Ch 48 Osmoregulation and Disposal of Metabolic Wastes Flashcards
– active regulation of osmotic pressure of body fluids
– maintains fluid and electrolyte homeostasis
– electrolyte
Osmoregulation
Dissociates into ions when dissolved in water, can conduct an electric current.
Electrolyte
– process of ridding body of metabolic wastes
– Excretory systems function in both osmoregulatrion and disposal of wastes
Excretion
Principal metabolic wastes of animals are
CO2, H2O, and nitrogenous compounds
: toxic nitrogenous compound
– a product of catabolism of amino acids and nucleic acids
– excreted mainly by aquatic animals
Ammonia (NH3)
– Require additional energy expenditure
– Urea
• principal nitrogenous excretion of amphibians and mammals
• soluble in water
– Uric acid (non-toxic)
• excreted by reptiles, birds, and insects
• insoluble in water; excreted as semisolid paste
• requires less water for excretion than urea
Less Toxic Nitrogen Waste Compounds
Animals with blood vessels
Excretory Systems
– tubules open at both ends
– some annelids and mollusks
Metanephridia
Fluid from coelom into tubule.
– needed materials reabsorbed by
Capillaries
Concentrated urine exits body through
Nephridiophores
Excrete nitrogenous wastes in urine in vertebrates
• maintain fluid balance by adjusting salt and water content
Kidneys
• Take in water osmotically
– excrete large volume of hypotonic (dilute) urine
Freshwater Fishes
- Lose water osmotically
- Compensate by drinking sea water and excreting salt and ammonia through their gills
- Produce only a small volume of isotonic urine
Marine Bony Fishes
– efficient kidneys and bladders
– excretion of uric acid
Water conservation strategies
– have a high metabolic rate
– produce large volume of nitrogenous wastes
Endotherms
birds (like other reptiles) nitrogenous waste:
Uric acid
Mammals nitrogenous waste:
Some through skin
- mostly through urinary system
• Principal excretory system in mammals
The Urinary System
Mammalian kidneys produce _____
– passes through ureters
– to urinary bladder for storage
Urine
• Urine is released from the body (urination) – through the
Urethra
– outer portion of kidney
Renal cortex
– inner portion of kidney
– contains 8 to 10 renal pyramids
Renal medulla
– Urine from collecting ducts flows through the tip of each pyramid into the renal pelvis (funnel-shaped chamber)
Renal pyramids
– functional units of kidney
– cluster of capillaries (glomerulus)
– surrounded by a Bowman’s capsule
• that opens into a long, coiled renal tubule
Nephron
Renal tubule consists of
– proximal convoluted tubule
– loop of Henle
– distal convoluted tubule
– mostly in cortex
Cortical nephrons
– extend deep into medulla
– important in concentrating urine
Juxtamedullary nephrons
• Two levels of capillaries • Blood flows – from renal artery – to afferent arterioles – to glomerular capillaries – into an efferent arteriole – delivers blood into peritubular capillaries that surround the renal tubule • Blood leaves kidney through renal vein
Renal Blood Vessels
Filters through glomerular capillaries into Bowman’s capsule
Pressurized plasma
– permeable walls of capillaries
– filtration slits between podocytes
Filtration membrane
– specialized epithelial cells
– make up inner wall of Bowman’s capsule
Podocytes
Filtration is ________
– small molecules become part of filtrate
– glucose, other needed materials, metabolic wastes
Nonselective
Water solution of nitrogenous wastes, excess salts, and other,substances not needed by the body (generally sterile) • Filtration – of plasma • Reabsorption – of needed • Secretion – of extra K+, H+, materials etc. into renal tubule • Results in Urine
Urine Production
