Transcript Respiration
Chapter 40 Respiration: A Summary AP Biology Spring 2011 The Basis of Gas Exchange Respiration: sum of physiological processes that move oxygen gas from surrounds to all metabolically active tissues in animal body and carbon dioxide from tissues to outside Relies on diffusion of gases down pressure gradients Gases enter and leave internal environment by crossing moist respiratory surfaces Factors Influencing Gas Exchange Surface to volume ratio As animal grows, its surface area increases at a lesser rate than its volume Makes diffusion of gases into interior a problem Animals either must have a small flattened body that keeps internal cells close to surface or they must have specialized respiratory organs to move gases inward Factors Influencing Gas Exchange Ventilation Moving air or water past a respiratory surface keeps pressure gradient across the surface high and thus increases rate of gas exchange Humans and frogs breathe in and out to move air in and out of the lungs Fish and other animals that live in the water have mechanisms that move water across their respiratory surfaces Factors Influencing Gas Exchange Respiratory Pigments The main transport pigment is hemoglobin (are proteins) Each molecule of hemoglobin binds 4 molecules of oxygen in the lungs (high concentration) and releases them in the tissues where oxygen is low Myoglobin is another iron-containing respiratory, which is a good storage molecule of oxygen because it has a higher affinity for oxygen Invertebrate Respiration Integumentary exchange: gases diffuse directly across a moist body surface Adequate for small animals such as sponges, cnidarians, flatworms Invertebrate Respiration Gills: highly folded, thin walled projections from the body Enhance exchange rates between blood of aquatic animals and their watery environment Snails and slugs live on land and water, have lungs in addition to gills Invertebrate Respiration Tracheal System: consists of repeatedly branching, air-filled tubes reinforced with chitin Tubes start at tiny openings (spiracles) across the integument Tube branches, then branches again; fluid fills tips of finest branches which end next to body cells Insects and spiders Spiders have book lungs in addition to tracheal tubes to enhance respiration Vertebrate Respiration The Gills of Fish Gills contain filaments that hold many capillary beds where gases are exchanged with blood In all fish, respiration occurs when water flows into the mouth, enters pharynx, then moves out of body through gill slits Vertebrate Respiration The Gills of Fish Water flows over the gills and blood circulates through them in opposing directions Countercurrent flow: highly efficient in extracting oxygen from water, whose oxygen content is lower than air Vertebrate Respiration Evolution of Paired Lungs Lungs became increasingly important as aquatic tetrapods spent more time on land Vertebrate Respiration Various animals use different mechanisms for respiration Frogs in the larvae stage utilize gills and skin; as adults they use paired lungs and skin for respiration Amniotes have waterproof skin and no gills; they use well developed lungs for respiration Human Respiratory System Lungs accomplish gas exchange via alveoli The respiratory system assists in sense of smell and in speech It also helps return venous blood to the heart and helps rid the body of excess heat and water Controls over breathing adjust the body’s acid-base balance as well as the body’s temperature Human Respiratory System: airways to lungs Air enters or leaves the respiratory system through nasal cavities where hair and cilia filter dust and particles, blood vessels warm the air, and mucus moistens the air Human Respiratory System: airways to lungs Air moves via this route: Pharynx Larynx (route blocked by epiglottis during swallowing) Vocal Cords (space between is glottis) Trachea Bronchi Bronchioles Alveoli Human Respiratory System: airways to lungs Vocal cord lies at entrance to larynx When air is exhaled through the glottis, the folds of the cords vibrate to produce sound Under regulation by nerve commands to the elastic ligaments that regulate the glottal opening Human Respiratory System: airways to lungs Human Respiratory System: paired lungs Human lungs are located in the thoracic cavity, one on each side of the heart Rib cage encloses