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Unformatted text preview: 1 Anatomy of Circulatory Systems Basic components of closed circulatory and respiratory systems: Heart – pumps blood around body Vessels – carries blood to all cells in body Blood & Respiratory pigments (RPs) – transport medium and RPs increase the capacity of blood to carry many times more O 2 than without RPs Lungs/Gills/ventilation surface – designed to take in O 2 and release CO 2 efficiently and load/offload respiratory pigments Oxygen transport • Not enough oxygen dissolves into blood to support metabolic needs • Respiratory pigments increase the amount of gas carried in solution ¾ May be contained within red blood cells or in plasma ¾ Proteins with one or more metal ions (Iron or Copper are most common) Hemoglobin • Found in RBC • Special protein made up of four sub-units • Each sub-unit has heme molecule that contains an iron ion (Fe 2+) • Oxygen binds reversibly to iron core • Each hemoglobin can bind to four oxygen molecules • Formed in stem cells within bone marrow Brooker Fig. 47.7 or Campbell 42.28 The transport of oxygen is governed by partial pressure gradients. Partial pressure of O 2 at lungs: HIGH ~104 mmHG Partial pressure of O 2 at tissue: LOW~40 mmHG Gases diffuse DOWN their pressure gradient. To be an effective carrier of O 2 and CO 2 hemoglobin must reversibly bind O 2 & CO 2 . The partial pressure of the gas (O 2 or CO 2 ) at different locations in the body allow hemoglobin to diffuse into the red blood cell or away from the red blood cell. Oxygen-hemoglobin dissociation curve The conditions under which hemoglobin will bind to or release oxygen are described by an oxygen-hemoglobin dissociation curve . Partial pressure of O 2 mm HG % Saturation of Hb 100 100 20 40 60 80 20 40 60 80 Tissues (Rest) Tissues (Exercise) Lungs Partial pressure of O 2 mm HG % Saturation of Hb 100 100 20 40 60 80 20 40 60 80 Tissues At rest Lungs Amount of O 2 unloaded during normal metabolism Tissues At exercise Amount O 2 available to highly metabolic tissues 2 Oxygen-hemoglobin dissociation curve • When P O2 is high, more O 2 binds to hemoglobin • When P O2 is low, less O 2 binds to hemoglobin • Sigmoidal curve due to cooperation – shape of hemoglobin changes as oxygen loads and unloads- Active metabolic tissues generate products that can shift the curve...
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- Winter '08
- Anatomy, respiratory surfaces, Skin Tracheae Gills