Chapter 49 By: Kayla Nida

 This system is needed to allow for removal of impurities and waste from the body.  Helps maintain homeostasis in the body ◦ Regulating Body temperature ◦ Regulating Blood glucose ◦ Oxygen ◦ pH concentrations

EarthwormsInsects  Contain Nephridia, which are similar to the human kidney.  Obtain fluid from the body through the filtration system called Nephrostomes ◦ Removes salt through active transport ◦ Forms urine  Have Malpighian tubules ◦ Urine is not formed by filtration ◦ Waste molecules and potassium are secreted into the tubules trough active transport ◦ Most of the potassium and water is reabsorbed into the circulatory system through the hind gut

 Kidneys first developed among bony fish ◦ Body fluids are hypotonic to surrounding sea water so water leaves their body by osmosis through the gills and urine ◦ Drink large amounts of sea water to compensate ◦ Kidney is needed to get rid of the divalent ions, such as salt  Cartilaginous Fish ◦ Kidney helps to reabsorb urea from the nephron tubule and maintain a blood urea concentration a 100 times higher than mammals ◦ Urea makes the blood isotonic to the sea water, preventing water loss

 Kidney in Amphibians: first terrestrial vertebrate ◦ Identical to fresh water fish ◦ Makes sense because they stay in moist places ◦ Transport sodium across their skin from surrounding water  Reptiles ◦ Fresh water reptiles have similar kidneys to amphibians ◦ Marine reptiles tend to lose water and obtain a lot of salt  Process similar to bony fish; eliminate excess salt through salt glands

 Only ones able to produce urine with a higher osmotic concentration than their body fluid  Can excrete waste in small amounts so that more water can be retained in the body  Human kidneys can produce urine that is more than 4.2 times concentrated as blood plasma  Only ones to have loop of Henle that produces the hypertonic urine  Kangaroo rat kidneys are so efficient that it never has to drink water !

 Nitrogen containing by-products that must be removed from the body though urine ◦ Ammonia- toxic to cells and only safe in very dilute concentrations ◦ Urea- mammals excrete ammonia in this form  water soluble and can be excreted in large amounts through urine ◦ Uric acid- Humans, Apes, and Dalmatians lack enzyme uricase, which converts uric acid into a more soluble derivative and must excrete the uric acid

 Fist sized organ located in the lower back ◦ Juxtamedullary nephrons- long loops that go deeply  Receives blood from a renal artery from which urine is produced  Ureter: where urine drains and carries it to the urinary bladder  Renal pelvis: mouth of the ureter when flared up ◦ Has cup-shaped extensions that receive urine from renal tissue ◦ Tissue is split into an outer renal cortex and inner renal medulla

 Each kidney contains 1 million nephrons into the medulla ◦ Cortical nephrons – shorter loops  Each nephron consists of a long tubule and small blood vessels

 Glomerulus- a group of capillaries in the renal cortex  Capillaries filter the blood  Filtrate enters the first region of the nephron tubule= Bowman’s Capsule  Proximal convoluted Tubule- sends filtrate to the loop of Henle  Fluid is then sent to the Distal Tubule, which drains into the collecting duct  All the collecting ducts merge in the medulla to empty the urine

 Filtration  Reabsorption

ReabsorptionSecretion  Driven by active transport and secondary active transport  Reabsorbs glucose, amino acids, and other molecules needed by the body  Moves out of tubules and into the blood  Moves from the blood and into the tubule to be excreted  Involves the transport of molecules across the capillaries and kidney tubules into the filtrate

 Elimination of nitrogenous wastes, potassium, and other ions  Urin’s high hydrogen concentration helps maintain the acid base balance of the blood from  Maintains blood volume and pressure because of the excretion of water ◦ More water excreted means lower blood volume and visa-versa  Important for homeostasis

 Include volume of blood, blood pressure, and osmolality of blood plasma  Antidiuretic Hormone (ADH) ◦ Produced by hypothalamus and secreted by pituitary gland ◦ Secreted when a person is dehydrated or eats salty food, making you thirsty ◦ Causes walls of distal tubules and collecting ducts to become more permeable to water= conserving water

 Aldosterone- secreted by the adrenal cortex ◦ Stimulated by the drop in blood sodium concentration ◦ Stimulates the distal convoluted tubules and collecting ducts to reabsorb sodium, decreasing the excretion of sodium in the urine ◦ Promotes secretion of potassium to help regulate the potassium concentrations in the blood  Atrial Natriuretic Hormone (ANH) ◦ Secreted by the right atrium of the heart in response to an increase in blood volume ◦ Promotes excretion of salt and water into the blood to lower the blood volume

 The Kidneys maintain a constant internal environment  When affected by disease, a rise in the blood concentration of waste products, disturbances of electrolyte balance, and failure of blood pressure regulation occur  This causes other systems to develop problems because the homeostasis is thrown off

 Kidney disease- gradual and permanent loss of kidney over time. ◦ Five stages of severity ◦ Cured by replacing the kidney, watching your diet, some antibiotics  Gout- build up of uric acid in the body because the kidneys cannot process it correctly ◦ Causes joint pain and kidney stones ◦ Diet change and antibiotics are used to help clear it  Nephritis- inflammation of the nephron ◦ Can suffer permanent damage= chronic ◦ Most can be cured but severe cases have ◦ lead to death