Osmoregulation and Human Excretory System PDF

13_Osmoregulation and Excretion Osmoregulation and excretion Human excretory system © 2016 Pearson Education, Ltd.  Key Concepts Osmoregulation is the way organism used to regulate solute concentration and b...

13_Osmoregulation and Excretion Osmoregulation and excretion Human excretory system © 2016 Pearson Education, Ltd.  Key Concepts Osmoregulation is the way organism used to regulate solute concentration and balance the gain and loss of water. Marine and freshwater fishes faced different challenges. The urinary system forms and excretes urine to regulate the amount of water and solutes in the body fluids. Nephron is the functional unit of the kidney. Nephron extract fluid from capillaries to form filtrate. Filtrate is refined, water and some solutes are reabsorbed back into the capillaries, toxin and hydrogen ions are secreted from the capillaries into the nephron tubules. Liquid excreted out from the kidney is called urine. Antidiuretic hormone regulates the amount of water excreted by the kidney. Dialysis machine removes wastes from patient with kidney failure. © 2016 Pearson Education, Ltd.  OSMOREGULATION & EXCRETION © 2016 Pearson Education, Ltd.  Animals balance their levels of water and solutes through osmoregulation Osmoregulation - the homeostatic maintenance of solute concentrations and the balance of water gain and loss Osmosis - the passive diffusion of water across a selectively permeable membrane, from a solution with a lower solute concentration (and thus more water) to one with a higher solute concentration When an animal cell is in an environment where the solute concentration is lower than that inside the cell (hypotonic) - water ???, causing the cell ??? When an animal cell is in an environment where the solute concentration is higher than that of the cell (hypertonic), water ???, causing the cell ??? © 2016 Pearson Education, Ltd.  Adaptation of saltwater and freshwater fish Saltwater fish (marine fish) live in a ?? environment lose water by osmosis from their body surfaces Gain water and salt from food and drinking of seawater balance solutes by pumping out excess salt through their gills Freshwater fish live in ?? environment gain water by osmosis through their body surface, especially through the gills lose salt by diffusion to the more dilute environment take in salt through their gills and in food dispose of excess water by producing large amounts of dilute urine © 2016 Pearson Education, Ltd. Figure 25.4-0 Marine fish Freshwater fish Gain of water and Excretion Osmotic water Gain of water and Uptake Osmotic water salt ions from food of salt ions loss through gills some ions in food of salt ions gain through gills from gills and other parts by gills and other parts of body surface of body surface SEAWATER FRESH WATER Gain of water Excretion of salt ions and small Excretion of salt ions and and salt ions from amounts of water in concentrated large amounts of water in drinking seawater urine from kidneys dilute urine from kidneys Key Water Salt © 2016 Pearson Education, Ltd.  Adaptation of land animals Land animals face the risk of dehydration lose water across their skin and moist respiratory surfaces and in urine and feces gain water by drinking, eating, and performing cellular respiration conserve water by external and internal adaptations such as a waterproof exoskeleton, water-tight eggshells, and kidneys that conserve water © 2016 Pearson Education, Ltd.  HUMAN EXCRETORY SYSTEM © 2016 Pearson Education, Ltd.  The urinary system plays several major roles in homeostasis The urinary system  forms and excretes urine  regulates the amount of water and solutes in body fluids In humans, the kidneys are the main processing centers of the urinary system Our kidneys extract about 180 L of fluid, called filtrate (water, urea, a number of valuable solutes, including glucose, amino acids, ions, and vitamins) Our kidneys then refine the filtrate by concentrating the urea and recycling most of the water and useful solutes back to the blood In a typical day, we excrete only about 1.5 L of urine (the refined filtrate, which contains the wastes) © 2016 Pearson Education, Ltd.  The excretion processes During filtration, the pressure of the blood forces water and other small molecules (solutes) through a capillary wall into the start of a kidney tubule, forming filtrate Urine, the final product of filtration, leaves each kidney through a duct called a ureter Both ureters drain into the urinary bladder During urination, urine is expelled from the bladder through a tube called the urethra © 2016 Pearson Education, Ltd.  Nephrons, the functional units of the kidneys Nephrons o are the functional units of the kidneys o extract a fluid referred as “filtrate” from the blood o refine the filtrate to produce urine © 2016 Pearson Education, Ltd. © 2016 Pearson Education, Ltd.  Filtrate formation and refining Blood enters the nephron through the renal artery and flows into a ball of capillaries called the glomerulus (plural, glomeruli) The filtrate forced into Bowman’s capsule flows into the nephron tubule where it will be refined Two processes refine the filtrate o In reabsorption, water and valuable solutes (such as glucose, salt, and amino acids) are reclaimed from the filtrate o In secretion, excess H+ and toxins are added to the filtrate Finally, in excretion, urine is expelled from the kidney filtration – refining (reabsorption & secretion) - excretion © 2016 Pearson Education, Ltd. Figure 25.6c-0 Key refining Filtration Reabsorption Secretion Excretion Bowman’s From capsule renal Filtration Reabsorption Secretion Excretion artery (Removal from filtrate) (Addition to filtrate) Nephron tubule Filtrate H2O, other small molecules Urine Interstitial fluid To renal vein Capillary © 2016 Pearson Education, Ltd.  Hormones regulate the urinary system Antidiuretic hormone (ADH) regulates the amount of water excreted by the kidneys by o signaling nephrons to reabsorb water from the filtrate into the blood o decreasing the amount of water excreted o Diuretics o inhibit the release of ADH o include alcohol and caffeine © 2016 Pearson Education, Ltd.  Kidney dialysis can save lives Kidney failure can result from hypertension, diabetes, and prolonged use of common drugs, including alcohol. A dialysis machine removes wastes from the blood and maintains its solute concentration © 2016 Pearson Education, Ltd.