Phases involved with urine production: 1) _____________ movement of fluid/wastes across filtration membrane 2) _____________ movement of substances (H 2 O etc.) back into blood 3) _____________ active transport of solutes into filtrate (inside nephron) 4) ____________ regulating concentration/vol. 5) ____________ the act of urinating How is urine produced? BI 203 Human Anatomy & Physiology II

Filtration Pressure… Why is there a difference in pressure? = Glomerular capillary pressure = Capsule pressure = Colloidal osmotic pressure What is involved with producing filtrate? BI 203 Human Anatomy & Physiology II

Take 5!!! Discuss with your neighbor and predict an answer. What effect does constriction of the afferent arteriole have on the filtration pressure? What effect does a decrease in the concentration of plasma proteins have on filtration pressure? BI 203 Human Anatomy & Physiology II

What components are in the blood that could end up in the filtrate? PlasmaFiltrateUrine 180l 45000mg/l l l BI 203 Human Anatomy & Physiology II

Amount of cardiac output reaching kidneys = Volume of blood/minute that renal fraction represents = Volume of plasma/minute that renal blood flow rate represents = Amount of plasma and solutes that enters nephron = Volume of filtrate produced/day = What is involved with producing filtrate? BI 203 Human Anatomy & Physiology II

Take 2!!! Discuss with your neighbor and predict an answer. If the filtration fraction increases from 19% to 22% what will the daily volume of filtrate be? BI 203 Human Anatomy & Physiology II

Steps of reabsorption: 1) 2) Water follows via _______ 3) Water and solutes enter _______________ (~ 300 mOsm/l) 4) Low pressure in _______________________ 5) Water and solutes ______ ___________ Why don’t we urinate 180 liters per day? BI 203 Human Anatomy & Physiology II

What form of epithelium would you expect to facilitate reabsorption? **** Why abundant mitochondria? BI 203 Human Anatomy & Physiology II

Reabsorption in _________ _________________: > concentration of __________________ in medulla (_________) More ______________ and some solutes move in (_____________________) How many liters still need reabsorbed? BI 203 Human Anatomy & Physiology II

Reabsorption in ascending loop of Henle: Tubule __________ _________ ________________ occurs (sparing salts) Filtrate becomes dilute (__________) Water has been reabsorbed but what about the salts? BI 203 Human Anatomy & Physiology II

How much has been reabsorbed from the filtrate thus far? How much is left? How many liters of urine would that be? 80% of 180 l = 144 liters ? ? ? BI 203 Human Anatomy & Physiology II

Distal tubule mostly impermeable to H 2 O… BUT under hormonal control. ______________________ ________________________ How is the remaining filtrate volume reduced? BI 203 Human Anatomy & Physiology II

Take 2!!! Discuss with your neighbor and predict an answer. If a blood clot in the brain caused damage to the hypothalamus what might the effect be on urine production and why? BI 203 Human Anatomy & Physiology II

Moving wastes into nephron both passive and active ______________ Active / countertransport (_____________) What is the role of secretion in urine production? BI 203 Human Anatomy & Physiology II

Why is the secretion of H + important? We produce about 60ml of acids in the form of _________, ____________ and _______ acids as a result of digestion. H+ combine with HCO3- to form _________, which disassociates to form H2O and CO2. Some of the CO2 is exhaled So where does the HCO3- come from? BI 203 Human Anatomy & Physiology II

Why is the secretion of H + important? The kidneys help generate a sink for the H+, which helps drive the reaction of… The ______ can then combine with metabolic ____ and the cycle is complete BI 203 Human Anatomy & Physiology II