Biology: Life on Earth (Audesirk) Chapter 27 Biology: Life on Earth (Audesirk) Circulation Chapter 27

Circulatory System Basics Chapter 27 Fluid—blood Channels—vessels A pump—the heart

Types of Circulatory Systems Chapter 27 Open Open space within the body cavity—hemocoel Arthropods (insects, spiders, and crustaceans) Most mollusks (snails and clams) Closed Confined blood in continuous vascular network Pumping heart Some invertebrates (earthworm, cephalopod mollusks) All vertebrates

Open & Closed Systems Chapter 27

The Evolution of the Vertebrate Heart Biology: Life on Earth (Audesirk) The Evolution of the Vertebrate Heart Chapter 27 (b) Amphibians Reptiles” (a) Fish Gill Capillaries (c) Mammals, Birds Lung Capillaries Lung Capillaries (a) The earliest vertebrate heart is represented by the two-chambered heart of fishes. (b) Amphibians and most reptiles have a heart with two atria, from which blood empties into a single ventricle. Many reptiles have a partial wall down the middle of the ventricle. (c) The hearts of birds and mammals are actually two separate pumps that prevent mixing of oxygenated and deoxygenated blood. Note that in this and in subsequent illustrations, oxygenated blood is depicted as bright red, while deoxygenated blood is colored blue. Ventricle Atria Atrium Ventricle Ventricles Body Capillaries Body Capillaries Body Capillaries Chapter 27

Vertebrate Circulatory System: Functions Chapter 27 Transport of O2 and CO2 Distribution of nutrients Transport of waste Distribution of hormones Regulation of body temperature Protection against blood loss and disease

Mammal Circulatory System Chapter 27

Vertebrate Circulatory System: The Heart Chapter 27 Structure Atria Ventricles Structural evolution among the vertebrates The cardiac cycle Systole—period of ventricle contraction Diastole—relaxation of all the chambers followed by contraction of the atria

Heart - Human Chapter 27

Biology: Life on Earth (Audesirk) Chapter 27 Aorta Human Heart Superior Vena Cava (from upper body) Pulmonary Artery (to left lung) Pulmonary Veins (from left lung) Pulmonary Artery (to right lung) Left Atrium Pulmonary Veins (from right lung) The heart is drawn as if it were in a body facing you, so that right and left appear reversed. Note the thickened walls of the left ventricle, which must pump blood much farther through the body than does the right ventricle, which propels blood to the lungs. One-way valves, called semilunar valves, are located between the aorta and the left ventricle, and between the pulmonary artery and the right ventricle. Atrioventricular valves separate the atria and ventricles. Atrioventricular Valve Right Atrium Left Ventricle Atrioventricular Valve Semilunar Valves Right Ventricle Descending Aorta (to lower body) Inferior Vena Cava (from lower body) Chapter 27

The Cardiac Cycle Chapter 27 Oxygenated blood from lungs Deoxygenated blood to lungs (c) Heart Relaxes; atria fill passively Oxygenated blood to body Deoxygenated blood from body (a) Atria Contract (b) Ventricles Contract

Cardiac Cycle Chapter 27

Path of Blood Flow Chapter 27

Measuring Blood Pressure Biology: Life on Earth (Audesirk) Measuring Blood Pressure Chapter 27 Blood pressure is measured with an inflatable blood pressure cuff and a stethoscope. The cuff is inflated until its pressure closes off the arm’s main artery, blood ceases to flow, and no pulse can be detected below the cuff. Then the pressure is gradually reduced. When the pulse is first audible in the artery, the pressure pulses created by the contracting left ventricle are just overcoming the pressure in the cuff and blood is flowing. This is the upper reading: the systolic pressure. Cuff pressure is then further reduced until no pulse is audible, indicating that blood is flowing continuously through the artery and that the pressure between ventricular contractions is just overcoming the cuff pressure. This is the lower reading: the diastolic pressure. The numbers are in millimeters of mercury, a standard measure of pressure also used in barometers. Chapter 27

