Osmoregulation and Excretory Systems (1).pptx

Osmoregulation and Excretory Systems 1  Osmoregulation and Excretory Systems I. Osmotic Regulation II. Excretory Systems 2  Learning Objectives 1. Describe the effects of osmosis in cells. 2. Compare the e...

Osmoregulation and Excretory Systems 1  Osmoregulation and Excretory Systems I. Osmotic Regulation II. Excretory Systems 2  Learning Objectives 1. Describe the effects of osmosis in cells. 2. Compare the effects of tonicity on the osmotic pressure of cells 3. Distinguish the characteristics of euryhaline and stenohaline animals. 4. Compare the osmotic regulation strategies of freshwater and seawater animals 5. Describe anhydrobiosis 3  Learning Objectives 6. Evaluate the sources of water gain and forms of water loss among land animals 7. Identify the forms of nitrogenous waste produced by animals 8. Explain the function of excretory systems 9. Describe the types of invertebrate excretory systems 10. Explain the function of the vertebrate kidney 4  I. Osmotic Regulation A. Osmosis. It is defined as the movement of water molecules across a cell membrane from areas of high water concentration to areas of low water concentration. 5 B. The environment in which animals live can be described as: 1. Hypertonic: Higher solute and lower water concentration. 2. Hypotonic: Lower solute and higher water concentration. 3. Isotonic: equal water and solute concentration. The ideal environment for most animal cells is an isotonic one. This is maintained internally by a process called osmotic regulation. 6 7 C. Osmotic regulation in marine invertebrates: 1. Osmotic conformers: - Maintain an equal solute concentration to sea water - Limited osmotic regulation - Stenohaline species tolerate little changes in salinity (spider crab). - Euryhaline tolerate a wider range of salinity (shore crab). 8 D. Osmotic regulation in fish. 1. Marine fish live in a hypertonic environment and must deal with a constant water loss and salt uptake by hypoosmotic regulation - Drinking water - Producing a concentrated urine - Excreting salt through gills by active transport 9 2. Freshwater fish live in a hypotonic environment and must deal with a constant salt and minerals loss and water uptake by hyperosmotic regulation. - Drinking limited water - Producing a diluted urine 10 E. Life in Temporary Pools Some aquatic invertebrates in temporary ponds lose almost all their body water and survive in a dormant state This adaptation is called anhydrobiosis – Example: Tardigrades 11 F. Terrestrial animals lose water by evaporation from breathing and body surfaces, excretion in urine and feces, and replace it by water in food, drinking, and metabolic water (resulting from cellular respiration). 12 G. Transport Epithelia 1. Animals regulate the solute content of body fluid that bathes their cells 2. Transport epithelia are epithelial cells that are specialized for moving solutes in specific directions 3. They are typically arranged in complex tubular networks 4. An example is in nasal glands of marine birds, which remove excess sodium chloride from the blood 13  II. Excretory Systems A. Nitrogenous Wastes 1. Aquatic organisms release ammonia across the whole body surface or through gills 2. Mammals and most adult amphibians converts ammonia to the less toxic urea in the liver, and the circulatory system carries it to the kidneys. 3. Insects, land snails, and many reptiles, including birds, mainly excrete uric acid, which is relatively nontoxic and does not dissolve readily in water 14 B. Excretory System Functions Most excretory systems produce urine by refining a filtrate derived from body fluids Key functions of most excretory systems – Filtration: Filtering of body fluids – Reabsorption: Reclaiming valuable solutes – Secretion: Adding nonessential solutes and wastes from the body fluids to the filtrate – Excretion: Processed filtrate containing nitrogenous wastes, released from the body 15 C. Protonephridia in acoelomates (flatworms) and pseudocoelomates (nematodes and rotifers) collects body fluids through collecting tubules and the action of a flame cell. Wastes are expelled through an excretory pore. (Closed system) 16 D. Metanephridia in annelids is more sophisticated system than protonephridia, having two openings and being surrounded a network of blood vessels. Fluid enters the ciliated nephrostome, and waste is released through the nephridiopore. 17 E. Antennal glands (green glands) take a protein-free ultrafiltrate from the blood, and reabsorbs salts prior to excretion. 18 F. Malpighian tubules in insects and spiders operate in conjunction with the rectum to secrete insoluble uric acid. Muscle contractions force fluid into the tubules 19 D. Vertebrate kidneys. 1. The functional unit of the kidney is the nephron. 2. Has three physiological functions: filtration, re-absorption, secretion and excretion. 20 21 E. Nephron Function. 1. The glomerulus produces a protein- free filtrate. 2. The proximal convoluted tubule reabsorbs 60% of filtrate (H2O, glucose, amino acids and vitamins) 3. The descending limb of loop of Henle is permeable to water and impermeable to NaCl 22 5. The ascending limb of Henle’s loop reabsorbs NaCl and is impermeable to water. 6. The distal convoluted tubule re-absorbs NaCl and secretes potassium under the control of aldosterone 7. The collecting duct’s permeability to H2O and urea is controlled by anti-diuretic hormone. 8. Blood pressure is regulated in part by the 23 enzyme renin.