Respiration Chapter 39
Impacts, Issues Up in Smoke Smoking immobilizes ciliated cells and kills white blood cells that defend the respiratory system; highly addictive nicotine discourages quitting
39.1 The Nature of Respiration All animals must supply their cells with oxygen and rid their body of carbon dioxide Respiration The physiological process by which an animal exchanges oxygen and carbon dioxide with its environment
Interactions with Other Organ Systems
Partial Pressure Partial pressure Of the total atmospheric pressure measured by a mercury barometer (760 mm Hg), O 2 contributes 21% (160 mm Hg)
The Basis of Gas Exchange Respiration depends on diffusion of gaseous oxygen (O 2 ) and carbon dioxide (CO 2 ) down their concentration gradients Gases enter and leave the internal environment across a thin, moist layer (respiratory surface) that dissolves the gases
Factors Affecting Diffusion Rates Factors that increase diffusion of gases across a respiratory surface: High partial pressure gradient of a gas across the respiratory surface High surface-to-volume ratio High ventilation rate (movement of air or water across the respiratory surface)
Respiratory Proteins Respiratory proteins contain one or more metal ions that reversibly bind to oxygen atoms Hemoglobin: An iron-containing respiratory protein found in vertebrate red blood cells Myoglobin: A respiratory protein found in muscles of vertebrates and some invertebrates
39.2 Gasping for Oxygen Rising water temperatures, slowing streams, and organic pollutants reduce the dissolved oxygen (DO) available for aquatic species
39.1-39.2 Key Concepts Principles of Gas Exchange Respiration is the sum of processes that move oxygen from air or water in the environment to all metabolically active tissues and move carbon dioxide from those tissues to the outside Oxygen levels are more stable in air than in water
39.3 Invertebrate Respiration Integumentary exchange Some invertebrates that live in aquatic or damp environments have no respiratory organs; gases diffuse across the skin Gills Filamentous respiratory organs that increase surface area for gas exchange in water
Invertebrate Respiration Lungs Saclike respiratory organs with branching tubes that deliver air to a respiratory surface Snails and slugs that spend some time on land have a lung instead of, or in addition to, gills
Snails with Lungs
Invertebrate Respiration Tracheal system Insects and spiders with a hard integument have branching tracheal tubes that open to the surface through spiracles (no respiratory protein required) Book lungs Some spiders also have thin sheets of respiratory tissue that exchange oxygen with a respiratory pigment (hemocyanin) in blood
Insect Tracheal System
A Spider s Book Lung
39.3 Key Concepts Gas Exchange in Invertebrates Gas exchange occurs across the body surface or gills of aquatic invertebrates In large invertebrates on land, it occurs across a moist, internal respiratory surface or at fluid-filled tips of branching tubes that extend from the surface to internal tissues
39.4 Vertebrate Respiration Fishes use gills to extract oxygen from water Countercurrent flow aids exchange (blood flows through gills in opposite direction of water flow) Amphibians exchange gases across their skin, and at respiratory surfaces of paired lungs Larvae have external gills
Fish Gills
Countercurrent Flow
Frog Respiration
Vertebrate Respiration Reptiles, birds and mammals exchange gases through paired lungs, ventilated by chest muscles Birds have the most efficient vertebrate lungs Air sacs allow oxygen-rich air to pass respiratory surfaces on both inhalation and exhalation
Bird Respiratory System
Fig. 39-12 (inset), p. 687
39.5 Human Respiratory System The human respiratory system functions in gas exchange, sense of smell, voice production, body defenses, acid-base balance, and temperature regulation
Airways Air enters through nose or mouth, flows through the pharynx (throat) and the larynx (voice box) Vocal cords change the size of the glottis The epiglottis protects the trachea, which branches into two bronchi, one to each lung Cilia and mucus-secreting cells clean airways
Larynx: Vocal Cords and Glottis
From Airways to Alveoli Inside each lung, bronchi branch into bronchioles that deliver air to alveoli Alveoli are small sacs, one cell thick, where gases are exchanged with pulmonary capillaries
Muscles and Respiration Muscle movements change the volume of the thoracic cavity during breathing Diaphragm A broad sheet of smooth muscle below the lungs Separates the thoracic and abdominal cavities Intercostal muscles Skeletal muscles between the ribs
Functions of the Respiratory System
39.6 Cyclic Reversals in Air Pressure Gradients Respiratory cycle One inhalation and one exhalation Inhalation is always active Contraction of diaphragm and external intercostal muscles increases volume of thoracic cavity Air pressure in alveoli drops below atmospheric pressure; air moves inward
