CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry Cain Wasserman Minorsky Jackson Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 34 Circulation and Gas Exchange

© 2014 Pearson Education, Inc. Do now:  What is the purpose of a circulatory system?  What are the different organs of the human circulatory system?  List some organisms that might have circulatory systems different from humans  List some organisms that might not have circulatory systems

© 2014 Pearson Education, Inc. Main Ideas to know:  Different types of circulatory systems  Role of carbon dioxide/pH and homeostasis  Positive feedback of blood clotting  Respiratory pigments

© 2014 Pearson Education, Inc. Gastrovascular Cavities  Some animals lack a circulatory system  Some cnidarians, such as jellies, have elaborate gastrovascular cavities  A gastrovascular cavity functions in both digestion and distribution of substances throughout the body

© 2014 Pearson Education, Inc. Figure 34.2 Gastrovascular cavity Mouth 1 mm Flatworms have a gastrovascular cavity and a flat body shape to optimize diffusional exchange with the environment

© 2014 Pearson Education, Inc. Open and Closed Circulatory Systems  A circulatory system has a circulatory fluid, a set of interconnecting vessels, and a muscular pump, the heart  Several basic types of circulatory systems have arisen during evolution, each representing adaptations to constraints of anatomy and environment

© 2014 Pearson Education, Inc. Figure 34.3 Branch vessels in each organ Tubular heart Pores Hemolymph in sinuses (a) An open circulatory system Heart (b) A closed circulatory system Heart Blood Dorsal vessel (main heart) Auxiliary hearts Ventral vessels Interstitial fluid

© 2014 Pearson Education, Inc.  All circulatory systems are either open or closed  circulatory fluid bathes the organs directly in an open circulatory system  Ex: insects, arthropods and molluscs  In an open circulatory system, there is no distinction between circulatory fluid and interstitial fluid, and this general body fluid is called hemolymph

© 2014 Pearson Education, Inc.  In closed circulatory systems the circulatory fluid called blood is confined to vessels and is distinct from interstitial fluid  Ex: annelids (earthworms), vertebrates  One or more hearts pump blood through the vessels  Chemical exchange occurs between blood and interstitial fluid and between interstitial fluid and body cells

© 2014 Pearson Education, Inc. Organization of Vertebrate Circulatory Systems  Humans and other vertebrates have a closed circulatory system called the cardiovascular system  The three main types of blood vessels are arteries, veins, and capillaries  Blood flow is one-way in these vessels

© 2014 Pearson Education, Inc. Figure 34.9 Connective tissue Smooth muscle Connective tissue Smooth muscle Endothelium Artery Vein Artery Vein Red blood cells Basal lamina Capillary Red blood cell Capillary Arteriole Venule Valve 100  m 15  m LM

© 2014 Pearson Education, Inc.  Arteries branch into arterioles and carry blood away from the heart to capillaries  Networks of capillaries called capillary beds are the sites of chemical exchange between the blood and interstitial fluid  Venules converge into veins and return blood from capillaries to the heart  Arteries and veins are distinguished by the direction of blood flow, not by O 2 content

© 2014 Pearson Education, Inc. Figure 34.4 Lung and skin capillaries Body capillaries Vein Gill capillaries (a) Single circulation: fish Heart: (b) Double circulation: amphibian Key Systemic capillaries Pulmocutaneous circuit Artery Ventricle (V) Atrium (A) Oxygen-rich blood Oxygen-poor blood Right Left A A V Systemic circuit Lung capillaries (c) Double circulation: mammal Systemic capillaries Pulmonary circuit Right Left A A V Systemic circuit V

© 2014 Pearson Education, Inc. Figure Interstitial fluid Lymphatic vessel Lymphatic vessel Blood capillary Tissue cells Lymph node Masses of defensive cells Lymphatic vessels Lymph nodes Peyer’s patches (small intestine) Appendix (cecum) Thymus (immune system) Adenoid Tonsils Spleen

© 2014 Pearson Education, Inc. Figure 34.13b Cellular elements 45% Functions Leukocytes (white blood cells) Transport of O 2 and some CO 2 Cell type Number per  L (mm 3 ) of blood Basophils Lymphocytes Eosinophils Neutrophils Monocytes Platelets Erythrocytes (red blood cells) 250,000–400,000 5,000,000–6,000,000 Blood clotting 5,000–10,000 Defense and immunity

© 2014 Pearson Education, Inc. Figure Stem cells (in bone marrow) Basophils Lymphocytes Eosinophils Neutrophils Monocytes Platelets Erythrocytes Myeloid stem cells Lymphoid stem cells B cells T cells

© 2014 Pearson Education, Inc. Blood Clotting  Coagulation is the formation of a solid clot from liquid blood  A cascade of complex reactions converts inactive fibrinogen to fibrin, which forms the framework of a clot  A blood clot formed within a blood vessel is called a thrombus and can block blood flow

