Essentials of Human Anatomy & Physiology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Seventh Edition Elaine N. Marieb Chapter 11 The Cardiovascular System

The Cardiovascular System Slide 11.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  A closed system of the heart and blood vessels  The heart pumps blood  Blood vessels allow blood to circulate to all parts of the body  The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products

The Heart Slide 11.2a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Location  Thorax between the lungs Called the Mediastinum  About the size of your fist  Less than 1 lb.

The Heart Slide 11.2b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 11.1

The Heart: Coverings Slide 11.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Pericardium – a double serous membrane The Heart: Heart Wall (3 Layers)  Epicardium  Outside layer  Connective tissue layer  Myocardium  Middle layer  Mostly cardiac muscle  Endocardium  Inner layer

External Heart Anatomy Slide 11.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 11.2a

The Heart: Chambers Slide 11.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Right and left side act as separate pumps  Four chambers  Atria (Superior)  Receiving chambers: Small with thin walls  Right atrium  Left atrium  Ventricles (Inferior)  Discharging chambers: Big with thick walls  Right ventricle  Left ventricle

Blood Vessels  Arteries: “Superhighways”  Carry blood away from the heart to the body  Thick elastic walls to withstand spurts of blood produced by heart contractions Veins: “Roads” Thin walled and less elastic Collect blood after it passes through capillaries and sends blood back to the heart

Blood Vessels Capillaries: “Side-streets and alleys” Smallest, microscopic vessels Wastes and nutrients are diffused through capillary membranes into and out of cells

Blood Circulation Slide 11.7 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 11.3

Pathway of Blood Pulmonary Circuit Right side of heart  heart to lungs back to heart Oxygen poor and carbon dioxide rich blood Short, low pressure circuit Right ventricle is not as thick as the left

Pathway of Blood Systemic Circuit Left side of the heart  from heart to body to heart Oxygen rich and carbon dioxide poor blood Long, high pressure circuit because it pumps to entire body Left ventricle is 3x as thick as the right

Pathway of Blood 1.Superior/Inferior Vena Cavae 2.Right Atrium 3.Right Ventricle 4.Pulmonary Artery 5.Lungs 6.Pulmonary Veins 7.Left Atrium 8.Left Ventricle 9.Aorta 10.Arteries and Capillaries 11.Veins back to the Heart

The Heart: Valves Slide 11.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Allow blood to flow in only one direction  Four valves  Atrioventricular valves – between atria and ventricles  Bicuspid valve (left)  Tricuspid valve (right)  Semilunar valves between ventricle and artery  Pulmonary semilunar valve  Aortic semilunar valve: guards base of artery

The Heart: Valves Slide 11.9 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Valves open as blood is pumped through  Held in place by chordae tendineae (“heart strings”)  Close to prevent backflow

Operation of Heart Valves Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 11.4

A graphic picture of cardiac conduction cycle Three formations “waves” –P wave: Atria depolarize and contract –Small, lasts.08 seconds –QRS complex: ventricles depolarize and contract –Larger, lasts.08 seconds –T wave: ventricles repolarize and relax –More spread out, low height Electrocardiograms (EKG/ECG)

Electrocardiograms (EKG/ECG) (cont.) Figure 8.15B, C

Blood Pressure Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Measurements by health professionals are made on the pressure in large arteries  Force exerted by blood against inner walls of blood vessels  Systolic – left ventricle; contracting and pushing blood into Aorta causes pressure to peak  Diastolic – amount of pressure that the Aorta and Arteries can maintain on reducing blood volume. Ex: 120/70

Measuring Arterial Blood Pressure Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 11.18

Variations in Blood Pressure Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Human normal range is variable  Normal  140–110 mm Hg systolic  80–75 mm Hg diastolic  Hypotension  Low systolic (below 110 mm HG)  Often associated with illness  Hypertension  High systolic (above 140 mm HG)  Can be dangerous if it is chronic

Heart Sounds  “Lub-dub”: closing of the heart valves  1 st Sound: “Lub”  AV valves closing  2 nd Sound: “Dub”  Semi-lunar valves closing  Heart Murmurs  Indicate valve problem (Ex: Leaky Valve)  Pacemaker  Small mass of cells on the posterior of right atrium just inferior to superior vena cava  They “excite” themselves and initiate rhythmic contractions of the heart, the S-A node

The Heart: Cardiac Output Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Cardiac output (CO)  Amount of blood pumped by each side of the heart in one minute  CO = (heart rate [HR]) x (stroke volume [SV])  Stroke volume  Volume of blood pumped by each ventricle in one contraction

Cardiac output, cont. CO = Heart Rate x Stroke Volume – Normal = 5000 ml/min Example: HR= 75 beats/min SV= 70 mL/ beat CO=? Entire blood supply passes through body once per minute. CO varies with demands of the body. CO= 75 x 70 CO= 5250 ml/min= 5.25 L/min

Cardiac Reserve Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  The ability of the heart to push its cardiac output beyond normal limit depends on the person  Most can push their CO up to 4x beyond normal, whereas trained athletes can push their CO up to 7x above normal

Sterling’s Law of the Heart Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  The enlargement of the ventricular chambers drives stroke volume and the force of heart contractions  The more blood received by the right atrium through the SVC and IVC the stronger the ventricular contraction and the greater the stroke volume and cardiac output