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LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 42 Circulation and Gas Exchange Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc. Overview: Trading Places • Every organism must _________________with its environment • Exchanges ultimately occur at the _____________ by crossing the _____________________ • In unicellular organisms, these exchanges occur _______________ with the environment © 2011 Pearson Education, Inc. • For most cells making up multicellular organisms, direct exchange with the environment is not possible • __________are an example of a specialized exchange system in animals – ___ diffuses from the water into blood vessels – ___ diffuses from blood into the water • Internal transport and gas exchange are functionally related in most animals © 2011 Pearson Education, Inc. Concept 42.1: Circulatory systems link exchange surfaces with cells throughout the body • __________________is proportional to the square of the distance • Diffusion is only efficient over ________distances • In _______________animals, cells can exchange materials directly with the surrounding medium • In most animals, cells exchange materials with the environment via a _________________________ © 2011 Pearson Education, Inc. Gastrovascular Cavities • Some animals ________ a circulatory system • Some cnidarians, such as jellies, have elaborate ___________________________________ • A ________________________functions in both digestion and distribution of substances throughout the body • The body wall that encloses the gastrovascular cavity is only ________ cells thick • ________________ have a gastrovascular cavity and a large surface area to volume ratio © 2011 Pearson Education, Inc. Figure 42.2 Circular canal Mouth Gastrovascular cavity Mouth Pharynx Radial canals 5 cm (a) The moon jelly Aurelia, a cnidarian 2 mm (b) The planarian Dugesia, a flatworm Evolutionary Variation in Circulatory Systems • A ____________________ minimizes the diffusion distance in animals with many cell layers © 2011 Pearson Education, Inc. General Properties of Circulatory Systems • A circulatory system has – A circulatory __________ – A set of interconnecting _________ – A muscular pump, the ___________ • The circulatory system connects the ______________________with the _______________ gases, ________ nutrients, and __________________of wastes • Circulatory systems can be _____ or _______ and vary in the number of circuits in the body © 2011 Pearson Education, Inc. Open and Closed Circulatory Systems • In insects, other arthropods, and most molluscs, blood bathes the organs directly in an __________ ______________________ • In an open circulatory system, there is no distinction between blood and interstitial fluid, and this general body fluid is called _______________ © 2011 Pearson Education, Inc. Figure 42.3a (a) An open circulatory system Heart Hemolymph in sinuses surrounding organs Pores Tubular heart • In a ____________________ is confined to vessels and is distinct from the interstitial fluid • Closed systems are more ________________ at transporting circulatory fluids to tissues and cells • Annelids, cephalopods, and vertebrates have closed circulatory systems © 2011 Pearson Education, Inc. Figure 42.3b (b) A closed circulatory system Heart Interstitial fluid Blood Small branch vessels in each organ Dorsal Auxiliary vessel hearts (main heart) Ventral vessels Organization of Vertebrate Circulatory Systems • Humans and other vertebrates have a closed circulatory system called the _________________ _________________ • The three main types of blood vessels are ______ ___________________ • Blood flow is _____________ in these vessels © 2011 Pearson Education, Inc. • ___________ branch into ____________ and carry blood away from the heart to ____________ • Networks of capillaries called ______________ are the sites of chemical exchange between the blood and interstitial fluid • _____________ converge into _________ and return blood from capillaries to the heart © 2011 Pearson Education, Inc. • Arteries and veins are distinguished by the ___________________, not by O2 content • Vertebrate hearts contain two or more _________ • Blood enters through an ______________ and is pumped out through a ____________________ © 2011 Pearson Education, Inc. Single