© 2014 Pearson Education, Inc. Figure Platelet plug Collagen fibers Platelets Clotting factors from: Damaged cells Plasma (factors include calcium, vitamin K) Fibrin Thrombin Fibrinogen Prothrombin Enzymatic cascade Fibrin clot formation Red blood cell 5  m 1 2 3

© 2014 Pearson Education, Inc.  A heart attack, or myocardial infarction, is the death of cardiac muscle tissue resulting from blockage of one or more coronary arteries  A stroke is the death of nervous tissue in the brain, usually resulting from rupture or blockage of arteries in the head  Angina pectoris is caused by partial blockage of the coronary arteries and may cause chest pain

© 2014 Pearson Education, Inc. Concept 34.5: Gas exchange occurs across specialized respiratory surfaces  Gas exchange is the uptake of molecular O 2 from the environment and the discharge of CO 2 to the environment

© 2014 Pearson Education, Inc. Figure Bronchiole Bronchus Right lung Trachea (Esophagus) Larynx Pharynx (Heart) Terminal bronchiole Left lung Nasal cavity Capillaries Alveoli Dense capillary bed enveloping alveoli (SEM) Branch of pulmonary vein (oxygen-rich blood) Branch of pulmonary artery (oxygen-poor blood) 50  m Diaphragm

© 2014 Pearson Education, Inc. Control of Breathing in Humans  In humans, the main breathing control center consists of neural circuits in the medulla oblongata, near the base of the brain  The medulla regulates the rate and depth of breathing in response to pH changes in the cerebrospinal fluid  The medulla adjusts breathing rate and depth to match metabolic demands

© 2014 Pearson Education, Inc. Figure Homeostasis: Blood pH of about 7.4 Stimulus: Rising level of CO 2 in tissues lowers blood pH.

© 2014 Pearson Education, Inc. Figure Carotid arteries Homeostasis: Blood pH of about 7.4 Stimulus: Rising level of CO 2 in tissues lowers blood pH. Sensor/control center: Aorta Cerebro- spinal fluid Medulla oblongata

© 2014 Pearson Education, Inc. Figure Carotid arteries Response: Signals from medulla to rib muscles and diaphragm increase rate and depth of ventilation. Homeostasis: Blood pH of about 7.4 Stimulus: Rising level of CO 2 in tissues lowers blood pH. Sensor/control center: Aorta Cerebro- spinal fluid Medulla oblongata

© 2014 Pearson Education, Inc. Figure Carotid arteries Response: Signals from medulla to rib muscles and diaphragm increase rate and depth of ventilation. Homeostasis: Blood pH of about 7.4 CO 2 level decreases. Stimulus: Rising level of CO 2 in tissues lowers blood pH. Sensor/control center: Aorta Cerebro- spinal fluid Medulla oblongata

© 2014 Pearson Education, Inc. Concept 34.7: 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 O 2 and CO 2

© 2014 Pearson Education, Inc. Figure 34.UN01 Hemoglobin Heme Iron

© 2014 Pearson Education, Inc. Respiratory Pigments  Respiratory pigments circulate in blood or hemolymph and greatly increase the amount of oxygen that is transported  A variety of respiratory pigments have evolved among animals  These mainly consist of a metal bound to a protein  Ex: hemoglobin  A single hemoglobin molecule can carry four molecules of O 2, one molecule for each iron- containing heme group

© 2014 Pearson Education, Inc.  CO 2 produced during cellular respiration lowers blood pH and decreases the affinity of hemoglobin for O 2 ; this is called the Bohr shift  Hemoglobin also assists in preventing harmful changes in blood pH and plays a minor role in CO 2 transport

© 2014 Pearson Education, Inc. Carbon Dioxide Transport  Most of the CO 2 from respiring cells diffuses into the blood and is transported in blood plasma, bound to hemoglobin or as bicarbonate ions (HCO 3 – )

© 2014 Pearson Education, Inc. Respiratory Adaptations of Diving Mammals  Diving mammals have evolutionary adaptations that allow them to perform extraordinary feats  For example, Weddell seals in Antarctica can remain underwater for 20 minutes to an hour  For example, elephant seals can dive to 1,500 m and remain underwater for 2 hours  These animals have a high blood to body volume ratio

© 2014 Pearson Education, Inc.  Deep-diving air breathers can store large amounts of O 2  Oxygen can be stored in their muscles in myoglobin 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

© 2014 Pearson Education, Inc. Figure 34.UN03 Alveolar epithelial cells Pulmonary arteries Systemic veins Pulmonary veins Systemic arteries Systemic capillaries Alveolar capillaries Alveolar spaces Exhaled air Inhaled air Heart Body tissue CO 2 O2O2 O2O2