Understanding Organism Adaptation: Respiratory System and Ventilation

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UNIT 3: HOW ARE ORGANISMS ADAPTED TO SURVIVE Respiratory system: Ventilation The respiratory system works together with the circulatory system to supply all the cells in the body with oxygen and give up the carbon dioxide. Aerobic respiration: is a biochemical pathway that requires oxygen breaking down the glucose molecule, releasing ATP Many people confuse aerobic respiration (a chemical reaction that occurs in all cells) with gas exchange (the diffusion of gases across an exchange surface, such as the cells lining the alveoli) and breathing (the mechanism for ventilating gases in and out of the lungs). Lungs are actively ventilated, but gas exchange occurs passively.

The total lung capacity varies between 4.2 litres in women and 5.8 litres in men. Structure of the respiratory system Do now: 1. Name 3 structures of the respiratory system 2. Is gas exchange considered passive or active? Why? 3. Is ventilation considered active or passive? Why? VENTILATION As you breathe in air and quickly breathe out again, you are bringing fresh air into your alveoli and removing carbon dioxide, this process is called ventilation. Normally in an adult, the breathing rate is between 12–20 times per minute, but that can increase to 30–40 times per minute when exercising.

Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries. The total lung capacity varies between 4.2 litres in women and 5.8 litres in men. What is the relationship between volume of a container and air pressure? How is this related with ventilation?

MUSCLES INVOLVED IN VENTILATION Ventilation consists of 2 steps: Inspiration (breathing in) Expiration (breathing out) When the volume is larger, the pressure is lower Air always flows from an area of high pressure to an area of low pressure When breathing in, the thorax expands and as a result the pressure inside the lungs is lower than atmospheric pressure, causing air to rush in This is essential to ensure that oxygen continuously diffuses into the blood from the alveoli and carbon dioxide diffuses out of the blood into the alveoli. The exchange of gases that occurs at the alveoli is called gas exchange and is directly dependent on ventilation.

Ventilation Always consider what happens to the: Ribs Diaphragm Intercostal muscles Volume of the thorax Pressure in the thorax Movement of air Complete the table (10 minutes) Gas exchange Systems working together Two locations: Alveoli: O2 leaves / CO2 enters Capillary beds: CO2 leaves / O2 enters It depends on the concentration gradient of oxygen and carbon dioxide How is this gradient created? How are alveoli adapted for gas exchange ADAPTATION ADVANTAGE Spherical shaped Large surface area for diffusion Flattened single celled thickness Quick diffusion Moist inner lining Efficient diffusion Associated capillary Diffusion close by Gaseous Exchange Answer these questions in your book: 1.

What do we mean by gaseous exchange, and where does it occur in the lungs? 2. What is the name of the process by which oxygen moves from the lungs to the blood? 3. What 'gradient' must be maintained to enable this process to occur? How is this achieved? 4. Draw and label a diagram of one alveolus and detail three structural features that improve the efficiency of gas exchange. 5. Describe and explain the likely effect of doing exercise on the respiratory system (on breathing rate, breathing depth, concentration gradients and gas exchange) How are the lungs kept free of particles of dirt and bacteria? Chemicals in smoke can destroy the cilia in the trachea and bronchi.

Smoking also irritates the lining of the airways, stimulating goblet cells to release more mucus. What effects might this have? Which disease is this associated with? Smoking can damage the walls of the alveoli, causing them to form enlarged, irregular spaces. This is called emphysema What effect might this have on the surface area of the lungs? Tobacco smoke contains carcinogens. What effect might this have? What disease is it associated with? Cigarette smoke contains the poisonous gas carbon monoxide (CO) CO can combine with haemoglobin more tightly than oxygen can, to form a compound called carboxyhaemoglobin. What effect might this have?

How might this affect the development of a foetus in a pregnant woman? Progress check - answer 1+2 OR 3 The diagram shows an alveolus. 1. Name structure A on the diagram. 2. Describe the movement of oxygen and carbon dioxide with reference to label D and E. 3. Explain how the alveolus is adapted to maximise gas exchange. 5 minutes Task - you are going to produce a resource that helps educate young people on the breathing system and effects of smoking. Your resource needs to include the following information: An overview of normal lung function (a description of what the breathing system is and an explanation of how it works).

An overview of the effects of smoking on lung function (identify the main diseases associated with smoking/vaping, plus a description and explanation of the symptoms of these). This is an individual task. You will need to create a leaflet.