Chapter 1 Homeostasis and Excretory System PDF

HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  LESSON OUTCOMES At the end of this topic, you will be able to: define key terms related to homeostasis and A explain how homeostasis is achieved. distinguish the way in which a...

HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  LESSON OUTCOMES At the end of this topic, you will be able to: define key terms related to homeostasis and A explain how homeostasis is achieved. distinguish the way in which aquatic animals and terrestrial animals can eliminate toxic ammonia from B their systems. compare the major byproduct of ammonia metabolism in mammals to that of birds and C reptiles. describe protonephridia, metanephridia, and D Malpighian tubules, and compare their functions. relate the function of the vertebrate kidney to the success of vertebrates in a wide variety of E habitats. designed by tinyPPT.com HOMEOSTASIS HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Maintenance of a constant internal environment when dealing with external changes. Reactions and enzymes work best in specific conditions. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Three Components of a Homeostatic Control System Receptor: senses a change in the environment. Control Center: determines how to respond to Effector: the change. receives the signal, and adjusts accordingly HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Homeostatic control mechanism Negative Positive feedback feedback Shut off the Increase the Make variable Reduce the original original farther from its initial intensity stimulus stimulus original value HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM Examples of Homeostatic Regulation Thermoregulation: Maintaining a constant optimal body temperature Glucose Regulation: Maintaining a constant optimal blood glucose level Osmoregulation: Maintaining a constant optimal osmotic pressure Excretion: Removal of nitrogenous-waste products of metabolism HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM Skin hairs: The hairs trap a layer of air above the skin, which helps to insulate the skin against heat loss. Skin hairs lie flat when we Hypothalamus: are warm. Part of the brain which monitors the body's temperature. It receives information from temperature- sensitive receptors in the skin and circulatory system. Skin hairs rise when we are cold. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM T H E R M O R E G U L A T I O N Two hormones involve in controlling blood glucose levels: insulin and glucagon Both hormones are secreted by the pancreas and are transported to the liver in the bloodstream. G L U C O S E R E G U L A T I O N  Osmoregulation Osmosis The process of maintaining salt The diffusion of water and water balance (osmotic across a balance) across membranes membrane in response to within the body.The fluids inside osmotic pressure and surrounding cells are composed of water, electrolytes, caused by an imbalance of and nonelectrolytes. molecules on either side of the membrane. Osmotic pressure Osmolarity The solute A measure of the concentration of a tendency solution, determines of water to move the movement of into one solution water from another across a selectively by osmosis. permeable membrane.  Water Solutes Net water flow - If two solutions are isosmotic, the movement of water is equal in both directions. - If two solutions differ in osmolarity, the net flow of water is from the hyposmotic to the hyperosmotic solution. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM O M O C N F R M R S S O O E Animals which are isoosmotic with their surroundings and do not actively adjust their internal osmolarity. O R U R S S M O E G L A T O Animals whose body fluids are not isotonic with the outside environment, must either discharge excess water if they live in a hypotonic environment or continuously take in water if they live in a hypertonic environment. S O T E N H A L I N E Animals that cannot tolerate substantial changes in external osmolarity. Can live in either freshwater or seawater, but not both. E H I N E R U R Y A L Animals that survive radical fluctuations of osmolarity in their surroundings. They either conform to the changes or regulate their internal osmolarity within a narrow range even as the external osmolarity changes. o Marine bony fishes (vertebrates) are hypoosmotic to sea water. o Tend to lose water by osmosis and gain salt by both diffusion and from food. o They balance water loss by drinking seawater and actively excretes salts. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  o Freshwater animals are hyperosmotic to fresh water. o Tend to absorb water by osmosis from their hyposmotic environment and lose salts by diffusion. o They maintain water balance by excreting large amounts of dilute urine. o They do not drink much water. o Salts lost by diffusion are replaced by foods and by active uptake across the gills. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM EXCRETION HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Excretion ❖Excretion is a process where waste products are expelled from the body. ❖The type and quantity of an animal’s waste products may have a large impact on its water balance. ❖Among the most significant wastes are nitrogenous breakdown products of proteins and nucleic acids. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM FORMS OF NITROGENOUS WASTES HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Ammonia Ammonia are quickly changed Not allowed into a less to accumulate Liver toxic form, in the body. Very toxic urea. Aquatic species Most Need access to common in lots of water, to Water Gills aquatic dilute ammonia species for into a non- Structure example, lethal fresh water concentration. fishes. The site where ammonia are released or across the HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM body surface.  