Biology Sylvia S Mader Michael Windelspecht Chapter 35

Biology Sylvia S. Mader Michael Windelspecht Chapter 35 Respiratory Systems Lecture Outline See separate Flex. Art Power. Point slides for all figures and tables pre-inserted into Power. Point without notes. 1 Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display.

Outline • 35. 1 Gas Exchange Surfaces • 35. 2 Breathing and Transport of Gases • 35. 3 Respiration and Human Health 2

35. 1 Gas Exchange Surfaces • Respiration results in gas exchange between the body’s cells and the environment – In terrestrial vertebrates, respiration includes: • Ventilation (i. e. , breathing) • External respiration - gas exchange between the air and the blood within the lungs • Internal respiration - gas exchange between the blood and the tissue fluid 3

Respiration Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display.

Gas Exchange Surfaces • Gas exchange takes place by diffusion • For external respiration to be effective, gasexchange regions must be: – Moist – Thin – Large in relation to body size • Effectiveness of diffusion is enhanced by vascularization • Delivery to cells is promoted by respiratory pigments (e. g. , hemoglobin) 5

Gas Exchange Surfaces • Overview of Gas-Exchange Surfaces – Gases of air can dissolve in water – However, • When saturated, water contains a small fraction of the O 2 in same volume of air • Water is much more dense than air • Aquatic animals expend more energy to breathe than do terrestrial animals 6

Gas Exchange Surfaces • Hydras and planarians – Small animals with a large surface area – Most of their cells exchange gases directly with the environment • Larger aquatic animals – Often have gills • Finely divided vascularized outgrowths of the body surface or pharynx • Gills of bony fishes – Outward extensions of pharynx – Ventilation is brought about by combined action of the mouth and gill covers (opercula) – Utilize a countercurrent exchange system to transfer oxygen from the environment to their blood 7

Hydra Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display.

Earthworm Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display.

Respiratory Organs Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. gill CO 2 gill filament capillaries blood vessels trachea a. mammalian lung tracheoles CO 2 spiracles trachea CO 2 O 2 alveoli O 2 CO 2 c. O 2 CO 2 spiracle 10 b.

Anatomy of Gills in Bony Fishes Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. operculum lamellae 900 X a. Water passes out of the pharynx and over the finely divided gills. Water passes by the gill lamellae in a direction opposite to blood flow. Oxygen content of water is always higher than the oxygen content of the blood. O 2 -rich blood Direction of H 2 O flow O 2 -poor blood lamellae Direction of H 2 O flow water flow O 2 movement blood flow 40% 15% % 70 % 0 10 30% 5% 60% % 90 blood flow gill arch lamella gill filaments b. gill filament c. d. (fish): © Dr. Jeffrey Isaacson, Nebraska. Wesleyan University; (gills): © David M. Phillips/Photo Researchers, Inc. 11

Gas Exchange Surfaces • Insects and other terrestrial arthropods – A respiratory system consisting of branched tracheae – Oxygen enters tracheae at spiracles – Tracheae branch until they end in tracheoles that are in direct contact with body cells 12

Tracheae of Insects Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction

Gas Exchange Surfaces • Terrestrial vertebrates have evolved lungs – Vascular outgrowths from lower pharyngeal region – Lungs of birds and mammals are elaborately subdivided • All terrestrial vertebrates, except birds, use a ventilation mechanism whereby air moves in and out by the same route 14

Gas Exchange Surfaces • Lungs of Humans – As air moves through upper respiratory system – It is filtered to free it of debris • Warmed • Humidified – When air reaches lungs • It is at body temperature, and • It is saturated with water 15

Gas Exchange Surfaces • Lungs of Humans • Air passes from pharynx through the glottis • Larynx and trachea – Permanently held open by cartilage rings – Facilitates movement of air • When food is swallowed – The larynx rises – The glottis is closed by the epiglottis – Backward movement of soft palate covers the entrance of nasal passages into the pharynx 16

Gas Exchange Surfaces • Lungs of Humans (continued) – Trachea divides • Forms two primary bronchi • Bronchi enter the right and left lungs – Bronchi branch until there a great number of tiny bronchioles • Each bronchiole terminates in an elongated space enclosed by alveoli 17

The Human Respiratory Tract Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. cilia goblet cell epithelial cell blood flow particle movement nasal cavity blood flow pulmonary arteriole nostril pulmonary venule mucus pharynx bronchiole epiglottis air glottis larynx tracheal lumen trachea bronchus b. Tracheal lining lobule bronchiole lung capillary network diaphragm alveoli a. The path of air b: © Ed Reschke c. Bronchiole and alveoli 18

35. 2 Breathing and Transport of Gases • Breathing – Inspiration in mammals • • Creation of negative pressure in lungs The rib cage is elevated The diaphragm contracts and lowers Thoracic pressure decreases to less than atmospheric pressure • Atmospheric pressure forces air into the lungs 19

Breathing and Transport of Gases • Breathing – Expiration in mammals • • Creation of positive pressure in lungs The rib cage is lowered The diaphragm rises Thoracic pressure increases to more than atmospheric pressure • Forces air out the lungs 20

Inspiration Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. trachea intercostal muscles Rib cage moves up and out. lungs Diaphragm contracts and moves down. air in lung rib cage When pressure in lungs decreases, air comes rushing in. 21

Expiration Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Rib cage moves down and in. Diaphragm relaxes and moves up. air out When pressure in lungs increases, air is pushed out. 22

Breathing and Transport of Gases • Ventilation – All terrestrial vertebrates, with the exception of birds, utilize a tidal ventilation mechanism for breathing • Volume of thoracic cavity and lungs is increased by muscle contractions that lower the diaphragm and raise the ribs – Create negative pressure in the thoracic cavity and lungs, and then air flows into the lungs during inspiration 23

