muscle contractions

Question 1

micro anatomy of skeletal muscle

Answer 1

Each muscle cell is called a muscle fiber. Within each muscle fiber are many myofibrils.

Question 2

myosin molecule

Answer 2

• elongated with an enlarged head at the end
• many myosin molecules form the thick myosin filament. it has many heads projecting away from the main molecule

Question 3

actin filament

Answer 3

• composed of three parts; actin, tropomyosin and troponin

Question 4

muscle contraction steps

Answer 4

• myosin head attach to binding sites and create a power stroke
  -ATP detaches myosin heads and energises them for another contraction
• when action potential cease, the muscle stop contracting

Question 5

muscle fatigue

Answer 5

• lack of oxygen causes ATP deficit, lactic acid builds up from anaerobic respiration

Question 6

muscle atrophy

Answer 6

• wearing and shrinking of muscle
• causes; immobilisation, loss of neural stimulation

Question 7

muscle hypertrophy

Answer 7

• enlargement of muscle
  -more capillaries
• more mitochondria
  -caused by: strenuous exercise and steroid hormones

Question 8

isometric contractions

Answer 8

• produces no movement
• used in: standing, sitting, posture

Question 9

isotonic contractions

Answer 9

• produces movement
• used in: walking, moving any part of body, concentric and eccentric