11.18.16 Respiration

Mechanisms of Gas Exchange Gas exchange has three phases: breathing transport of gases exchange of gases with tissue cells It provides O2 for cellular respiration and removes its waste product, CO2 Respiratory & Circulatory systems

The 3 Phases of Gas Exchange 1. Breathing O2 is taken into lungs and blood vessels CO2 diffuses out and leaves body 2. Transport of gases by the circulatory system O2 attaches to hemoglobin and is carried in blood to body tissues CO2 is transported from tissues back to lungs 3. Exchange of gases with tissue cells Body cells take up O2 from blood and release CO2 back to the blood This is diffusion through the plasma membrane (mitochondria internally)

LE 22-1 O2 Breathing CO2 Lung Circulatory system Transport of gases by the circulatory system Mitochondria Exchange of gases with body cells O2 CO2 Capillary Cell

Human Air Pathway: Inhaled through the nostrils  Passes through the pharynx and larynx (including vocal cords)  Into the trachea, bronchi, and bronchioles* * Bronchioles end in clusters of tiny alveoli, where gas exchange occurs Cilia and mucus are the respiratory system's cleaning elements

Partner 1 - Describe how oxygen gets into your body Partner 1 - Describe how oxygen gets into your body. Partner 2 – Describe how carbon dioxide leaves.

Oxygen-poor blood Oxygen-rich blood Bronchiole Alveoli Blood LE 22-5b Oxygen-poor blood Oxygen-rich blood Bronchiole Alveoli Blood capillaries

Alveoli walls and gas exchange 6.4.U2 Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange. AND 6.4.U3 Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension. Alveoli walls and gas exchange Connective tissue Type I pneumocytes A Single layer of cells form the walls of an alveolus Extremely thin – short diffusion distance Permeable – aids diffusion Type II pneumocytes Secrete fluid to moisten the inner surface of the alveolus Fluid aids diffusion of gases Fluid contains surfactant to prevent the walls sticking together – maintains the lumen Can divide to form Type I pneumocytes – repair damage Edited from: https://beyondthedish.files.wordpress.com/2011/11/gas-barrier-small.jpg http://neurobio.drexelmed.edu/education/pil/microanatomy/Cases/01_Quintana/4_Epithelium/Images/alveolarepithelium.jpg

Smoking is a deadly assault on our respiratory system Tobacco smoke irritates cells lining the bronchi Inhibits or destroys cilia Kills defensive macrophages Causes: lung cancer, emphysema, cardiovascular disease Choosing not to smoke is the most important lifestyle choice for health

LE 22-6 Lung Heart

Breathing* ventilates the lungs *alternation of inhalation and exhalation Maintains high O2 and low CO2 at the respiratory surface

Negative pressure breathing During inhalation, changes in lungs, diaphragm, and rib cage reduce air pressure in alveoli Air rushes in due to higher pressure outside During exhalation, decreased volume of chest cavity forces air out A residual volume of air ("dead air") remains in lungs even after exhalation Vital capacity is the maximum volume of air we can inhale and exhale during forced breathing

Rib cage gets smaller as rib muscles relax Rib cage expands as rib muscles contract Air inhaled Air exhaled Lung Diaphragm Diaphragm contracts (moves down) Diaphragm relaxes (moves up) Inhalation Exhalation

Summary of the mechanics of ventilation 6.4.A3 External and internal intercostal muscles, and diaphragm and abdominal muscles as examples of antagonistic muscle action. AND 6.4.U5 Muscle contractions cause the pressure changes inside the thorax that force air in and out of the lungs to ventilate them. Summary of the mechanics of ventilation Inspiration Expiration pressure change decrease in pressure (draws air inwards) increase in pressure (pushes air outwards) volume change increase decrease ribcage movement up and outward down and inward external intercostal muscles contract relax internal intercostal muscles diaphragm Contract (flattens, moves downwards) abdominal muscles Contract (pushes diaphragm up) diagrams causes causes http://media1.shmoop.com/images/biology/biobook_animalmovement_graphik_36.png