Circulation • Bony fishes, rays, and sharks have single circulation with a ___________________heart • In __________________, blood leaving the heart passes through two capillary beds before returning © 2011 Pearson Education, Inc. Figure 42.4a (a) Single circulation Gill capillaries Artery Heart: Atrium (A) Ventricle (V) Vein Body capillaries Key Oxygen-rich blood Oxygen-poor blood Double Circulation • Amphibian, reptiles, and mammals have __________________________ • Oxygen-poor and oxygen-rich blood are pumped ____________ from the _________ and ______ sides of the heart © 2011 Pearson Education, Inc. Figure 42.4b (b) Double circulation Pulmonary circuit Lung capillaries A V Right A V Left Systemic capillaries Key Systemic circuit Oxygen-rich blood Oxygen-poor blood • In reptiles and mammals, oxygen-poor blood flows through the _________________to pick up oxygen through the lungs • In amphibians, oxygen-poor blood flows through a _____________________ to pick up oxygen through the lungs and skin • Oxygen-rich blood delivers oxygen through the ___________________ • Double circulation maintains ______________ _______________ in the organs than does single circulation © 2011 Pearson Education, Inc. Adaptations of Double Circulatory Systems • Hearts vary in different vertebrate groups © 2011 Pearson Education, Inc. Amphibians • Frogs and other amphibians have a __________ _______________: two atria and one ventricle • The ventricle pumps blood into a forked artery that splits the ventricle’s output into the _______________circuit and the ________circuit • When underwater, blood flow to the lungs is nearly ________________ © 2011 Pearson Education, Inc. Figure 42.5a Amphibians Pulmocutaneous circuit Lung and skin capillaries Atrium (A) Atrium (A) Right Left Ventricle (V) Systemic capillaries Systemic circuit Key Oxygen-rich blood Oxygen-poor blood Reptiles (Except Birds) • Turtles, snakes, and lizards have a __________ ________________: two atria and one ventricle • In alligators, caimans, and other crocodilians a ________________ divides the ventricle • Reptiles have _____________________, with a pulmonary circuit (lungs) and a systemic circuit © 2011 Pearson Education, Inc. Figure 42.5b Reptiles (Except Birds) Pulmonary circuit Lung capillaries Right systemic aorta Atrium (A) Ventricle (V) A Right V Left Left systemic aorta Incomplete septum Systemic capillaries Systemic circuit Key Oxygen-rich blood Oxygen-poor blood Mammals and Birds • Mammals and birds have a ______________ with two atria and two ventricles • The ___________of the heart pumps and receives only oxygen-rich blood, while the ____________ receives and pumps only oxygen-poor blood • Mammals and birds are endotherms and require more _______ than ectotherms © 2011 Pearson Education, Inc. Figure 42.5c Mammals and Birds Pulmonary circuit Lung capillaries A Atrium (A) Ventricle (V) Right V Left Systemic capillaries Systemic circuit Key Oxygen-rich blood Oxygen-poor blood Figure 42.5 Amphibians Pulmocutaneous circuit Pulmonary circuit Lung and skin capillaries Atrium (A) Atrium (A) Right Pulmonary circuit Lung capillaries Lung capillaries Right systemic aorta A V Right Left Mammals and Birds Reptiles (Except Birds) A V Left Left systemic aorta Incomplete septum A V Right A V Left Ventricle (V) Systemic circuit Key Oxygen-rich blood Oxygen-poor blood Systemic capillaries Systemic capillaries Systemic capillaries Systemic circuit Systemic circuit Concept 42.2: Coordinated cycles of heart contraction drive double circulation in mammals • The mammalian cardiovascular system meets the body’s continuous demand for _______ © 2011 Pearson Education, Inc. Mammalian Circulation • Blood begins its flow with the ________ ventricle pumping blood to the __________ • In the lungs, the blood loads ___ and unloads ___ • Oxygen-rich blood from the lungs enters the heart at the ____________and is pumped through the _________ to the body tissues by the __________ • The aorta provides blood to the heart through the _____________________ © 2011 Pearson Education, Inc. • Blood returns to the heart through the ________ ________________(blood from head, neck, and forelimbs) and ___________________ (blood from trunk and hind limbs) • The superior vena cava and inferior vena cava flow into the _________________ Animation: Path of Blood Flow in