Muscles Flashcards
3 types of muscle
Smooth = contracts without conscious control. Found in wall of internal organs
2. Cardiac = contracts without conscious control (myogenic ) and only found within heart
3.Skeletal = used in movement and can only pull
Structure of skeletal muscle
Sarcolemma = cell surface membrane
Lots of mitochondria
Sarcoplasm = cytoplasm
Sarcoplasmic reticulum = modified endoplasmic reticulum
Myofibril = made from sarcomere which consists of actin and myosin = where contraction happens
Sacromere
Thin myofilament = actin
Thick myofilament = myosin
T tubule
Draw and label everything on a sarcomere
M - line = middle
Z- line
Whole thing = myofibril
H -zone
I - band
Z - disc
One square = sarcomere
What does everything in labelled muscle stand for ? ( IHAD)
Z - disc= actin filaments are connected
M line = middle line
I= I band = actin only
H - zone= myosin only where actin and myosin DONT overlap
A - band = actin and myosin
In a muscle contraction what happens to each structure in myofibril
- Depolarisation of pre-synaptic membrane at presynaptic knob of a motor neuron causes calcium 2+ voltage gated channels to open.
- Influx of calcium 2+ ions by facilitated diffusion into sign synaptic knob
- Calcium 2+ activate enzymes which causes vesicles contains acetylcholine to fuse with the pre synaptic membrane
- Vesclies leave the membrane by exocytosis using ATP and they diffuse across the synaptic cleft
- Bind to complementntary acetylcholine receptors on sarcomere
What is a neuromuscular junction?
Morton neuron attached to a muscle ( sarcolemma )
Describe events on the synapse that allow for transmission of nerve impulse neuromuscular junction?
- Depolarisation of pre-synaptic membrane at presynaptic knob of a motor neuron causes calcium 2+ voltage gated channels to open.
- Influx of calcium 2+ ions by facilitated diffusion into sign synaptic knob
- Calcium 2+ activate enzymes which causes vesicles contains acetylcholine to fuse with the pre synaptic membrane
- Vesclies leave the membrane by exocytosis using ATP and they diffuse across the synaptic cleft
- Bind to complementntary acetylcholine receptors on sarcolemma .
- Sarcolemma is folded to increase surfaced area for more receptors.
- This cusses sodium ion voltage gated channels to open and influx of sodium ions enter by facilitated diffusion into sign
- Threshold is reached and depolarisation of Sarcolemma due to all or nothing principle
- Action potential travels down t tumble which runs deep into the muscle.
- Sarcoplasmic reticulum has a high concentration of calcium 2+ ions and their gated channels opens and calcium 2+ ions diffuse out by facilitated diffusion into the Sarcoplasmic cusses muscle to contract
Describe the sliding filament theory ?
- Calcium 2+ ions from Sarcoplasm bind to troponin molecules on actin which causes them to change shape, this moves the tropomysosin away from the actinomysin binding sites so they are exposed on the actin
- Myosin head groups binds to actinomysin binding sites and form a actionomysin cross barge
- Head changes its angle and pulls actin along, also the ADP molecule is released from the myosin head
- Molecule of ATP attaches to myosin causing it to detach from the binding sites
- Myosin head acts as a ATPase by hydrolysing ATP into ADP and pi which is activated by calcium 2+
- Energy from ATP hydrolysis is used to return myosin head to its original angle
What is the role of calcium 2+ ions in the sliding filament model of muscle contraction?
Calcium 2+ diffuses into myofibril from Sarcoplasm
Causes movement of tropomyosin to expose myosin head binding sites on actin which causes
Allows myosin head to attach to exposed binding site forming actinomysin cross bridge
Activates ATPase allowing hydrolysis of ATP to release energy
What is the role of glycogen in the sliding filament model of muscle contraction?
Glycogen is a polymer of glucose that can be high realised to release glucose for glycolysis in respiration to provide ATP
Describe and explain how creatine can help athletes in regards to the sliding filament model?
Creatine used to form phosphocreatine
Phosphocreatine stores phosphate which can combine with ADP to form ATP
ATP used to detach myosin from actinomysin Cross bridge and used to return my accent into its original angle.
Describe and explain how carbohydrate loading can help athletes in regards to sliding filament model?
Carbohydrate loading converted and stored as glycogen
Glycogen hydrolysed into glucose
Glucose used in glycolysis in both anaerobic and aerobic respiration to produce ATP
Slow twitch muscle fibres vs fast twitch muscle fibres
- Use during longer term exercise with sustained contraction and in calf muscles for posture vs used fir short term exercise with rapid contraction such as weight lifting
- Aerobically respires only so no lactic acid for fatigue vs anaerobically respires so fast ATP production
- Lots of mitochondria vs little mitochondria
- Little phosphocreatine vs lots of phosphocreatine that can be rapidly used up to regenerate ATP
- Higher concentration of myoglobin which has a higher affinity to oxygen to more oxygen loads and has a very red colour vs little myoglobin so little red colour
- Slow rate of fatigue vs faster rate of fatigue
7.Lots of capillaries so shorter diffusion pathway for oxygen and glucose vs higher content of glycogen so quick source of glucose fir glycolysis
