Topic 7: Run for your Life Flashcards
What are ligaments?
Tough, elastic connective tissue, which attach bone to bone. They provide stability
What are tendons?
Touch elastic connective tissue comprised of collagen and fibres which attach muscle to bone.
What are antagonistic muscle pairs?
A pair of muscles that work together to produce a movement. As muscles are only capable of contracting or pulling they operate in pairs to produce movement: when one of the muscles contracts (extensors) and the other relaxes (flexors)
What is the role of an extensor in muscle movement?
In an antagonist pair the muscle that contracts and shortens is the extensor.It is known as the agonist.
What is the role of the flexor in muscle movement?
In an antagonistic pair muscle that relaxes and lengthens is the flexor. It is known as the antagonist.
What is cartilage?
This is tough, elastic tissue found in joints between bones. It is responsible for protecting the skeletal systems acting as shock absorbers.
What is a skeletal muscle?
Skeletal muscles are the muscles in the body that are attached to the skeleton. They are made up of muscle fibres.
What is sarcolemma?
This is the cell membrane that surrounds muscle fibres. They have deep tube like projections that’s fold in forms it’s outer surface known as T - tubules, which help disperse impulses to different parts of the muscle fibres.
What is sarcoplasm?
This is the cytoplasm found in muscle fibres. It gives the cell shape and contains mitochondria and myofibrils that perform cell reactions.
What is the sarcoplasmic reticulum?
This is a double membrane organelle which act like the endoplasmic reticulum. The membrane of the SR contains protein pumps that transport and release calcium ions for muscle contraction.
What is a myofibril?
Long cylindrical organelle in muscle fibres located in the sarcoplasm. They consist of sarcomeres (monomer unit)
What are sarcomeres?
These are the monomer units that make up microfibrils. They contain myosin filaments, actin filament, tropomyosin and troponin.
What are myosin filaments?
These are thick myofilaments made of the protein myosin. They have hinged globular heads that contain actin binding sites and ATL binding sites. They enable muscle contraction.
What are actin filaments?
These are thin myofilaments made up of the protein actin. They have actin-myosin binding sites for the hinged globular myosin heads.
What is tropomyosin?
This is a protein that is found between thin actin filaments. They bind to actin-myosin binding sites preventing muscle contraction when the muscles if at rest.
What is troponin?
This is a protein that is found between thin actin filaments. Troponin holds tropomyosin in place when tropomyosin binds to the actin-myosin binding sites.
What are the two types of muscle fibres?
- fast twitch
- slow twitch
Humans muscles are made up of both fibre and each muscle have different proportions of each depending in their function.
What are fast twitch muscle fibres?
Fast twitch muscles connect rapidly, with the myosin heads bind and unbind from the the actin binding sites five times faster than slow twitch muscle fibres. They are suited to short bursts of high intensity activity as they fatigue quickly due to lactate production.
E.g. human eyelids
What are slow twitch muscle fibres?
Slow twitch muscle fibres contract more slowly and are suited to sustained activity (walking). They fatigue less quickly due to less lactate production making them good for endurance.
E.g. Human back muscles
What are the main characteristics of slow twitch muscle fibres?
- rely on aerobic respiration for ATP
- contain many capillaries (increasing blood flow)
- contain many many mitochondria
- low glycogen content
- they are redder as contain high amounts of myoglobin
What are the main characteristics of fast twitch muscles?
- fewer capillaries (reduced blood flow)
- white in coconut as don’t have much myoglobin
- ATP supplied from anaerobic respiration
- fewer smaller mitochondria
- large stores of calcium ions
- large amount of glycogen
What is the structure of thick muscle filaments?
The thick filaments within a myofibril are made up if myosin molecule
- these are fibrous proteins with a globular head
- fibrous part of the myosin molecule anchors the molecule into the thick filament
What is the structures of thin muscle filaments?
The thin filaments are made up of actin molecules
- they are globular protein molecules
- they link together to form a chain , with two chains that twist together to form one thin filaments
- tropomyosin is twisted around the two actin chains
- troponin is attached to the chains as regular intervals
What is the process of muscle contractions?
- Motor neurones transmit impulses from the CNS to the effector cells (muscle cells). This creates an action potential between a motor neurone and muscle fibre
- Calcium ions are released from the sarcoplasmic reticulum (SR)
- The calcium ions bind to troponin molecules on actin filament stimulating them to change shape
- This causes troponin and tropomyosin proteins to change position on actin filaments exposing the myosin binding sites.
- The globular heads of the myosin molecules bind with these sites, forming cross-bridges between the two types of filament.
- The formation of the cross bridges causes the myosin heads to nod forward pulling the actin filament towards the centre of the sarcomeres (it shortens) and ADP and Pi are released and muscle is contracted.
- ATP binds to ATP binding sites on the hinged globular myosin heads. This breaks down the actin myosin cross bridges causing the myosin to detach form the actin.
- The enzyme ATPase hydrolyses ATP into ADP and Pi causing the the myosin heads to move back to their original positions.
- As long as troponin and tropomyosin are not blocking the Muslims binding sites and the muscles has a supply of ATP, this process repeats until the muscle is fully contracted.
- Once muscle contractions stop, calcium ions leave their binding sites in the troponin molecule and actively transport back to SR.