Breathing and Transport of Gases • Ventilation (continued) – Birds use a one-way ventilation mechanism in lungs • Fresh air never mixes with used air • Increases gas-exchange efficiency 24

Respiratory System in Birds Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. inhalation lung trachea exhalation lung anterior air sacs posterior air sacs trachea lung 1 Inhalation: Air enters posterior air sacs. anterior air sacs 2 Exhalation begins: Air enters lung. inhaled air exhaled air anterior air sacs exhalation posterior air sacs 4 Exhalation ends: Air exits anterior air sacs. 3 Exhalation continues: Air enters anterior air sacs. 25

Breathing and Transport of Gases • Modifications of Breathing in Humans • Normally, adults have a breathing rate of 12 to 20 ventilations per minute • The rhythm of ventilation is controlled by a respiratory center in the medulla oblongata of the brain – Sends out impulses to the diaphragm and intercostal muscles of the rib cage so that inspiration occurs – When the respiratory center stops sending neuronal signals to the diaphragm and the rib cage, expiration occurs 26

Nervous Control of Breathing Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. brain respiratory center: automatically regulates breathing intercostal nerves: stimulate the intercostal muscles phrenic nerve: stimulates the diaphragm 27

Breathing and Transport of Gases • Gas Exchange and Transport • Partial pressure • The amount of pressure exerted by a gas • Gases diffuse from areas of higher to lower partial pressure • Ventilation causes the alveoli to have a higher partial pressure of oxygen and a lower partial pressure of carbon dioxide than the blood in the pulmonary capillaries • This accounts for the exchange of gases in the lungs • The opposite occurs in the tissues of the body 28

Breathing and Transport of Gases • Transport of Oxygen and Carbon Dioxide • External Respiration • Most oxygen entering the pulmonary capillaries from the alveoli combine with hemoglobin in red blood cells to form oxyhemoglobin • Internal Respiration • Oxyhemoglobin gives up oxygen, which diffuses out of the blood into the tissues where it is taken up by cells • A small amount of carbon dioxide enters the blood from the tissues and binds with hemoglobin to form carbaminohemoglobin • Most of the carbon dioxide is transported in the form of bicarbonate ion 29

Hemoglobin Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display.

External and Internal Respiration Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. alveolus HCO 3 - plasma External respiration H+ + HCO 3 - pulmonary capillary Hb. H+ CO 2 RBC H 2 CO 3 Hb. O 2 H 2 O CO 2 RBC Hb. CO 2 pulmonary capillary O 2 CO 2 exits blood O 2 alveolus plasma O 2 enters blood lung pulmonary artery pulmonary vein heart systemic vein tissue cells systemic artery HCO 3 H+ + HCO 3 H 2 CO 3 plasma Hb. H+ CO 2 H 2 O Hb. CO 2 O 2 O 2 Hb Internal respiration tissue fluid CO 2 enters blood RBC systemic capillary RBC tissue cell tissue fluid 31 O 2 exits blood

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35. 3 Respiration and Human Health • Disorders of the Upper Respiratory Tract – Cold • Mild viral infections • Characterized by sneezing, runny nose, mild fever • Antibiotics are ineffective for treatment – Strep Throat • Acute pharyngitis caused by a bacterium (Streptococcus pyogenes) • Severe sore throat, high fever, swollen tonsils • Curable with antibiotics 34

Respiration and Human Health • Disorders of the Lower Respiratory Tract – Trachea and Bronchi • Choking • Acute bronchitis – Infection of primary and secondary bronchi • Chronic bronchitis – Airways become inflamed and filled with mucus • Asthma – Airways are unusually sensitive to specific irritants » When exposed to these irritants, smooth muscles in the bronchioles undergo spasms 35

Respiration and Human Health • Disorders Affecting the Lungs – Pneumonia • Viral, bacterial, or fungal infection of the lungs in which bronchi and alveoli fill with fluid – Pulmonary tuberculosis • Caused by Mycobacterium tuberculosis • Results in lung damage and reduced function – Pulmonary fibrosis • Fibrous connective tissue builds up in the lungs 36

Respiration and Human Health • Disorders Affecting the Lungs – Emphysema • Alveoli are distended and walls are damaged, reducing the surface area available for gas exchange – Lung Cancer • Begins with thickening and callusing of the cells lining the airways • Atypical cells appear in the thickened lining • Cells from the tumor break loose and metastasize 37

Respiration and Human Health • Disorders Affecting the Lungs – Cystic fibrosis (CF) • Defective gene results in accumulation of mucus secretions in the lungs – Secretions become sticky and form plugs that interfere with breathing • Treatment involves clearing mucus from airways administering mucus-thinning drugs and vigorously slapping the patient on the back 38

Common Bronchial and Pulmonary Diseases Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. asbestos body mucus a. Acute Bronchitis Airways are inflamed due to infection or due to an irritant. Coughing brings up mucus and pus. f. Pulmonary Fibrosis Fibrous connective tissue builds up in lungs, reducing their elasticity. tubercle b. Asthma Airways are inflamed due to irritation, and bronchioles constrict due to muscle spasms. c. Pneumonia Alveoli fill with pus and fluid, making gas exchange difficult. d. Pulmonary Tuberculosis tubercles encapsulate bacteria, and elasticity of lungs is reduced. e. Emphysema Alveoli burst and fuse into enlarged air spaces. Surface area for gas exchange is reduced. 39

Smoking and Lung Disorders Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. tumor a. Normal lungs b. Emphysema c. Lung cancer a: © Matt Meadows/Peter Arnold, Inc. ; b: © SIU/Visuals Unlimited; c: © Biophoto Associates/Photo Researchers, Inc. 40