Biol 2401 Pre chp 9-11

A muscle contraction increases in strength up to a point because ______. 

• additional neurons begin stimulating each muscle fiber 

• more calcium is available in the sarcoplasm 

• recruitment occurs and more motor units respond to stronger stimuli 

• stronger stimuli inhibit motor unit activation 

Cellular respiration involves three pathways to produce ATP. Which pairing is incorrect? 

• Glycolysis: doesn't require O2; produces 2 ATP

• Citric acid cycle: requires O2; produces 6 ATP 

• Electron transport chain: requires O2; produces 32 ATP 

• all are correctly paired

Which are causes of muscle fatigue? 

• Decreased ATP

• Potassium imbalances

• Damage to the SR 

• All of the above

Theoretically, skeletal muscle contraction would not occur if ______. 

• Z discs contact the thick myofilaments

• Actin and myosin filaments do not overlap

• There is optimal overlap between actin and myosin

• 1 and 2

Which pathway for generating ATP produces lactic acid? 

• Direct phosphorylation 

• Anaerobic pathway 

• Aerobic pathway 

• None of the above 

Of the following muscle types, which is the only one subject to conscious control? 

• smooth

• cardiac

• skeletal

• a and b 

 In order to receive a signal to contract, each skeletal muscle must be served by a(n) _______. 

• vein

• ligament

• artery

• nerve

The thin filaments are not comprised of which of the following components? 

• Titin

• Troponin

• Actin

• Tropomyosin

Myosin heads contain binding sites for each of the following, except ______. 

• ATPase enzymes

• ATP

• Actin

• Calcium

At the neuromuscular junction, the muscle contraction initiation event is _______. 

• binding of acetylcholine to membrane receptors on the sarcolemma 

• sliding of actin and myosin filaments past each other 

• conduction of an electrical impulse down the T tubules 

• a release of calcium ions from the sarcoplasmic reticulum