Mammals © 2011 Pearson Education, Inc. Figure 42.6 Capillaries of head and forelimbs Superior vena cava Pulmonary artery Capillaries of right lung Pulmonary vein Right atrium Right ventricle Pulmonary artery Aorta Capillaries of left lung Pulmonary vein Left atrium Left ventricle Aorta Inferior vena cava Capillaries of abdominal organs and hind limbs The Mammalian Heart: A Closer Look • A closer look at the mammalian heart provides a better understanding of double circulation © 2011 Pearson Education, Inc. Figure 42.7 Aorta Pulmonary artery Pulmonary artery Right atrium Left atrium Semilunar valve Semilunar valve Atrioventricular valve Atrioventricular valve Right ventricle Left ventricle • The heart contracts and relaxes in a rhythmic cycle called the _________________ • The contraction, or pumping, phase is called _______________ • The relaxation, or filling, phase is called ________ © 2011 Pearson Education, Inc. Figure 42.8-3 2 Atrial systole and ventricular diastole 1 Atrial and ventricular diastole 0.1 sec 0.4 sec 0.3 sec 3 Ventricular systole and atrial diastole • The______________, also called the pulse, is the number of beats per minute • The _________________is the amount of blood pumped in a single contraction • The ___________________ is the volume of blood pumped into the systemic circulation per minute and depends on both the heart rate and stroke volume © 2011 Pearson Education, Inc. • Four __________ prevent backflow of blood in the heart • The _____________________ separate each atrium and ventricle • The ____________________ control blood flow to the aorta and the pulmonary artery © 2011 Pearson Education, Inc. • The “lub-dup” sound of a heart beat is caused by the ____________ against the AV valves (lub) then against the semilunar (dup) valves • Backflow of blood through a defective valve causes a ____________________ © 2011 Pearson Education, Inc. Maintaining the Heart’s Rhythmic Beat • Some cardiac muscle cells are _______________, meaning they contract without any signal from the nervous system • The __________________, or pacemaker, sets the rate and timing at which cardiac muscle cells contract • Impulses that travel during the cardiac cycle can be recorded as an ________________________ __________________ © 2011 Pearson Education, Inc. Figure 42.9-4 1 SA node (pacemaker) ECG 2 AV node 3 Bundle branches 4 Heart apex Purkinje fibers • Impulses from the SA node travel to the _______________________________ • At the AV node, the impulses are delayed and then travel to the __________________that make the ventricles contract © 2011 Pearson Education, Inc. • The pacemaker is regulated by two portions of the nervous system: the __________________ and __________________ divisions • The _________division speeds up the pacemaker • The _________________division slows down the pacemaker • The pacemaker is also regulated by __________ and ___________________ © 2011 Pearson Education, Inc. Concept 42.3: Patterns of blood pressure and flow reflect the structure and arrangement of blood vessels • The _______________________ that govern movement of water in plumbing systems also influence the functioning of animal circulatory systems © 2011 Pearson Education, Inc. Blood Vessel Structure and Function • A vessel’s cavity is called the _______________ • The epithelial layer that lines blood vessels is called the ____________________ • The endothelium is __________________and minimizes resistance © 2011 Pearson Education, Inc. Figure 42.10a Valve Basal lamina Endothelium Smooth muscle Connective tissue Endothelium Capillary Smooth muscle Connective tissue Artery Vein Arteriole Venule • __________have thin walls, the endothelium plus its basal lamina, to facilitate the exchange of materials • __________and __________have an endothelium, smooth muscle, and connective tissue • ______________ have thicker walls than veins to accommodate the high pressure of blood pumped from the heart • In the thinner-walled _______, blood flows back to the heart mainly as a result of __________ action © 2011 Pearson Education, Inc. Blood Flow Velocity • Physical laws governing movement of fluids through pipes affect blood ________ and blood _________________ • Velocity of blood flow is slowest in the ________ beds, as a result of the high _____________ and large total __________________________ • Blood flow in capillaries is necessarily slow for __________________ of materials © 2011 Pearson Education, Inc. Velocity (cm/sec) 5,000 4,000 3,000 2,000 1,000 0 50 40 30 20 10 0 Pressure (mm Hg) Area (cm2) Figure 42.11 120 100 80 60 40 20 0 Systolic pressure Diastolic pressure Blood Pressure • Blood flows from areas of __________ pressure to areas of ________________ pressure • _________________ is the pressure that blood exerts against the wall of a vessel • In rigid vessels blood pressure is _____________; less rigid vessels ______________ and blood pressure is lost © 2011 Pearson Education, Inc. Changes in Blood Pressure During the Cardiac Cycle • ________________ is the pressure in the arteries during ventricular systole; it is the highest pressure in the arteries • ________________is the pressure in the arteries during diastole; it is lower than systolic pressure • A __________ is the rhythmic bulging of artery walls with each heartbeat © 2011 Pearson Education, Inc. Regulation of Blood Pressure • Blood pressure is determined by ____________ and ___________________ due to constriction of arterioles • __________________is the contraction of smooth muscle in arteriole walls; it increases blood pressure • ___________________is the relaxation of smooth muscles in the arterioles; it causes blood pressure to fall © 2011 Pearson Education, Inc. • Vasoconstriction and vasodilation help maintain adequate blood flow as the body’s demands change • ____________ is a major inducer of vasodilation • The peptide ________________ is an important inducer of vasoconstriction © 2011 Pearson Education, Inc. Blood Pressure and Gravity • Blood pressure is generally measured for an ____________ in the arm at the same height as the heart • Blood pressure for a healthy 20-year-old at rest is _______ mm Hg at systole and ______ mm Hg at diastole © 2011 Pearson Education, Inc. Figure 42.12 Blood pressure reading: 120/70 1 3 2 120 120 70 Artery closed Sounds audible in stethoscope Sounds stop • _____________ is caused by inadequate blood flow to the head • Animals with longer necks require a higher ___________ pressure to pump blood a greater distance against gravity • Blood is moved through _________ by smooth muscle contraction, skeletal muscle contraction, and expansion of the vena cava with inhalation • _____________ in veins prevent backflow of blood © 2011 Pearson Education, Inc. Figure 42.13 Direction of blood flow in vein (toward heart) Valve (open) Skeletal muscle Valve (closed) Capillary Function • Blood flows through only ______% of the body’s capillaries at a time • Capillaries in _______________ are usually filled to capacity • Blood supply ____________ in many other sites © 2011 Pearson Education, Inc. • Two mechanisms regulate distribution of blood in capillary beds – ___________________________ layer in the wall of an arteriole constricts the vessel – ______________________control flow of blood between arterioles and venules • Blood flow is regulated by __________impulses, ____________, and other__________________ © 2011 Pearson Education, Inc. Figure 42.14 Precapillary sphincters Thoroughfare channel Arteriole (a) Sphincters relaxed Arteriole (b) Sphincters contracted Capillaries Venule Venule • The exchange of substances between the blood and interstitial fluid takes place across the thin endothelial walls of the _____________ • The difference between _________________ and _______________________ drives fluids out of capillaries at the arteriole end and into capillaries at the venule end • Most blood __________and all blood _________ are too large to pass through the endothelium © 2011 Pearson Education, Inc. Figure 42.15 INTERSTITIAL FLUID Net fluid movement out Body cell Blood pressure Osmotic pressure Arterial end of capillary Direction of blood flow Venous end of capillary Fluid Return by the Lymphatic System • The _________________ returns fluid that leaks out from the capillary beds • Fluid, called_____________, reenters the circulation directly at the venous end of the capillary bed and indirectly through the lymphatic system • The lymphatic system drains into _____________ ________________________ • ________________ in lymph vessels prevent the backflow of fluid © 2011 Pearson Education, Inc. • __________________ are organs that filter lymph and play an important