Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh Edition Solomon Berg Martin Chapter 46 Osmoregulation and Disposal of Metabolic Wastes

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Osmoregulation The active regulation of osmotic pressure of body fluids so that homeostasis is maintained Excretory systems Help maintain homeostasis by regulating the concentration of body fluids

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Principal waste products of animal metabolism Water Carbon dioxide Nitrogenous wastes –Ammonia (excreted mainly by aquatic animals) –Urea –Uric acid

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Osmoconformers Includes most marine invertebrates Salt concentration of their body fluids varies with changes in the seawater

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Osmoregulators Marine invertebrates that inhabit coastal habitats Maintain an optimal salt concentration despite changes in the salinity of their surroundings

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Nephridial organs Include protonephridia and metanephridia Function in osmoregulation and waste disposal

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Protonephridia Found in flatworms and nemerteans Tubules with no internal openings Interstitial fluid enters their blind ends, which consist of flame cells Beating of the cilia propels fluid through the cilia

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Protonephridia of a flatworm

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Metanephridia Found in annelids and mollusks Tubules open at both ends As fluid from the coelom moves through the tubule, materials are reabsorbed by capillaries Urine exits the body through nephridiopores

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Metanephridia of an earthworm

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Malpighian tubules Extensions of the insect gut wall Have blind ends that lie in the hemocoel Cells of the tubule actively transport uric acid, etc., into the tubule Water follows by diffusion

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Malpighian tubules, cont. Contents of the tubule pass into the gut and water and some other solutes are reabsorbed in the rectum Malpighian tubules effectively conserve water

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Malpighian tubules of an insect

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Freshwater fishes Take in water osmotically Excrete a large volume of dilute urine Marine bony fishes Lose water osmotically Compensate by drinking seawater and excreting salt through gills Produce a small volume of urine

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Sharks and other marine cartilaginous fishes Retain large amounts of urea Take in water osmotically through the gills Excrete a large volume of urine

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Osmo- regulation in fishes

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Marine mammals Ingest seawater with their food Produce a concentrated urine

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Terrestrial vertebrates Must conserve water Endotherms have high metabolic rate Produce a large volume of nitrogenous wastes Conserve water through efficient kidneys and other adaptations

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Excretory organs in terrestrial vertebrates

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Vertebrate kidney Functions in excretion and osmoregulation Is vital in maintaining homeostasis Its structure and function are adapted to the lifestyle of the animal

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Organs of the mammalian urinary system Kidney –Key organ of the urinary system, the principal excretory system in humans and other vertebrates –In mammals, the kidney produces urine

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Organs of the mammalian urinary system, cont. Urine passes through the ureters to the urinary bladder During urination, the urine is released through the urethra

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes The human urinary system

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Structure of the kidney Outer portion is the renal cortex Inner portion is the renal medulla –Contains eight to ten renal pyramids –Tip of each pyramid is a renal papilla –Urine flows into collecting ducts, which empty through a renal papilla into the renal pelvis Functioning unit is a nephron

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Structure of the kidney

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Structure of the nephron

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Detailed view of Bowman’s capsule

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Urine formation is accomplished by the Filtration of plasma Reabsorption of needed materials Secretion of substances such as potassium and hydrogen ions into the renal tubule

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes General regions of filtration, reabsorption, and secretion

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Filtration membrane of the kidney

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Movement of water, ions, and urea through the renal tubule and collecting duct

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Concentration of the filtrate as it moves through the nephron

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Urine volume is regulated by ADH Released by the pituitary gland in response to an increase in osmotic concentration of the blood ADH increases the permeability of the collecting ducts to water As a result, more water is reabsorbed

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Regulation of urine volume by ADH

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Aldosterone andatrial natriuretic peptide work antagonistically When blood pressure decreases, cells of the juxtaglomerular apparatus secrete renin, which leads to production of angiotensin II Angiotensin II stimulates aldosterone release, which raises blood pressure

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes When blood pressure increases Atrial natriuretic peptide (ANP) increases sodium excretion Inhibits aldosterone secretion These actions increase urine output and lower blood pressure

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 46 Osmoregulation and Disposal of Metabolic Wastes Hormonal control of kidney function