respiration part 3 Flashcards
Describe the structure and characteristics of hemerythrin.
Violet-pink when oxygenated, trimeric or octomeric, contains 2x Fe2+, found inside the coelomic cells of invertebrates
Describe the structure and characteristics of Hemocyanin.
Blue when oxygenated, can have up to 48 subunits, contains 2x Cu2+, dissolved in hemolymph and mainly found in arthropods & molluscs
Describe the structure and characteristics of Hemoglobin.
Red when oxygenated, 4 protein subunits (2 alpha, 2 beta), contains Fe2+, 250 000 000 per erythrocyte
What are metalloproteins? What are the 3 major types?
Proteins which contain metal ions which reversibly bind to O2 (respiratory pigments)
- Hemoglobins
- Hemocyanins
- Hemerythrins
What is dead space? What are its 2 components?
Air that does not participate in gas exchange
- Anatomical dead space (vol. of trachea and bronchi)
- Alveolar dead space (vol. of alveoli that are not perfused)
What is meant by P50?
The PO2 at which respiratory pigments are 50% saturated
What would a graph of % saturation look like for Myoglobin? What about for Hemoglobin? What explains this difference?
Myoglobin: Hyperbolic
Hemoglobin: Sigmoidal
Because Hemoglobin has cooperative binding where it is easier to bind more O2 when O2 is already bound
What is meant by the “Root effect”?
Decrease in pH can reduce the O2 carrying capacity of hemoglobin
What is meant by the “Haldane effect”?
Deoxygenated blood can carry more CO2 than oxygenated blood
What is meant by the “Bohr effect”?
Increasing pH can increase the affinity of hemoglobin for O2, while decreasing pH can reduce the affinity of hemoglobin for O2
How do organic modulators affect the O2 affinity of hemoglobin? Give an example of an organic modulator.
2,3-DPG (or 2,3-BPG) can decrease the affinity of hemoglobin for oxygen, helping to unload oxygen at the tissues faster
How can temperature affect the oxygen affinity of hemoglobin?
Increases in temperature decrease O2 affinity (think increased O2 delivery to warm muscles), while decreases in temperature increase O2 affinity
Where is carbonic anhydrase located in the body? What is its purpose?
Located in the erythrocytes, carbonic anhydrase catalyzes the reaction which forms bicarbonate from CO2 for transport through the body
How is ventilation regulated in the brain?
Through the rhythmic firing of central pattern generators in the pons and medulla
How is ventilation regulated by negative feedback?
Mainly by chemoreceptors which detect elevated CO2, but these can also detect low pH or O2. These chemoreceptors modulate output of the central pattern generators to regulate ventilation
