Biology 203 1st Edition Lecture 21Outline of Last Lecture I. Animals are HeterotrophicII. How do animals find food?III. Handling FoodIV. Digestion and uptake of consumed foodV. Gut MorphologyVI. FrogsOutline of Current Lecture I. Remembering CatabolismII. Transferring nutrients/gasses to the bodyIII. GillsIV. Trachea and LungsV. Transport systemsVI. Open Circulatory SystemsVII. Closed Circulatory SystemsVIII. Blood VesselsCurrent LectureI. Remembering Catabolisma. Glycolysis takes place in the cytoplasm of cells and con occur without oxygenb. The Krebs cycle (citric acid cycle) occurs in the mitochondria and requires oxygeni. It generates reduced NADH molecules that transfer energy to the electrontransport chainii. Oxidation of NADH creates a concentration gradient of H+ ions that drive ATP productionc. Uptake of Oxygeni. Aerobic metabolism depends on oxygen being made available to respiringtissuesii. Fundamentally this depends upon diffusion – oxygen molecules moving from high concentration to lowd. Fick’s Law of diffusion – rate of gas diffusion depends on 5 parameters:i. Solubility of gas and temperatureii. Area for gas exchangeiii. Difference in partial pressure of gas on either side of barrier to diffusioniv. Distance (thickness of barrier to diffusion)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.II. Transferring nutrients/gases to the bodya. Platyhelminthesi. Rely on diffusionii. Across the body wall (tegument)iii. Plus caeca in some speciesb. Coelom and pseudocoelomi. Fluid-filled cavity (coelom) for nutrient distributionii. Transport via muscular contractionsiii. Fluid has oxygen-binding molecules like hemoglobinIII. Gillsa. Evaginated extension of the body surfaceb. Extraction of oxygen from waterc. High surface area but thin tissued. Highly vascularizede. Internal or externalf. Fish gills:i. Structure is conserved across species1. Both sides of head2. Have 4 gill arches3. Lots of filamentsii. Water is pumped over the gills via mouth movements and the operculaiii. Generates a UNIDIRECTIONAL flow of water over gill surfacesg. Countercurrent exchangei. Oxygen rich water flows over the gills as oxygen poor blood moves through the capillaries in the opposite directionii. This sets up a diffusion gradientiii. Oxygen moves from the high concentration (water) to the lower concentration )blood ) across the lamellae membraneIV. Trachea and Lungsa. Tracheai. Direct transport of air to cellsii. Spiracles, tracheal trunk, tracheal tubeiii. Tracheole – site of gas exchangeb. Lungsi. Invaginated internalized surfacesii. Often associated with a ventilation system to move air into and out of thelungsV. Transportation Systemsa. One solution to the limitations imposed by diffusion is the evolution of circulatory systemsb. The function of a circulatory system is to carry a transport fluid into close contact with every cell in the bodyi. Increased capacity for oxygen uptakeii. They rapidly remove oxygen from the respiratory surfaces and maintain a steep oxygen gradient = increased oxygen uptakec. Two types of circulatory systems: open and closedi. Both require muscular pumps and/or muscular, pulsating blood vesselsVI. Open Circulatory Systemsa. Heart as pumpb. Some blood vesselsc. Transport fluid is not confined exclusively to blood vesselsd. Hemolymph as transport fluidi. Hemocytese. Overall pressure in the system is lowf. Arthropodsi. Many arthropods are very activeii. How does an open circulatory system meet the metabolic demands of arthropods? ‘Tube Heart’iii. Heart is made up of a number of linearly arranged chambersiv. Allow a large amount of blood to flow into and out of the surrounding sinusVII. Closed Circulatory Systemsa. Both coelomic fluid and blood carry food, wastes and respiratory gasesb. Blood circulates in a closed systemc. The dorsal vessel above the alimentary canal functions as a true heartd. The dorsal vessel pumps blood anteriorly into five pairs of aortic archese. Benefits:i. Allows for enough pressure to maintain a high flow rateii. Allows for precise alteration of blood flowiii. Includes a pump and a full circuitVIII. Blood Vesselsa. Arteries carry blood away from the heart to the capillaries (or alveoli)i. Blood leaves the heart under high pressureii. Arteries are much thicker and more elastic to accommodate this pressureb. Veins carry blood back to the heart after it passes through the capillaries (or alveoli)i. After exiting the tissues, blood is under relatively low pressureii. Veins have much thinner walls and much larger interior diametersc. The pressure generated from the heart provides enough force to transport blood to and through the