THIS WEEK'S LABORATORY EXERCISE: CARDIOVASCULAR SYSTEM READING: RAVEN & JOHNSON: CHAPTER 40, PP 756-770. ANNOUNCEMENTS: 1. STUDENTS WHO HAVE A WEDNESDAY LAB, MUST ATTEND THAT LAB, UNLESS THEY ARE BEING HONORED (AND CAN PROVE IT). THEY MUST ASK THEIR TAs FOR A MAKE-UP ASSIGNMENT. 2. NO CONTACT LENSES, ESPECIALLY GAS PERMEABLE LENSES. IF YOU CHOOSE TO WEAR THEM, IT IS AT YOUR OWN RISK! LAB LECTURE A. COMPONENTS OF THE CARDIOVASCULAR SYSTEM HEART, LUNGS, BLOOD VESSELS B. HEART STRUCTURE PATHWAY OF BLOOD BLOOD PRESSURE C. ELECTRICAL ACTIVITY NODES, FIBERS EKG D. HUMAN DISORDERS COMPONENTS OF THE CIRCULATORY SYSTEM The Heart: a muscle that receives oxygenated blood from the lungs and sends it to the body, receives deoxygenated blood from the body and sends it to the lungs. The Lungs: oxygen diffuses into the blood, going from an area of high concentration (the alveoli) to low concentration (blood cells within capillaries). Blood Vessels: All blood vessels containing blood leaving the heart are called arteries. Those that contain blood traveling to the heart are called veins. Arteries carry oxygenated blood, except when carrying blood from the heart to the lungs. Veins carry deoxygenated blood except when taking blood from the lungs to the heart. Arteries are have a thick layer of muscle that helps squeeze the blood to all parts of the body. Veins have a thin layer of muscle but they contain valves to prevent blood from flowing backwards. As arteries leave the heart, they branch into smaller vessels called arterioles. These in turn branch into tiny, one-cell thick vessels called capillaries. The walls of the capillaries are so thin that oxygen can diffuse into the surrounding tissue and other waste gases, carbon dioxide for example, can diffuse in. Capillaries join together to form venules, which then join to form veins as the blood is carried back to the heart. THE HEART Structure: The heart contains four chambers, the anterior atria (singular - atrium) and the posterior ventricles. The right ventricle is much smaller than the left ventricle because it need only pump the blood a short distance, while the left side needs to pump blood to all parts of the body. The atria are smaller than the ventricles because they only pump blood into the ventricles. There are valves separating the valves separating the ventricles from the vessels leaving them are called the semilunar valves. Show cow heart, show how to tell front from back. Pathway of Blood: Blood enters the right atrium from the superior and inferior vena cava. These vessels carry blood from the body above and below the heart, respectively. The right atrium pump blood into the right ventricle, which pumps blood through the pulmonary artery to the lungs. Oxygenated blood from the lungs enters the left atrium through the pulmonary vein. The left atrium pumps it into the left ventricle. The left ventricle pumps blood to the body through the aorta. Blood is carried to and from the heart itself is in the coronary vein and artery. Blood Pressure: Anne A. COMPONENTS OF THE CIRULATORY SYSTEM The Heart: a muscle that receives oxygenated blood from the lungs and sends it to the body, receives deoxygenated blood from the body and sends it to the lungs The Lungs: organs for gas exchange that take oxygen from the atmosphere. Oxygen passes into the capillaries in the lungs by diffusion. Waste gases pass from capillaries into the lungs and are exhaled. Blood Vessels: Heart------------arteries------------arterioles---------------capillaries | | | | | | --------veins-----------------------venules----------------------- LAB ACTIVITIES CONCERNING HEART FUNCTION Heart Sounds & Pulse The characteristic sound of your heart beat is "lub-dub". You'll listen to this with the use of a stethoscope. Cause: vibrations along the heart walls from the closing of the atrioventricular and semilunar valves. Lub = closing of atrioventricular valves when ventricles contract Dub = closing of semilunar valves as ventricles relax Period of Heart Contraction = Systole Period of Heart Relaxation = Diastole I. Pulse= surge of blood during systole period - time between audible pulse beats corresponds to one full cycle of systole and diastole.II. Blood pressure = force on the walls of the vessels exerted by the contraction of the heart - You will measure this with the use of a sphygmomanometer. A sphygomomanometer measures blood pressure in a column of mercury. blood pressure=systolic(arterial pressure during contraction) diastolic(arterial pressure between contractions) III. Electrical Activity of the Heart = measured with an electrocardiogram (EKG or ECG) An electrocardiogram measures electric current on the surface of your skin. This current reflects the electrical charge produced by the contracting heart. Refer to Figure 3 on p.90 of your lab manual -- a typical EKG wave. P = contraction of atria QRS complex = contraction of ventricles T = repolarization of ventricles = gearing up to pump again! Things to remember = TAKE OFF WATCHES AND JEWELRY - WEAR CLOTHES THAT MAKE IT EASY TO GET TO YOUR ANKLES AND WRISTS - DON'T MOVE WHEN YOUR TEST IS RUNNING. Heart Contraction: What makes it happen? 1) Contraction is started by your sinoatrial (SA) node = pacemaker which is located in the wall of your right atrium. (A node is simply a cluster of nerve cells.) 2) The SA node sends a wave of depolarization to the atrioventricular (AV) node and as it does the atria contract. The AV node sends this message (the depolarization wave) on to the Bundle of His = a cluster of nerve fibers located in the septum of the heart. This message continues out through the bundle branches and Purkinje fibers causing the ventricles to contract. TO VISUALIZE: LAB MANUAL, FIGURE 6, P.100 HOW AMERICANS DIE! (P.763 IN YOUR TEXTBOOK) #1 Heart Disease #3 Stroke Main Risk Factors = smoking, high cholesterol and high blood pressure Heart Attack - vessel to heart is blocked Stroke - vessel to brain bursts or is blocked Why? Atherosclerosis - fatty plaques accumulate on artery walls Arteriosclerosis - plaques calcify on artery walls See Figure 40.18, Textbook p.770 Hypertension= high blood pressure - pressure on artery walls increases likelihood of stroke or heart attack.