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Essentials of The Living World First Edition GEORGE B. JOHNSON 20 Circulation and Respiration PowerPoint® Lectures prepared by Johnny El-Rady Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.1 Open and Closed Circulatory Systems Cnidarians and flatworms have a gastrovascular cavity that functions in both digestion and circulation Fig. 20.1 Larger animals transport oxygen and nutrients from the environment and digestive cavity to body cells via a circulatory system Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Open circulatory system In mollusks and arthropods No distinction between circulating fluid (blood) and fluid of the body tissues (lymph) Hemolymph Fig. 20.1 Closed circulatory system In annelids and vertebrates Circulating fluid (blood) is always enclosed within vessels that transport blood away from, and back to a pump (heart) Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display In vertebrates, blood vessels from a tubular network Arteries carry blood away from the heart Veins return blood to the heart Capillaries connect arteries to veins As blood plasma passes through capillaries, pressure forces fluid out of the capillary walls Some of this interstitial fluid returns directly to capillaries Some enters lymph vessels This lymph is returned to venous blood at specific sites Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Functions of Vertebrate Circulatory Systems 1. Transportation Respiratory Transport O2 to cells for aerobic respiration Transport CO2 to lungs/gills for elimination Nutritive Transport of absorbed products of digestion to cells Excretory Metabolic wastes and excessive water are filtered in the kidney and excreted in urine Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 2. Regulation Fig. 20.2 Hormones are transported from endocrine glands to distant target organs Help maintain a constant body temperature in homeotherms Some vertebrates use a countercurrent heat exchange 3. Protection Warm blood going out heats cold blood coming in Blood clotting protects against blood loss White blood cells provide immunity against manydisease causing agents Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.2 Architecture of the Vertebrate Circulatory System The cardiovascular system of vertebrates consists of 1. Heart Pump 2. Blood vessels Network of tubes 3. Blood Circulating fluid Fig. 20.8 The flow of blood Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.3 The capillary network connects arteries with veins Blood loses most of its pressure and velocity as it passes through the vast capillary network Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Arteries: Highways from the Heart Blood comes from the heart in large pulses Thus the artery must be able to expand Arterial walls are made up of three layers Fig. 20.4a Arterioles are smaller in diameter than arteries Their surrounding muscle layer can be relaxed to enlarge diameter Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Capillaries: Where Exchange Takes Place Transport oxygen and nutrients from blood to body’s cells and pick up carbon dioxide They have thin walls to allow diffusion to take place Fig. 20.4b Individual capillaries have high resistance to flow But the total cross-sectional area of capillaries is greater than that of arteries leading to it Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Veins: Returning Blood to the Heart Fig. 20.4c Walls have thinner layers of muscle and elastic fiber than arteries Fig. 20.6 Vein Artery When empty, walls collapse Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Veins: Returning Blood to the Heart Blood flow back to the heart is aided by 1. Low pressure in veins 2. Skeletal muscles 3. Unidirectional valves Fig. 20.7 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.3 The Lymphatic System: Recovering Lost Fluid The cardiovascular system is very leaky To collect and recycle leaked fluid, the body uses a second circulatory system called the lymphatic system Fig. 20.9 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Blood pressure forces fluid out of capillaries Most of this interstitial fluid returns by osmosis Excess fluid is drained into lymphatic capillaries In the lymphatic system the fluid is called lymph Fig. 20.10 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Lymphatic vessels contain a series of one-way valves Permit movement only in the direction of the neck The lymphatic system has three important functions 1. Returns proteins to circulation If proteins are not returned to the blood, a condition called edema (body swelling) results 2. Transports fats absorbed from the intestine Lymph capillaries, called lacteals, absorb fats from the small intestine 3. Aids in the body’s defense Lymph nodes are filled with white blood cells Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.4 Blood Blood comprises about 5% of body mass It is composed of A fluid called plasma Several different kinds of cells Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Blood Plasma: The Body’s Fluid Blood plasma is a complex solution of water and 1. Metabolites and wastes Glucose, vitamins, hormones and wastes 2. Salts and ions Chief plasma ions: sodium, chloride, bicarbonate Minor ions: calcium, magnesium, copper 3. Proteins Act as an osmotic counterforce Major protein: serum albumin Other proteins: fibrinogen and antibodies Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Blood Cells Circulate Through the Body The fraction of blood volume that is occupied by cells is termed the blood’s hematocrit In humans it is usually about 45% The three principal types of blood cells are Erythrocytes Leukocytes Platelets Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Erythrocytes (red blood cells) Carry hemoglobin, and therefore, oxygen to cells Do not contain a nucleus Leukocytes (white blood cells) Defend the body against microbes and foreign substance Neutrophils Monocytes/Macrophages Lymphocytes B cells – Produce antibodies T cells – Drill holes in invading bacteria Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Platelets Cell fragments that are bits of the cytoplasm of large bone marrow cells called megakaryocytes Do not contain a nucleus Play a key role in blood clotting