Foundations of Anatomy and Physiology II AOHS Foundations of Anatomy and Physiology II Lesson 19 The Nephron Copyright © 2014‒2016 NAF. All rights reserved.

What have you learned so far about nephrons? The renal cortex and medulla are packed with millions of nephrons Nephrons are small tubes that “process” blood fluid from the blood. They collect substances from blood plasma on one end and make them into urine, which flows out the other end. What have you learned so far about nephrons?

Three sections of the nephron contribute to most of fluid processing Glomerulus Proximal convoluted tubule (PCT) Distal convoluted tubule (DCT) What do proximal and distal refer to in these anatomical structures?

There are three stages to urine production, and they occur in specific areas of the nephron Filtration occurs in the glomerulus Selective reabsorption happens in the PCT Reabsorption and secretion occur in the DCT

The glomerulus filters everything but blood cells, proteins, and large proteins from your blood The glomerulus is a space containing a long, coiled capillary. Pores between cells of the capillary walls let many kinds of substances through. The blood pressure in the glomerular capillaries is very high, forcing these particles into the glomerular capsule, which is the space surrounding the glomerular capillary.

In the PCT, useful substances like glucose, amino acids, and sodium are reabsorbed When glucose and other solutes go back into the bloodstream, their concentration becomes less inside the tubule. This change in concentration makes water flow out of the tubule and into the blood via osmosis.

In the DCT, antidiuretic hormone (ADH) fine-tunes the balance of water ADH makes the DCT more permeable to water. The less water in your body, the more ADH is secreted. Also in the DCT, some molecules such as potassium and H+ ions move from the nephron back into the blood.