Question

7) Relate the three factors affecting the affinity of Hb for O2 on slide 77, to exercise. Does each have any connection to exercise?

8) Since a person always needs oxygen, why would the bronchioles have the ability to contract at all? Why would the trachea not have that ability?

Answer 1

1) shifting the curve to right means hemoglobin oxygen decreased affinity

     shifting to the left means increases hemoglobin oxygen affinity

• The partial pressure of CO2
  • Increasing CO2 shifts the curve to the right
  • Hyperventilation and hypocapnia shifts the curve to the left
• pH, independent of CO2
  • Decreasing pH (acidosis) shifts the curve to the right
  • Alkalosis shifts the curve to the left
• The concentration of 2,3-DPG inside the erythrocytes
  • Increased 2,3-DPG (eg. in response to hypoxia or erythropoietin) shifts the curve to the right
  • Decreased 2,3-DPG (eg. as a red cell storage lesion ) shifts the curve to the left
• The presence of unusual haemoglobin species
  • Methaemoglobin, carboxyhaemoglobin and foetal haemoglobin shift the curve to the left
  • Sulfhaemoglobin shifts the curve to the right
• Temperature
  • Hyperthermia shifts the curve right
  • Hypothermia shifts it left

2) The lining of the bronchioles, called lamina propria , is thin and surrounded by a layer of smooth muscle that contracts when the flow of blood is decreased and dilates when the flow of blood is increased.

The trachea, commonly known as the windpipe, is a tube about 4 inches long and less than an inch in diameter in most people. The trachea begins just under the larynx (voice box) and runs down behind the breastbone (sternum). The trachea then divides into two smaller tubes called bronchi: one bronchus for each lung.

The trachea is composed of about 20 rings of tough cartilage. The back part of each ring is made of muscle and connective tissue. Moist, smooth tissue called mucosa lines the inside of the trachea.

The lumen of the trachea doesnot change with breathing, because it is a tough structure compared to the bronchioles.