Nitrogenous Wastes Ammonia- fish Urea- mammals Uric acid- birds

Nitrogenous waste in insects  Malphigian tubules –Open circulatory system

The Kidney Excretion-removal from body of waste products of metabolic pathways 1.Renal artery and vein 2.Renal pelvis 3.Ureter 4.Renal medulla 5.Renal cortex

Nephron  Each kidney has about 1.25 million filtering units…these are nephrons.  Each one consists of: –Glomerulus –Bowman’s capsule –Tubule extending from Bowman’s capsule (3 parts consisting of proximal convoluted tubule, loop of Henle, and distal convoluted tubule –Peritubular capillary bed

Ultrafiltration of blood  Occurs in Bowman’s capsule  Glomerulus has fenestrations; will open in high bp  High bp exists in glomerulus  Afferent vs. efferent arterioles  Basement membrane

Osmoregulation  The control of water balance of the blood, tissue or cytoplasm of an organism. Very important in homeostatic control.  Reabsorption: proximal convoluted tubule with microvilli to increase surface area.  Water, salt ions, and glucose need to be reabsorbed into bloodstream  Peritubular capillary bed (substances that leave the filtrate are taken back into bloodstream here)

Osmoregulation (continued)  Volume of water eliminated depends on: –Total volume injested –Perspiration rate –Ventilation rate  Loop of Henle creates hypertonic environment in medulla

Anti-diuretic hormone (ADH)  Filtrate is hypotonic (high water content)  Target tissue of ADH is kidney collecting ducts

How do Kidneys change blood?  Blood plasma- blood that enters glomerulus, originally from renal artery- no filtration  Glomerular filtrate- fluid (now called filtrate) which enters proximal convoluted tubule after ultrafiltration within Bowman’s capsule; no reabsorption yet  Urine- fluid which was filtrate, now undergone reabsorption and osmoregulation and is taken to bladder for elimination

Osmoregulators  Animals whose internal tissues have a different solute concentration compared with their environment.

Osmoconformers  Animals that have internal tissues that have virtually the same solute concentration as their environment.

 Dehydration vs. overhydration