Major Organ Systems PDF

Major organ systems BI2CV1 Comparative Vertebrate Biology Dr Manabu Sakamoto [email protected] Major organ systems Circulatory system Respiratory system Excretory system Circulatory system Circulatory system Vertebrates have a closed circulatory system:...

Major organ systems BI2CV1 Comparative Vertebrate Biology Dr Manabu Sakamoto [email protected] Major organ systems Circulatory system Respiratory system Excretory system Circulatory system Circulatory system Vertebrates have a closed circulatory system: Blood Heart Arteries Veins Capillaries The vertebrate blood The vertebrate blood comprises: Plasma Fluid component Formed elements Cellular components The vertebrate heart Vertebrates have multi- chambered hearts: Atrium Receives blood Ventricle Pumps out blood Blood vessels Oxygenated blood is delivered to the rest of the body through the arteries. Deoxygenated blood returns to the heart through the veins. Capillaries are the tiny vessels that lie between the arteries and veins. Blood vessels The interior surface of vertebrate blood vessels are lined with an endothelium. Endothelium forms a barrier between blood and tissue. More efficient transfer of blood? Capillaries Exchange between capillaries and body tissue occurs through differentials in blood and osmotic pressures. Gas exchange in respiratory organs will be covered in the respiratory system section. Waste/water exchange will be covered in the excretory system section. Single and double circulation Blood travels in one of two Two-chambered hearts of fish general patterns: Single circulation Blood passes through heart only once during each complete circuit. Fish Four-chambered hearts of amniotes Double circulation Blood passes through the heart twice during each circuit. Amniotes Single and double circulation Double circulation is also Two-chambered hearts of fish called a “figure of eight system". Four-chambered hearts of amniotes Evolution of the vertebrate heart The ancestral vertebrate heart was two- chambered with a single flow-through system. Tetrapods acquired a three-chambered heart. Amniotes evolved a double-circuit circulatory system. Four-chambered hearts acquired in archosaurs Excretory system Excretion Management and elimination of excess substances that enter the body. Water Salts Metabolic by-products and waste Nitrogenous wastes Nitrogenous wastes Formed as by-product of metabolic breakdown of nitrogen-containing molecules (mainly proteins and nucleic acid). Carbon, hydrogen and oxygen are extracted and stored in the form of carbohydrates and fats. Excess nitrogen (most commonly ammonia, NH3) is extracted from the body (through excretion). Ammonia is toxic! NH3 Nucleic acid Amino acid Nitrogenous waste NH3 Nitrogenous waste is excreted as urine. Aquatic animals can directly excrete ammonia (NH3). Ammonotelism: excretion of ammonia. Terrestrial animals need to convert ammonia into something less toxic. Urea (amphibians and mammals) Ureotelism: excretion of urea Uric acid (reptiles and birds) Uricotelism: excretion of uric acid Excretory system: nephridia Nephridia (singular: nephridium) are an ultrafiltration (UF) based excretory system common to bilaterians. Ultrafiltration site Flow of water Excretion of urine In vertebrates, urine is excreted in four steps: Ultrafiltration Protein- and cell-free ultrafiltrate (primary urine) made by filtering through permeable membrane (ultrafilter). Reabsorption Water, glucose and amino acids Nephro are selectively reabsorbed. n Secretion Wastes selectively secreted out into ultrafiltrate. Excretion Final urine is excreted. Nephridial system in cephalochordates Lancelets have paired nephridia consisting of a cluster of podocytes on a branch of the dorsal aorta. aor: aorta Urine discharged into the fcl: filtration cell atr: atrium coe: coelom gls: gill slit atrium – a not: notochord npr: nephridiopore (kidney) sbc: subchordal coelom circumpharyngeal water jacket. Ruppert 1994. Am Zool 34: 542–5  1. Renal pyramid 2. Interlobular artery Vertebrate kidneys 3. Renal artery 4. Renal vein 5. Renal hilum 6. Renal pelvis 7. Ureter 8. Minor calyx 9. Renal capsule 10. Inferior renal capsule 11. Superior renal capsule 12. Interlobular vein[citation needed] 13. Nephron Vertebrate kidneys are 14. Renal sinus 15. Major calyx 16. Renal papilla 17. Renal column Nephro ultrafiltration (UF)-based n Nephro excretory organs, derived n from chordate nephridial