A Journey Through the Nephron Jowie Papa

Kidneys and Homeostasis Functions of the loop of Henle Osmoregulation – Controls balance of water in blood and tissues – Comprises of processes within the nephrons

Ultrafiltration Filtration inside the glomerulus – Blood enters glomerulus by the… – Permeability (fenestration) and high pressure push small molecules such as water and salts through a thin layer of glycoproteins into the Bowman’s capsule – Filtrate enter the tubules for reabsorption

Reabsorption Occurs in proximal convoluted tubule Osmolarity of the blood in the capillary network is the same as the osmolarity of the filtrate Sodium and chloride ions are pumped into the capillaries Changed osmolarity of blood allows water to enter capillary via osmosis Carrier proteins carry nutrients into capillaries by way of active transport Enter tubules cells through microvilli, passes through cell and into capillary network

Reabsorption and Equilibrium Among nutrients absorbed is glucose – Glucose returns to blood and reused Helps in regulating blood glucose levels – Unabsorbed glucose will be in the urine Too much is very detrimental because less water will be absorbed (diffusion) More water is lost Urea is also absorbed – Makes the urine hyperosmotic, also preventing extreme water loss – Lack of urea means more water enters the urine

The Loop of Henle Ideal in maintaining balance of salt and water in the filtrate Salt passively transports out of the ascending limb into the renal medulla Urea will leak out of the collecting duct, creating a hypertonic surrounding in the renal medulla Water diffuses out of the descending limb and is returned to the cardiovascular system Antidiuretic hormone (ADH) will increase water absorption to prevent extreme loss of water

Exit What is not reabsorbed or whatever has reentered the filtrate goes to the collecting duct Goes to the ureter then to the bladder and then is excreted

Review 1.What allows small molecules from the blood to enter the Bowman’s capsule in ultrafiltration? 2.Explain why too much glucose in urine restricts water reabsorption. 3.What substance increases water reabsorption? E.C. Draw and label a nephron. (max. 5 points)