Answer Happy

23) 23) Air contains O2 at a partial pressure of 160mmHg. Air reaches alveollat a partial pressure of 100mmHg. Which of the following is the correct explanation for this? A) Through the bronchi and bronchioles, some of the O2 is absorbed by these cells B) Pressure in the lungs is lower during inhalation, and this lowered pressure is simply reflected as a lowered partial pressure C) Exhaling does not expel 100% of the air in the system. Remaining air gets mixed with the inhaled air, lowering the partial pressure D) We don't breathe in all the air quantity some of the inhaled portion contains water vapor displacing the normal amount of O2 3 24) 24) of the following, which is NOT a property of smooth muscle? A) IP3-receptor calcium channel B) calcium-troponin binding required C) no sarcomere-like arrangement of filaments D) slower-acting myosin-ATPase 25) If a small amplitude efferent signal leaves the primary motor cortex and travels down the spinal cord into 25) the ventral gray matter, which of the following motor units will likely be activated first? A) motor unit with the fewest # of muscle fibers and a motor neuron with the highest threshold B) motor unit with the largest of muscle fibers and a motor neuron with the lowest threshold C) motor unit with the fewest # of muscle fibers and a motor neuron with the lowest threshold D) motor unit with the largest # of muscle fibers and a motor neuron with the highest threshold 26) Which of the following is the best explanation for the oxygen saturation curve shifting to the right when 26) the presence of 2,3-BPG increases? A) 2,3-BPG is a metabolite of glycolysis decreased CO2 from glycolysis changes the partial pressure B) 2,3-BPG is a metabolite of glycolysis increases in CO2 will stimulate more conversion from HCO3 C) 2,3-BPG is a metabolite of glycolysis increases in 2,3-BPG contribute more H to the plasma D) 2,3-BPG is a metabolite of glycolysis: decreased O2 means more glycolysis and more 2,3-BPG