Stimulate the formation of fibrin from fibrinogen Fibrin Fig. 20.11 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.12 Types of blood cells Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.12 Types of blood cells Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.5 Fish Circulation The fish heart is a tube consisting of four chambers Sinus venosus and atrium, are collection chambers Ventricle and conus arteriosus, are pumping chambers Fig. 20.13a Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display The heart beat in fishes has a peristaltic sequence Starts at the rear (SV) and moves to the front Gill respiration provides fully oxygenated blood to the body However, circulation is sluggish This limits rate of oxygen delivery to rest of body Fig. 20.13b Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.6 Amphibian and Reptile Circulation The advent of lungs resulted in two circulations 1. Pulmonary circulation Delivers blood to the lungs 2. Systemic circulation Delivers blood to the rest of the body Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display The amphibian heart has two structural features that reduce mixing of oxygenated & deoxygenated blood 1. The atrium is divided into two chambers by a septum 2. Conus arteriosus is partially separated by another septum Fig. 20.14a Amphibians in water supplement the oxygenation of blood by a process called cutaneous respiration Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Among reptiles, additional modifications have further reduced the mixing of blood in the heart The ventricle is partially divided into two chambers by a septum The separation is complete in the crocodiles Fig. 20.14b They thus have completely divided pulmonary and systemic circulation Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.7 Mammalian and Bird Circulation Mammals and birds have a four-chambered heart that is really two separate pumping systems One pumps blood to the lungs The other pumps blood to the rest of the body The two pumps operate together within a single unit Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Circulation Through the Heart Oxygenated blood from lungs empties into the left atrium through the pulmonary veins Then from the atrium to the left ventricle Ventricle contracts forcing blood out in a single strong pulse Bicuspid (mitral) valve prevents backflow Blood then moves into the aorta Aortic valve prevents backflow into ventricle Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Circulation Through the Heart Blood eventually returns to the heart The superior vena cava drains the upper body The inferior vena cava drains the lower body Blood passes from the right atrium into the right ventricle through the one-way tricuspid valve Ventricle contracts forcing blood through the pulmonary valve into the pulmonary arteries Oxygenated blood eventually returns to the heart It is then pumped to the rest of the body Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.15 The heart and circulation of mammals and birds Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display How the Heart Contracts Heartbeat originates in the sinoatrial (SA) node Its membranes spontaneously depolarize This wave of depolarization spreads to the atria, causing them to contract The wave reaches the atrioventricular (AV) node It passes to the ventricles via the Bundle of His It is then conducted rapidly over the surface of the ventricles by Purkinje fibers Ventricular contraction empties the heart Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.16 How the mammalian heart contracts Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Electrocardiogram (ECG or EKG) Shows how heart cells depolarize and repolarize Depolarization causes contraction of the heart Repolarization causes relaxation of the heart Depolarization of the ventricles Depolarization of the atria Repolarization of the ventricles Fig. 20.16 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Monitoring the Heart’s Performance Simplest way is to listen to the heart at work using a stethoscope If valves are not fully opening or closing, turbulence is created This can be heard as a heart murmur Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Another way is to monitor blood pressure A sphygmomanometer is used to record two measurements Systolic pressure – High point Diastolic pressure – Low point Fig. 20.17 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.8 Cardiovascular Diseases The leading cause of deaths in the US Heart attacks Caused by an insufficient supply of blood to one or more parts of the heart muscle Also called myocardial infarctions Angina pectoris (“Chest pain”) Warning sign of a potential heart attack Strokes Caused by interference with blood flow to brain Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Atheroscleroris Accumulation of fatty materials on inner surfaces of artery The lumen (interior) becomes narrower Fig. 20.18 Arterioscleroris Hardening of the arteries Occurs when calcium is deposited in arterial walls Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Treatment of Blocked Coronary Arteries Atherosclerosis is treated with 1. Medications Enzymes Anticoagulants Nitroglycerin 2. Invasive procedures Heart transplants Coronary bypass surgery Angioplasty Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.9 Types of Respiratory Systems Respiration is the uptake of oxygen and the simultaneous release of carbon dioxide Most of the primitive phyla of organisms obtain oxygen by direct diffusion from seawater Fig. 20.19 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Aquatic animals possess special respiratory organs called gills Fig. 20.19 Terrestrial arthropods use a network of air ducts called trachea Terrestrial vertebrates use respiratory organs called lungs Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.10 Respiration in Aquatic Vertebrates A fish continuously opens and closes its mouth It pushes water through mouth and out of gills This permits countercurrent flow Oxygenated water flows through the gills in a direction opposite blood flow in the capillaries The higher oxygen concentration in water drives the diffusion of oxygen into blood Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.20 Structure of a fish