7A- Muscles and Movement Flashcards
(24 cards)
What is skeletal muscle?
The type of muscle which allows you to move.
What attaches skeletal muscles to bones?
Tendons
What hold bones together?
ligaments
Muscles which contract to straighten out the bone are known as?
Extensors
Muscles which contract to bend a joint is known as a?
Flexor
What are antagonistic pairs?
Explain what they do.
They are muscles which work in opposite directions, and work together to move a bond. For example, the bicep is a flexor, is moves the arm so that it bend, and whilst this occurs the tricep relaxes. When the arm straightens, the bicep relaxes and the tricep contracts.
How is a muscle highly adapted for its role?
Skeletal muscle is made up of long bundles of long cells, called muscle fibres. These muscle fibres have a membrane called the sarcolemma, this membrane folds inwards at a point known as the transverse T tubules. (These T tubules are able to transmit electrical impulses to the internal structures of the muscle fibre by means of the sarcoplasmic reticulum, where calcium ions involved in muscle contraction are released).
Muscle fibres have lots of mitochondria so that they can release lots of ATP for respiration. They contain myofibrils, which are long cylindrical organelles which contain highly specialised proteins for contraction.
They are multinucleated, so that they can produce many of such proteins.
What make up myofibrils?
Thick Myosin Filaments
Thin Actin Filaments.
Which of the two filaments in a myofibril appear dark under an electron microscope?
Which appear light?
The thick myosin filaments appear dark
The thin actin filaments appear light.
What is a unit of such small specialised proteins called?
A sarcomere.
Name all the different areas within a sarcomere.
The Z line- The end of each sarcomere
The actin filament
The myosin filament
The H zone- the zone where only myosin resides. It also looks like the gaop between the two filaments.
The A band- The length of the Myosin, which may include some overlapping actin depending on the extent of muscle contraction.
The I band- The length of the actin filament which isnt overlapping the myosin filament.
M line- This is the middle of the sarcomere
The phrase involving simultaneous contraction
The simultaneous contraction of sarcomeres when actin slides over myosin causes the myofibrils and the muscle fibres to contract, and therefore the skeletal muscle its self.
What do muscles contain?
BUNDLES of muscle fibres
Explain the sliding filament theory!
When the T tubules induce the sarcoplasmic reticulum to release calcium ions after receiving an action potential, these calcium ions travel to the actin filament where they bind to troponin. The troponin is attached to a protein called tropomyosin, which undergoes a confirmational shape change. It is no longer blocking the myosin head binding sites on the Myosin filament, and therefore the globular myosin head is able to bind to it. Here, a myosin-actin cross bridge is formed. The ATP and inorganic phosphate group attached to the myosin head release from the myosin, releasing energy when doing so, causing the myosin head to ‘nod’ forward, and a power stroke occurs, where the actin filament slides over the myosin filament. ATP then binds to the myosin head, and causes the myosin head to detach from the actin. The enzyme ATPase attached to the myosin head hydrolyses the ATP and breaks it down into ADP and an inorganic phosphate. This causes the myosin to change back to its original shape. It can then rebind if need be to continue with muscle contraction.
Compare and contrast:
Fast Twitch
Slow twitch
Fast Twitch:
Fast twitch muscle fibres are designed for short bursts of speed, and therefore contract fast. They release a short intense burst of ATP, but fatigue quickly. They have few mitochondria or blood vessels, but release their ATP through anaerobic respiration using glycogen (stored glucose). They appear white in colour, and this is due to a lack of myoglobin (they don’t store much oxygen)
Slow twitch:
They are designed for endurance activities. They are found mainly in support muscles such as muscles involved in posture. They release ATP slowly, through anaerobic respiration. They contract slowly, and can do this for a while. They have a good supply of oxygen/are very vascular. They are red in colour due to the presence of myoglobin which stores oxygen.
Glycolysis
Glucose – 2x triose phosphate
2x triose phosphate – 2xpyruvate
NET 2 ATP
Link reaction
Pyruvate(3C) — Acetate (2C) CO2 leaves
Acetate —- Acetyl coenzyme A
Krebs cycle
Acetyl coenzyme A reacts with a 4C acceptor molecule, forms a 6C molecule —- 5C molecule when CO2 leaves and NAD goes to reduced NAD —- 4C molecule again when 2NAD goes to 2 reduced NAD FAD goes to Reduced FAD and ADP and Pi go to ATP and CO2 leaves.
Oxidative phosporylation
Reduced coenzymes Reduced FAD and reduced NAD are oxidised. The hydrogen atom they release splits into H+ ion and electons. The electrons move into the electron carrier proteins and and move down the electron transport chain, where their energy is used to power the movement of H+ ions into the intermembranal space from the matrix of the mitochondria. This increases the concentration of H+ ions in the intermembranal space, so that they are forced to diffuse down the concentration gradient through ATPsynthase, where ATP is made from ADP and Pi. This process is known by chemisomosis.
What is the number of ATP made per glucose molecule?
38
Devise an experiment to determine the rate of respiration of an organism by using a respirometer.
Set up the respirometer apparatus To have a test tube with wood lice suspended on gauze over a solution of sodium hydroxide solution (this solution will absorb any carbon dioxide). Have the test tube connected by tube to a manometer with a coloured liquid and a calibrated scale, connecting to a control tube with an equal volume anf concentration of potassium hydroxide solution and the same mass of inert rocks. Use the syringe to move the liquid to a desired position, and then leave the apparatus for 20 minutes to allow to woodlice to respire. After the time has passed, measure any distsnce travelled by the liquid, this will be as a result of the woodlice respiring, because they will use Oxygen (the final acceptor molecule) to respire, which will decrease the volume of air in the tube, and will force the liquid to move towards the test tube. The experiment should be repeated, to get a more valid conclusion. Relevant variable such as temperature should be controlled.
Explain anaerobic respiration.
This occurs when there is a lack of oxygen. This means that oxidative phosphorylation, the krebs cycle and the link reaction cannot occur because the reduced coenzymes arent recycled. Instead, pyruvate is converted to lactate during glycolysis, which recycles reduced NAD to produce NAD, which can allow for glycolysis to occur, and for some (although a small amount) ATP to be produced still, so some basic metabolic processes can still occur.
How is lactic acid broken down?
By liver cells when they convert it back to glucose (which can be respired and stored).
By cells when they convert the lactic acid back to pyruvate, which re enters at the krebs cycle)
