Ch. 13 – Cardiovascular/Circulatory System I.Introduction A.The blood vessels form a closed tube that carry 7,000 liters of blood away from the heart, to the cells, and back again B.Vessels – 5 types 1.the heart pumps blood thru arteries, then to smaller arterioles, to tiny capillaries  Arteries are thick vessels adapted for carrying high-pressure blood away from the heart

capillaries are the sites of nutrient, electrolyte, gas, & waste exchange 3.capillaries return blood to small venules, then onto larger veins  Veins are thinner than arteries & return blood to the heart Pg. 338

This is what happens when blood is drawn from a deeper artery, rather than a superficial vein

C.Two Circuits 1.Pulmonary Circuit – sends deoxygenated blood to lungs (to pick up O 2 and drop off CO 2 ) 2.Systemic Circuit – sends oxygenated blood and nutrients to all body cells and removes wastes Pg. 324

II. Structure of the Heart A.The heart is a hollow, muscular pump within the thoracic cavity B.Coverings of the Heart 1.Pericardial sac encloses the heart a.fibrous pericardium - outer, tough connective tissue b.parietal pericardium - lines fibrous pericardium 2.visceral pericardium (epicardium) – surrounds the heart 3.pericardial cavity – fluid filled space b/t sac & v.p. to reduce friction Pg. 325

C.Wall of the Heart – 3 layers 1.Epicardium - outermost layer made of connective tissue; houses capillaries, coronary arteries, & cardiac veins 2.Myocardium – thickest, middle layer that consists of cardiac muscle 3.Endocardium - inner layer; lines inside of heart Pg. 326

D.Heart Chambers 1.The heart has 4 chambers – 2 atria & 2 ventricles a.Atria receive blood returning to the heart and have thin walls & flap-like auricles projecting from their exterior b.The thick-walled ventricles pump blood to the body 2.Each also has an atrioventricular (A-V) valve to ensure one way flow of blood 3.A septum divides the atrium & ventricle on each side Pg. 331

Deoxygenated Blood  Superior & Inferior vena cava  Right atrium  Tricuspid valve  Right ventricle  Pulmonary Valve  Pulmonary trunk  2 Pulmonary arteries  Capillaries of LUNGS  E.Path of Blood through the Heart Oxygenated Blood  4 Pulmonary veins  Left atrium  Bicuspid/Mitral valve  Left ventricle  Aortic valve  Aorta  Cells of the Body

A-V valves open & close using chordae tendinae (heart strings), attached to papillary muscles  Valves prevent backflow of blood into atria 2.Pulmonary & Aortic valves are also known as Semi-Lunar valves, due to their crescent shapes Pg. 328 Pg (Blood Flow) Circulatory System rap!

F.Blood Supply to the Heart Muscle 1.Coronary arteries feed the heart muscle (myocardium) with O 2, from the aorta 2.Cardiac veins drain CO 2 -ridden blood from the myocardium & carry it to the superior and inferior vena cavae Pg. 331

III. Heart Actions A.Blood pressure is the force of blood against the inner walls of arteries (120/60)  systolic pressure over diastolic pressure B.The cardiac cycle consists of: 1.Atria beating in unison (atrial systole) 2.Contraction of both ventricles (ventricular systole = systolic pressure) 3.The entire heart relaxes for a moment (diastole = diastolic pressure) C.Pulse - ventricle contraction felt in arteries

D.Heart Sounds – due to vibrations in heart tissues as blood rapidly changes velocity within the heart 1.Heart sounds can be described as "lubb-dupp" sounds or“Korotkoff” sounds 2.“lubb” occurs as ventricles contract (Tricuspid & Bicuspid valves close) 3.“dupp” occurs as ventricles relax (Pulmonary & Aortic valves close) LISTEN:

IV.Cardiac Conduction System A.A few clumps of cardiac muscle tissue initiate & distribute impulses through the myocardium, from 1 intercalated disk of a cardiac muscle cell to the next disk B.Sinoatrial (S-A) Node – a pacemaker 1.a small, elongated mass of tissue beneath the epicardium 2.located in the R-atrium, near the opening of the superior vena cavae 3.w/o outside agents, the nodal cells spread impulses to cause the heart to contract

C.Path of Stimulation 1.S-A node sends impulse & the atria contract simultaneously, sending blood into the ventricles 2.The impulse then travels to the atrioventricular (A- V) node & onto the A-V bundle at the top of the septum 3.About halfway down the septum, the A-V bundle branches into Purkinje fibers 4.Purkinje fibers spread to papillary muscles that form whorls in the walls of the ventricles Pg. 334

When impulses reach Purkinje fibers, the ventricles contract with a twisting motion, forcing blood into the aorta and pulmonary trunk LOOK & LISTEN: Cardiac Conduction & Sounds Arrhythmias Pg. 334

D.Electrocardiogram (ECG or EKG) 1.a recording of the electrical changes that occur in the myocardium during a cardiac cycle 2.body fluids can conduct electrical currents, so such changes can be detected on the surface of the body Pg. 335

Patterns  P wave: depolarization of atrial fibers that lead to atrial contraction  QRS complex: when rapid depolarization in ventricular fibers comes to an end (at the same time, atrial fibers repolarize, but are immeasurable)  T wave: repolarization of ventricular muscle fibers Pg. 335 Time b/t intervals can signal heart problems