role in the body’s defense • _______________ is swelling caused by disruptions in the flow of lymph © 2011 Pearson Education, Inc. Concept 42.4: Blood components contribute to exchange, transport, and defense • With________________, the fluid that is pumped comes into direct contact with all cells • The _______________________of vertebrates contain ________, a specialized connective tissue © 2011 Pearson Education, Inc. Blood Composition and Function • Blood consists of several kinds of cells suspended in a liquid matrix called ____________ • The cellular elements occupy about ___% of the volume of blood © 2011 Pearson Education, Inc. Figure 42.17a Plasma 55% Constituent Major functions Water Solvent for carrying other substances Ions (blood electrolytes) Sodium Potassium Calcium Magnesium Chloride Bicarbonate Osmotic balance, pH buffering, and regulation of membrane permeablity Plasma proteins Albumin Fibrinogen Immunoglobulins (antibodies) Osmotic balance, pH buffering Clotting Defense Substances transported by blood Nutrients Waste products Respiratory gases Hormones Separated blood elements Figure 42.17b Cellular elements 45% Number per L (mm3) of blood Cell type Leukocytes (white blood cells) Separated blood elements 5,000–10,000 Functions Defense and immunity Lymphocytes Basophils Eosinophils Neutrophils Monocytes Platelets Erythrocytes (red blood cells) 250,000–400,000 5–6 million Blood clotting Transport of O2 and some CO2 Plasma • Blood plasma is about 90% ____________ • Among its solutes are inorganic salts in the form of dissolved ions, sometimes called______________ • Another important class of solutes is the ________ ____________, which influence blood pH, osmotic pressure, and viscosity • Various plasma proteins function in __________ ___________, __________, and _____________ © 2011 Pearson Education, Inc. Cellular Elements • Suspended in blood plasma are two types of cells – ______________________________ transport oxygen O2 – ______________________function in defense • _______________, a third cellular element, are fragments of cells that are involved in clotting © 2011 Pearson Education, Inc. Erythrocytes • Red blood cells, or_______________, are by far the most numerous blood cells • They contain_________________, the ironcontaining protein that transports O2 • Each molecule of hemoglobin binds up to _______ molecules of O2 • In mammals, mature erythrocytes lack ________ _________________________ © 2011 Pearson Education, Inc. • ___________________is caused by abnormal hemoglobin proteins that form aggregates • The aggregates can deform an erythrocyte into a sickle shape • Sickled cells can rupture or block blood vessels © 2011 Pearson Education, Inc. Leukocytes • There are five major types of white blood cells, or ________________: monocytes, neutrophils, basophils, eosinophils, and lymphocytes • They function in defense by ______________ bacteria and debris or by producing ______________ They are found both in and outside of the circulatory system © 2011 Pearson Education, Inc. Platelets • ______________ are fragments of cells and function in blood clotting © 2011 Pearson Education, Inc. Blood Clotting • _________________ is the formation of a solid clot from liquid blood • A cascade of complex reactions converts inactive fibrinogen to fibrin, forming a clot • A blood clot formed within a blood vessel is called a _______________ and can block blood flow © 2011 Pearson Education, Inc. Figure 42.18a 3 2 1 Collagen fibers Platelet plug Platelet Fibrin clot Clotting factors from: Platelets Damaged cells Plasma (factors include calcium, vitamin K) Enzymatic cascade Prothrombin Thrombin Fibrinogen Fibrin Fibrin clot formation Stem Cells and the Replacement of Cellular Elements • The cellular elements of blood ____________ and are being replaced constantly • Erythrocytes, leukocytes, and platelets all develop from a common source of ______________ in the red marrow of bones, especially ribs, vertebrae, sternum, and pelvis • The hormone __________________ stimulates erythrocyte production when O2 delivery is low © 2011 Pearson Education, Inc. Figure 42.19 Stem cells (in bone marrow) Myeloid stem cells Lymphoid stem cells B cells T cells Erythrocytes Neutrophils Basophils Lymphocytes Monocytes Platelets Eosinophils Cardiovascular Disease • _______________________are