The Structure of Cardiac Muscle Biology: Life on Earth (Audesirk) The Structure of Cardiac Muscle Chapter 27 Cardiac muscle cells are branched. Adjacent plasma membranes meet in folded areas that are densely packed with gap junctions (pores), which connect the interiors of adjacent cells. This arrangement allows direct transmission of electrical signals between the cells, coordinating their contractions. Chapter 27

Coordination of Heart Activity Chapter 27 Atrioventricular and semilunar valves The sinoatrial node (SA node) The atrioventricular node (AV node) Influences on heart rate Parasympathetic nervous system - decreases heart rate Sympathetic nervous system - increases heart rate Hormones

The Heart’s Pacemaker and Its Connections Biology: Life on Earth (Audesirk) Chapter 27 The Heart’s Pacemaker and Its Connections Sinoatrial Node Atrioventricular Node The sinoatrial (SA) node, a spontaneously active mass of modified muscle fibers in the right atrium, serves as the heart’s pacemaker. The signal to contract spreads from the SA node through the muscle fibers of both atria, finally exciting the atrioventricular (AV) node in the lower right atrium. The AV node then transmits the signal to contract through bundles of excitable fibers that stimulate the ventricular muscle. Excitable Fibers Chapter 27

Cardiac cycle Chapter 27

Stab Wound - Heart Chapter 27

Composition of Blood Chapter 27

Blood Cells Red blood cells—erythrocytes (RBCs) Chapter 27 Red blood cells—erythrocytes (RBCs) 99% of the total cellular component in the blood Carry O2 bound to hemoglobin from lungs to tissue Buffer CO2 carried from the tissues White blood cells—leukocytes (WBCs) 1% of the total cellular component of blood Five white blood cell type Platelets Cellular fragments from megakaryocyte in the bone marrow Function in blood clotting

Blood Smear Neurtophil Lymphocyte Red Blood Cell White Cell Platelet Chapter 27 Neurtophil Lymphocyte Red Blood Cell White Cell Platelet

Red Blood Cells (Erythrocytes) Chapter 27 Red Cells Made in the bone marrow Destroyed in the liver Stored in the spleen Heme + Globin + Iron = Hemoglobin Anemia = Lack of red blood cells

Biology: Life on Earth (Audesirk) Hemoglobin Chapter 27 Polypeptide Chains A molecule of hemoglobin is composed of four polypeptide chains (two pairs of similar chains), each surrounding a heme group. The heme group contains an iron atom and is the site of oxygen binding. When saturated, each hemoglobin molecule can carry four oxygen molecules (eight oxygen atoms). RBCs Heme Group Chapter 27

RBC Regulation by Negative Feedback Biology: Life on Earth (Audesirk) RBC Regulation by Negative Feedback Chapter 27 Oxygen deficiency Stimulates Red blood cell regulation by negative feedback Stimulates Erythropoietin production by kidneys Red blood cell production in bone marrow Inhibits Causes Restored oxygen level Chapter 27

White Blood Cells - Platelets Chapter 27 White Blood Cells Made in the Bone Marrow Programmed in the lymph glands and thymus glands Platelets Made in the bone marrow

A White Blood Cell Attacks Bacteria Biology: Life on Earth (Audesirk) A White Blood Cell Attacks Bacteria Chapter 27 Macrophage Bacteria An amoeba-like white blood cell is seen capturing bacteria (in yellow). These bacteria are Escherichia coli, intestinal bacteria that can cause disease if they enter the blood-stream. Pseudopodia Chapter 27

The Production of Platelets Biology: Life on Earth (Audesirk) The Production of Platelets Chapter 27 Here a single megakaryocyte, found in bone marrow, is budding off dozens of membrane-enclosed pieces of cytoplasm called platelets. Chapter 27

Blood Clotting Ruptured Platelet Thromboplastin B L prothrombin Chapter 27 Ruptured Platelet Thromboplastin B L O D prothrombin Thrombin Fibrinogen Fibrin

Biology: Life on Earth (Audesirk) Blood Clotting (a) Chapter 27 (a) Injured tissue and adhering platelets cause a complex series of biochemical reactions among blood proteins. These reactions produce thrombin, which catalyzes the conversion of fibrinogen to insoluble fibrin strands. Chapter 27

