3/25/2015

Circulatory Systems • Chambers isolate pulmonary and • Open vs. closed systemic circuits

• Components of • 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 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, • – bound with CO , reversible Blue 2 +Cu2+ 0.3-0.5 25-7000 Solution cephalopods, (colorless) • Carbon monoxide hemoglobin – combined with CO, not Nematodes, reversible Hemoglobin Protein+ Red 1.2-1.4 16-2000 Either , +Fe2+ (purple/blue) Protein+heme Annelids, marine Chlorocruorin Green 0.6-0.9 3000 Solution +Fe2+ Protein Violet , some 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

• in 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 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

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