disorders of the heart and the blood vessels • Cardiovascular diseases account for more than ____________________ in the United States • ___________________ , a steroid, helps maintain membrane fluidity © 2011 Pearson Education, Inc. • _________________________ delivers cholesterol to cells for membrane production • _________________________ scavenges cholesterol for return to the liver • Risk for heart disease increases with a ______ LDL to HDL ratio • ____________________ is also a factor in cardiovascular disease © 2011 Pearson Education, Inc. Atherosclerosis, Heart Attacks, and Stroke • One type of cardiovascular disease ,____________ , is caused by the buildup of plaque deposits within arteries © 2011 Pearson Education, Inc. Figure 42.20 Lumen of artery Endothelium Smooth muscle 1 LDL Foam cell Macrophage Plaque 2 Extracellular matrix Plaque rupture 4 3 Fibrous cap Cholesterol Smooth muscle cell T lymphocyte • A_________________, or myocardial infarction, is the death of cardiac muscle tissue resulting from blockage of one or more coronary arteries • _______________ supply oxygen-rich blood to the heart muscle • A _____________ is the death of nervous tissue in the brain, usually resulting from rupture or blockage of arteries in the head • ______________ is caused by partial blockage of the coronary arteries and results in chest pains © 2011 Pearson Education, Inc. Risk Factors and Treatment of Cardiovascular Disease • A high _____ to ________ ratio increases the risk of cardiovascular disease • The proportion of LDL relative to HDL can be decreased by _____________________________ ____________________ • Drugs called ____________ reduce LDL levels and risk of heart attacks © 2011 Pearson Education, Inc. • ________________ plays a role in atherosclerosis and thrombus formation • _____________ inhibits inflammation and reduces the risk of heart attacks and stroke • ________________, or high blood pressure, promotes atherosclerosis and increases the risk of heart attack and stroke • Hypertension can be reduced by dietary changes, exercise, and/or medication © 2011 Pearson Education, Inc. Concept 42.5: Gas exchange occurs across specialized respiratory surfaces • __________________ supplies O2 for cellular respiration and disposes of CO2 © 2011 Pearson Education, Inc. Partial Pressure Gradients in Gas Exchange • A gas diffuses from a region of ______________ ___________to a region __________________ ______________ • _________________ is the pressure exerted by a particular gas in a mixture of gases • Gases diffuse _____________ pressure gradients in the lungs and other organs as a result of differences in partial pressure © 2011 Pearson Education, Inc. Respiratory Media • Animals can use _____ or __________ as a source of O2, or respiratory medium • In a given volume, there is __________ available in water than in air • Obtaining O2 from water requires __________ __________________ than air breathing © 2011 Pearson Education, Inc. Respiratory Surfaces • Animals require large, moist respiratory surfaces for exchange of gases between their cells and the respiratory medium, either air or water • Gas exchange across respiratory surfaces takes place by ______________ • Respiratory surfaces vary by animal and can include the outer surface, ___________________ ___________________________ © 2011 Pearson Education, Inc. Gills in Aquatic Animals • ___________ are outfoldings of the body that create a large surface area for gas exchange © 2011 Pearson Education, Inc. Figure 42.22 Coelom Gills Parapodium (functions as gill) (a) Marine worm Gills Tube foot (b) Crayfish (c) Sea star • _______________ moves the respiratory medium over the respiratory surface • Aquatic animals move through water or move water over their gills for ventilation • Fish gills use a _____________________ system, where blood flows in the opposite direction to water passing over the gills; blood is always less saturated with O2 than the water it meets © 2011 Pearson Education, Inc. Figure 42.23 O2-poor blood Gill arch O2-rich blood Lamella Blood vessels Gill arch Water flow Operculum Water flow Blood flow Countercurrent exchange PO (mm Hg) in water 2 150 120 90 60 30 Gill filaments Net diffusion of O2 140 110 80 50 20 PO (mm Hg) 2 in blood Tracheal Systems in Insects • The ______________ of insects consists of tiny