BPK 105 Study Guide - Final Guide: Carbonic Anhydrase, Hemoglobin, Cellular Respiration
27 Apr 2018
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Module 10 - Review Questions - Part 4
7. Describe the transport of oxygen in circulation. What environmental changes occur as
blood enters active muscle influence the release of oxygen from hemoglobin? How does
the release of oxygen differ during exercise? [6 marks]
OXYGEN TRANSPORT
- After O2 diffuses through the respiratory membrane into the blood, about 98.5% of the
O2 transported in the blood combines reversibly with the iron-containing heme groups of
hemoglobin (see chapter 11). About 1.5% of the O2 remains dissolved in the plasma.
Hemoglobin with O bound to its heme groups is called oxyhemoglobin.
- The ability of hemoglobin to bind to O2 depends on the Po2. At high Po2, hemoglobin
binds to O2, and at low Po2, hemoglobin releases O2.
- In the lungs, Po2 normally is sufficiently high so that hemoglobin holds as much O2 as it
can.
- In the tissues, Po2 is lower because the tissues are using O2. Consequently,
hemoglobin releases O2 in the tissues.
- Oxygen then diffuses into the cells, which use it in cellular respiration.
- At rest, approximately 23% of the O2 picked up by hemoglobin in the lungs is released to
the tissues.
- The amount of O2 released from oxyhemoglobin is influenced by four factors.
- More O2 is released from hemoglobin if (1) the Po2 is low, (2) the Pco2 is high, (3) the
pH is low, and (4) the temperature is high.
- Increased muscular activity results in a decreased Po2, an increased Pco2, a reduced
pH, and an increased temperature. Consequently, during physical exercise, as much as
73% of the O2 picked up by hemoglobin in the lungs is released into skeletal muscles.
8. Describe the various ways carbon dioxide is transported in circulation, including the
approximate percentage that is transported in each way. Include the full reaction
catalyzed by carbonic anhydrase. How does this equilibrium reaction change between
the tissues and the lungs? [6 marks]
Carbon dioxide diffuses from cells, where it is produced, into the tissue capillaries.
- After CO2 enters the blood, it is transported in three ways: (1) About 7% is transported
as CO2 dissolved in the plasma; (2) 23% is transported in combination with blood
proteins, primarily hemoglobin; and (3) 70% is transported in the form of bicarbonate
ions.
Document Summary
Module 10 - review questions - part 4: describe the transport of oxygen in circulation. After o2 diffuses through the respiratory membrane into the blood, about 98. 5% of the. O2 transported in the blood combines reversibly with the iron-containing heme groups of hemoglobin (see chapter 11). About 1. 5% of the o2 remains dissolved in the plasma. Hemoglobin with o bound to its heme groups is called oxyhemoglobin. The ability of hemoglobin to bind to o2 depends on the po2. At high po2, hemoglobin binds to o2, and at low po2, hemoglobin releases o2. In the lungs, po2 normally is sufficiently high so that hemoglobin holds as much o2 as it can. In the tissues, po2 is lower because the tissues are using o2. Oxygen then diffuses into the cells, which use it in cellular respiration. At rest, approximately 23% of the o2 picked up by hemoglobin in the lungs is released to the tissues.
