The Circulatory System The Heart, Blood Vessels, Blood Types
The Closed Circulatory System Humans have a closed circulatory system, typical of all vertebrates, in which blood is confined to vessels and is distinct from the interstitial fluid. The heart pumps blood into large vessels that branch into smaller ones leading into the organs. Materials are exchanged by diffusion between the blood and the interstitial fluid bathing the cells.
The Cardiovascular System Three Major Elements Heart, Blood Vessels, & Blood 1. The Heart- cardiac muscle tissue highly interconnected cells four chambers Two atria Upper chambers Left and right Two ventricles Lower chambers Left and right
Heart coverings Pericardium Heart: Structures Covers the heart and large blood vessels attached to the heart Visceral pericardium Innermost layer Directly on the heart Parietal pericardium Layer on top of the visceral pericardium
Heart Wall Three layers of tissue Epicardium: This serous membrane of smooth outer surface of heart Myocardium: Middle layer composed of cardiac muscle cell and responsibility for heart contracting Endocardium: Smooth inner surface of heart chambers
Heart: Structures
Superior Vena Cava Right Atrium Tricuspid Valve Right Ventricle Pulmonary Semilunar Valve Lungs Pulmonary Vein Bicuspid Valve Left Ventricle Aortic Semilunar Valve Aorta To the bodies organs & cells Pathway of the blood
Pathway of the blood Right Atrium Tricuspid Valve Right Ventricle Pulmonary Valve Body Lungs Aortic Semilunar Valve Left Ventricle Bicuspid Valve Left Atrium Pulmonary Semilunar Valve
Heart: External Anatomy Four chambers 2 atria 2 ventricles Auricles Major veins Superior vena cava Pulmonary veins Major arteries Aorta Pulmonary trunk
External Anatomy
Heart: Valves Prevent blood from flowing back
Heart Valves
Function of the Heart Valves
Heart: Cardiac Muscle Elongated, branching cells containing 1-2 centrally located nuclei Contains actin and myosin myofilaments Intercalated disks: Specialized cell-cell contacts Desmosomes hold cells together and gap junctions allow action potentials Electrically, cardiac muscle behaves as single unit
Heart: Functions Generating blood pressure Routing blood Heart separates pulmonary and systemic circulations Ensuring one-way blood flow Heart valves ensure one-way flow Regulating blood supply Changes in contraction rate and force match blood delivery to changing metabolic needs
Cardiac Cycle Heart is two pumps that work together, right and left half Repetitive contraction (systole) and relaxation (diastole) of heart chambers Blood moves through circulatory system from areas of higher to lower pressure. Contraction of heart produces the pressure
The Heart: Cardiac Cycle One heartbeat = one cardiac cycle Atria contract and relax Right atrium contracts Tricuspid valve opens Blood fills right ventricle Left atrium contracts Bicuspid valve opens Blood fills left ventricle Ventricles contract and relax Right ventricle contracts Tricuspid valve closes Pulmonary semilunar valve opens Blood flows into pulmonary artery Left ventricle contracts Bicuspid valve closes Aortic semilunar valve opens Blood pushed into aorta 27-18
Cardiac Cycle
The Heart: Cardiac Cycle (cont.) Influenced by Exercise Parasympathetic nerves Sympathetic nerves Cardiac control center Body temperature Potassium ions Calcium ions 27-20
Heart: Electrical Properties Resting membrane potential (RMP) present Cardiac Cell at rest are considered polarized, meaning no electrical activity takes place. Electrical impulses are generated by automaticity of specialized cardiac cells A certain amount of electrical impulse needed to release action potential Once an electrical cell generates an electrical impulse, this electrical impulse causes the ions to cross the cell membrane and causes the action potential, also called depolarization The movement of ions across the cell membrane through sodium, potassium and calcium channels, is the drive that causes contraction of the cardiac cells/muscle
Depolarization with corresponding contraction of myocardial muscle moves as a wave through the heart Repolarization is the return of the ions to their previous resting state, which corresponds with relaxation of the myocardial muscle Depolarization and repolarization are electrical activities which cause muscular activity The action potential curve shows the electrical changes in the myocardial cell during the depolarization repolarization cycle This electrical activity is what is detected on ECG, not the muscular activity
Action Potentials in Skeletal and Cardiac Muscle
SA Node Action Potential
Electrocardiogram Action potentials through myocardium during cardiac cycle produces electric currents than can be measured Pattern P wave Atria depolarization QRS complex Ventricle depolarization Atria repolarization T wave: Ventricle repolarization
