Physiology of the Circulatory System PDF

10/30/24 Physiology of the Circulatory System Introduction Aquatic Organism The circulatory system is a vital physiological syste...

10/30/24 Physiology of the Circulatory System Introduction Aquatic Organism The circulatory system is a vital physiological system that plays a crucial role in maintaining homeostasis and supporting the metabolic demands of aquatic organisms. Unlike terrestrial animals, aquatic organisms face unique challenges in oxygen acquisition and nutrient distribution due to their underwater environment. Their circulatory systems have evolved to optimize these processes, facilitating efficient gas exchange, nutrient transport, and waste removal. 1 2 Types of Circulatory System Closed Circulatory Closed Circulatory system It is found in vertebrates and a few invertebrates In this way, blood is kept separate from body tissues. This system has a heart that pumps blood through a continuous circulation pattern. Blood is always contained within vessels Open Circulatory System Common to most arthropods and mollusks They have a heart that pumps blood into a hemocoel. The blood then diffuses back into the blood vessels. Tissues tend to be surrounded by blood, and the blood flows freely throughout the body tissues. Animals with an open circulatory system tend to be small organisms, so the blood doesn’t have far to travel 3 4 1  10/30/24 Open Circulatory Lung Capillaries Lung Capillaries 5 6 Circulation Pattern Circulatory System in Finfish Single Circulation Blood circulation in teleosts is simple with as blood passing Blood flows only once through the heart during one cycle of passage through once through the heart during each circuit the body. Fish have a single circulation system. The blood pumped by the heart circulates clockwise (fish in left Only venous blood passes through the heart. lateral view) and is distributed by vessels, i.e. arteries, veins and capillaries. Double Circulation Arteries diameter is almost uniform throughout and distribute Blood flows twice through the heart during during one cycle of passage blood to the entire body losing very little pressure. through the body. Separate systems of pulmonary circulation and the systemic circulation Mixed, Oxygenated, venous blood passes through the heart. 7 8 2  10/30/24 Circulatory System in Finfish Veins collect blood from the capillaries, carry it to the heart, and act as a reservoir where blood can accumulate, forming a low blood pressure system. Capillaries form networks that irrigate organs and tissues, and their thin walls favor gaseous exchange. Fish heart carries only a deoxygenated heart, which is called a venous heart. 9 10 Blood vessels Arteries Are blood vessels that distribute oxygen-rich blood Veins These are blood vessels that take oxygen-poor blood 11 12 3  10/30/24 Circulatory in Fish The Heart of a fish Fish have a closed circulatory system with a heart that pumps ln fishes, the heart is a simple, two-chambered, muscular blood around the body in a single loop-from the heart to the structure that is located below the pharynx and immediately gills, from the gills to the rest of the body, and then back to the behind the gills. It is enclosed by the pericardial membrane or heart. pericardium. The fish's heart consists of four parts: the sinus venosus, ln most of the fishes, the heart consists of an atrium, a ventricle, atrium, ventricle, and bulbus arteriosus. a sac-like thin-walled structure known as sinus venosus and a The circulatory system of fish is quite simple and consists of tube, known as bulbus arteriosus. ØHeart ØBlood ØBlood Vessels 13 14 Conus Arteriosus The heart of a fish 15 16 4  10/30/24 Sinus Venosus Atrium The first chamber is called the sinus From the sinus venosus the blood flows venosus; it is the preliminary collecting into the atrium. the atrium is the largest chamber. In teleosts, it is filled from two of the chambers and weakly muscular. It major veins called the hepatic veins and pushes the blood, with weak the left and right branches of the contractions in the ventricle. Curvierian ducts which in turn collect blood from the paired (left and right) lateral veins the inferior jugulars, the anterior cardinals and the posterior cardinals. However, in the elasmobranchs only one hepatic vein leads into it. 17 18 Bulbus arteriosus Ventricle The ventricle is the only well muscled The last chamber of the fish heart is chamber, nearly as large as the atrium it called the bulbus arteriosus in the is the work horse of the heart, its teleosts, but the conus arteriosus in the contractions drive the blood around the elasmobranchs. The difference between body. these chambers is that the conus arteriosus of sharks and rays contains many valves while the bulbus arteriosus of bony fish contains none. Both are alike in being primarily elastic and work to reduce the pulsed nature of the blood leaving the ventricle giving it a more even, constant flow. 19 20 5  10/30/24 Circulation Mechanism Circulation Mechanism The deoxygenated blood collected by the veins accumulates in Then the oxygenated blood is transported throughout the body the sinus venosus, before entering the heart. with the help of blood vessels. Blood first enters the atrium of the heart, which is a large Blood facilitates the transport of oxygen and nutrients. It also chamber. Then it enters the ventricle, from where it is pumped collects carbon dioxide which is again transported to the heart into the tube, bulbus arteriosus. and then to the gills, to be removed from the body. Through bulbus arteriosus, the blood reaches the aorta and then the gills. They facilitate the exchange of gases, i.e. absorption of oxygen from water and elimination of carbon dioxide. 21 22 23 24 6  10/30/24 Blood in Fish The blood in fishes is red in color and consist of fluid plasma and blood cells. Red Blood cells, White Blood Cells and Thrombocytes are present in plasma Respiratory Pigment in Fishes: Hemoglobin 25 26 Circulatory System in Prawn Circulatory system of Prawn In prawn circulatory system is open or lacunar type, in which the 1. Pericardium - The pericardium cavity pumps blood into the heart veins and capillaries are totally absent. 2. Heart - it is a triangular and muscular structure and is found in the The blood vessels open into spaces. These spaces are without a pericardial sinus in the median dorsal part of the thorax. proper epithelial lining and are called lacunae or sinuses. 3. Arteries - supply blood to different organs of the body The sinuses together form the body cavity which looks like a coelom 4. Blood Sinuses - Various arteries on reaching the organs, branch but filled with blood and devoid of epithelial lining is known as repeatedly into minute branches which do not form capillaries but end haemocoel into wide space blood sinuses or blood lacunae. 27 28 7  10/30/24 Circulatory system of Prawn Haemocyanin (Respiratory pigments): 5.Blood Channels - The blood is oxygenated while passing the gills and It is high molecular weight protein (75 kD) containing two copper (Cu) atoms. It is this blood is carried to the pericardium by efferent branchial dissolved in blood plasma. Deoxygenated blood is white while oxygenated blood is blue channels. in colour. 6.Blood - The color of blood is white when it is deoxygenated and faintly bluish when it is oxygenated. This is due to the presence of respiratory pigment haemocyanin. 29 30 31 32 8