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Cardiovascular physiology Oxygen delivery and uptake Circulatory systems Gastrovascular cavity thin body walls flagella stir fluid Fig. 9.1 Open circulatory system hemolymph g volume large low pressure most invertebrates Closed circulatory system blood small volume high pressure vertebrates some invertebrates Bulk flow of fluid in animals that lack a circulatory system Fig 9 5 Fig.9.5 Types of circulatory systems 1 OPEN CIRCULATORY SYSTEM 1. (most invertebrates) Low pressure (< 1.5 kPa) High volume (30% body vol.) Sl Slow velocity l it pump + vessels Fig. 9.7 Insects Open circulatory system multiple hearts one o e heart/segment ea t/seg e t peristalsis hemocoel Fig. 9.9 Most invertebrates have open circulatory systems but: Cephalopods (Molluscs) and Oligochaetes (Annelids) have a closed circulatory system Fig. 9.3 2. CLOSED CIRCULATORY SYSTEM (cephalopods, vertebrates) High pressure (>12 kPa) Low volume (5-10%) High velocity Distribution regulation g Ultrafiltration Lymphatic system Fig. 9.10 Circulation C cu at o in birds b ds and a d mammals a as respiratory and systemic circulations in parallel F Four chambered h b d heart h t Two completely p y separate p circuits pulmonary circuit (low pressure) systemic circuit (high pressure) Fig. 9.37 Cardiovascular system in water-breathing teleost Fig. 12.16 Eckert Cardiovascular system in air or water-breathing teleost The African lungfish Fig. 12.16c Eckert Circulatory systems in air-breathing fish, amphibians, and reptiles Air-breathing organ (e.g. lung) arranged in parallel to other tissues Yet the heart is a four chambered pump only in Birds and Mammals Comparative anatomy of vertebrate hearts Fish heart: 1 atrium + 1 ventricle [sinus venosus] atrium (1) ventricle (1) [bulbus or conus arteriosus] chambers arranged in series Amphibian heart: 2 atria + 1 ventricle [sinus venosus] right i ht atrium ti to ventricle left atrium to ventricle conus arteriosus with spiral fold systemic arteries (oxygenated blood) pulmocutaneous artery (deoxygenated) Cardiovascular system in amphibian Non-crocodilian reptiles 2 atria t i + 2(3) iincompletely l t l separated t d ventricles ti l Fig. 9.16 Crocodilian reptiles - 2 atria + 2 completely separated ventricles Non-Crocodilian Reptile partial ventricular septum RA contracts earlier than LA earlier flow in pulm.artery than systemic arches …diving turtles… …varanid lizards… Mammalian circulation Fig. 12.22 Eckert adult fetal heart Mammalian fetal circulation Where is blood oxygenated? Where does oxygenated blood enter heart? pulmonary y artery yg go? How can oxygenated yg blood be sent Where does blood in p to brain and other systemic tissues? Solutions? Fetal circulation FetalÆ Postnatal circulation PlacentalÆ Pulmonary Gas Exchange At birth: - umbilical vessels constrict ↑ peripheral resistance Î ↑ peripheral blood pressure ↑ Psystemic Î ↓ flow to R atrium - umbilical venous flow ceases ductus venosus closes - lungs inflate ↓ pulmonary resistance Î ↑ blood flow to lungs ↓ Ppulmonary Î ↑ flow to L atrium LA pressure > RA pressure foramen ovale closes fusion of septal leaves (several days) aortic pressure > pulmonary a. pressure blood flow in ductus arteriosus reverses high Po2 in ductus arteriosus vasoconstriction of d. arteriosus progressive constriction complete 1-2 days Effects of gravity on blood pressure and the circulatory system ΔP = ρ g Δh ΔP diff difference in i pressure (hydrostatic) (h d t ti ) between two points in a fluid column ρ ((rho)) densityy of the fluid g acceleration due to gravity Δh difference in height of the fluid column Fig. 9.30 Cardiovascualr challenges in a giraffe g Changes in posture standing feeding/drinking How to mainten blood flow to the head How to prevent edema in the feet Vasodilation Vasoconstriction Anatomical adaptations Fig. 12.33 Eckert Cardiovascular system in a giraffe Cardiovascular challenges in a giraffe Solutions? Fig. 9.43 Fig. 9.36 Net filtration pressure along a capillary