Cyclic Reversals in Air Pressure Gradients Exhalation is usually passive As muscles relax, the thoracic cavity shrinks Air pressure in the alveoli rises above atmospheric pressure, air moves out Exhalation may be active Contraction of abdominal muscles forces air out
The Thoracic Cavity and the Respiratory Cycle
First Aid for Choking Heimlich maneuver Upward-directed force on the diaphragm forces air out of lungs to dislodge an obstruction
Respiratory Volumes Air in lungs is partially replaced with each breath Lungs are never emptied of air (residual volume) Vital capacity Maximum volume of air the lungs can exchange Tidal volume Volume of air that moves in and out during a normal respiratory cycle
Respiratory Volumes
Control of Breathing Neurons in the medulla oblongata of the brain stem are the control center for respiration Rhythmic signals from the brain cause muscle contractions that cause air to flow into the lungs Chemoreceptors in the medulla, carotid arteries, and aorta wall detect chemical changes in blood, and adjust breathing patterns
Respiratory Responses
39.7 Gas Exchange and Transport Gases diffuse between a pulmonary capillary and an alveolus at the respiratory membrane Alveolar epithelium Capillary endothelium Fused basement membranes O 2 and CO 2 each follow their partial pressure gradient across the membrane
The Respiratory Membrane
Oxygen Transport In alveoli, partial pressure of O 2 is high; oxygen binds with hemoglobin in red blood cells to form oxyhemoglobin (HbO 2 ) In metabolically active tissues, partial pressure of O 2 is low; HbO 2 releases oxygen Myoglobin, found in some muscle tissues, is similar to hemoglobin but holds O 2 more tightly
Hemoglobin and Myoglobin
Carbon Dioxide Transport Carbon dioxide is transported from metabolically active tissues to the lungs in three forms 10% dissolved in plasma 30% carbaminohemoglobin (HbCO 2 ) 60% bicarbonate (HCO 3- ) Carbonic anhydrase in red blood cells catalyzes the formation of bicarbonate CO 2 + H 2 O H 2 CO 3 HCO 3 - + H +
Partial Pressures for Oxygen and Carbon Dioxide
The Carbon Monoxide Threat Carbon monoxide (CO) A colorless, odorless gas that can fill up O 2 binding sites on hemoglobin, block O 2 transport, and cause carbon monoxide poisoning Carbon monoxide poisoning often results when fuel-burning appliance are poorly ventilated Symptoms include nausea, headache, confusion, dizziness, and weakness
39.4-39.7 Key Concepts Gas Exchange in Vertebrates Gills or paired lungs are gas exchange organs in most vertebrates The efficiency of gas exchange is improved by mechanisms that cause blood and water to flow in opposite directions at gills, and by muscle contractions that move air into and out of lungs
39.8 Respiratory Diseases and Disorders Interrupted breathing Brain-stem damage, sleep apnea, SIDS Potentially deadly infections Tuberculosis, pneumonia Chronic bronchitis and emphysema Damage to ciliated lining of bronchioles and walls of alveoli; tobacco smoke is the main risk factor
Cigarette Smoke and Ciliated Epithelium
Risks Associated With Smoking and Emphysema
39.8 Key Concepts Respiratory Problems Respiration can be disrupted by damage to respiratory centers in the brain, physical obstructions, infectious disease, and inhalation of pollutants, including cigarette smoke
39.9 High Climbers and Deep Divers Altitude sickness Hypoxia can result when people who live at low altitudes move suddenly to high altitudes People who grow up at high altitudes have more alveoli and blood vessels in their lungs Acclimatization to altitude includes adjustments in cardiac output, rate and volume of breathing Hypoxia stimulates erythropoietin secretion
Adaptation to High Altitude Llamas that live at high altitudes have special hemoglobin that binds oxygen more efficiently
Deep-Sea Divers Water pressure increases with depth; human divers using compressed air risk nitrogen narcosis (disrupts neuron signaling) Returning too quickly to the surface from a deep dive can release dangerous nitrogen bubbles into the blood stream ( the bends ) Without tanks, trained humans can dive to 210 meters; sperm whales can dive 2,200 meters
Adaptations for Deep Diving Leatherback turtles dive up to one hour Move air to cartilage-reinforced airways Flexible shell for compression Four ways diving animals conserve oxygen Deep breathing before diving High red-cell count, large amounts of myoglobin Slowed heart rate and metabolism Conservation of energy
Deep Divers
39.9 Key Concepts Gas Exchange in Extreme Environments At high altitudes, the human body makes shortterm and long-term adjustments to thinner air Built-in respiratory mechanisms and specialized behaviors allow sea turtles and diving marine mammals to stay under water, at great depths, for long periods