UNIT B: Human Body Systems Chapter 8: Human Organization Chapter 9: Digestive System Chapter 10: Circulatory System and Lymphatic System: Section 10.3 Chapter 11: Respiratory System Chapter 12: Nervous System Chapter 13: Urinary System Chapter 14: Reproductive System

Chapter 10: Circulatory System and Lymphatic System In this chapter, you will learn about the structure and function of the circulatory system and lymphatic system. UNIT B Chapter 10: Circulatory System and Lymphatic System TO PREVIOUS SLIDE What is the composition of blood, including blood cells? What organs and structures control the flow of blood throughout the body? In 2013, Lance Armstrong confessed to long-term blood doping and the use of banned substances. Blood doping involves artificially boosting the blood’s ability to bring more oxygen to muscles. Aerobic capacity and endurance improve where there are additional red blood cells available to carry oxygen.

10.3 The Human Heart The heart is a muscular organ about the size of a fist. Myocardium: the major portion of the heart; consists of cardiac muscle tissue Pericardium: a thick membrane within which the heart lies; secretes lubricating liquid Endocardium: the inner surface of the heart; a membrane composed of connective and endothelial tissue UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

Structure of the Heart The septum separates the heart into a right side and a left side. The heart has four chambers: Two upper, thin-walled atria o Atria fill with blood returning from the body and lungs Two lower, thick-walled ventricles o Ventricles receive blood from atria and pump it out to body and lungs UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

Structure of the Heart The heart has four valves that direct the flow of blood and prevent its backward movement. Two atrioventricular valves that are supported by strong fibrous strings called chordae tendineae o tricuspid valve: the valve on the right side o bicuspid (mitral valve): the valve on the left side Two semilunar valves o pulmonary semilunar valve: lies between right ventricle and pulmonary trunk o aortic semilunar valve: lies between the left ventricle and aorta UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System Figure Internal view of the heart. a. The heart has four valves. When the atrioventricular valves open, blood passes from the atria to the ventricles, and when the semilunar valves open, blood passes out of the heart.

UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System Figure External heart anatomy. a. The venae cavae and the pulmonary trunk are attached to the right side of the heart. The aorta and the pulmonary veins are attached to the left side of the heart.

UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System Figure External heart anatomy. b. The coronary arteries and cardiac veins pass through cardiac muscle. The coronary arteries bring oxygen and nutrients to cardiac cells, which derive no benefit from blood coursing through the heart. The cardiac veins drain blood into the right atrium.

Path of Blood through the Heart The superior vena cava and the inferior vena cava, which carry O 2 -poor blood, enter the right atrium. UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

The right atrium sends blood through the tricuspid valve to the right ventricle. UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

The right ventricle sends blood through the pulmonary semilunar valve into the pulmonary trunk and through the two pulmonary arteries to the lungs. UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

Four pulmonary veins, which carry O 2 -rich blood, enter the left atrium. UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

The left atrium sends blood through the bicuspid valve to the left ventricle. UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

The left ventricle sends blood through the aortic semilunar valve into the aorta and on to the rest of the body. UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

The heart is a double pump. o Right ventricle sends blood into the lungs o Left ventricle sends blood into the rest of the body −A stronger pump, since it has to pump blood to the body Cardiac output is the volume of blood that the left ventricle pumps per minute. o Cardiac output is about 5.25 L of blood per minute in a person with an average heart rate of 70 beats per minute The pulse is a wave effect that passes down the walls of the arteries when the aorta expands and recoils with each ventricular contraction; can be used to determine heart rate UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

The Heartbeat Each heartbeat is called a cardiac cycle. When a heart beats: The two atria contract at the same time, and the ventricles are relaxed and fill with blood Then, the two ventricles contract at the same time Then, all the chambers relax UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System Figure Generation of heart sounds during the cardiac cycle. a. When the atria contract, the ventricles are relaxed and filling with blood. b. When the ventricles contract, the atrioventricular valves close, preventing blood from flowing back into the atria and producing the “lub” sound of the heartbeat. c. After the ventricles contract, the “dub ” sound of the heartbeat results from the closing of the semilunar valves to prevent arterial blood from flowing back into the ventricles.

The heart beats about 70 times a minute; each heartbeat is 0.85 s. Systole is the contraction of the heart muscle Diastole is the relaxation of the heart muscle UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

Intrinsic Control of Heartbeat The heart is able to contract and relax rhythmically due to the presence of nodal tissue, a type of cardiac muscle. Nodal tissue is located in two areas:: SA (sinoatrial) node: initiates the heartbeat and sends out an impulse every 0.85 s; also called the pacemaker AV (atrioventricular) node: transmits an impulse through specialized cardiac muscle fibres called the atrioventricular bundle (AV bundle), which send the signal to Purkinje fibres UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System Figure Conduction system of the heart. a. The SA node sends out a stimulus (black arrows), which causes the atria to contract. When this stimulus reaches the AV node, it signals the ventricles to contract. Impulses pass down the two branches of the atrioventricular bundle to the Purkinje fibres, and thereafter the ventricles contract.

Extrinsic Control of Heartbeat The body also has extrinsic ways to regulate the heartbeat. Medulla oblongata (portion of the brain that controls internal organs) Can alter heartbeat by the autonomic nervous system o Parasympathetic: decreases SA and AV nodal activity when inactive o Sympathetic: increases SA and AV nodal activity when active Epinephrine and norepinephrine (hormones) Released by the adrenal medulla Heart pumps faster and stronger due to sympathetic stimulation and release of epinephrine and norepinephrine UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

The Electrocardiogram An electrocardiogram (ECG) is a recording of the electrical changes that occur in the myocardium during a cardiac cycle. UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System Figure Conduction system of the heart. b. A normal ECG usually indicates that the heart is functioning properly. The P wave occurs just before atrial contraction; the QRS complex occurs just before ventricular contraction; and the T wave occurs when the ventricles are recovering from contraction.

Different types of abnormalities, known as arrhythmias can be detected by an ECG Atrial fibrillation (AF): multiple, chaotic impulses are generated from the AV node, causing an irregular, fast heartbeat Ventricular fibrillation (VF): uncoordinated contraction of the ventricles; can occur after a heart attack, injury, or drug overdose o Heart in VF is not pumping blood and must be defibrillated by applying an electrical current to reestablish heartbeat o Automatic external defibrillators(AEDs) can be used to administer an electrical current to the chest UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System Figure Conduction system of the heart. b. A normal ECG. c. Ventricular fibrillation produces an irregular electrocardiogram due to irregular stimulation of the ventricles.

Check Your Progress 1.Name each blood vessel and heart chamber that blood passes through on its journey through the heart and lungs. 2.Predict what might happen to the lungs if the left ventricle was not able to pump blood properly. UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

Check Your Progress 3.Describe the specific cause of each sound of the heartbeat. 4.Explain why it is important for the speed and strength of heart contractions to be regulated both intrinsically and extrinsically. UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System

UNIT B TO PREVIOUS SLIDE Section 10.3 Chapter 10: Circulatory System and Lymphatic System