gill Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Diffusion continues Fig. 20.21 Countercurrent flow Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display No further net diffusion 20.11 Respiration in Terrestrial Vertebrates Amphibians on land are able to respire through moist skin However, the main respiration route is the lung A sac with a convoluted internal membrane Reptiles are more active so they need more oxygen But they cannot respire through skin Instead, their lungs contain many more small chambers, greatly increasing the surface area Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.11 Respiration in Terrestrial Vertebrates Mammals have an even greater oxygen demand because they maintain a constant body temperature They increase the lung surface area even more Alveoli Small chambers in interior of lung Bronchioles Short passageways connecting clusters of alveoli Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.22 Evolution of the vertebrate lung Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Birds Perfect the Lung Flying creates a very large oxygen demand Therefore, birds must possess very efficient lungs Air flows through the lungs in one direction This one-way air flow results in 1. No dead volume Air is always fully oxygenated 2. A crosscurrent flow Blood leaving the lung can still contain more oxygen than exhaled air Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.23 How a bird breathes Most efficient Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.12 The Mammalian Respiratory System A pair of lungs hang free in the thoracic cavity An air tube called bronchus connects each lung to a trachea Air normally enters through the nostrils It passes to the larynx (voice box) and then the trachea And then through the bronchus to the lungs Lungs contain millions of alveoli Sites of gas exchange between air and blood Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.24 The human respiratory system Each lung is covered by a pleural membrane The thoracic cavity is bounded on the bottom by a thick layer of muscle called the diaphragm Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display The Mechanics of Breathing Breathing – Active pumping of air in and out of lungs During inhalation Diaphragm contracts and flattens Chest cavity expands downwards and outwards This creates negative pressure in lungs and air rushes in During exhalation Diaphragm relaxes Volume of chest cavity decreases Pressure in lungs increases and air is forced out Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.25 How breathing works Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display The Mechanics of Breathing In a human, a typical breath at rest moves about 0.5 liters of air called the tidal volume When each breath is completed, the lung still contains a volume of air (~ 1.2 liters) called the residual volume Each inhalation adds from 500 milliliters (resting) to 3,000 milliliters (exercising) of additional air Each exhalation removes approximately the same volume as inhalation added Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.13 How Respiration Works: Gas Exchange Oxygen moves within the circulatory system carried piggyback on the protein hemoglobin Hemoglobin contains iron, which combines with oxygen in a reversible way Fig. 20.26 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display O2 Transport Hemoglobin bind O2 within red blood cells (RBCs) This causes more to diffuse in from blood plasma In the lungs, most hemoglobin molecules carry a full load of O2 The presence of carbon dioxide (CO2) in tissues speeds up the unloading of O2 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display CO2 Transport As red blood cells are unloading O2 they are also absorbing CO2 from the tissue The enzyme carbonic anhydrase combines CO2 and H2O to form carbonic acid (H2CO3–) This acid dissociates into bicarbonate (HCO3–) and hydrogen (H+) A transporter protein moves one bicarbonate out of the RBC and brings in one chloride ion This “chloride shift” facilitates the diffusion of more CO2 into the RBC Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display CO2 Transport RBC carry the bicarbonate ions back to the lungs There, the lower CO2 concentration causes the carbonic anhydrase reaction to occur in reverse CO2 is released from RBC and ultimately exhaled Hemoglobin can now pick up O2 again Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.27 How respiratory gas exchange works Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display NO Transport Hemoglobin also has the ability to hold and release the gas nitric oxide (NO) NO causes dilates blood vessels Thus, it regulates blood flow and blood pressure Hemoglobin picks up NO in the lungs and releases it in the tissues Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20.14 The Nature of Lung Cancer One of the leading causes of deaths among adults in the world Fig. 20.28 The incidence of cancer is not uniform throughout the US This suggests environmental factors Most carcinogens are also mutagens High incidence in cities and Mississippi Delta Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Cancer-causing genes are involved in regulating cell growth and division Tumor suppressor genes actively prevent tumors from forming Rb Encodes the Rb protein Slows down cell division by inhibiting DNA replication p53 Encodes the p53 protein Inspects the DNA for damage before If DNA repair is unsuccessful, the cell is destroyed Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 20.29 The roles Rb and p53 play in controlling cell division Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Smoking Causes Lung Cancer After the incidence of smoking began to increase in the US, so did the incidence of lung cancer Fig. 20.30 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Smoking Causes Lung Cancer Cigarette smoke contains many powerful mutagens Benzo[a]pyrene binds to three sites in the p53 gene Mutations at these sites inactivate the gene Research found that the p53 gene is inactivated in 70% of all lung cancers Moreover, the inactivating mutations occurred at the binding sites of benzo[a]pyrene! Nicotine in cigarette smoke is an addictive drug! Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display