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

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

3. 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

4. Open & Closed Systems
Chapter 27

5. 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

6. 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

7. Mammal Circulatory System
Chapter 27

8. 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

9. Heart - Human
Chapter 27

10. 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

11. 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

12. Cardiac Cycle
Chapter 27

13. Path of Blood Flow
Chapter 27

14. 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

15. 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

16. 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

17. 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

18. Cardiac cycle
Chapter 27

19. Stab Wound - Heart
Chapter 27

20. Composition of Blood
Chapter 27

21. 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

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

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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

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

30. 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

31. 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

32. 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

33. Blood Vessels
Chapter 27
Smooth Muscle
Vein
Artery

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

35. 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

36. Chapter 27
Femoral Artery
Femoral Vein

37. 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

38. 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

39. 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

40. 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

41. 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

42. 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

43. Normal Artery - Plaque
Chapter 27

44. Chapter 27
The End