T7 - Run for your life Flashcards
Define a joint
- the physical point of connection between 2 bones
- the point at which 2 or more bones articulate
What is a ligament
- connect bone to bone and help stabilize joints they surround
- composed of long, collagen fibres
- that create bands of tough, fibrous connective tissue
- slightly elastic, increasing flexibility
- can become overstretched
What is a tendon
- tough and inelastic bands of fibrous tissue that attach skeletal muscles to bone
What is cartilage
- firm, flexible tissue that acts as a shock absorber and reduces friction
What does the flexor muscle do
- bends a joint (decreases angle between 2 bones)
What does the extensor muscle do
- straightens a joint (increases angle between 2 bones)
Define antagonistic muscles
- when two muscles work in a pair, one contracts as the other one relaxes to allow movement
- e.g. bicep and tricep
Examples of joints
- ball and socket joints - shoulders and hips
- pivot joints - neck
- hinge joints - knee and elbow
Why are muscle cells multinucleated
- for sufficient mRNA and so that mRNA is in the right place for translation into proteins
- proteins can be synthesised close to the site of function so less need for transport over large distances
- more efficient
Where are the mitochondria located in a muscle cell
right beside / under the sarcolemma
Why are the mitochondria not located within the myofibrils?
- they would be in the way of the contracting microfibril
- it takes longer for blood to reach the microfibril
Properties of fast twitch muscles
- fast speed of contraction + short bursts of movement
- strong power of contraction
- a short length of contraction
- adapted for activities that require power and speed
- white in colour
Properties of slow twitch muscles
- slow speed of contraction + gently
- weak power of contraction
- long lengths of contraction
- adapted for endurance activities
- dark red in colour
Why are chicken breasts white in colour
- they are fast twitch muscles
- they don’t need much myoglobin and oxygen
- as they respire anaerobically
- few blood vessels
Why is duck meat dark red in colour
- they are slow twitch muscles
- they need lots of myoglobin and oxygen
- as they respire aerobically
- lots of blood vessels
Why do fast twitch muscles have fewer mitochondria
- it has a bigger store of glycogen than glucose
- energy from the hydrolysis of glycogen is used instead of ATP from mitochondrial
- respire anaerobically
- it uses creatine phosphate to produce ATP from ADP for energy
Why do slow twitch muscles have more mitochondria
- it has a bigger store of glucose than glycogen
- ATP from aerobic respiration is used as energy
In muscles cells, is actin thick or thin
Thin
In muscles cells, is myosin thick or thin
Thick
A band in muscle cells contains what
Both myosin and actin
I band in muscle cells contains what
Only actin and Z line
What is rigor mortis and how is it caused?
- stiffening of the joints and muscles of a body a few hours after death
- because there is no aerobic respiration after death ATP is not made
- as there is no ATP to detach the myosin heads, the muscles remain contracted
Sliding filament theory process
- An action potential arrives at the neuromuscular junction
- Calcium ions (Ca2+) are released from the sarcoplasmic reticulum
- Calcium ions bind to troponin molecules, stimulating them to change shape
- This causes troponin and tropomyosin proteins to change position on the actin filaments
- Myosin binding sites are exposed on the actin
- The globular heads on the myosin molecules bind with these sites, forming cross-bridges between them
- The formation of the cross-bridges causes the myosin heads to bend
- Releasing ADP and Pi, pulling the actin filaments towards the centre of the sarcomere
- ATP binds to the myosin heads producing a change in shape that causes the myosin heads to release from the actin filaments
- The enzyme ATPase hydrolyses ATP into ADP and Pi which causes the myosin heads to move back to their original positions, known as the recovery stroke
- The myosin heads can now bind to new binding sites on the actin, closer to the Z line
- The myosin heads move again, pulling the actin filaments closer to the centre of the sarcomere.
Ethical reasons why the use of drugs should be banned from sport
- it can be a health risk to the athletes
- not fair to other athletes who do not use drugs
- pool role model to young kids