Gas Exchange (Topic 6.4)

Components of the Gas Exchange System

Terms to Differentiate Ventilation: movement of air into and out of the lungs in two stages; inspiration and expiration. Controlled by the rib cage and the diaphragm Gas Exchange: The diffusion of oxygen and carbon dioxide to and from the blood; occurs at the alveoli in lungs Respiration: the chemical conversion of glucose to ATP (form of energy used by most living organisms); oxygen is a required reactant for aerobic respiration

Purpose of Ventilation, Gas Exchange, & Respiration Process Purpose Ventilation Maintain concentration gradients for gas exchange to occur through diffusion Gas Exchange Take in oxygen required for respiration ; excrete excess CO2 to control blood pH Respiration Convert sugars into a form of energy (ATP) that can be used by cells

Why do we need a ventilation system?

Why do we need a ventilation system? 1) We are large organisms. Oxygen cannot diffuse into all our cells directly from the air, nor can waste products be directly ejected from the body. We have specialized organ systems, which are efficient, but need delivery of nutrients and removal of wastes. The ventilation system ensures the blood can be the medium for this. 2) We are land-borne. Gases need moist surfaces (membranes) in order to diffuse. Our lungs have moist membranes, allowing oxygen to diffuse into the blood and carbon dioxide to diffuse out.

Why do we need a ventilation system? 3) The ventilation system maintains a large concentration gradient between the alveoli and the blood. The constant flow of blood past the alveoli brings blood with a high CO2 concentration and low O2 concentration. Breathing out keeps the CO2 concentration in the alveoli low, so it diffuses out of the blood. Breathing in keeps O2 concentration in the alveoli high, so it diffuses into the blood.

How are alveoli adapted for gas exchange? Epithelium (wall of each alveoli) is one cell thick to minimize distance for diffusion They are surrounded by a dense capillary network with a lot of surface area for gas exchange Their round shape and high numbers increase surface area for gas exchange Their internal surface is covered with a layer of fluid, as dissolved gases are better able to diffuse into the bloodstream

How are alveoli adapted for gas exchange How are alveoli adapted for gas exchange? Type I & Type II Pneumocytes specialized cells Type I Pneumocytes Type II Pneumocytes -make up epithelium of alveoli -secrete “pulmonary surfactant” to keep alveoli moist -helps to make sure alveoli inflate at the same rate to prevent lung collapse when breathing

3!

How do pressure-volume laws relate to ventilation?

What muscles are used for breathing in and out What muscles are used for breathing in and out? The external and internal intercostal muscles Are antagonistic (work opposite of one another)

Lung Conditions Research Directions: Research one of the following conditions related to the gas exchange system in humans. (See next slide for possible conditions. You may choose to research a condition that is not listed.) Points to Research: -Symptoms -Causes (genetic, environmental, etc.) -Treatment options -How does it specifically affect the gas exchange system What to Produce: -A poster, PowerPoint/Google slides presentation, or Prezi. YOUR PRODUCT MUST INCLUDE IMAGES/DIAGRAMS TO SUPPORT.

Possible Conditions for Research Lung cancer Asthma Emphysema Cystic fibrosis Tuberculosis Common cold Flu Bronchitis Pneumonia Sinusitis. PRESENTATIONS ARE DUE MONDAY 3/13

Assessment -Out of 10 points total ; one grade for both partners. (Individual scores can change depending on participation.) -5 Points: Presentation includes all information required, with images or diagrams to support. -5 Points: -Both presenters contribute equally -Both presenters give best effort during presentation

Asthma = chronic condition that cannot be cured, only managed Inhalers contain hormones which cause the muscles of the bronchi to relax and open up so air can flow more regularly.

Breathing Exercises – desk yoga (it’s IBDP after all, let’s bust some stress) Simple exercises. Keep your neck straight. Rotate shoulders forwards, then backwards, 5 times each. Bend your neck to touch your head to your shoulder, left then right, 5 times each. Tilt your head forward, touching chest, then backward, 5 times each. Breathing observation Close your eyes, breathe normally. “Observe” the breathing process. Pranayama Stand up. Take gentle, deep breaths. Feel the air moving in and out, trying to control its flow. Think happy thoughts about graduation.