Animal Phys transport of gases

5. Discuss three factors that decrease Hb affinity for O2.

ANSWER: 1) An increase in carbon dioxide, 2) lower pH, and 3) an increase in temperature shift the affinity curve to the right. When CO2 is increased, the Hb affinity for O2 is decreased and Hb affinity for CO2 increases. As pH lowers and acidity increases, the Hb has a lower O2 affinity. Increased CO2 and lactic acid production increases blood acidity. As temperature increases, the bond between Hb and O2 weakens making it easier for O2 to separate from the Hb.

10. Describe the ways CO2 is carried in the blood in order of most common method to least.

ANSWER: 1) Bicarbonate Ions: most carbon dioxide is carried as bicarbonate ions in the blood. It is much easier to get carbon dioxide to enter a liquid than oxygen because CO2 when combined with water forms carbonic acid. 2) Bound to hemoglobin: 25-30% of CO2 in bound to hemoglobin forming carbaminohemoglobin (HbCO2). The carbon dioxide binds to the globin and not the heme group like oxygen does. 3) Dissolved: 5-10% of CO2 is dissolved directly in the blood.

7. Fetal mammals produce different globin subunits than adults (Fig. 24.2). Explain why. Why do the young stop producing these subunits after birth?

ANSWER: A fetus must have a supply of oxygen to survive. The globins produced in fetal mammals need to have higher affinities than the mother's so that the fetus can have access to the oxygen that enters the blood of the mother; the fetus attracts oxygen from the mother's blood. The young stop production of these globins because it could interfere with unloading of O2 at tissues.

4. A right shift in a Hb O2 saturation curve indicates that Hb has a lower affinity for O2. Explain using P50.

ANSWER: A shift in the right means that Hb lets go of O2 more readily. Therefore, the P50 is larger, and the O2 affinity is lower. The higher the P50, the lower the O2 affinity. The lower the P50, the higher the O2 affinity because hemoglobin can hold on to the O2 molecules better. When the blood is at a higher partial pressure, hemoglobin holds tightly onto the O2, the partial pressure of O2 must fall greatly for hemoglobin to release the O2. But it must fall less when the saturation curve is shifted to the right.

1. (A) What are respiratory pigments? (B) Describe three different types of respiratory pigments.

ANSWER: A) Respiratory pigments are metal ion pigments that act to carry oxygen through the blood by binding the metal ions to O2. B) Three types of respiratory pigments are hemoglobin, hemocyanin, and chlorocruorin. Hemoglobin is found in vertebrates, annelids, mollusks, and crustaceans. it is a highly folded polypeptide chain (globin) and iron-containing heme group. It's red when oxygenated; blue when deoxygenated. Hemocyanin B found in arthropods, crustaceans, annelids, and mollusks (typical invertebrate). It's composed of large protein with copper ios as its metal group. It's blue when oxygenated; colorless when deoxygenated. Chlorocruorin is found in some annelids like marine worms. Composed of large proteins with iron and heme proteins. Green then oxygenated; red when deoxygenated.

8. Different animals have Hb with different affinities for O2 give an example of an animal with high affinity and explain why this animal would need this adaptation.

ANSWER: Fish typically live in water which has low O2 content and water is not a good medium for gas exchange compared to air. Therefore, fish have a high affinity for O2 because of this low O2 content of water. Factors to aid fish with O2 content would be fast moving rivers and cold water. Fast moving water provides O2 molecules to be at a higher content. Cold water is more favorable for gas exchange than warm water.

Explain the concept depicted in slide #8 (Fig. 24.6 in your text). Be sure to include an explanation of the axes shown in the graph.

ANSWER: On the Y axis there is O2 concentration of blood and on the X axis there is partial pressure of O2 in blood.When partial pressure is high like in capillaries then hemoglobin binds to oxygen easily. Each ↓ in the graph means 5 mL of oxygen released per 100 mL of blood. The first drop is because partial pressure of O2 needs to drop for 5 mL of O2 to be offloaded. The second drop is because the partial pressure needs to only drop a little to release 5 mL of O2. The last drop is because this makes it easier to offload O2 at active tissues.

9. Different animals have different blood oxygen carrying capacities. At a partial pressure of 60 mm Hg, a human has a concentration of ~17 mL of O2 in 100mL of blood, while a Weddell seal has ~27 mL of O2 in the same volume of blood (slide #16; fig. 24.8 in your text). (A) What are two mechanisms the seal could use to have this increased carrying capacity? (B) Why aren't there any insects in the blood oxygen carrying capacity graph?

ANSWER: Seals have a higher hematocrit as well as an increased myoglobin, increases the storage capacity which increases the gradient differential toward the cell which steps up the oxygen cascade to increase diffusion rate. B) Insects have a tracheal system for oxygen exchange that does not require oxygen to be carried in the circulatory system.

6. Explain how the Bohr and Haldane effects interact with each other.

ANSWER: The Bohr effect is an increase of O2 offloading in tissue due to a decrease in Hb O2 affinity. This leads to the Haldane effect, which is increasing ability for deoxygenated Hb to carry CO2. Their interactions regulate CO2 and O2 circulation. Oxygenation lowers Hb's capacity to bind CO2, increasing CO2 offloading in the lungs because there is increased O2 binding Hb.

11. Describe the brain centers that control breathing in vertebrates

ANSWER: Vertebrates have several brain centers that control breathing. These centers are mainly located in the hypothalamus and cortex. The hypothalamus increases ventilation rate. The cortex is involved in voluntary changes in breathing. Some other areas involved are the medullary rhythmicity area, the DRG, and VRG. The medullary rhythmicity area is a collection of neurons in the reticular formation within the medulla oblongata that is involved in establishing or modifying the pattern for breathing. Within the medulla oblongata are the DRG and VRG. The DRG is involved in altering the pattern for ventilation in response to the body's need for O2 and CO2.

12. Compare and contrast peripheral and central chemoreceptors involved in breathing rate. What factor influences these receptors the most and therefore breathing rate the most? The least?

ANSWER:Peripheral chemoreceptors of the vagus nerve and the carotid sinus nerve are influenced by CO2 concentration, pH and O2 sensors. The peripheral chemoreceptors are most influenced by CO2 and least influenced by O2 sensors. Central chemoreceptors of the medulla and in CNS are influenced by the amount of hydrogen in the brain that is converted from CO2 in brain EC-. H+ leads to increased depth and rate of breathing.

2. Explain the concept depicted in slide #5 (Fig. 24.7 in your text). Be sure to include an explanation of the axes shown in the graph.

independent binding (such as myoglobins) functions as a hyperbolic curve. This independent binding means that there is a high o2 affinity and requires a low partial pressure to unload its oxygens. Cooperative binding (hemoglobin) functions as a sigmoidal curve. There is a lowered affinity for 02 therefore o2 is released at much higher partial pressures compared to a non-cooperative binding curve. The x axis represents partial pressure, the y axis represents oxygen saturation.