Respiratory System

Learning Objectives To identify and describe 5 structures of the respiratory system. To describe the process of inspiration To describe the process of expiration

Starter Activity Write a list of as many structures of the respiratory system as you can.

Introduction The purpose of the respiratory system is to… “bring the air we breathe into close contact with the blood so that oxygen can be absorbed and carbon dioxide removed.” Basically it consists of: A pair of lungs connected to the mouth via the trachea and bronchi. The ribs and intercostal muscles of the chest which protect the lungs, trachea and bronchi.

Respiratory System The lungs are in the thoracic cavity and are also protected by 12 pairs of ribs that articulate with the vertebrae towards the back of the body. The sternum breastbone) is at the front of the rib cage. Sternum The portions of the ribs that articulate with the breastbone are made of cartilage rather than bone. Cartilage is softer and more pliable than bone and this helps the movement of the rib cage during breathing. Sets of antagonistic muscles are found between the ribs - the intercostal muscles. Cartilage

Position of the diaphragm The Thoracic Cavity This chest X-ray shows the organs within the thoracic cavity. Ribs Air-filled lung Position of the heart Position of the diaphragm

The Respiratory System Trachea (wind pipe) Ribs Alveoli Bronchus Bronchioles Lung Intercostal muscles Diaphragm

The trachea or windpipe is about 10 cm long and is supported by C-shaped rings of cartilage to prevent the tube from collapsing during breathing. Air enters the body through the nasal passages and mouth, and passes via the pharynx and larynx to the trachea. The trachea subdivides into the left and right bronchus. The bronchi are also strengthened by cartilage. Air is delivered to the alveoli as the trachea branches into bronchi and bronchioles. The two bronchi subdivide to form an extensive network of Bronchioles that deliver air to the gas exchange surfaces – the alveoli.

The respiratory system

The respiratory system

Worksheet – Identify and describe the different structures of the lungs

Functions of the respiratory system Mechanism of breathing (inspiration and expiration) Gaseous exchange

The Mechanism of Breathing They are not controlled by the central nervous system Lungs are NOT muscle Lungs cannot move of the own accord So, how do they move when we breath in and out?

The Mechanism of Breathing The Key to Breathing is the Diaphragm and the intercostal muscles between the Ribs

The nasal passages and lungs Air is drawn into the body via the nose or mouth. There are advantages to breathing through your nose: the air is warmed so that it is closer to body temperature tiny hairs and mucus in the nose filter the air, preventing larger dust and pollen particles reaching the alveoli mucus moistens the air, making it easier for the alveoli to absorb. Air then travels through the larynx, trachea (windpipe), bronchi (one bronchus to each lung) and bronchioles to the alveoli, where oxygen passes into the bloodstream.

Inspiration When you breathe in: Intercostal muscles pull ribs up and out When you breathe in: intercostal muscles between the ribs contract, pulling the chest walls up and out the diaphragm muscle below the lungs contracts and flattens, increasing the size of the chest the lungs increase in size, so the pressure inside them falls. This causes air to rush in through the nose or mouth. Diaphragm contracts and moves down

Diaphragm relaxes and bulges up Expiration When you breathe out: Ribs move in and down Intercostal muscles between the ribs relax so that the chest walls move in and down. The diaphragm muscle below the lungs relaxes and bulges up, reducing the size of the chest. The lungs decrease in size, so the pressure inside increases and air is pushed up the trachea and out through the nose or mouth. Diaphragm relaxes and bulges up

Summary of respiratory system Air passes through the nose or mouth and then on to the larynx. It carries on through the trachea. The trachea splits into tubes called bronchi (each one is a bronchus) – one each going to the lungs. The bronchi split into progressively smaller tubes called bronchioles. The bronchioles finally end at small bags called alveoli (each one is an alveolus) where the gas exchange takes place.

Summary Task 1 bronchi bronchioles trachea larynx alveoli List the following five words in the order that breathed in air would go through them trachea larynx alveoli

Summary Question Time During exercise why is it better to breath in through our nose rather than our mouths???? When air is breathed in through the nose, it is: Filtered by the hairs at the entrance to the nose and by mucus which is a sticky substance. Warmed by blood vessels passing to the lining of the nose. Moistened by water vapour. The trachea and the bronchi also help get the air ready – they have tiny hairs and are covered in mucus helping to clean the air.