1 Explain the events of inspiration and expiration in terms of muscle contractio

Question

1 Explain the events of inspiration and expiration in terms of muscle contraction, change in volume (space), change in pressure and flow of air. 2 What factors stimulate breathing? Between O2 and CO2, which is more important in terms of stimulation of breathing? Why? 3 What does GFR stand for? What happens in nephrons if GFR is too high? Too low? 4 Describe the positive feedback mechanism used by the nephron loop to make the medulla salty. What is the purpose of this mechanism? 5 Where does the water in our bodies come from? How is it lost? How is it retained?




1 Explain the events of inspiration and expiration in terms of muscle contraction, change in volume (space), change in pressure and flow of air. 2 What factors stimulate breathing? Between O2 and CO2, which is more important in terms of stimulation of breathing? Why? 3 What does GFR stand for? What happens in nephrons if GFR is too high? Too low? 4 Describe the positive feedback mechanism used by the nephron loop to make the medulla salty. What is the purpose of this mechanism? 5 Where does the water in our bodies come from? How is it lost? How is it retained?




1 Explain the events of inspiration and expiration in terms of muscle contraction, change in volume (space), change in pressure and flow of air. 2 What factors stimulate breathing? Between O2 and CO2, which is more important in terms of stimulation of breathing? Why? 3 What does GFR stand for? What happens in nephrons if GFR is too high? Too low? 4 Describe the positive feedback mechanism used by the nephron loop to make the medulla salty. What is the purpose of this mechanism? 5 Where does the water in our bodies come from? How is it lost? How is it retained?

Explanation / Answer

1. Breathing involve inspiration and expiration.

Inspiration

Inspiration is the inhalation or intake of air in to lungs from atmosphere. The diaphragm and intercostal muscles are main muscles of respiration. The diaphragm contract and moves inferiorly towards abdominal cavity, and external intercostal muscle contract and moves rib out ward and upward. Both of this increases volume of thoracic cavity. This expansion of thoracic cavity causes the lungs to expand. The increase of volume decreases intraalveolar pressure, creating a pressure lower than atmospheric pressure. This pressure gradient drives the air in to the lungs. The inspiration is an active process.

The expiration is a passive process. The lung recoil back due to elasticity of lung tissue. The diaphragm and intercostal muscles relaxed following inspiration. This results in decrease in the volume of thoracic cavity and lungs causing increase in intra pulmonary pressure above atmospheric pressure causes air leave the lungs (expiration)

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