system. Nephro n Osmotic regulation in fishes Freshwater fish are osmoregulators. Actively control salt concentrations despite the salt concentrations in the environment Saltwater fish are osmoconformers. Match their body osmolarity to their environment. Birds and reptiles Birds and reptiles form urine in paired kidneys as in other vertebrates. Urine passes by way of tubes called ureters to the cloaca. There is no urinary bladder Excrete nitrogenous waste as uric acid. Often white solid. Mammals Mammals form urine in paired kidneys as in other vertebrates. Urine passes from kidney via the ureters to the bladder. Urine excreted through 1. Human urinary system: 2. Kidney 3. Renal pelvis 4. Ureter the urethra. 5. Bladder 6. Urethra. (Left side with frontal section 7. Adrenal gland Vessels: 8. Renal artery and vein 9. Inferior vena cava 10. Abdominal aorta 11. Common iliac artery and vein With transparency: 12. Liver 13. Large intestine 14. Pelvis Respiratory system Respiration = gas exchange Physiological respiration Also called gas exchange. Movement of gas across the external boundary of an organism and its surroundings. Uptake of O2. Release of CO2. Provides O2 for cellular respiration. Production of energy; adenosine triphosphate Blood flow (ATP). Mechanism of gas exchange Passive diffusion of gas across boundaries between the body and surrounding medium (water or air). Membranes in respiratory organs (gills, lungs). Cell membranes (sponges). Water flow reaches each cell. Body walls (cnidarians). Epidermis and gastrodermis. Mechanism of gas exchange Diffusion across 𝜑: concentration d𝜑/dx: concentration gradient across membranes occurs along membrane a concentration gradient. J: flux, the amount of gas diffusing per Gas flows from high to low unit area per unit time. concentrations. Concentration gradient dependent on thickness Simple diffusion across body walls does not work on larger animals. Mechanism of gas exchange Decreasing concentration differential between two flows Cocurrent exchange Respiratory medium and blood flow in the same direction. Inefficient exchange rate. Consistent concentration Countercurrent exchange differential between two flows Respiratory medium and blood flow in opposite directions. Efficient exchange rate. CROSSCURRENT FLOW Crosscurrent exchange Respiratory medium and blood flow in oblique directions. Oxygen transport Once diffused across a surface: O2 may be transported in physical solution in plasma or coelomic fluid or O2 binds to respiratory pigment in blood or coelomic fluid. Complex of metal and protein. Increases the oxygen- carrying capacity of the fluid. Respiratory pigments Three types of respiratory pigments: Hemoglobin Iron-based Widely found across Bilateria Hemerythrin Iron-based Rare (only in a few invert Hemoglobin Heme species) Found in cells Hemocyanin Copper-based Molluscs and arthropods Hemocyanin Gas exchange in vertebrates Gas exchange in vertebrates occur fundamentally in the same way as in other phyla: Gas exchange across a surface between respiratory medium (water or air) and blood flow. Gills Lungs Skin (cutaneous respiration) Gas exchange in vertebrates In gill respiration the flow of water is unidirectional. Continuous flow. In lung respiration the flow of air is bidirectional. Intermittent flow Aquatic respiration in cyclostomes In larval lampreys, water is drawn into the mouth by muscular velum. Water is driven across gills, exiting through pharyngeal slits. Blood in gill filaments flow in opposite direction (countercurrent flow). Ammocoete larva of lamprey Adult lamprey Aquatic respiration in cyclostomes In parasitic adult lampreys, the mouth grips its prey, prohibiting water entering to ventilate the gills. Water flows in and out of the pharyngeal slits. Muscles of the branchial apparatus drive this tidal flow. Ammocoete larva of lamprey Adult lamprey Aquatic respiration in cyclostomes In hagfish, water is drawn in through the nostrils by currents generated by the scrolling and unscrolling of the velum. Gas exchange occurs along the gill lamellae inside branchial pouches. Aquatic respiration in chondrichthyans In chondrichthyans, each gill consists of an interbranchial septum, covered on each face by primary lamellae (gill filaments). Primary lamellae are composed of secondary lamellae. Aquatic respiration in chondrichthyans Ventilation in sharks is alternating negative and positive pressures. Negative pressure