Lecture 25: Skeletal Muscle: Structure & Function Flashcards Preview

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Flashcards in Lecture 25: Skeletal Muscle: Structure & Function Deck (15)

Why do we need cardiac muscle?

- The main function is to contract and make sure that the heart is pumping blood


Why do we need smooth muscle?

- For the control of movement of fluids contraction = movement of blood, urine, digested food


Why do we need skeletal muscle?

- To move
- Maintain posture
- Heat generation (numerous + highly active)


Structure of Skeletal Muscle

- Muscle
- Muscle bundle
- Muscle Fibre / Myocyte / Muscle Cell
- Myofibril
- Sarcomere
- Myofilaments


The skeletal muscle cell membrane is called the....and the cytoplasm is called...

- Sarcolemma
- Sarcoplasm


The contractile unit is called the...

- Sarcomere


The sarcoplasmic reticulum acts as an....

- Internal calcium store


A triad is a...

- T-tubule sandwiched between two sarcoplasmic reticulum


The motor unit consists of ....

- One somatic neuron and muscle fibres innervated by its branched


Excitation occurs at the....an AP reaches end of motor neuron, which causes _____ entry into nerve terminal. Synaptic vesicles release ____, which diffuse into synaptic cleft. ____ stimulates receptors on the adjacent muscle fibre. ____polarisation of muscle sarcolemma, initiating an action potential. ______ coupling occurs. AP travels over _____ and T-Tubules, triggering release of _____ ions from the adjacent _____ _____. Ca2+ ions diffuse in the _______ where a cross-bridge formation occurs.

- Neuromuscular Junction
- Ca2+
- ACh
- De
- Electro-chemical-electro
- Sarcolemma
- Ca2+
- Sarcoplasmic Reticulum
- Myofilaments


What is cross-bridge cycling?

- The myosin head is in an energised state, with ATP bound. In this stage it has a high affinity to bind with the actin
- Calcium interacted with troponin which exposes active sites
- Actin and Myosin interact
- Energised myosin head pulls the actin / POWERSTROKE
- Each part is driven by high energy bonds of ATP


Do the actin and myosin become shorter?

- No, they just slide into each other


What is the powerstroke?

- The flipping of the myosin head


How does uncoupling of the cross-bridge formation occur?

- ATP must bind to the myosin


During the relaxation state there's ______ re-uptake and _____ of the cross-bridge.

- Calcium
- Uncoupling

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