Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
GASEOUS EXCHANGE AS PE LEARNING OBJECTIVES By the end of this lesson you will: Recap the mechanics of breathing and lung volumes Understand the process of diffusion Know how gaseous exchange takes place at the lungs and the muscles RECAP Complete the worksheet provided , explaining the processes of inspiration and expiration both at rest and during exercise 1. Is the process active or passive? 2. Muscles involved and their role 3. Changes from rest to exercise 4. Additional muscles involved Inspiration Expiration Air into the lungs Rest 1. Diaphragm contracts downwards 2. External intercostals contract (between the ribs/outside of them) – pull the ribs upwards and outwards – ribcage 3. Combined movements above mean that thoracic cavity area increases – air rushes in from outside environment (high pressure) to lungs (now lower pressure due to enlarged chest cavity) Air out of the lungs Rest 1. Passive process – does not need muscle contraction 2. Diaphragm and external intercostal muscles relax – rib cage falls back inwards, recoils – thoracic volume decreases – pressure increases – air flows out of the lungs 3. Pressure inside chest higher than outside of body During exercise 1. Active process During exercise 2. Internal intercostals (inside of the ribs) – contract and 1. Diaphragm and external intercostals contract pull the ribs down and in – thoracic volume smaller 2. Additional muscles help – pectoralis minor (contracts to 3. Diaphragm relax and create a dome shape help top ribs move up and out to assist increasing area) 4. Abdominals – contract to aid diaphragm relaxing – – sternocleidomastoid/scalenes – neck muscles (attach decrease chest cavity quicker on top sets of ribs – increase area) 5. Pressure builds inside thoracic cavity and air rushes out 3. Aim to make thoracic chest cavity greater, larger volume of air in lungs RECAP In pairs, match the lung volume or capacity with the correct definition, value at rest and the changes that take place during exercise Complete the blank spirometer chart LUNG VOLUMES AND CAPACITIES GASEOUS EXCHANGE Gaseous exchange is the exchange of gases at different parts of the body. There are two sites for this: 1. Between the air in the alveoli of the lungs and the blood surrounding alveolar capillaries 2. Between the tissues / muscles of the body and the surrounding blood capillaries The object of this exchange is to convert deoxygenated blood returning from the body into oxygenated blood PARTIAL PRESSURE (P) Partial (part) pressure (p) is the pressure exerted by an individual gas when it exists within a mixture of gases The gas exerts a pressure that is proportional to its concentration within the whole gas E.g. atmospheric pressure is composed of nitrogen (79%), oxygen (21%) and carbon dioxide (0.03%) – together they exert a barometric (atmospheric) pressure of 760mmHg P02 = 760mmHg x 0.21 = 159.6mmHg DIFFUSION Gases move from areas of high pressure to areas of low pressure Diffusion is the movement of gases from areas of a higher partial pressure to a lower partial pressure until equilibrium is reached The difference in high and low partial pressure creates a pressure or diffusion gradient The larger the gradient, the greater the diffusion GASEOUS EXCHANGE AT THE ALVEOLI https://www.youtube.com/watch?v=AJpur6XUiq4 This process involves movement of oxygen and carbon dioxide between the alveoli of the lungs and the surrounding capillaries As blood circulates through the alveolar capillaries, oxygen is picked up from the alveoli and carbon dioxide is lost to them so that it can be expired GASEOUS EXCHANGE AT THE ALVEOLI Blood entering the alveolar capillaries has a low partial pressure of oxygen (40mmHg), compared to that in the alveoli (104mmHg) Diffusion gradient = 104mmHg – 40mmHg = 64mmHg What happens? Oxygen diffused from the alveoli into capillary blood GASEOUS EXCHANGE AT THE ALVEOLI In the meantime, the partial pressure of carbon dioxide within the blood entering the alveolar capillaries is relatively high (46mmHg), compared to that in the alveoli (40mmHg) What is the diffusion gradient? 46mmHg – 40mmHg = 6mmHg What happens? Carbon dioxide diffuses from the capillary blood into the alveoli until the pressure on both sides of the respiratory membrane becomes equal GASEOUS EXCHANGE AT THE MUSCLES / TISSUES OXYGEN Capillary membranes surrounding the muscles, the p02 in the blood (105mmHg) p02 in the muscle tissues is 40mmHg Q: Where will the oxygen move from and to? CARBON DIOXIDE The partial pressure of the carbon dioxide from the heart arriving at the muscles is 40mmHg The partial pressure of the Carbon dioxide in the muscle is 46mmHg Q: Where will the carbon dioxide move from and to? Move from the blood into the muscle tissue Move from the muscle into the blood GASEOUS EXCHANGE PROCESS THE PROCESS OF GASEOUS EXCHANGE OXYGEN IS INHALED AND DIFFUSES INTO THE BLOOD BECAUSE THE PRESSURE IS HIGHER IN THE ALVEOLI THAN IN THE BLOOD THE OXYGENATED BLOOD IS THEN PUMPED BY THE HEART TO THE WORKING MUSCLES WHERE IT IS USED TO PRODUCE ENERGY CARBON DIOXIDE ON THE OTHER HAND IS THE WASTE PRODUCT FROM ENERGY PRODUCTION IN THE MUSCLES AND THEREFORE THE CONCENTRATION IN THE MUSCLES IS HIGH. THE CARBON DIOXIDE MOVES FROM THE MUSCLE INTO THE BLOOD AND IS PUMPED BY THE HEART TO THE ALVEOLI WHERE IT DIFFUSES INTO THE ALVEOLI AND IS THEN EXHALED FACTORS INCREASING THE EFFICIENCY OF DIFFUSION Large number of alveoli Large surface area of each alveoli Diameter of capillaries is very narrow – forces blood cells to travel through them slowly – maximises diffusion of gases across the cell Short diffusion pathway – capillary walls one cell thick Large blood supply to the capillary network surrounding each alveoli and the muscle cells Layer of moisture - allows the gases to dissolve and diffuse quicker HOMEWORK 1. Complete the exam question provided 2. Create an information poster on gaseous exchange (use diagrams to support) – pages 46-48 in your textbook. Your poster must have 3 questions (with answers) on it that can be asked to the rest of the class to check their understanding of gaseous exchange