 THE FUNCTION OF RESPIRATION

Almost every organism requires oxygen for cellular respiration: C 6 H 12 O 6 + O 2 → H 2 O + CO 2 + ATP (energy) The job of our respiratory system is to get oxygen into our bodies, where it can then be supplied to each and every cell for cellular respiration

THE FUNCTION OF RESPIRATION There are two parts to this process: 1. Breathing: inhalation/inspiration and exhalation/expiration 2. Gas Exchange: exchanging oxygen for carbon dioxide a) External Respiration: exchange of oxygen and carbon dioxide between the inspired air inside the lungs and blood b) Internal respiration: exchange of oxygen and carbon dioxide between the blood and body’s tissue cells 3. Cellular Respiration: energy releasing chemical reactions in cells

THE FUNCTION OF RESPIRATION 2. Gas Exchange GAS EXHANGE: the two way movement of gases (oxygen, O 2 and carbon dioxide, CO 2 ) between internal (inside the organism) and external (outside the organism) environments. OXYGEN: required to release the energy in glucose during cellular respiration CARBON DIOXIDE: given off as a waste product

THE FUNCTION OF RESPIRATION 2. Gas Exchange The gases can only be exchanged when they are dissolved in water because that is the only way they can diffuse through tissues Every cell in an organism requires oxygen and needs to get rid of carbon dioxide

THE FUNCTION OF RESPIRATION A good gas exchange system requires the following qualities: 1. Large Respiratory Surface Area - large area for diffusion to occur 2. Moist Surface - dissolves oxygen in the air 3. Close to Transport/Circulatory System - delivers oxygen to circulatory system so that it can be transported throughout the body

THE FUNCTION OF RESPIRATION Where and how do the following organisms exchange gases? Amoeba – body surface, diffusion Worm – body surface, diffusion Fish – gills, diffusion Frog – lungs, gulping and swallowing; moist outer skin, diffusion Human – lungs, breathing

THE FUNCTION OF RESPIRATION

GAS EXCHANGE IN AQUATIC ENVIRONMENTS Oxygen is found as a dissolved gas Oxygen can be taken in through gills GILLS: respiratory organ found in many aquatic animals that extracts dissolved oxygen from water, and excretes carbon dioxide - Oxygen diffuses into the blood and circulates through surrounding capillaries - Carbon dioxide diffuses from the blood, across the gill tissue, into the water

GAS EXCHANGE IN AQUATIC ENVIRONMENTS

GAS EXCHANGE ON LAND Air breathing vertebrates (Ex. Reptiles, birds and mammals) rely on lungs for gas exchange

GAS EXCHANGE ON LAND ANATOMY OF RESPIRATORY SYSTEM REQUIRED FOR BREATHING

GAS EXCHANGE ON LAND The DIAPHRAGM and INTERCOSTALS MUSCLES work together to bring air into and out of the lungs

GAS EXCHANGE ON LAND EXPIRATIONINSPIRATION Exhaling: air out of lungsInhaling: air into lungs Air pressure in lungs is GREATER than air pressure outside Air pressure in lungs is LOWER than air pressure outside Diaphragm relaxesDiaphragm contracts Diaphragm moves upwardsDiaphragm moves downwards Intercostals relaxIntercostals contract Rib cage moves in and downRib cage moves up and out LOWER volume, HIGHER air pressureHIGHER volume, LOWER air pressure

GAS EXCHANGE ON LAND THE PHYSIOLOGY OF GAS EXCHANGE AT THE CELLULAR LEVEL Alveoli: thin, moist, high surface area ratio - bathed by 4-6 L of blood every minute Blood returning to the heart from the body is relatively low in O 2 (P O2 = 40) and high in CO 2 (P CO2 = 46) This blood is pumped by the right ventricle to the lungs In the alveoli of the lungs, gases are exchanged:  O 2 diffuses into capillaries and is carried by hemoglobin in RBCs  CO 2 diffuses out into the alveoli and is carried as carbonic acid

GAS EXCHANGE ON LAND THE PHYSIOLOGY OF GAS EXCHANGE AT THE CELLULAR LEVEL STRUCTUREGASPRESSURE AlveoliOxygen105 CapillaryOxygen40 AlveoliCarbon dioxide40 CapillaryCarbon dioxide46

GAS EXCHANGE ON LAND THE PHYSIOLOGY OF GAS EXCHANGE AT THE CELLULAR LEVEL

RESPIRATORY VOLUMES

Tidal Volume: Amount of air inhaled and exhaled with each normal breath Inspiratory Reserve Volume: Maximum amount of gas that can be forcefully inhaled after a normal inhalation Expiratory Reserve Volume: Maximum amount of gas that can be forcefully exhaled after a normal exhalation

RESPIRATORY VOLUMES Vital Capacity: The volume of gas that can be expelled from the lungs after a full inspiration  Inspiratory Capacity + Expiratory Reserve Volume Residual Volume: Amount of gas left in the lungs after a maximum (forced) exhalation Total Lung Volume: The volume of gas contained in the lung at the end of maximal inspiration  Vital Capacity + Residual Volume

RESPIRATORY VOLUMES