branching tubes that penetrate the body • The tracheal tubes supply O2 ____________ to body cells • The respiratory and circulatory systems are __________________ • Larger insects must ventilate their tracheal system to meet O2 demands © 2011 Pearson Education, Inc. Tracheoles Mitochondria Muscle fiber 2.5 m Figure 42.24 Tracheae Air sacs Body cell Air sac Tracheole Trachea External opening Air Lungs • _____________ are an infolding of the body surface • The _______________ system (open or closed) transports gases between the lungs and the rest of the body • The size and complexity of lungs correlate with an animal’s_______________________ © 2011 Pearson Education, Inc. Mammalian Respiratory Systems: A Closer Look • A system of branching ducts conveys air to the lungs • Air inhaled through the ______________ is warmed, humidified, and sampled for odors • The _________________directs air to the lungs and food to the stomach • Swallowing tips the epiglottis over the glottis in the pharynx to prevent food from entering the_______ © 2011 Pearson Education, Inc. Figure 42.25a Nasal cavity Pharynx Left lung Larynx (Esophagus) Trachea Right lung Bronchus Bronchiole Diaphragm (Heart) Figure 42.25b Branch of pulmonary vein (oxygen-rich blood) Terminal bronchiole Branch of pulmonary artery (oxygen-poor blood) Alveoli Capillaries • Air passes through the pharynx,___________, trachea, ___________, and _______________ to the alveoli, where gas exchange occurs • Exhaled air passes over the vocal cords in the larynx to create sounds • ________ and _________ line the epithelium of the air ducts and move particles up to the pharynx • This “________________” cleans the respiratory system and allows particles to be swallowed into the esophagus © 2011 Pearson Education, Inc. • Gas exchange takes place in__________, air sacs at the tips of bronchioles • Oxygen diffuses through the moist film of the epithelium and into ______________ • __________________ diffuses from the capillaries across the epithelium and into the air space © 2011 Pearson Education, Inc. • Alveoli lack __________ and are susceptible to contamination • Secretions called _________________ coat the surface of the alveoli • Preterm babies lack surfactant and are vulnerable to respiratory distress syndrome; treatment is provided by artificial surfactants © 2011 Pearson Education, Inc. Concept 42.6: Breathing ventilates the lungs • The process that ventilates the lungs is __________ , the alternate inhalation and exhalation of air © 2011 Pearson Education, Inc. How an Amphibian Breathes • An amphibian such as a frog ventilates its lungs by ___________________, which forces air down the trachea © 2011 Pearson Education, Inc. How a Bird Breathes • Birds have eight or nine ____________ that function as bellows that keep air flowing through the lungs • Air passes through the lungs in _______________ • Every exhalation _____________________ the air in the lungs © 2011 Pearson Education, Inc. Figure 42.27 Anterior air sacs Posterior air sacs Lungs Airflow Air tubes (parabronchi) in lung 1 mm Posterior air sacs Lungs 3 Anterior air sacs 2 4 1 1 First inhalation 3 Second inhalation 2 First exhalation 4 Second exhalation How a Mammal Breathes • Mammals ventilate their lungs by______________ ________________, which pulls air into the lungs • Lung volume increases as the rib muscles and ___________________ contract • The _________________ is the volume of air inhaled with each breath © 2011 Pearson Education, Inc. Figure 42.28 1 Rib cage expands. 2 Air inhaled. Lung Diaphragm Rib cage gets smaller. Air exhaled. • The maximum tidal volume is the _____________ • After exhalation, a __________________ of air remains in the lungs © 2011 Pearson Education, Inc. Control of Breathing in Humans • In humans, the main __________________ are in two regions of the brain, the _________________ and the _________ • The medulla regulates the rate and depth of breathing in response to ____ changes in the _________________ • The medulla adjusts breathing rate and depth to match ___________________ demands • The pons regulates the ___________ © 2011 Pearson Education, Inc. • Sensors in the aorta and carotid arteries monitor ____ and ____ concentrations in the blood • These sensors exert ___________________ over breathing © 2011 Pearson Education, Inc. Figure 