Urea ~can be transported in circulatory system and stored safely at high concentration~ Liver Kidneys Water Energy Structure Mammals and Urea is Excretion of Energy cost to most adult concentrated urea requires produce urea amphibians and excreted. less water from convert than ammonia. ammonia to ammonia. less toxic urea. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Uric Acid Waste materials for animals that lay hard-shelled eggs. Type of Toxicity Water Energy Animals Relatively Uric acid is More energy Reptiles, nontoxic insoluble in cost than birds, insects although its water. urea. and land nitrogen Synthesis of snails. content is Excretion of uric acid high. uric acid involves 15 requires little enzymes and water needs a lot of energy. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  All animals own a specialized excretory system and organs for osmoregulation and the removal of nitrogenous wastes. Key functions of most excretory systems are: FILTRATION Pressure-filtering of body fluids producing a filtrate. REABSORPTION Reclaiming valuable solutes from the filtrate. Addition of toxins and other SECRETION solutes from the body fluids to the filtrate. The filtrate leaves the EXCRETION system. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Dead end tubules that connected to Tubules external openings, which function mainly in osmoregulation. A cellular unit that cap the smallest Flame bulb branches of the network. The beating of cilia makes interstitial Cilia fluid to be filtered through openings in the flame cell. Solutes will be reabsorbed as the fluid Reabsorption passes through the tubule. Excess water and wastes will be excreted Excretion in the form of urine through nephridiopores to external environment. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Metanephridia Each segment of an earthworm has a pair of open-ended metanephridia Reabsorption Useful solute are reabsorbed into Filtration capillaries, when the Coelomic fluid is filtrate moves along filtered into the the metanephridial nephrostome. tubules. Excretion A dilute urine is excreted through nephridiopores. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Mechanism Organism Salts and uric acid are transported using transport epithelium into Insects and other the tubule from the hemolymph. Water enters terrestrial arthropod. the lumen by osmosis. Reabsorption Excretion Salts and water are Wastes are excreted reabsorbed from the with feces through the hindgut into the anus. hemolymph. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Excretory organs of vertebrates, function in both excretion and osmoregulation. Principle site of salt regulation and water balance. Consists of specialized structures and capillary networks that assist in the excretory process. The human excretory system includes the kidneys and their functional unit, the nephron. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  BLOOD Enters the kidney through renal arteries and leaves via renal veins. KIDNEYS Produce urine ( a watery solution consists of waste products, salts, organic compounds, as well as two important nitrogen compounds: uric acid and urea) URETERS Carry urine from the kidneys to urinary bladder. URINARY BLADDER Temporarily stores urine before elimination. URETHRA Transports urine to exterior. ~Nephron: The functional unit of the vertebrate kidney, consists of a single long tubule and ball of capillaries called the glomerulus~ HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Proximal Distal tubule tubule Bowman’s Loop of Collecting capsule Henle duct HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  ADAPTATIONS OF VERTEBRATE KIDNEYS HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  The juxtamedullary nephron, with its urine concentrating features enabling mammals to get rid of salts and nitrogenous wastes without squandering water Desert Mammals: Example: Bannertail Kangaroo rats: Have loops of Henle that extend deep into the medulla. - maintain steep osmotic gradients, resulting in urine becoming very concentrated. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Aquatic Mammals: Example: Beaver - Spend much of their time in fresh water, thus, rarely face problems of dehydration. - Have nephrons with relatively short loops, thus, lower the ability to concentrate urine. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Example: Roadrunner - Most birds live in environments that are dehydrating. - Have kidneys with juxtamedullary nephrons specialize in conserving water, but loops of Henle extend less far into the medulla than those of mammals. - Main water conservation adaptation: - having uric acid as the nitrogenous waste molecule, which can be excreted as a paste. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Example: Desert Iguana - Having only cortical nephrons that produce urine which is isoosmotic/ hypoosmotic to body fluids. - Excrete nitrogenous waste in the form of uric acid. Credit: Photo by Jim Rorabaugh HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Fresh water: Excrete dilute urine while the skin accumulates certain salts from the water by active transport. On land: Conserve body fluid by reabsorbing water across the epithelium of the urinary bladder. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Example: Cat fish - Hyperosmotic to their surrounding must excrete excess water continuously. Credit: http://marinefishexport.com/freshwater- fishes/ - Produce large volumes of very dilute urine. - Conserve salts by reabsorbing ions from the filtrate in their distal tubules. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM  Example: Atlantic bluefin tuna - Have fewer, smaller nephron and lack of distal tubule. - Some have small / lack of glomeruli entirely. Credit: Wildlife Society - Filtration rates are low, very little urine is excreted. HOMEOSTASIS AND EXCRETORY SYSTEM ANIMAL AND PLANT PHYSIOLOGY ENMM