Module 8 Intro

Module 8—Circulation, Immunity, and Excretion

Lesson 8—Urine Formation in the Nephron

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While the filtration system of a water treatment plant may seem quite sophisticated with the removal of solids, as well as the processes of purification and disinfection, it is in reality much less so than the human filtration system.

Water treatment plants do not have millions of filtering tubes as there are in the kidney. However, they are similar in the sense that movement of the water through a filter is dependent on varying fluid pressures and the permeability or size of the filter. This is the same concept for the filtering of water and various components in and out of blood by the human kidney.

The glomerular ball accepts components out of the circulatory system forming the filtrate or what remains. The filtrate is then processed by the nephron to reabsorb into the blood valuable materials the body can use. Other materials left in the nephron form waste materials.

The water treatment plant continuously produces wastes and clean water as the products of its process. Urine formation by the kidneys is also a continuous process—it occurs independent of conscious thought. The unrelenting nature of this physiological activity requires you to release this liquid by-product of metabolism as it constantly builds up in the bladder.

At some point in a normal day, you have to urinate, whether it’s convenient or not. The excretory system recycles and reabsorbs what the body can use and removes waste materials the body can’t use.

In this lesson you will explore the following questions:

• How does the nephron function in maintaining the composition of blood plasma?
• How do the kidneys function in excreting metabolic wastes and expelling them into the environment?

Module 8: Lesson 8 Assignment 

Your teacher-marked Module 8: Lesson 8 Assignment requires you to submit a response to the following:

• TR 1. Glomerular Filtration
• TR 2. Tubular Reabsorption

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