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Excretion. Kidney Bones In The News. Excretion. Removes metabolic wastes Balances water & salt. Excretion. Types of Excretory Organs. Cell membrane Contractile vacuoles Nephridia Antennal gland Malpighian tubules Kidneys. Cell Membranes in Excretion.
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Excretion • Removes metabolic wastes • Balances water & salt
Types of Excretory Organs • Cell membrane • Contractile vacuoles • Nephridia • Antennal gland • Malpighian tubules • Kidneys
Cell Membranes in Excretion • Transport across the cell membrane • Diffusion • Osmosis • Active transport
Contractile Vacuoles • Found in protozoans & sponges • Collects excess water • Contracts when they reach a critical size
Nephridia • In Platyhelminthes & Annelida
Antennal Gland • Found in crustaceans • Primarily excretes water & salts • Nitrogenous waste excreted at gills
Malpighian Tubules • Insects & some other arthropods • Tubes found in blood-filled body cavity • Empty into intestine
Kidneys • Found in vertebrates • Made up of nephrons • Secretion is urine
Excretory Products of Humans • Carbon dioxide • Water • Salts • Nitrogenous molecules
Human Organs of Excretion • Skin • Salt • Water • Lungs • Carbon dioxide • Water • Liver • Produces bile pigments • Worn out red blood cells
Human Organs of Excretion • Large intestine • Salts • Kidneys • Nitrogenous wastes • Water
Nitrogenous Wastes • Produced from metabolic breakdown • Proteins • Nucleic acids • Forms of excreted waste • Urea • Ammonia combined with carbon dioxide • Creatinine • Derived from molecule in muscle cells • Uric acid • From nucleic acid breakdown
Kidney Excretions • Ions of salts • Sodium • Potassium • Chloride • Magnesium • Calcium • Nitrogenous wastes • Water • Some other substances
Urine • Excretion product of kidney • Derived from filtering blood • Transferred to bladder by ureter
Kidney Structure • Nephron – microscopic filtering units • Collecting ducts • Blood vessels
Areas of Kidney • Outer cortex • Inner medulla • Renal pyramids • Renal arteries • Ureter
Tasks of Nephrons • Filtration • Selective reabsorption • Tubular secretion
Filtration • Glomerulus • Tuft of capillaries • Between arterioles • Afferent arteriole • Efferent arteriole • High pressure maintained • Glomerular capsule surrounds glomerulus • Connects to convoluted tubule
Filtration • Fluid forced through capillary walls • Blood cells & proteins retained • Filtrate passes into tubule
Selective Reabsorption • Convoluted tubules • Proximal convoluted tubule • Loop of Henle • Distal convoluted tubule • Surrounding capillaries
Selective Reabsorption • Materials are reclaimed into capillaries
Tubular Secretion • Materials not reclaimed enter collecting tube • Urine • Excess water • Waste products not reclaimed
Environment & Nephrons • Loop of Henle conserves water
Urinary System • System to remove urine from body
Urinary Bladder • Hollow muscular organ • Stores urine • Stretch receptors send message to brain when about half full
Urethra • From bladder to outside body • Gender differences • Men • Role in reproductive system • Passes through prostate • Women • No reproductive association • Shorter & more easily infected
Kidney & Homeostasis • Helps maintain water balance • Helps maintain ion balance • Depends on endocrine hormones • Antidiuretic hormone (ADH) • Regulates water • Aldosterone • Regulates ions
Kidney Stones • Some salts do not dissolve in filtrate • Salts form crystals • Stones may be jagged, block urine • Often treated with shockwave lithotripsy
Renal Failure • Kidneys stop working • Unable to excrete waste products • Types of renal failure • Acute • Filtration stops suddenly • Chronic • Filtration slows gradually
Dialysis • Filtering blood to replace kidney function