2 Systemic Circulation – delivers blood to all body cells and carries away waste Pulmonary Circulation – eliminates carbon dioxide and oxygenates blood (lung pathway)
3 Structure of the HeartHeart Size – about 14 cm x 9 cm (the size of a fist).Located in the mediastinum (space between lungs, backbone, sternum), between the 2nd rib and the 5th intercostal space.The distal end of the heart is called the apex.
4 Fibrous Pericardium encloses the heart (like a bag) and has 2 layers visceral pericardium (inner)and parietal pericardium (outer, attached to diaphragm, sternum and vertebrae)
5 Pericardial cavity – contains fluid for the heart to float in, reducing friction Wall of the HeartEpicardium – outer layer, reduces frictionMyocardium – middle layer, mostly cardiac muscleEndocardium – thin inner lining, within chambers of the heart
6 Heart Chambers & Valves Your heart is a double pump. Circulation is a double circuit: Pulmonary (lungs only) and systemic (rest of the body)Heart has 4 chambers:2 Atria – thin upper chambers that receive blood returning to the heart through veins.. Right and Left Atrium2 Ventricles – thick, muscular lower chambers. Receive blood from the atria above them. Force (pump) blood out of the heart through arteries. Right and left ventricle.Septum – separates the right and left sides of the heart
8 Valves of the Heart – allow one-way flow of blood. 4 total (2 Atrioventricular Valves (AV) & 2 Semilunar valves)Left Atrioventricular valve – also called the bicuspid valve or mitral valve. Between left atrium and ventricleRight Atrioventricular valve – also called the tricuspid valve. Between right atrium and ventricleAortic Semilunar – or just aortic valve. Between the left ventricle and the aortaPulmonary Semilunar, or just pulmonary valve. Between the left ventricle and the aorta
9 Mitral = bicuspid (left side) Tricuspid (right side) Aortic and Pulmonary are both semilunar valves
17 Heart ActionsCardiac Cycle: One complete heartbeat. The contraction of a heart chamber is called systole and the relaxation of a chamber is called diastole.
18 The cusps (flaps) of the bicuspid and tricuspid valves are anchored to the ventricle walls by fibrous “cords” called chordae tendineae, which attach to the wall by papillary muscles. This prevents the valves from being pushed up into the atria during ventricular systole.Can you identify these parts?
21 ECG – electrocardiogram – a recording of the electrical events (changes) during a cardiac cycle P Wave – depolarization of the atria (atrial contraction – systole)QRS Complex – depolarization of the ventricles (ventricular contraction, systole)T Wave – Repolarization of the ventriclesHeart Sounds – opening and closing of the valves, flow of blood into and out of the chambers, vibrations in muscle
22 Heart Sounds - Opening and Closing of Valves, "Lub Dub" Stethoscope - instrument to listen and measure heart sounds
26 1 Sinoatrial node (Pacemaker) 2 Atrioventricular node 3 Atrioventricular Bundle (Bundle of His) 4 Left & Right Bundle branches 5 Bundle Branches (Purkinje Fibers)
27 Regulation of Cardiac Cycle controlled by the cardiac center within the medulla oblongata. The cardiac center signals heart to increase or decrease its rate according to many factors that the brain constantly monitors.Muscle ActivityBody TemperatureBlood ion levels (potassium & calcium)
28 Cardiac OutputCardiac Output = Stroke Volume x Heart Rate
30 SADS = (Sudden Arrhythmia Death Syndromes or Sudden Adult Death Syndrome) Routine ECG Screening may help prevent deaths in young people
31 Interpreting ECGsAn ECG is printed on paper covered with a grid of squares.Notice that five small squares on the paper form a larger square. The width of a single small square on ECG paper represents 0.04 seconds.A common length of an ECG printout is 6 seconds; this is known as a "six second strip."
34 Analyze an ECGEach one of the figures represents an ECG pattern displaying three types of abnormal rhythms: Tachycardia, Bradycardia, and Arrhythmia. Identify each.
35 Defibrillator common treatment for life-threatening cardiac arrhythmia The device shocks the heart and allows it to re-establish its normal rhythmThe device can also be used to start a heart that has stopped.
36 Blood Vessels: arteries, veins, capillaries ARTERIES : strong elastic vessels which carry blood moving away from the heart. Smallest ones are arterioles which connect to capillaries.VEINS - Thinner, less muscular vessels carrying blood toward the heart. Smallest ones are called venules which connect to capillaries. Contain valves.
37 Capillaries: Penetrate nearly all tissues Capillaries: Penetrate nearly all tissues. Walls are composed of a single layer of squamous cells – very thin. Critical function: allows exchange of materials (oxygen, nutrients) between blood and tissues.
38 Control of Blood Flow: Precapillary sphincters – circular, valve-like muscle at arteriole-capillary junction Vasoconstriction – narrowing blood vessel’s lumen (“passageway” Vasodilation – explanding blood vessel’s lumen
39 Blood flow through veins – not very efficient Blood flow through veins – not very efficient. Slow, weak “pushing” by arterial blood pressure is not much of a factor at all. Important factors include: 1. Contraction of the diaphragm Pumping action of the skeletal muscles Valves in the veins.
40 Blood Clots can occur if blood does not flow properly through the veins - can occur if a person does not move enough
41 Factors affecting blood pressure: Average is 120/80 (higher number is the systolic pressure) 1. Cardiac Output2. Blood volume (5 liters for avg adult)3. Blood Viscosity4. Peripheral ResistanceCardiac output =stroke volume xheart rate
42 Major Blood VesselsAorta - Ascending Aorta, Aortic Arch, Descending Aorta, Abdominal Aorta. The aorta is the largest artery. (leaves left ventricle) Pulmonary Trunk – splits into left and right, both lead to the lungs (leaves left ventricle) Pulmonary Veins – return blood from the lungs to the heart (connects to left atrium)Superior and Inferior Vena Cava – return blood from the head and body to the heart (connects to right atrium)
44 Disorders of the Circulatory System 1 Disorders of the Circulatory System 1. MVP - mitral valve prolapse, the mitral valve does not close all the way; this creates a clicking sound at the end of a contraction Heart Murmurs – valves do not close completely, causing an (often) harmless murmur sound. Sometimes holes can occur in the septum f the heart which can also cause a murmur 3. Myocardial Infarction (MI) - a blood clot obstructs a coronary artery, commonly called a “heart attack”
45 4. Atherosclerosis – deposits of fatty materials such as cholesterol form a “plaque” in the arteries which reduces blood flow. Advanced forms are called arteriosclerosis. Treatment: Angioplasty, where a catheter is inserted into the artery and a balloon is used to stretch the walls open. A bypass can also treat clogged arteries, a vein is used to replace a clogged artery. Coronary bypass refers to a procedure where the coronary artery is bypassed to supply blood to the heart. (The phrase “quadruple bypass” means that 4 arteries were bypassed.) Video Showing a Stent and Angioplasty (Mayo Clinic) 5. Hypertension – high blood pressure, the force within the arteries is too high. A sphygmomanometer can be used to diagnose hypertension