Water Balance & Excretion

Osmoregulation active regulation of the osmotic pressure of bodily fluids and cells osmotic pressure = pressure resulting from a difference in solute concentration across a selectively permeable membrane

Osmoregulation hyperosmotic hypoosmotic isoosmotic hyperosmotic (hypertonic) hypoosmotic (hypotonic) isoosmotic (isotonic)

Unicellular Organisms water balance is often maintained by contractile vacuoles video of Paramecium: http://www.youtube.com/watch?v=mTXRcbjuYGU

Excretion eliminating waste is important for all living organisms (Image from: http://www.cartoonstudio.co.uk/Pages/kmeters1.html)

Types of Waste wastes are eliminated through various organs: lungs (CO2) large intestine (solid wastes) liver (transforms toxins for removal) kidneys (soluble wastes)

Nitrogenous Wastes mostly from deamination animals that live in water can remove ammonia with lots of water mammals, some reptiles, most amphibians form urea birds and some invertebrates produce uric acid Ammonia (NH3) is highly toxic

Human Excretory System Image from: http://cabeijo.com/39245025_human-excretory-system-facts.html

Renal Blood Flow) blood is brought to the kidneys by the renal arteries filtered blood leaves the kidneys through the renal veins (Image from: http://www.revolutionhealth.com/articles/blood-supply-to-the-kidneys/tp13026

The Urinary System kidneys can hold up to 25% of the body’s blood at a time kidneys filter the blood urine (with wastes and toxins) is conducted to the bladder through the ureters

Kidney Structure Basic structure: cortex medulla renal pelvis (Image from: http://www.yalemedicalgroup.org/stw/Page.asp?PageID=STW028984)

Nephron the functional unit of the kidney is the nephron there are about 1 million nephrons in each kidney

Review Kidney Structure…

Image from: http://commons. wikimedia

Be able to label

Image from :http://kcfac. kilgore. cc. tx Label the diagram

Explain the production of Urine (Image from: http://www.medical-illustrations.ca/1010-kidney-nephron-diagram/) Afferent Arrives…Efferent Exits Explain the production of Urine

How is urine formed?

Urine Formation filtration reabsorption secretion Simple overview of urine formation: http://www.pennmedicine.org/encyclopedia/em_DisplayAnimation.aspx?gcid=000136&ptid=17 (Image on previous slide from: http://www.mountainside-medical.com/products/Urine-Specimen-Cup ,-Sterile.html

Filtration higher blood pressure in glomerulus water, ions, smaller dissolved molecules (glucose, amino acids, urea) can move through the walls of the glomerulus your kidneys filter your entire blood plasma 65 times every day! glucose, NaCl, H+ ions, amino acids,

Reabsorption ion pumps reabsorb Na+, K+, Cl- (active) active transport proteins reabsorb amino acids, glucose filtrate becomes hypoosmotic to interstitial fluid, so water is reabsorbed by osmosis and through aquaporins If you produced 120 mL of urine a minute… (your bladder’s stretch receptors signal to your brain when there is 200mL of urine; can hold up to 600-800) Osmotic gradient created by glucose, amino acids moves water back to blood.

Where? a lot of reabsorption occurs in the proximal convoluted tubule filtrate with high concentration of urea and other wastes enters loop of Henle and then distal convoluted tubule: more water and ions (Na+& Cl-)are reabsorbed

Where (cont’d)? collecting ducts are permeable to water but not salt ions, so more water is reabsorbed at bottom of medulla, urea is reabsorbed through passive urea transporters (increasing concentration gradient…more water reabsorbed)

Secretion H+ ions (active) to adjust blood pH (HCO3- is also reabsorbed to balance) products of detoxified poisons (passive) water-soluble drugs (passive) nitrogen-containing wastes (such as small amounts of NH3) in the proximal and distal convoluted tubules

Animations Narrated animation on urine formation; good amount of detail: http://davisplus.fadavis.com/scanlon6e/Animations/animations.cfm?exercise=NephronFiltration&title=Nephron%20Filtration Narrated animation of structure & function; quite detailed: http://bcs.whfreeman.com/thelifewire/content/chp51/51020.html

Other links… Khan academy…this video starts off with the structure of the kidney & nephron, then goes into detail about the formation of urine (covered in 9.5) http://www.khanacademy.org/video/the-kidney-and-nephron?playlist=Biology