 Parts of the kidney  Urine formation

 Why is urine more concentrated then other times?  Due to reabsorption of water

 Recall  Water and small ions are filtered through at the glomerulus  Most of this is reabsorbed back into the blood stream at the proximal convoluted tubule

 3 parts to water reabsorption:  1. reabsorption of salt  2. establishment of solute gradient  3. reabsorption of water

 Sodium (Na) and water is filtered through at glomerulus however, about 99% of is reabsorbed back into the blood stream  This occurs at:  proximal convoluted tubule (67%)  Loop of Henle (25%)  Rest at the distal convoluted tubule and collecting duct

 Hormones help regulate the reabsorption of salt at the distal convoluted tubule  Renin  Is secreted at the juxtaglomerular apparatus  Causes the release of aldosterone

 Aldosterone  Secreted by the adrenal cortex  Excretes Potassium ions (K+) and reabsorption of Sodium ions (Na+)  Reabsorption of Na+ causes water to be reabsorbed into blood

 Na that isn’t reabsorbed at the PCT is reabsorbed at the Loop of Henle  Loop of Henle  Located deep inside the medulla  Has an ascending limb and descending limb

 Descending Limb  Permeable to water  Filtrate is more concentrated here  water goes out into the medulla salt stays in

 Ascending Limb  Impermeable to water  Filtrate becomes more dilute here  Water stays in, Salt goes out into the medulla  Creates more “salty” medulla

 Solute Gradient  This produces a solute gradient  What causes the filtrate To move through the tubules

 Filtrate in the collecting duct is more dilute then the “salty” medulla

 2 things can happen here:  1. If the body needs water (dehydrated) it releases antidiuretic hormone (ADH)  Antidiuretics mean decreased amount of urine  ADH causes the collecting duct becomes permeable to water  Water diffuses out of the collecting duct  Less urine, and more concentrated  More ADH is produced at night

 2. If the body is hydrated it will not release ADH  diuretic means increase amount of urine  Collecting duct remains impermeable to water  More urine, more diluted expelled from the bladder

 Diuretics are chemicals that increase the flow of urine  There are many types of supplements and drinks that act as diuretics for different reasons

 Alcohol is a diuretics  It inhibits ADH release  Part of the symptoms of a hangover are due to dehydration

 Working together in pairs answer the following questions  What causes the dehydration in a hangover?  Come up with a list of other types of diuretics

Alcohol suppresses ADH production by the pituitary Without ADH, higher amounts of water stay in the urine Urine with high concentrations of water leaves the body

 Examples of diuretics  Coffee  Tea  Energy drinks  Supplements/pills

 Diuretics like these increase the flow of urine  In your pairs explain:  Why having a cup of coffee wouldn’t be a good idea to help cure a hangover  Why certain athletes might take diuretics  Why body builders or people wanting to lose weight would take a diuretic. Does this really work?

 Coffee and alcohol  Coffee increases urine from increased filtration rate  However alcohol is preventing the body from reabsorbing water  Going to the bathroom more but loosing more and more water from the body each time

 Athletes and Diuretics  More difficult to detect drugs in dilute urine  Weight loss  Not really losing “fat” but losing water

 Help lower blood pressure  Reduce bloating

 Frequent urination  Electrolyte abnormalities  Extreme tiredness or weakness  Muscle cramps or weakness  potassium  Dizziness, lightheadedness

 Dehydration  Loss of appetite, nausea, vomiting