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Description
Flashcards by Czean Holgado, updated more than 1 year ago
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Created by Czean Holgado
over 5 years ago
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| Question | Answer |
| What is the first level of structure in a muscle? | -the entire muscle is surrounded by a protective membrane called the Epimysium. |
| What is the second level of structure in a muscle? | Muscle is composed of bundles of muscle fibres, called Fascicles. -These fascicles are surrounded by a membrane called the Perimysium. |
| What is the third level of structure in a muscle? | -Each muscle fibre is surrounded by a membrane called the Endomysium. |
| What is a single muscle fibre composed of? | -it is composed of groups of myofibrils, each surrounded by a membrane called the sarcolemma |
| What are myofibrils? | -Myofibrils are individual muscle fibres containing myosin (thick filament) and actin (thin filament). |
| How does movement happen? | Muscles contract as actin and myosin filaments slide over each other. |
| Why do muscles get smaller as they contract? | -when muscles contract, sarcomeres get smaller -the filaments don't change in length, instead they slide over each other (overlap) |
| What are three different types of muscle fibres? | -Slow oxidative/Type 1/SO -Fast Oxidative Glycolytic/Type IIa -Fast Twitch Glycolytic/FTG |
| Slow oxidative muscle fibres are most suitable for which type of performers? | -Endurance athletes -Low intensity/long duration exercises |
| Fast oxidative glycolytic muscle fibres are most suitable for which type of performers? | -Moderate intensity/moderate duration |
| Fast twitch glycolytic muscle fibres are most suitable for which type of performers? | -Power athletes -High intensity -Short duration |
| What are the characteristics of phosphocreatine? | -high energy source of ATP -provides a very quick release of ATP |
| Which muscle fibre type consists of the most phosphocreatine? Provide an example of a sport/event that would benefit this. | -Fast twitch glycolytic. -Fast explosive movements = 100m sprinter |
| Why don't slow oxidative muscle fibres need lots of PC stores? | -the energy source is slow-releasing |
| Describe what myoglobin is and its function. | -Myoglobin is a binding agent that has a higher affinity for oxygen. -It attracts the oxygen out of the blood stream and transports it to the mitochondria in order for it to be used as energy |
| What gives muscle fibres their red colour? | -Myoglobin, which is an iron based protein. |
| Which muscle fibres need oxygen as a critical element and why? | Slow oxidative muscle fibres have the highest amount of myoglobin as they need oxygen to function - oxygen provides slow but high amounts of energy for a long duration. |
| What are mitochondria? | -these are known as the powerhouses of the cell, which plays a central role in the production of ATP in aerobic conditions. -they act like a digestive system that that takes in nutrients, breaks them down, and converts energy in the form of ATP |
| What is the neuromuscular system? | -This is composed of all the motor units, muscles, and nerves that work together. |
| What are the stages involved in the chain of command? | -Environmental information gets sent to the brain -The brain converts the thought process into an electrical impulse from the brain down through the CNS |
| What is the function of dendrites? | -acts as a communication channel by branching out and picking up the electrical impulse |
| What is the function of the axon? | -carries electrical messages to the muscle fibre |
| What is the function of the myelin sheath? | -allows rapid conduction of impulses, protecting the impulse from getting lost. |
| What is the function of the nodes of ranvier? | -allows the impulse to jump from node to node to speed up the impulse |
| What is the neuromuscular junction? | -this is where the axon terminal and the motor end plate meet |
| When the electrical impulse reaches the motor end plate, it is converted into what? | -It turns into a chemical messenger, in the form of acetylcholine |
| What is the all or none law? | -It is the principle that all muscle fibres in that specific motor unit will contract if there is enough action potential -If there is NOT enough action potential, then no muscle fibres will contract -Either all of the muscle fibres contract, or none of them will. |
| What is a motor unit? | A single motor unit is made up of a motor neuron and all the muscle fibres it controls. Motor units can contain of any amount of muscle fibres. |
| Name the four types of the motor neuron firing patterns. | 1) Graduation of contraction 2) Wave Summation 3) Absolute/Tetanic Contraction 3) Spatial Summation |
| What is Tetanic/Absolute Contraction? | -This is when all the motor units in a muscle are contracting/being recruited - all the muscle fibres are contracting maximally for a continuous amount of time |
| What is Wave Summation? | -This is when motor units are being recruited more frequently, so there is less time for motor units to recover. The strength of contraction increases as more motor units are recruited |
| What is Spatial Summation? | -This is when not all motor units are recruited at the same time. Some motor units are recruited while some are off, allowing them to recover. -This allows constant, low level force of contraction. |
| What is Graduation of Contraction? | -This is when we have a conscious thought of specifically how many motor units to recruit to allow an effective contraction -This is developed through practise and is otherwise known as muscle memory - this helps in the prevention of fatigue (there is not a surplus amount of motor units being recruited) |
| What is the structure of a muscle fibre? | -Numerous myofibrils -Sarcolemma (membrane of muscle cell) -Sarcoplasm (cytoplasm of muscle cell) -Many mitochondria -Transverse tubules -Sarcoplasmic Reticulum -Many nuclei |
| What is the function of transverse tubules? | -These carry the action potential to the sarcoplasmic reticulum, triggering the release of calcium ions. |
| What is a sarcomere? | -Sarcomeres are made up of thin and thick protein filaments -actin and myosin. Each sarcomere is seperated from the next by Z lines. |
| Name and describe the different bands found in a sarcomere. | I band - this is the light area that consists only of the filament actin A band - this is the dark area that consists of both actin and myosin. H zone - only myosin is found in this area, found centrally. |
| Explain how actin and myosin filaments in the sarcomere bind together to cause muscular contraction. | -Initially the filaments are unable to bind due to tropomyosin (protein that winds around actin) -A nerve impulse is sent to the myofibril via transverse tubules. -The action potential triggers the release of calcium ions via the sarcoplasmic reticulum. -The calcium ions attach to the troponin, causing it to change shape, moving the tropomyosin -This exposes the binding site on the actin filaments, allowing the myosin heads to attach and bind to the actin. -Cross bridges are formed between actin and myosin. -The myosin heads pull on the actin, meaning Z lines come closer together, shortening the muscle causing contraction. |
| Define the term 'power stroke'. | -This is the process of a singular contraction, where myosin heads pull on the actin. |
| Define the term 'ratchet mechanism'. | -This is the continuous action of myosin heads pulling on the actin filaments - causing constant contraction. |
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