[Outer cortex, inner medulla, and renal pelvis] Kidney Structure [Outer cortex, inner medulla, and renal pelvis] Cortex contains NEPHRON filtering units. Nephron = Bowman's capsule containing Glomerulus (capillary bed) ---> tubules of nephron.

Kidney Structure Bowman's capsule --> proximal convoluted tubule --> Loop of Henle --> distal convoluted tubule --> collecting duct --> The urine then drains down the ureter --> urinary bladder (storage area). Passes out of the body through the urethra. Note: There are thousands of nephrons in each kidney.

Make note of location of Cortex & Medulla- now locate the Nephron in relation to these 2 structures

Nephron Function Bowman's capsule: blood enters under very high pressure arrives directly from the aorta blood forced into glomerulus & Water, salts, glucose, urea, & amino acids forced out into the nephron - forms crude filtrate. Up to 95% water & salts resorbed.

Nephron Function B) filtrate travels to the proximal convoluted tubule majority water & salt resorption occurs water moves from tubule to blood via steep osmotic gradient sodium/potassium exchange pump brings sodium back in glucose & chlorine ions resorbed.

Nephron Function C) filtrate moves to the Loop of Henle Descending part of the loop --> water flows out of the filtrate [thus concentrating filtrate, by absorbing water back into circulatory system] --> medulla tissue becomes more salty salty medulla --> causes a lot of water absorbed by adjacent capillaries. Ascending loop --> sodium pumped out (keeps medulla salty) --> water leaves descending loop. Note: much of the sodium is absorbed by the descending part, through a countercurrent exchange of salt.

Nephron Function D) Distal convoluted tubule: sodium & chlorine ions actively transported out water "follows" and is resorbed by cappilaries of juxtaglomerular complex. Tubular secretion formed: Ammonia, urea, H+ ions pass out of tubule as waste products contained within the filtrate. Note: ammonia is by product of protein digestion

Nephron Function E) Collecting tubule: sodium ions & water move out of filtrate other wastes move in countercurrent exchange of urea final filtrate forms in duct = URINE

4 5 2 1 Use numbers To trace flow of Filtrate through nephron. 3 Detail of Nephron structure

Read: Step by step process of filtration of blood brought to nephron

Control of Nephron Function Antidiuretic Hormone (ADH): controls water absorbtion Recall, main function of nephron is to help maintain osmotic balance of your body Hypothalamus --> signals posterior pituitary to release ADH when dehydration detected [e.g if you eat too much salt] . ADH --> targets cells within collecting ducts Function: increases cellular permeability to water. As more water is resorbed, the osmolarity of the blood returns to "normal" and the hypothalamus switches off the production of ADH (Negative Feedback Loop).