Transcript Respiration
Respiration Asthma Treatment In The News Respiration • Take up of oxygen from environment • Release of carbon dioxide • Respiratory gasses move across respiratory surfaces by diffusion Methods of Animal Respiration • Over cell & skin surfaces – Cell membrane – Outer layer of cells – Skin • Use of special organs – Tracheal system – Gills – lungs Respiration Using Cell Membranes • Used by bacteria & protists Respiration Using Outer Cells • Used by sponges, corals, jellyfish & worms Respiration Using the Skin • Used by amphibians & some other vertebrates Respiration Using a Tracheal System • Used by insects & some spiders Tracheal system • Opens to the environment at spiracle • Series of tubes transports air to cells Respiration Using Gills • Used by large aquatic organisms Gills • Oxygen flows from water to blood • Possible because of countercurrent flow Respiration Using Lungs • Used by mammals & other large land animals General Lung Structure • Microscopic air sacs • Many blood vessels • Moist membranes allow gas diffusion – Oxygen into blood – Carbon dioxide out of blood Animal Lung Variation • Frogs – Gulp air – Pump air into lungs • Birds – Air sacs in addition to lungs Human Respiration • Breathing = moving air in & out of lungs • Inspiration = taking air in • Expiration = expelling air • Average rate = 14-20 breaths per minute Organs of the Respiratory System • • • • • • Nasal cavities Pharynx Larynx Trachea Bronchi Alveoli Nasal Cavities • Air enters nostrils • Hairs filter particles • Air is warmed & moistened • Moist, mucous secreting epithelium (moistens air, helps trap dust & dirt) covered in cilia Pharynx • Begins behind nasal cavities • Extends to epiglottis • Passageway for air & food Larynx • Cartilaginous box • Contains vocal cords • Only carries air Trachea • Windpipe • Tube enforced with cartilage Bronchi • Branches at end of trachea • Enters lungs • Continues to branch – Primary bronchi, secondary bronchi, … • Ends in respiratory bronchioles • Alveoli at end of respiratory bronchiole Alveoli • Region of gas exchange • Air on one side, blood capillaries on other Particle Filtration • Particles are trapped in mucus • Cilia sweep out particles Air Flow in Lungs • Air flows due to pressure differences – Low pressure causes air to flow in – High pressure forces air out • Muscles cause pressure differences – Diaphragm – Intercostal muscles • external – quiet breathing ( expiration a passive process) • internal – deep breathing (expiration an active process) Inspiration • Muscles increase volume of thoracic cavity • Lungs expand to decrease pressure inside • Air flows into lungs Expiration • • • • Stretch receptors activated by expanded lung Muscles relax Thoracic volume decreases Air is forced out Lung Volumes • Tidal volume – Air exchanged per breath – About 500 ml – 350 ml reaches alveoli • Not all air is exchanged with each breath – Residual air Gas Transport to Cells • Circulatory system transports gasses External Respiration • Oxygen & carbon dioxide exchanged • Exchange works due to diffusion • Gasses move from high to low concentration Gas Travel in the Blood • Oxygen – 98.5% attaches to hemoglobin on red blood cells – 1.5% dissolves in plasma • Carbon dioxide – 25% carried on red blood cells – 6% dissolved in blood – 69% carried in plasma as bicarbonate ions Internal Respiration • Exchange of gasses by body tissue • Works by diffusion Chronic Obstructive Pulmonary Disease (COPD) • Disorders that block airways & impair breathing • Fourth leading cause of death • Common examples – Chronic bronchitis – Emphysema Chronic Bronchitis • Inflammation of bronchi & bronchioles • Primary cause is cigarette smoking – Paralyzes epithelial cells – Particles are not removed – Infections are common Emphysema • Lungs lose elasticity • Must work to exhale Unblocking Airways • Abdominal thrusts can dislodge blockage End chapter 29