11.1 The Function of Respiration

What is Respiration? Respiration: the main function is to obtain oxygen for use by the body’s cells and to eliminate the carbon dioxide the cells produce Inspiration: breathing in Expiration: breathing out Cellular Respiration: chemical reactions at the cellular level that use O2 to power all of life’s processes It is also the fourth and final stage in respiration Sugar/Glucose (C6H12O6)+ O2 -> CO2 + NRG + H2O

Continued…. External respiration: refers to the entire sequence of events in the exchange of oxygen and carbon dioxide between the external environment and the cells of the body The air is moved in and out of the lungs so that air can be exchanged between the atmosphere (external environment) and the air sacs (alveoli) of our lungs O2 diffuses from the air in the alveoli to the blood within the pulmonary capillaries; CO2 diffuses in the opposite direction The blood transports O2 from the lungs to the tissues and CO2 from the tissues to the lungs O2 and CO2 are exchanged between tissues and blood by the process of diffusion across the systemic (tissue) capillaries

Requirements for Respiration You need a large surface area, called respiratory surface, in which O2 and CO2 are exchanged, and you need a moist environment for the gases to dissolve Animals may use skin, gills or trachea to move O2 over the respiratory surface…See page 444 for various method’s

Gas Exchange in Aquatic Environments O2 is dissolved in water H2O enters the mouth and flows through the gills Gills contain capillaries which absorb the O2 and give up the CO2 gases move along a diffusion gradient – gas moves from a region of high to low concentration -fish, just like us, inhale oxygen and expire carbon dioxide -fish do not have lungs like us so instead they use the capillaries in their gills

Gas Exchange on Land Reptiles, birds, and mammals use lungs Diaphragm (sheet of muscle) contracts and relaxes to draw and push air out of the lungs Inhalation: the rib cage moves up and out, diaphragm contracts and moves down. This causes the thoracic cavity to increase in size and air rushes in to fill the new space. Exhalation: the rib cage moves down and in, diaphragm relaxes and moves up. This causes the thoracic cavity to decrease in size, and air then gets squeezed out of the lungs.

Respiratory Volumes Tidal volumes: normal volume of air inhaled and exhaled Inspiratory reserve volume: additional volume taken in when inhaling Expiratory reserve volume: additional volume forced out when exhaling Vital capacity: total volume inhaled and exhaled Residual volume: the amount of air left in lungs even after forcing it all out -get students to take a breath, take a breath and then take some more in before exhaling, take a breath and exhale and then exhale some more before inhaling

Spirograph

Homework Review 11.1 Work on your projects!! Read over tomorrow’s lecture