water balance water nitrogen chapter 42

Transcription

1 water balance chapter 42 water osmoregulation water and dissolved solutes adjusting the composition of internal body fluids in arthropods -- hemolymph in vertebrates -- interstitial fluid transport epithelia extensive surface area water balance and excretory examples marine birds like albatross drink seawater nitrogen removal of nitrogenous wastes breakdown of proteins and nucleic acids --> ammonia NH3 toxic must be converted to a less toxic form and removed type of waste depends on many factors Nasal salt gland Ducts Nostril with salt secretions

2 ammonia many aquatic invertebrates highly soluble, but very toxic -- requires lots of water ammonium -- NH4+ common in freshwater fish... exchanged for Na+ in freshwater fish urea mammals, adult amphibians, many marine fishes, and turtles -- low toxicity, can be concentrated requires much less water than ammonia requires energy to produce from ammonia uric acid Land snails, insects, spiders, birds, and many reptiles relatively nontoxic. largely insoluble in water more expensive related to mode of reproduction amniotic eggs osmosis central problem of osmoregulation -- how to balance uptake and outflow of water? osmosis osmolarity human blood is about 300 mosm/l seawater is about 1,000 mosm/l. hypertonic = hyperosmotic; hypotonic = hypoosmotic marine hypoosmotic regulators -- problems retaining water getting rid of salt isoosmotic conformers. fresh hyperosmotic regulators -- problems removing excess water acquiring salt Gain of water and salt ions from food Gain of water and salt ions from drinking seawater Excretion of salt ions from gills Osmotic water loss through gills and other parts of body surface Excretion of salt ions and small amounts of water in scanty urine from kidneys (a) Osmoregulation in a saltwater fish Uptake of water and some ions in food Uptake of salt ions by gills Osmotic water gain through gills and other parts of body surface Excretion of large amounts of water in dilute urine from kidneys (b) Osmoregulation in a freshwater fish

3 methods of dealing with salinity stenohaline / euryhaline anadromy / catadromy dehydration symptoms often associated with other conditions altitude hangovers desiccation spider in a jar basic needs adaptations to prevent water loss: anhydrobiosis nocturnal activity waxy cuticle in arthropods... keratin many desert animals can reabsorb water from the bladder (we cannot)

4 excretion Excretory systems general scheme for filtration blood or hemolymph or coelomic fluid collected filtration composition of filtrate is changed protonephridia network of branching tubules flame cell or solenocyte nephridiopores osmoregulation Nucleus of cap cell Cilia Interstitial fluid flow Tubule cell Flame bulb Opening in body wall Tubule Tubules of protonephridia metanephridia nephrostome capillaries surrounding tubules nephridiopore malpighian tubules connected to digestive tract tips immersed in hemolymph water, various solutes reabsorbed in rectum Midgut (stomach) Salt, water, and nitrogenous wastes Digestive tract Malpighian tubules Feces and urine Rectum Intestine Hindgut Rectum Reabsorption HEMOLYMPH

5 Vertebrate kidneys profused by renal artery and renal vein nephron glomerulus afferent arteriole efferent arteriole bowman s capsule proximal tubule loop of henle distal tubule Posterior vena cava artery and vein Kidney Aorta Ureter Urinary bladder Urethra two distinct regions renal cortex and renal medulla cortical nephrons juxtamedullary nephrons medulla cortex pelvis Juxtamedullary nephron Cortical nephron Collecting duct To renal pelvis cortex medulla homeostatic control mechanisms antidiuretic hormone - osmolarity blood pressure renin - angiotensin II - aldosterone atrial natriuretic factor - opposes RAAS reduces blood pressure Liver Angiotensinogen Renin Angiotensin I ACE Angiotensin II Distal tubule Juxtaglomerular apparatus (JGA) STIMULUS: Adrenal gland Low blood volume or blood pressure Aldosterone Increased Na+ and H O reabsorption 2 in Arteriole constriction Homeostasis: Blood pressure, volume PSA about next slide

6 kidney disease -- inflammation causes an increase in renin can be genetic, viral or cancerous or bacterial... E. coli -- HUS -- kidneys shut down... Streptococcus -- strep throat hemodialysis peritoneal dialysis