3/25/2015 Circulatory Systems Vertebrate hearts • Chambers isolate pulmonary and • Open vs. closed systemic circuits • Components of • Blood pressure and regulation of hemolymph or blood flow rates • Hearts • Vasoconstriction and dilation – Simplest forms are thickened smooth • Flow velocity minimized, area muscle in arteries maximized in capillaries • Flow pressure minimized in largest veins Respiratory Pigments • Molecules that bind oxygen, facilitate transfer from respiratory surface to tissues that need it. Tissues Lungs Bind Release High PO2 Low PO2 • Oxygen affinity – [ ] • % = x 100 [] 1 3/25/2015 Structure of Hemoglobin Respiratory Pigments Oxygen Molecular • Oxyhemoglobin – bound with O2, reversible Color Cells or Pigment Structure capacity Weight Animal Groups (change) Solution • Deoxyhemoglobin – not bound with oxygen, Fe reduced (ml g-1) (kDa) Mollusks, • Carbaminohemoglobin – bound with CO , reversible Hemocyanin Blue 2 Protein+Cu2+ 0.3-0.5 25-7000 Solution cephalopods, (colorless) • Carbon monoxide hemoglobin – combined with CO, not arthropods Nematodes, reversible Hemoglobin Protein+heme Red 1.2-1.4 16-2000 Either annelids, +Fe2+ (purple/blue) vertebrates Protein+heme Annelids, marine Chlorocruorin Green 0.6-0.9 3000 Solution +Fe2+ polychaetes Protein Violet Brachiopods, some Hemerythrin 1.6-1.8 16-125 Either +Fe2+ (colorless) marine annelids • Intracellular vs. solution • Various other forms, recall gene families Before/after methemoglobinemia P50 Oxygen carrying capacity • Total oxygen capacity of blood depends on – Volume of blood – % saturation (environmental PO2, respiratory surface efficiency and respiratory pigment affinity) – Concentration of P50 – partial pressure of oxygen where blood is respiratory pigment in 50% saturated blood • Hematocrit – 2 3/25/2015 Blood Properties Icefish Adaptations • Why not have very high hematocrit? • Only vertebrate without respiratory pigments or red blood cells • Why is hemoglobin inside red blood cells? • Low metabolic rate – 0-1.3 C temperature range – Low activity, large body size • What are the tradeoffs? • Cold increases blood viscosity • High oxygen in environment, plasma carries all oxygen • Myoglobin in heart muscle Altering Affinity for Oxygen Altering Affinity for Oxygen Bohr shift – oxygen dissociation curve shifts right with increasing Root effect – lower pH shifts curve down temperature 3 3/25/2015 Bohr and Root Gas Glands Lungs Bind Release Tissues High PO2 Low PO2 Low High temperature, temperature, low CO2 high CO2 • Conditions in metabolically active tissue will facilitate oxygen movement to tissues by shifting the curve down and to the right. • Hemoglobin affinity for oxygen drops. Review – Gene families Hb forms • Fetal Hb • Both myoglobin and fetal hemoglobin have greater affinity • Myoglobin • Fetal hb – facilitates oxygen transfer across placenta • Myoglobin – storage of oxygen in muscle 4 3/25/2015 Other modifiers of oxygen affinity Shifts in affinity • Ions – implications for • Physiological shifts osmoconformers – Temperature lower – Increased salinity lower • Organic compounds - • Acclimation shifts 2,3-Diphosphoglycerate – Altitude (DPG) lower (DPG) • Evolutionary trends – Small vs. large body lower – More vs. less active lower – Air vs. water breather lower – Fetal vs. maternal – High vs. low altitude A few examples… 5 3/25/2015 CO2 release • 5-10% of CO2 carried in blood cells • Carbonic anhydrase – catalyst for formation of bicarbonate - • HCO3 diffuses out, Cl- in to balance charge • Osmolarity and CL- ions facilitate further dumping of O2 6.