Biology Biology Chapter 34 The Breathing System Copyright © James Greally 2003
Functions of the Breathing System 1.To take in oxygen gas 2.To excrete carbon dioxide gas 3.To excrete water vapour Go to and view video on respiratory system.
Aim To understand the physical process of breathing in humans You will learn What happens during breathing The structure of the breathing system in humans How breathing happens Prove that exhaled air contains more carbon dioxide than inhaled air. Explain how gaseous exchange ocurrs (HONOURS). Learn about the dangers of smoking Do an experiment to show the effect of exercise on breathing.
External Respiration When we respire externally, we breathe in oxygen gas and we breathe out carbon dioxide gas and water vapour.
Definition of External Respiration “External respiration is a physical process that transfers gases between the body and the outside world.”
Definition of Cellular Respiration “Cellular respiration is a chemical process that causes the release of energy from food.”
Sheep’s Breathing Organs Sheep’s breathing organs are similar to ours.
Parts of the Breathing System: The Trachea Air travels through the trachea (or windpipe) as it passes in and out of your lungs. Trachea
Rings of Cartilage The trachea is surrounded by several “c-shaped ” rings of a tough material called cartilage. The cartilage strengthens the trachea so that it doesn’t collapse easily. Rings of Cartilage
The Larynx The larynx (or voice box) is the upper part of the trachea. The larynx is used to make sounds. Larynx
The entrance to the lungs
Did You Know? All animals must take in oxygen and get rid of carbon dioxide. Not all animals have lungs. Insects have tiny holes called spiracles on their bodies, through which air passes. Insect body showing spiracles
The Lungs You have two lungs, right and left. They are made of a spongy tissue that can expand as it fills with air. The lungs
The Bronchi Near the lungs, the trachea splits into two major branches. Each one of these branches is known as a bronchus. The bronchi carry air into the lungs. Lungs Right Bronchus
The Bronchioles Inside each lung, the bronchus divides into many narrow tubes called bronchioles. These carry air throughout the entire lung. LungBronchus Bronchioles
The Alveoli Each bronchiole ends in a tiny “bag” called an alveolus (or air sac). This is the end of the journey for the air. Each lung contains over 300 million alveoli. Alveoli LungBronchus Bronchioles
Structure of the Alveolus Alveoli surrounded by blood capillaries Bronchiole Alveoli Network of blood capillaries
Alveolus Gaseous Exchange Blood containing carbon dioxide, no oxygen Gaseous exchange occurs in the alveolus Carbon dioxide leaves blood Carbon dioxide breathed out Oxygen breathed in Blood containing oxygen, no carbon dioxide Oxygen enters blood Capillary
Gaseous Exchange
Did You Know? If all the alveoli in your lungs could be spread out, they would cover a surface area about two- thirds of the size of a tennis court! This increases the surface area over which oxygen can be absorbed.
The Diaphragm The chest and the abdomen are separated by a thin sheet of muscle called the diaphragm. The diaphragm is involved in the mechanism of breathing in and out. Diaphragm LungBronchusAlveolus Bronchioles
Did You Know? Fish do not have any lungs. They breathe the oxygen which is dissolved in the water using their gills.
The Rib Cage There are 12 pairs of ribs in the rib cage. The rib cage is also involved in the mechanism of breathing in and out. Rib Cage LungBronchusAlveolus Bronchioles
The Rib Cage There are 12 pairs of ribs in the rib cage. The rib cage is also involved in the mechanism of breathing in and out. LungBronchusAlveolus Bronchioles
The Rib Cage There are 12 pairs of ribs in the rib cage. The rib cage is also involved in the mechanism of breathing in and out. Rib Cage LungBronchusAlveolus Bronchioles
The Rib Cage There are 12 pairs of ribs in the rib cage. The rib cage is also involved in the mechanism of breathing in and out. LungBronchusAlveolus Bronchioles
The Rib Cage There are 12 pairs of ribs in the rib cage. The rib cage is also involved in the mechanism of breathing in and out. Rib Cage LungBronchusAlveolus Bronchioles
The Intercostal Muscles The intercostal muscles are found in between the ribs. Intercostal Muscles
Did You Know That Kermit Has Lungs? As stated already, not all animals have lungs. Frogs have lungs, but they only use them to breathe air when they are out of the water. When they are under the water, however, frogs can take oxygen in through their skin!
Taking a Breath ‘Inhalation’ means ‘breathing in’. ‘Exhalation’ means breathing out. When we need to take a breath, the brain sends a signal to the diaphragm and to the intercostal muscles.
Inhalation (Breathing In) The diaphragm pulls downwards. The rib cage expands. The lungs also expand. Air is drawn into the lungs and they expand. Diaphragm pulls down Rib cage expands Air drawn in
Inhalation or Breathing In
Exhalation (Breathing Out) The diaphragm pushes upwards. The rib cage contracts and presses inwards. The lungs also contract. Air is squeezed out of the lungs. Rib cage pushes in Air pushed out Diaphragm pushed up
Exhalation (Breathing Out) Exhalation or Breathing Out
Model of the Lungs Bell-Jar (rib cage) Balloon (lung) Glass tube (trachea) (diaphragm) Rubber Sheet Y-tube (bronchi)
Using the Model of the Lungs Bell-Jar (rib cage) Balloon (lung) Glass tube (trachea) (diaphragm) Rubber Sheet Y-tube (bronchi) Q.What happens when the rubber sheet is pulled downwards? A.The balloons will inflate (or expand)!
Using the Model of the Lungs Bell-Jar (rib cage) Balloon (lung) Glass tube (trachea) (diaphragm) Rubber Sheet Y-tube (bronchi) Q. What do you think will happen when the rubber sheet is pushed upwards? A.The balloons are squeezed so all the air is pushed out, and the balloons deflate again!
Comparing Inhaled Air and Exhaled Air
The End