Settler Pass it on First person – Start off the mechanism of inhalation, turn to the person on your right – next stage, continue (include exhalation) Review previous learning on ventilation

Module 2 Exchange and transport 7.2 Lungs

What do you know?? - Structure of the lungs Boardworks AS Biology Gas Exchange What do you know?? - Structure of the lungs

Learning Objectives Success Criteria Describe the distribution of cartilage, ciliated epithelium, goblet cells and smooth muscle and elastic fibres in the trachea, bronchi and bronchioles and alveoli of the mammalian gaseous exchange system Describe the functions of cartilage, goblet cells, smooth muscle and elastic fibres Identify tissues in the lungs (Grade E - D) Describe the distribution of tissues in the lungs (Grade C –B) Explain the functions of tissues in the lungs (Grade B – A)

Trachea The trachea is a flexible airway supported by C- rings of cartilage which prevent the trachea collapsing when the air pressure inside falls. Inner lining is a ciliated epithelium and goblet cells. The goblet cells produce mucus which traps dirt and bacteria. The cilia move the mucus up to the throat where it is swallowed.

Bronchi – Similar in structure to trachea only narrower Bronchi – Similar in structure to trachea only narrower. 2 divisions of the trachea. Larger bronchi are supported by cartilage. Bronchioles – branching subdivisions of the bronchi. Larger bronchioles may have cartilage, walls are made mainly of smooth muscle and elastic fibres. The muscle enables them to control the flow of air in and out of the alveoli.

Gas exchange in the alveoli Boardworks AS Biology Gas Exchange Gas exchange in the alveoli

Task Design a table to include distribution and function of cartilage, ciliated epithelium, goblet cells, smooth muscle and elastic fibres in the trachea, bronchi, bronchioles and alveoli You may include diagrams if you wish

Tasks HSW 1)Attacking asthma 2)The first breath

Structures of the human lung Boardworks AS Biology Gas Exchange Structures of the human lung Photo credit (Q1): Susumu Nishinaga / Science Photo Library Coloured scanning electron micrograph (SEM) of a bronchiole (yellow) and alveoli (air sacs, pink) in a healthy human lung. The large holes are capillaries running through the alveoli and bronchiole. The bronchiole carries inhaled air from the upper airway to the alveoli in the lung. The alveoli are the sites of gaseous exchange; oxygen enters the blood and carbon dioxide leaves. Photo credit (Q2): Susumu Nishinaga / Science Photo Library Coloured scanning electron micrograph (SEM) of mucus-producing cells (orange, round) and cilia (yellow) lining a bronchus (lung airway). Mucus secreted here traps bacteria, dust and other particles. Rhythmic movements of the cilia serve to move the mucus and the trapped particles away from the gas-exchanging parts of the lung, and towards the throat, where they can be expelled. Photo credit (Q3): Eye Of Science / Science Photo Library Coloured scanning electron micrograph (SEM) of alveoli in a human lung. Each alveolus is a site for gas exchange between the air in the air sac and the blood in adjacent capillaries. Red blood cells (erythrocytes) can be seen through the walls of the alveoli. Oxygen diffuses from the inhaled air across these walls into the red blood cells. It binds with haemoglobin and is delivered to the body's cells for respiration. Carbon dioxide is returned from the cells to the lungs and diffuses out of the blood to be exhaled. Magnification: x300 when printed at 10cm wide.

Plenary Complete match up for cut and stick Homework – Complete exam questions Explain the functions of tissues in the lungs (Grade B – A)