein that holds actin together Protein that holds the myosin together Both actin and myosin and myosin alone Just actin Light band Dark band Striated Electron microscope
Thick filaments What are the thick filaments? What are the capable of doing? With energy from what? What does this cause? What are they held together by? What does it consist of?(2)
Myosin Changing shape with energy from hydrolysis of ATP to ADP Contraction Protein H line Myosin head and filament
Thin Filaments What is it of? What is it a polymer of? What is it held by? How many actin are there to myosin when they overlap?
Actin
Globular protein
Protein z line
6:1
Sliding filament theory
What is it?
Actin filaments slide between myosin filaments using energy from ATP
Sequence of sliding filament theory (16)
Nerve impulse reaches muscle fibre
AP travels down transverse tubules
Causes membrane of adjacent sarcoplasmic reticulum to become temporarily permeable to Ca2+
Ca2+ flow into cytoplasm of myofibrils
Ca2+ binds to proteins troponin on actin causing to change shape
Myosin uses energy from hydrolysis of ATP to move towards binding site of the actin forming cross bridges
As the myosin head binds it tilts pulling the actin past
As actin moves the myosin head detaches and reattaches to the next binding site using energy to form ATP from hydrolysis
Muscle contracts
Stream of AP across sarcolemma stops
Sarcoplasmic reticulum stops releasing Ca2+
Ca2+ levels return to original level
Troponin and myosin move back to original position
Contraction seases
