Muscle structure

• Muscles are effectors , they contract when stimulated by an impulse.
• There are three types of muscle:

  • smooth muscle and cardiac muscle contract without conscious control.
  • smooth muscle is found in walls of internal organs including the stomach, intestines and blood vessels.
  • Skeletal are attached to a skeleton by tendons ,and they are used to move bones which they pull against. they are under conscious control.
• The cytoplasm is called the sarcoplasm
• The cell membrane is called the sarcolemma , this folds inward in places forming transverse tubules which help to spread electrical impulses.
• They have lots of mitochondria to carry out respiration and provide atp for muscle contraction.
• They have a network of internal membranes known as the sarcoplasmic reticulum. which releases and stores the calcium ions needed for muscle contraction.
• Each myofibril contains bundles of thick (myosin) and thin (actin) filaments which slide past each other to make muscles contract.