Chapter 34, Problem 27A

Summary Introduction

To write:

About the waste products present in the urine

Introduction:

The excretory system is the system of an organism's body that performs the function of excretion, the bodily process of discharging wastes. Several parts of the body are involved in this process, such as sweat glands, the liver, the lungs and the kidney system. The kidneys maintain homeostasis by removing wastes and excess water from the body and by maintaining the pH of the blood. The kidneys are the major excretory organ in the body. It is a bean-shaped organ that is involved in urine formation performs filtration of blood.

Explanation of Solution

Water and substances dissolved in the water, such as the nitrogenous waste product called urea, are pushed through the capillary walls into the Bowman’s capsule. The filtrate collected in the Bowman’s capsule flows through the renal tubule that consists of the convoluted tubule, the loop of Henle, and the collecting tubule. Much of the lost water and useful substance such as glucose and minerals are reabsorbed back into the capillaries surrounding the renal tubule. This process is called reabsorption. At the same time, excess fluids and toxic substances in the capillaries are passed to the collecting tubules. This waste product is called urine. Urine leaves the kidney through ducts called the ureters. Urine is then stored in the urinary bladder and exits the body through the urethra. Each kidney produces only about 1.5 L of urine.

Conclusion

Urea is the major protein metabolism waste which accounts for about half of total urinary waste. Most of the urea is disposed of by urine.