Download Unit D Chapter 1 Notes

Unit D
Chapter 1
Respiration and Excretion
Lesson 1: How Does Your Body Take in Oxygen?
About 1/5 of the air that you breathe in is a gas called oxygen.
Your cells must have oxygen to do their work.
When you breathe in your respiratory system bring air containing oxygen into your
body. The cells in your body use the oxygen. As your cells work they produce
carbon dioxide, which leaves your body as a waste when you breathe out.
The respiratory system includes your nose, your lungs, and the tubes that connect
with them.
The inner lining of the nose produces a sticky liquid called mucus. Mucus adds
moisture to air as it is breathed in and works with tiny hairs in the nose to trap
dust and germs. Breathing out is called exhaling.
Inhale means to breathe in.
After the air you breathe is warmed, moistened, and cleaned by the nose, the air
goes to the throat and down the trachea, or windpipe.
The trachea then divides into two bronchial tubes, each of which goes into a lung.
The bronchial tubes divide into smaller and smaller tubes. The smallest tubes lead
to clusters of tiny pouches called air sacs.
Diaphragm is the large muscle below the lungs that helps you breathe.
Inhaled air comes in that is rich in oxygen and enters these sacs. The blood in
vesses around the air sacs contains carbon dioxide. An exchange quickly takes
place. Oxygen passes from the air sacs and into the blood vessels. The blood now
goes to the body cells.
Lesson 2: How Does Your Body Use Oxygen
Capillaries are tiny blood vessels with very tiny walls. Almost every body cell is
positioned bear a capillary.
Oxygen, carbon dioxide, most nutrients, and cell wastes are exchanged between
the body’s cells and red blood cells in the capillaries.
Oxygen is needed by the cells to do their work.
Lesson 3: How Does Your Body Get Rid of Cell Wastes?
As body cells carry out life activities, they produce wastes. Cell wastes are
different from undigested food, otherwise known as solid wastes.
Your excretory system is the group of organs that get rid of cell wastes.
Kidneys, one of the pair of organs of the excretory system that filter cell wastes
from blood.
When red blood cells have picked up their oxygen and are traveling away from the
heart, their color is bright red.
Cell release energy when they break down sugar by combing the sugar with oxygen.
Nitrogen wastes are carried away from the cells by the plasma.
An artery brings blood to the kidneys. The blood that enters the kidneys contains
poisonous nitrogen wastes, as well as other wastes produced by body cells.
Most of the carbon dioxide produced in the body’s cells is carried away by the
plasma, but some is carried by the red blood cells.
The kidneys remove wastes from the blood. Each kidney has about one million tiny
tubes that filter wasters from the blood.
Until they are ready to leave the body, liquid wastes are stored in the urinary
bladder.
One job of the kidneys is to cleanse the blood of the nitrogen wastes.
The body gets rid of its excess water through the lungs, the skin, and the kidneys.