D2.2 - Breathing and Respiration (Updated 2024) PDF

D2.2 - Breathing and Respiration I can... Explain the mechanism of breathing in gas exchange Breathing Movements The Mechanics of Breathing The Mechanics of Breathing Breathing relies on the movement of gases from an area of high pressure to an area of low pressure via the action of th...

D2.2 - Breathing and Respiration I can... Explain the mechanism of breathing in gas exchange Breathing Movements The Mechanics of Breathing The Mechanics of Breathing Breathing relies on the movement of gases from an area of high pressure to an area of low pressure via the action of the diaphragm The pressure difference between the chest cavity and atmosphere is what moves gases into and out of lungs ○ Atmospheric pressure is constant, but lung pressure changes The Mechanics of Breathing 1. CO2 in the bloodstream increases. This is detected by the brain, which triggers the diaphragm to contract. 2. As the diaphragm contracts, it pulls downwards, creating an area of low pressure inside the lungs (aka a vacuum) relative to the air outside. 3. Recall that gases always move from areas of high pressure to areas of low pressure. As a result, air rushes into the lungs, causing them to expand (inhalation). Gas exchange occurs (O2 diffuses into the bloodstream, CO2 diffuses out). 4. CO2 in the bloodstream decreases, and the brain triggers the diaphragm to relax. As it relaxes, it moves upwards, pushing the CO2-rich air out of the lungs (exhalation). 5. Cell respiration can now continue as cells receive O2 from the bloodstream. Cells release CO2 into the bloodstream (a by-product of cell respiration). Breathing Movements Inhalation: ○ Diaphragm contracts ○ Intercostal muscles contract ○ Increase in lung volume ○ Environmental air pressure is greater than the lung pressure ○ Air rushes into the lungs to equalize pressure Breathing Movements Exhalation: ○ Diaphragm relaxes ○ Intercostal muscles relax ○ Decrease in lung volume ○ Environmental air pressure is less than than the lung pressure ○ Air rushes out of the lungs to equalize pressure Gas Exchange Gas exchange occurs by diffusion between air in the alveoli and gases dissolved in the blood flowing through the adjacent capillaries The blood has a high concentration of CO2, so CO2 diffuses into the alveoli and is exhaled The alveoli have a high concentration of O2 after inhaling so O2 diffuses into the blood and is transported throughout the body so that cells can use it for cell respiration Gas Exchange Gas Exchange 1. Oxygen enters the body when you inhale, makes its way into the alveoli of the lungs. 2. Oxygen then diffuses down its concentration gradient (from high to low concentration) from inside the alveoli into the capillaries/blood stream. The blood is now oxygenated. 3. CO2 from the capillaries diffuses down its concentration gradient (from high to low concentration) into the alveoli. 4. CO2 is then released from the body when we exhale. Adaptations for Gas Exchange In small aquatic organisms, gases diffuse directly between the environment and all body cells. In larger, more complex organisms, specialized respiratory structure are required: ○ Must have thin walls ○ Must be kept moist ○ Must be richly supplied with blood vessels ○ Must have large surface area Breathing and Muscles Measuring Respiratory Volumes Respiratory volumes can be measured with a device known as a spirometer Measuring Respiratory Volumes Spirograph: Represents amount of air that moves into and out of lungs between breath Tidal volume: Volume of air when you breathe normally Inspiratory reserve volume: Additional volume of air that’s taken in lungs beyond regular inhalations Expiratory reserve volume: Additional volume of air that can be forced out lungs beyond regular exhalations Vital capacity: Total lung volume capacity; total volume of gas that can be moved into and out of lungs Residual volume: Amount of gas that remains in lungs and passageways even after a full exhalation Gas never leaves respiratory system Prevents lungs and respiratory pathways from collapsing tidal volume + inspiratory reserve = total in tidal volume + expiratory reserve = total out Typical Spirograph Measuring Your Own Vital Capacity 1. Grab a balloon. Stretch out your balloon well. 2. Take a deep breath and exhale completely into the balloon. Force out as much air as you can with one breath. 3. The volume of air in the balloon is your vital capacity. To calculate this, find the diameter of the balloon by laying the balloon on it’s side on a flat surface beside a standing-up ruler. Measure the height of the balloon at its widest part. 4. Repeat the test and measure 3 times, then take an average of your results. We will share these results with the class. Measuring Your Own Vital Capacity Age, size, biological sex and genetic factors, etc. account for differing vital capacities A person’s usual vital capacity can also change because of illness Vital capacity is often measured by a medical professional to help diagnose and monitor diseases such as asthma or chronic obstructive pulmonary disease (COPD) Summary Gases diffuse from an area of _____________ pressure to an area of ____________ pressure The partial pressure of _____________ is highest in the atmosphere and lowest in the veins and tissues. The partial pressure of __________________________ is highest in the tissues and veins and lowest in the atmosphere To help maintain ___________________, chemical receptors detect a change in gas levels and send a message to increase or decrease the __________________ rate Video - How do lungs work? (TedED) https://www.youtube.com/watch?v=8NUxvJS-_0k&ab_channel=TED-Ed