42.29 Homeostasis: Blood pH of about 7.4 CO2 level decreases. Response: Rib muscles and diaphragm increase rate and depth of ventilation. Stimulus: Rising level of CO2 in tissues lowers blood pH. Carotid arteries Sensor/control center: Cerebrospinal fluid Medulla oblongata Aorta Concept 42.7: Adaptations for gas exchange include pigments that bind and transport gases • The metabolic demands of many organisms require that the blood transport large quantities of O2 and CO2 © 2011 Pearson Education, Inc. Coordination of Circulation and Gas Exchange • Blood arriving in the lungs has a low partial pressure of __ and a high partial pressure of ____ relative to air in the alveoli • In the__________, O2 diffuses into the blood and CO2 diffuses into the air • In tissue capillaries, partial pressure gradients favor diffusion of O2 into the ________________ and CO2 into the _____________ © 2011 Pearson Education, Inc. Figure 42.30a 1 Inhaled air 8 Exhaled air Alveolar epithelial cells 2 Alveolar spaces CO2 O2 Alveolar capillaries 7 Pulmonary arteries 3 Pulmonary veins 6 Systemic veins 4 Systemic arteries Heart CO2 O2 Systemic capillaries 5 Body tissue (a) The path of respiratory gases in the circulatory system Partial pressure (mm Hg) Figure 42.30b 160 PO 2 PCO Inhaled air 2 Exhaled air 120 80 40 0 1 2 3 4 5 6 7 8 (b) Partial pressure of O2 and CO2 at different points in the circulatory system numbered in (a) Respiratory Pigments • _________________, proteins that transport oxygen, greatly increase the amount of oxygen that blood can carry • Arthropods and many molluscs have _________________with __________ as the oxygen-binding component • Most vertebrates and some invertebrates use ________________ • In vertebrates, hemoglobin is contained within ___________________ © 2011 Pearson Education, Inc. Hemoglobin • A single hemoglobin molecule can carry __________ molecules of O2, one molecule for each _______________________ group • The hemoglobin dissociation curve shows that a small change in the partial pressure of oxygen can result in a large change in delivery of O2 • CO2 produced during cellular respiration lowers blood pH and decreases the affinity of hemoglobin for O2; this is called the___________________ © 2011 Pearson Education, Inc. Figure 42.UN01 Iron Heme Hemoglobin O2 saturation of hemoglobin (%) Figure 42.31a 100 O2 unloaded to tissues at rest 80 O2 unloaded to tissues during exercise 60 40 20 0 0 20 40 60 Tissues during Tissues at rest exercise PO2 (mm Hg) 80 100 Lungs (a) PO2 and hemoglobin dissociation at pH 7.4 O2 saturation of hemoglobin (%) Figure 42.31b 100 pH 7.4 80 pH 7.2 Hemoglobin retains less O2 at lower pH (higher CO2 concentration) 60 40 20 0 0 20 40 60 80 PO2 (mm Hg) (b) pH and hemoglobin dissociation 100 Carbon Dioxide Transport • Hemoglobin also helps transport ________and assists in buffering the blood • CO2 from respiring cells diffuses into the blood and is transported in blood plasma, bound to hemoglobin, or as ________________________ Animation: O2 from Blood to Tissues Animation: CO2 from Tissues to Blood Animation: CO2 from Blood to Lungs Animation: O2 from Lungs to Blood © 2011 Pearson Education, Inc. Figure 42.32a Body tissue CO2 produced CO2 transport from tissues Interstitial CO2 fluid Plasma CO2 within capillary Capillary wall CO2 H2O Red blood cell H2CO3 Hb Carbonic acid HCO3 Bicarbonate Hemoglobin (Hb) picks up CO2 and H+. H+ HCO3 To lungs Figure 42.32b To lungs CO2 transport to lungs HCO3 HCO3 H2CO3 H+ Hb Hemoglobin releases CO2 and H+. H2O CO2 CO2 CO2 CO2 Alveolar space in lung Respiratory Adaptations of Diving Mammals • _______________ have evolutionary adaptations that allow them to perform extraordinary feats – For example, Weddell seals in Antarctica can remain underwater for ____minutes to an ____ – For example, elephant seals can dive to 1,500 m and remain underwater for __ hours • These animals have a high ________ to _______ __________ ratio © 2011 Pearson Education, Inc. • Deep-diving air breathers stockpile ____ and deplete it slowly • Diving mammals can store oxygen in their _____________ in _____________ proteins • Diving mammals also conserve oxygen by – Changing their buoyancy to glide passively – Decreasing blood supply to muscles – Deriving ATP in muscles from fermentation once oxygen is depleted © 2011 Pearson Education, Inc.