Biology: Life on Earth (Audesirk) Blood Clotting (b) Chapter 27 Fibrin Network Platelets (b) Threadlike fibrin proteins produce a tangled sticky mass that traps red blood cells and eventually forms a clot. Trapped RBCs Chapter 27

Blood Vessels Arteries and arterioles Capillaries Venules and veins Chapter 27 Arteries and arterioles Thick walled, elastic to withstand high pressure Carry blood away from the heart Capillaries Tiniest vessels; thin, single-cell wall for easy diffusion Exchange of materials between blood & body cells Venules and veins Thin-walled vessels surrounded smooth muscle Low resistance to blood flow Return blood to the heart

Blood Vessels Chapter 27 Smooth Muscle Vein Artery

Distribution of Blood Flow Chapter 27 Regulated by muscular walls of arterioles Influenced by: Autonomic nerves Hormones Other chemicals released from nearby tissues

The Human Circulatory System Biology: Life on Earth (Audesirk) The Human Circulatory System Chapter 27 Carotid Artery Jugular Vein Most veins (right) carry deoxygenated blood to the heart, and most arteries (left) conduct oxygenated blood away from the heart. The pulmonary veins (carrying oxygenated blood) and arteries (carrying deoxygenated blood) are exceptions. All organs receive blood from arteries, send it back via veins, and are nourished by capillaries (only lung capillaries are illustrated and these are greatly enlarged, since capillaries are microscopic). Aorta Superior Vena Cava Heart Inferior Vena Cava Chapter 27

Chapter 27 Femoral Artery Femoral Vein

Interconnections & Structures Blood Vessels Biology: Life on Earth (Audesirk) Precapillary Sphincters Interconnections & Structures Blood Vessels Capillaries Chapter 27 Arteriole Arteries and arterioles are more muscular than are veins and venules. Capillaries have walls only one cell thick. Oxygenated blood moves from arteries to arterioles to capillaries. Capillaries empty deoxygenated blood into venules, which empty into veins. The movement of blood from arterioles into capillaries is regulated by muscular rings called precapillary sphincters. Venule Conn. Tissue Muscle Conn. Tissue Artery Endothelium Vein Chapter 27

Valves Direct Flow of Blood in Veins Biology: Life on Earth (Audesirk) Valves Direct Flow of Blood in Veins Chapter 27 Skeletal muscles help return blood to heart Valves prevent back-flow Veins and venules have one-way valves that maintain blood flow in the proper direction. When the vein is compressed by nearby muscles, the valves allow blood to flow toward the heart but clamp shut to prevent backflow. Chapter 27

The Lymphatic System Structure Functions Chapter 27 Structure Complex network of thin-walled vessels In proximity to the capillary network Composed of cells with openings between them that act as one-way valves Functions Removal of excess fluid Transport of fats from the intestine Cellular body defenses

Biology: Life on Earth (Audesirk) Thoracic Duct enters vena cava Chapter 27 Tonsil Lymphatic System Superior Vena Cava Thymus Spleen Heart (a) Lymph vessels, lymph nodes, and two auxiliary lymph organs, the thymus and spleen. Lymph is returned to the circulatory system by way of the thoracic duct, which empties into the vena cava, a large vein. (b) A cross section of a lymph node. The node is filled with channels lined with white blood cells (lymphocytes) that attack foreign matter in the lymph. Lymph Fluid Valve Thoracic Duct Lymph Vessels Lymphocytes Lymph Node Chapter 27

Lymph Capillary Structure Biology: Life on Earth (Audesirk) Chapter 27 Lymph Capillary Structure Lymph conducted to larger lymph vessels Lymph capillaries end blindly in the body tissues, where pressure from the accumulation of interstitial fluid forces the fluid into the lymph capillaries. Interstitial fluid enters lymph vessels Capillaries leak plasma to form interstitial fluid Chapter 27

Biology: Life on Earth (Audesirk) Plaques Clog Arteries Chapter 27 Diagrammatic cross section of an artery with a plaque. If the fibrous cap ruptures, a clot will form that can completely obstruct the artery, or the clot can break loose and clog a narrower artery “downstream.” Chapter 27

Normal Artery - Plaque Chapter 27

Chapter 27 The End