drives water in through the mouth. Positive pressure forces water across the gills. Aquatic respiration in bony fishes Water flows in In bony fishes, each gill is from the mouth V-shaped composed of primary lamellae and secondary lamellae. Water flows over Water flows in the the gills opposite direction to the blood flowing in the secondary lamellae, forming a countercurrent exchange system. Terrestrial respiration in vertebrates Respiration in lungfish Lungfish have lungs, as the name suggests, and lung respiration predominates over gill respiration. Australian lungfish has a single lung in a dorsal position. African lungfish has paired lungs. Lungs subdivided into faveoli. Gas exchange occurs with capillaries. Respiration in amphibians Amphibians undergo both gill respiration and lung respiration in their lifetime. Amphibian larvae have both internal and external gills. External gills are held out in passing current. Larval anurans use buccal and pharyngeal force pumps to produce unidirectional flow of water across internal gills. Respiration in amphibians Amphibians lose gills through metamorphosis. Adults typically respire through lungs. Lungs are ventilated by a buccal pump. Respiration in amphibians Skin is a major respiratory organ – gases easily diffuse across the thin moist skin with rich supply of capillaries. Cutaneous respiration Terrestrial respiration in reptiles Compression and expansion of the rib cage force air in and out of the lungs. Internal faveoli increase surface area for gas exchange. Capillaries line the walls of the faveoli. Many snakes have only 4: Vestigial left lung 5: Right lung one lung. Terrestrial respiration in birds Birds have a pair of lungs connected to the trachea and ventilated by an aspiration pump. Birds have a pulmonary flow-through system made up of small one-way passageways, the CROSSCURRENT FLOW parabronchi. Airflow is managed by extensive air sac system. Terrestrial respiration in mammals Mammals also have a pair of lungs. Mammalian ventilation is Intercostal muscles bidirectional. Air is forced in and out through an aspiration pump, driven by the rib cage and diaphragm. Mammal lungs terminate in small alveoli lined with arteries and veins. Patterns of gas transfer in animals Mammalian lungs are blind- ended. Air moves tidally. Gas exchange involving a uniform pool. Avian lungs are flow-through. Air moves one way. Blood flows obliquely to airflow. Crosscurrent gas exchange. Fish gills are also one-way systems. Blood flows in opposite direction to water. Countercurrent gas exchange. Evolution of the vertebrate lungs Lungs in sarcopterygians True paired lungs are only found in tetrapods. Unpaired Unpaired Paired Unpaired respiratory lungs are ventral fatty dorsal dorsal lung lung lungs Paired found in lungfish. ventral Dorsal position but opens from lungs the oesophagus ventrally. Coelacanths have unpaired fatty organ that is homologous to lungs in other sarcopterygians. Unpaired ventral lung is ancestral to Sarcopterygii. Evolution of the vertebrate lungs Lungs in sarcopterygians Actinopterygians (ray- finned fishes) lack Unpaired dorsal gas Unpaired ventral fatty Unpaired dorsal Paired dorsal respiratory lungs but have bladder lung lung lungs Paired gas-filled sacs called gas ventral lungs (swim) bladders. Some fish use them for respiration. Evolution of the vertebrate lungs Lungs in sarcopterygians Which came first, the gas bladder or the lungs? Unpaired dorsal gas Unpaired ventral fatty Unpaired dorsal Paired dorsal bladder lung lung lungs Paired ventral lungs Evolution of the vertebrate lungs Polypterids (bichirs), the basal actinopterygian, Polypterids have an unpaired ventral have an unpaired lung, which they use for ventral lung respiration. Evolution of the vertebrate lungs Polypterids (bichirs), the basal actinopterygian, have an unpaired ventral lung, which they use for respiration. Polypterids preferentially breath through spiracles at the back of their skulls. Evolution of the vertebrate lungs Polypterid lungs are developmentally Polypterids homologous to gas have an unpaired bladders and ventral lung sarcopterygian lungs. Evolution of the vertebrate lungs Unpaired, ventral lungs may be ancestral to Polypterids Osteichthyes (bony have an unpaired fishes). ventral lung Lungs came first! Then gas bladders evolved in ray-finned fishes. Paired lungs evolved in tetrapods. Unpaired ventral lung ancestral state to bony fishes?