Download HBS Ch.4 Sec.3

THE EXCRETORY
SYSTEM
Chapter 4 Section 3
Pages 127 - 131
Objectives:
*Describe the role of the excretory system
*Identify the major organs in the excretory system &
explain their functions
*Analyze how the digestive & excretory systems work
together
Excretion: The body’s removal process for wastes.
*Maintains homeostasis by getting rid of harmful waste
materials in the body.
The excretory system is the system in the body that
collects wastes produced by cells and removes the
wastes from the body
Urea: A chemical that comes from the break down of
proteins.
Kidneys: Major organs of the excretory system. They
eliminate urea, excess water, and other wastes.
Urine: Watery fluid produced by your kidneys.
Ureters: Two narrow tubes from the kidneys to the
bladder.
Urinary Bladder: Saclike muscular organ that stores
urine.
Urethra: Small tube from the bladder to the outside of
your body. This tube allows urine to leave your body.
Nephrons: Tiny filtering factories that remove wastes
from the blood and produce urine.
The nephrons filter wastes in 2 stages:
*First – Wastes and needed materials (like glucose)
are filtered out of the blood.
*Second – Much of the needed material is returned
to the blood, and the wastes are eliminated from the
body.
Excretion maintains homeostasis by keeping the body’s
internal environment stable and free of harmful levels of
chemicals.
In addition to the kidneys, organs of excretion that
maintain homeostasis include lungs, skin, & liver.
Kidneys regulate the amount of water in your body. It
helps you maintain homeostasis. You need 2 liters of
water per day.
Lungs: When you breathe out, carbon dioxide & some
water are removed from your body.
Skin: Sweat glands in your skin excrete water and some
chemical wastes in sweat.
Liver: Produces urea by breaking down protein
*Converts hemoglobin molecules into bile
*Breaks down fat
*The liver is the recycling factory