Skeletal Muscle Structure & Function

• What are the three main types of muscle in the body?

  Smooth, Cardiac and Skeletal.
• What is Smooth Muscle

  Mainly hollow line organs that are not under voluntary control.
• What is Cardiac Muscle?


  Located only in the heart to generate force to pump blood and not under voluntary control.
• What is Skeletal Muscle?

  Applies force to the bones to control posture and body movements and mostly under voluntary control.
• What are tissues at skeletal muscle structure?

  They are mostly under voluntary control.

  Its job is to develop force. The muscles develop force by contracting (shortening) which is important for movement and posture.

  It offers support and protection for soft internal organs and provides voluntary control, over major opening, which allows a passage for substances in and out of body.
• What are individual muscle cells in the skeletal muscle?

  They are fibres gathered in bundles - Fascicles.
• What are fascicles?

  Contains many blood vessels and nerves that are shattered in connective tissue to form tendons, which connects muscle to bone.
• What are tendons?

  From connective tissue bundled together and connects muscle to bone.
• What is the muscle fibre at the cellular levels in skeletal muscle?

  Sacrometers
• What are sacromeres?

  A muscle fibre composed of myofibrils.
• What are myofibrils?

  Made out of contractile proteins and myofilaments.

  Actin: thin filaments

  Myosin: Thick filaments.

  This gives the muscle the striated appearance.
• The muscle fibres possess a system of organised structures to regulate the activity of productivity elements. They're lined with a cell membrane = sarcolemma.
• What are sarcolemma?

  They have transverse tubes that conduct electrical signals into the deep core of the fibre.
• What is the sarcoplasmic reticulum?

  An extensive membrane network associated with T Tubes.

  Its function is to take up and store Ca+2, while the muscle is relaxed and relapse it.
• What is Exilation Contraction Couping?

  It is pairing of a signalling event with a mechanical event.
• What are th 3 key proteins that participate in the signalling event of ECC?

  1. Voltage gated sensor

  2. Rynaodine Receptors

  3. SR Calcium ATPase
• What is the voltage gated sensor?

  It receives signals from t-tubules and interacts with rynaodine receptors.
• What is Rynaodine receptors?

  A passive calcium channel on that SR that can open to allow Ca2+ out into the cell.
• What is SR Calcium ATPase?

  An active calcium pump that uses ATP to move Ca2+ back into the SR against the concentration gradient.
• The ECC initiates when signal starts transmitting down the t-tubules. The signals move into the cell and causes a release of calcium stores, which triggers a contraction.
• The voltage sensor is activated by the signal moving in the t-tubules. Then the active voltage sensor interacts with nearby rynaodine receptors causing them to open.

  Then calcium starts pouring out of the SR and into the cell.

  The diffuses throughout the cell, activating myofilaments and causes a contraction.
• What happens for relaxation to occur?

  Calcium must be removed from cell and pumped back into SR.

  SR pump senses the rise in intracellular calcium. iT BURNS SOME ATP to produce energy then use energy to pump calcium into the SR against concentration.