Biology 1442 1st EditionExam #3 Study Guide Chapter 44-47Chapter 44: Osmoregulation and Excretion VocabularyExcretion- how the body gets rid of nitrogenous metabolites and wastes like ammonia Osmolarity- concentration of a solute in a solutionIsosmotic- Osmolarity is equal on both sides of the concentration gradient and water molecules cross themembrane at the same rate no matter the directionHyposmotic (less concentrated) - lower solute concentration, higher free H2O concentrationHyperosmotic (more concentrated) - higher solute concentration, lower free H2O concentrationTonicity- the ability of a cell’s surrounding solution to cause that same cell to gain or lose water Need to Know 1. osmoregulation balances the uptake and loss of water and solutes through a concentration gradienta. water and solutes are constantly moving across the plasma membrane through a concentration gradient 2. Fresh water fish maintain salt/water homeostasis because…a. They are hyperosmoticb. take in water by osmosis from a Hyposmotic environmentc. lose salt by diffusiond. do not drink much H2O e. excrete a lot of dilute urine f. salt lost in diffusion is consumed in foods and uptake across the gillsg. Anhydrobiosis- ability of SOME aquatic invertebrates to lose most of their body water andsurvive dormant, as a dehydrated pod until conditions return to the favorable ones 3. Salt Water animals maintain salt/water homeostasis because…a. Most are osmoconformers or isoosmotic with the surrounding environment, they don’t have to regulate their Osmolarity, facing no challenges with water balanceb. Others are osmoregulators which balance water loss by drinking large quantities of seawater and getting rid of salt through the gills and kidneys i. Osmoregulators are always losing water by osmosis ii. Examples: marine bony fish and shark1. Marine bony fish is hypoosmotic to seawater 4. Land animals maintain salt/water homeostasis because…a. Body coverings prevent dehydrationb. Nocturnal lifestyle of desert animals or other adaptations such as a hard shellc. They eat moist foodd. Produce water through cellular respiration5. Osmoconformers are isoosmotic with its surroundings, meaning the fish has the same Osmolarity as the surrounding watera. There is no gain or loss of water 6. Osmoregulators: control Osmolarity internally and independent from the external environmenta. To live in a hypoosmotic environment they have to release excess waterb. To live in a hyperosmotic environment they have to take in water to offset osmotic loss7. The type and quantity of nitrogenous waste reflects its phylogeny and habitat.a. Phylogeny is the animal’s species evolutionary historyb. The habitat that the animal lives in reflects the kind of waste produced by animal depending on how much water is available c. Ammonia is excreted mainly by aquatic animals because it takes a lot of water to dilute itto a tolerable concentrationi. Energy efficientd. Urea less toxic to excrete and is much more suitable for animals that switch back and forth from terrestrial to aquatic environmentsi. Energy expensivee. Uric acid is excreted by insects, land snails, reptiles, and birdsi. Most energetically expensive form of wastef. Endotherms produce more nitrogenous waste than ectotherms because the endotherms eat more foodg. animals that eat high protein diets also produce more nitrogenous wastes than those who have a lipid and carbohydrate based diet 8. Urea is a less toxic form of ammonia and product of the metabolic cycle that is produced in the liver by combining ammonia and carbon dioxide.a. Urea is very low toxicity and helps reduce water loss when these animals are on land 9. Ammonia is excreted differently by different organisms.a. Saltwater fish excrete ammonia across the entire body surfaceb. Freshwater fish excrete ammonia across the entire body surfacec. Birds and reptiles excrete ammonia in the form of Uric Acid d. Land mammals like humans excrete ammonia as urea, other land mammals excrete ammonia as uric acid 10. There are 4 different excretory systems covered in this chaptera. Protonephridia (Flatworm)b. Metanephridia (earthworms)c. Malpighian tubulesd. The mammalian excretory systemChapter 45: Hormones and the Endocrine System11. Hormone and other signaling molecules bind to target receptors, triggering specific response pathways through intercellular communication and the use of chemical signals.a. Hormones secreting in extracellular fluids reach target cells through the blood stream andcommunication throughout the body 12. Hormones are chemical signals secreted into the circulatory system and communicate regulatorymessages within the body 13. Pheromones are chemicals released into the environment to signal and communicate between members of same species. Pheromones act like hormones by influencing physiology and behavior.14. Testosterone causes an increase in muscle mass and bone mass and is taken as a supplement to cause growth in muscles (carries health risks)15. Different types of Cellsa. Secretory Cells are the cells that secrete hormonesb. Endocrine cells are cells that are generally groups into ductless endocrine glands which secrete hormones directly into interstitial fluid, from where they diffuse into the bloodstreamc. Target cells are the cell with receptors for the specific hormones d. Regulatory cells16. Why do hormones only target specific cells?17. Polypeptide hormones and amines are water soluble, travel FREELY in the bloodstream and bind to cell-surface receptors, bind to hormone receptors to trigger signal transduction pathways and responses18. Polypeptide and amine hormones have 3 responses they may trigger, cytoskeletal, enzyme activation, or change in gene expression.19. Steroid hormones unlike polypeptides are non-polar and lipid soluble hormones that diffuse across cell membranes, travel in the blood stream BOUND to transport proteins and diffuse through the membrane of the target cells. Steroid hormones usually only cause changes in gene expression.20. Growth factors are responses produced from cells affected by growth hormones.21. Different types of Hormone Signalsa. Endocrine signaling- hormone secreted in extracellular fluids by endocrine cells reach target cells through the bloodstream, maintains homeostasis, mediates responses, regulates growth, and developmentb. Paracrine signaling and Autocrine signaling - local regulators act over short distances by diffusion,help regulation blood