and protects lungs Each lung is covered with a plural membrane Covers lung’s outer surface and line inside of the thoracic cavity Inside lungs, respiratory bronchioles bear outpouchings of their walls called alveoli, which are usually clustered as alveolar sacs Alveoli provide a tremendous surface area for gaseous exchange with the blood located in the dense capillary network surrounding each alveolar sac Human Respiratory System Human Respiratory System: muscles and respiration Diaphragm: sheet of smooth muscle beneath the lungs Intercostal muscles: skeletal muscles between ribs Diaphragm and intercostal muscles interact and exchange the volume of the thoracic cavity breathing Gas Exchange and Transport Exchanges at the respiratory membrane The alveolar epithelium, the capillary epithelium, and their basement membranes form a respiratory membrane Oxygen and carbon dioxide passively diffuse across the membrane in response to partial pressure gradients Gas Exchange and Transport Oxygen transport Blood cannot carry sufficient oxygen and carbon dioxide in dissolved form to satisfy the body’s demands Hemoglobin helps enhance its capacity Gas Exchange and Transport Oxygen transport Oxygen diffuses down pressure gradient into blood plasma Red blood cells Binds to hemoglobin (4 molecules per hemoglobin to form oxyhemoglobin) Gas Exchange and Transport Oxygen transport Hemoglobin gives up its oxygen in tissues where partial pressure of oxygen is low, blood is warmer, partial pressure of carbon dioxide is higher, and pH is lower All four conditions occur in tissues with high metabolism Myoglobin is found in cardiac muscle and some skeletal muscles Helps to store oxygen Gas Exchange and Transport Carbon Dioxide transport Because carbon dioxide is higher in body tissues, it diffuses into the blood Ten percent is dissolved in plasma Thirty percent binds with hemoglobin to form carbaminohemoglobin Sixty percent is in bicarbonate form Gas Exchange and Transport Carbon Dioxide exchange Bicarbonate and carbonic acid formation is enhanced by the enzyme carbonic anhydrase, which is located in the red blood cells Hemoglobin buffers these reactions, keeping the blood from becoming too acidic Gas Exchange and Transport Carbon monoxide threat Hemoglobin has a higher affinity for carbon monoxide than oxygen Carbon monoxide prevents proper oxygen transport causing carbon monoxide poisoning Cyclic Reversals in Air Pressure Gradients The Respiratory Cycle In inhalation, diaphragm contracts and flattens Muscles lift rib cage upward and outward Chest cavity volume increases Internal pressure decresaes Air rushes in Yc2AOJ3 Cyclic Reversals in Air Pressure Gradients The Respiratory Cycle In exhalation The actions in inhalation are reversed Elastic lung tissue recoils passivly Yc2AOJ3 Cyclic Reversals in Air Pressure Gradients The Respiratory Cycle Pressure gradients between air inside and outside respiratory tact change in each respiratory cycle of inhalation and exhalation Exhalation is passive when you are quietly breathing; it is active and energy requiring when exercising with the need to expel more air The Heimlich maneuver forces air out of lungs into the trachea and can dislodge the food, allowing victim to resume breathing Cyclic Reversals in Air Pressure Gradients Respiratory Volumes The maximum volume that the lungs can hold is the vital capacity Vital capacity is 5.7 liters in men and 4.2 liters in females Tidal volume: the volume of air flowing in and out of the lungs during one respiratory cycle Tidal volume is about 0.5 liters Cyclic Reversals in Air Pressure Gradients Control of Breathing Respiratory centers in the brain control the rate and depth of breathing When activity levels increase, chemoreceptors sense changes in the blood pH and signal the respiratory center to alter breathing levels Reflexes, such as swelling or coughing, and commands from the sympathetic nerves alter breathing patters Control of Breathing Respiratory Diseases and Disorders Interrupted breathing Infections Sleep apnea, SIDS TB, pneumonia Bronchitis, Emphysema Smoking (cigarettes, marijunana) High Climbers and Deep Divers Explain what occurs to those who are at high altitudes and those who deep-sea dive in terms of respiration Review http://www.youtube.com/watch?v=HiT621PrrO0 http://www.youtube.com/watch?v=TaAvhG2SInM&feature =related