Chapter 24 Outline
- BOX 24.1 Absorption Spectra of Respiratory Pigments
The Chemical Properties and Distributions of the Respiratory Pigments
- Hemoglobins contain heme and are the most widespread respiratory pigments
- Copper-based hemocyanins occur in many arthropods and molluscs
- BOX 24.2 Blood Cells and Their Production
- Chlorocruorins resemble hemoglobins and occur in certain annelids
- Iron-based hemerythrins do not contain heme and occur in three or four phyla
The O2-Binding Characteristics of Respiratory Pigments
- Human O2 transport provides an instructive case study
- A set of general principles helps elucidate O2 transport by respiratory pigments
- The shape of the oxygen equilibrium curve depends on O2-binding site cooperativity
- Respiratory pigments exhibit a wide range of affinities for O2
- The Bohr effect: Oxygen affinity depends on the partial pressure of CO2 and the pH
- The Root effect: In unusual cases, CO2 and pH dramatically affect the oxygen-carrying capacity of the respiratory pigment
- Thermal effects: Oxygen affinity depends on tissue temperature
- Organic modulators often exert chronic effects on oxygen affinity
- BOX 24.3 Resurrection of the Blood Hemoglobin of the Extinct Woolly Mammoth: Evidence for an Ancient Adaptation to the Challenges of Regional Hypothermia
- Inorganic ions may also act as modulators of respiratory pigments
The Functions of Respiratory Pigments in Animals
- Patterns of circulatory O2 transport: The mammalian model is common but not universal
- BOX 24.4 Heme-Containing Globins in Intracellular Function: Myoglobin Regulatory and Protective Roles, Neuroglobins, and Cytoglobins
- Respiratory pigments within a single individual often display differences in O2 affinity that aid successful O2 transport
- Evolutionary adaptation: Respiratory pigments are molecules positioned directly at the interface between animal and environment
- The respiratory-pigment physiology of individuals undergoes acclimation and acclimatization
- Icefish live without hemoglobin
- BOX 24.5 Blood and Circulation in Mammals at High Altitude
Carbon Dioxide Transport
- The extent of bicarbonate formation depends on blood buffers
- Carbon dioxide transport is interpreted by use of carbon dioxide equilibrium curves
- The Haldane effect: The carbon dioxide equilibrium curve depends on blood oxygenation
- Critical details of vertebrate CO2 transport depend on carbonic anhydrase and anion transporters
Acid–Base Physiology
- Acid–base regulation involves excretion or retention of chemical forms affecting H+ concentration
- Disturbances of acid–base regulation fall into respiratory and metabolic categories
- BOX 24.6 Acidification of Aquatic Habitats