Heart: Sounds First heart sound or lubb Atrioventricular valves and surrounding fluid vibrations as valves close at beginning of ventricular systole Second heart sound or dupp Results from closure of aortic and pulmonary semilunar valves at beginning of ventricular diastole, lasts longer Third heart sound (occasional) Caused by turbulent blood flow into ventricles and detected near end of first one-third of diastole
Heart: Mean Arterial Pressure (MAP) Average blood pressure in aorta MAP=CO x PR CO is amount of blood pumped by heart per minute CO=SV x HR SV: Stroke volume of blood pumped during each heart beat HR: Heart rate or number of times heart beats per minute Cardiac reserve: Difference between CO at rest and maximum CO PR is total resistance against which blood must be pumped
Heart: Effects of Aging Gradual changes in heart function, minor under resting condition, more significant during exercise Hypertrophy of left ventricle Maximum heart rate decreases Increased tendency for valves to function abnormally and arrhythmias to occur Increased oxygen consumption required to pump same amount of blood
The Cardiovascular System 2. Blood Vessels -A network of tubes Arteries arterioles move away from the heart Elastic Fibers Circular Smooth Muscle Capillaries where gas exchange takes place. One cell thick Serves the Respiratory System Veins Venules moves towards the heart Skeletal Muscles contract to force blood back from legs One way values When they break - varicose veins form
Circuits Pulmonary circuit The blood pathway between the right side of the heart, to the lungs, and back to the left side of the heart. Systemic circuit The pathway between the left and right sides of the heart.
Circulation Pulmonary circuit right atrium right ventricle pulmonary arteries lungs pulmonary veins heart (left atrium) Systemic circuit left atrium left ventricle aorta arteries arterioles capillaries venules veins vena cava heart (right atrium) 27-32
Circulation (cont.) Arterial system Carry oxygen-rich blood away from the heart Pulmonary arteries carry oxygen-poor blood Paired left and right artery of the same name 27-33
Circulation (cont.) Venous system Carries oxygenpoor blood toward the heart Except pulmonary veins Most large veins have the same names as the arteries they are next to Hepatic portal system Collection of veins carrying blood to the liver Click for Larger View 27-34
The Cardiovascular System 3. The Blood A. Plasma Liquid portion of the blood. Contains clotting factors, hormones, antibodies, dissolved gases, nutrients and waste
The Cardiovascular System The Blood B. Erythrocytes - Red Blood Cells Carry hemoglobin and oxygen. Do not have a nucleus and live only about 120 days. Cannot repair themselves.
The Blood The Cardiovascular System C. Leukocytes White Blood cells Fight infection and are formed in the bone marrow Five types Neutrophils Lymphocytes Eosinophils Basophils Monocytes
The Cardiovascular System The Blood D. Thrombocytes Platelets. These are cell fragment that are formed in the bone marrow from magakaryocytes. Clot Blood by sticking together via protein fibers called fibrin.
ABO Blood Grouping System According to the ABO blood typing system there are four different kinds of blood types: A, B, AB or O (null).
Blood Types http://www.bloodbook.com/world-abo.html
AB0 blood grouping system Blood group A If you belong to the blood group A, you have A antigens on the surface of your RBCs and B antibodies in your blood plasma. Blood group B If you belong to the blood group B, you have B antigens on the surface of your RBCs and A antibodies in your blood plasma.
Blood group AB If you belong to the blood group AB, you have both A and B antigens on the surface of your RBCs and no A or B antibodies at all in your blood plasma. Blood group O If you belong to the blood group O (null), you have neither A or B antigens on the surface of your RBCs but you have both A and B antibodies in your blood plasma.
Blood transfusions who can receive blood from whom? People with blood group O are called "universal donors" and people with blood group AB are called "universal receivers."
Blood Group Antigens Antibodies Can give blood to Can receive blood from AB A B O
Blood Group Antigens Antibodies Can give blood to Can receive blood from AB A and B None AB AB, A, B, O A A B A and AB A and O B B A B and AB B and O O None A and B AB, A, B, O O
Disorders of the Circulatory System Anemia - lack of iron in the blood, low RBC count Leukemia - white blood cells proliferate wildly, causing anemia Hemophilia - bleeder s disease, due to lack of fibrinogen in thrombocytes Heart Murmur - abnormal heart beat, caused by valve problems Heart attack - blood vessels around the heart become blocked with plaque, also called myocardial infarction
Cardiac Arrhythmias Tachycardia: Heart rate in excess of 100bpm Bradycardia: Heart rate less than 60 bpm Sinus arrhythmia: Heart rate varies 5% during respiratory cycle and up to 30% during deep respiration Premature atrial contractions: Occasional shortened intervals between one contraction and succeeding, frequently occurs in healthy people