Water Balance & Excretion 9.4 & 9.5

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

Unicellular Organisms water balance is often maintained by contractile vacuoles video of Paramecium: bjuYGU

Excretion eliminating waste is important for all living organisms

Types of Waste wastes are eliminated through various organs: lungs (CO 2 ) 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

Human Excretory System

Renal Blood Flow ) blood is brought to the kidneys by the renal arteries filtered blood leaves the kidneys through the renal veins

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

Kidney Kiwi

Kidney Kiwi Dissection

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

Review Kidney Structure…

How is urine formed?

Urine Formation filtration reabsorption secretion Simple overview of urine formation: n.aspx?gcid=000136&ptid=17http:// n.aspx?gcid=000136&ptid=17

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!

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

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 (HCO 3 - is also reabsorbed to balance) products of detoxified poisons (passive) water-soluble drugs (passive) nitrogen-containing wastes (such as small amounts of NH 3 ) in the proximal and distal convoluted tubules

Animations Narrated animation on urine formation; good amount of detail: phronFiltration&title=Nephron%20Filtrationhttp://davisplus.fadavis.com/scanlon6e/Animations/animations.cfm?exercise=Ne phronFiltration&title=Nephron%20Filtration Narrated animation of structure & function; quite detailed:

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) kidney-and-nephron?playlist=Biologyhttp:// kidney-and-nephron?playlist=Biology

Kidney Disorders

Urinalysis can be used to detect many metabolic and kidney disorders as well as urinary tract infections urine can be assessed using a dipstick or at a laboratory

Multiple Test Dipstick

Diabetes Mellitus Type 1 - body cannot produce insulin Type 2 - cells fail to use insulin properly gestational - hormones of pregnancy interfere with action of insulin urinalysis would show high levels of glucose (and greater volumes of urine)

Kidney Stones caused by precipitation of minerals, can be alkaline or acidic VERY painful

Kidney Stones - Treatment time… lithotripsy (shock- wave therapy) ureteroscopy (and placement of stent or surgical removal of stone)

Dialysis for low-functioning kidneys, dialysis machine can filter blood