Lecture Outline 1

Objectives Describe the structure, function, location, and orientation of the heart including external and internal features.

Chapter 20 The Cardiovascular System: The Heart Principles of Human Anatomy and Physiology, 11e3

ANATOM Y OF THE HEART Principles of Human Anatomy and Physiology, 11e4

ANATOMY OF THE HEART Principles of Human Anatomy and Physiology, 11e5

Location of the heart The heart is situated between the lungs in the mediastinum (Figure 20.1). Principles of Human Anatomy and Physiology, 11e6

Heart Orientation Principles of Human Anatomy and Physiology, 11e7

Pericardium Encloses and holds heart in place. Consists of an outer fibrous pericardium an inner serous pericardium (epicardium composed of a parietal layer a visceral layer. Fluid between these two layers reduces friction Principles of Human Anatomy and Physiology, 11e8

Layers of Heart Wall Epicardium visceral layer of serous pericardium Myocardium cardiac muscle layer is the bulk of the heart Endocardium chamber lining & valves Principles of Human Anatomy and Physiology, 11e9

Chambers and Sulci Principles of Human Anatomy and Physiology, 11e10 Anterior View

Chambers and Sulci Principles of Human Anatomy and Physiology, 11e11 Posterior View

Objectives Describe the structure, function, location, and orientation of the heart including external and internal features. Trace the flow of blood through the heart noting which part of the heart the blood is actually passing through.

Right Atrium Receives blood from: superior vena cava inferior vena cava coronary sinus Tricuspid valve Blood flows through into right ventricle Principles of Human Anatomy and Physiology, 11e13

Right Ventricle Chordae tendineae: cords between valve cusps and papillary muscles Interventricular septum: partitions ventricles Pulmonary semilunar valve: blood flows into pulmonary trunk Principles of Human Anatomy and Physiology, 11e14

Left Atrium Forms most of the base of the heart Receives blood from lungs - 4 pulmonary veins (2 right + 2 left) Bicuspid valve: blood passes through into left ventricle Principles of Human Anatomy and Physiology, 11e15

Left Ventricle Forms the apex of heart Chordae tendineae anchor bicuspid valve to papillary muscles Aortic semilunar valve: blood passes through valve into the ascending aorta just above valve are the openings to the coronary arteries Principles of Human Anatomy and Physiology, 11e16

Myocardial Thickness and Function Thickness of myocardium varies according to the function of the chamber Atria are thin walled, deliver blood to adjacent ventricles Principles of Human Anatomy and Physiology, 11e17 Ventricle walls are much thicker and stronger –right ventricle supplies blood to the lungs (little flow resistance) –left ventricle wall is the thickest to supply systemic circulation

Objectives Compare and contrast pulmonary and systemic circulation with respect to: Direction of blood flow Oxygen content of blood Vessels traveled through Organs involved The side of the heart involved in each case.

Blood Circulation Blood flow blue = deoxygenated red = oxygenated Principles of Human Anatomy and Physiology, 11e19

Blood Circulation Two closed circuits, Systemic circulation Left side of heart pumps blood through body Pathway oxygenated blood from LV  aorta  many arteries  arterioles in tissue of organs  capillaries (gas & nutrient exchange)  deoxygenated blood  venules  veins  right atrium Pulmonary circulation right side of heart pumps deoxygenated blood to lungs Pathway RV pumps blood  pulmonary trunk  pulmonary arteries  lungs (exchange of gases)  pulmonary veins  heart Principles of Human Anatomy and Physiology, 11e20

Objectives Explain the spread of conduction through the heart. Interpret an electrocardiogram.

Conduction System of Heart Principles of Human Anatomy and Physiology, 11e22 Coordinates contraction of heart muscle.

Autorhythmic Cells: The Conduction System Cardiac muscle cells are autorhythmic cells because they are self-excitable. They repeatedly generate spontaneous action potentials that then trigger heart contractions. These cells act as a pacemaker to set the rhythm for the entire heart. They form the conduction system, the route for propagating action potential through the heart muscle. Principles of Human Anatomy and Physiology, 11e23

Physiology of Contraction Depolarization, plateau, repolarization Principles of Human Anatomy and Physiology, 11e24

Electrocardiogram---ECG or EKG EKG Action potentials of all active cells can be detected and recorded P wave atrial depolarization P to Q interval conduction time from atrial to ventricular excitation QRS complex ventricular depolarization T wave ventricular repolarization Principles of Human Anatomy and Physiology, 11e25

Objectives Explain the feedback loop for heart rate. Describe the effects of exercise on the heart. Compare and contrast types of blood vessels. Describe blood pressure.

Regulation of Heart Rate Medulla Sympathetic =increase heart rate and force of contraction parasympathetic = decrease heart rate. Baroreceptors (pressure receptors) detect change in BP and send info to the cardiovascular center located in the arch of the aorta and carotid arteries Heart rate is also affected by hormones epinephrine, norepinephrine, thyroid hormones ions (Na +, K +, Ca 2+ ) age, gender, physical fitness, and temperature Principles of Human Anatomy and Physiology, 11e27

EXERCISE AND THE HEART A person’s cardiovascular fitness can be improved with regular exercise. Aerobic exercise (any activity that works large body muscles for at least 20 minutes, preferably 3 – 5 times per week) increases cardiac output and elevates metabolic rate. Several weeks of training results in maximal cardiac output and oxygen delivery to tissues Regular exercise also decreases anxiety and depression, controls weight, and increases fibrinolytic activity. Sustained.exercise increases oxygen demand in muscles Principles of Human Anatomy and Physiology, 11e28

Principles of Human Anatomy and Physiology, 11e29 Vessels Blood vessels form a closed system of tubes that carry blood away from the heart, transport it to the tissues of the body, and then return it to the heart. Arteries carry blood from the heart to the tissues. Arterioles are small arteries that connect to capillaries. Capillaries are the site of substance exchange between the blood and body tissues. Venules connect capillaries to larger veins. Veins convey blood from the tissues back to the heart. Vaso vasorum are small blood vessels that supply blood to the cells of the walls of the arteries and veins.

Principles of Human Anatomy and Physiology, 11e30 Arterial Branches of Systemic Circulation

Principles of Human Anatomy and Physiology, 11e31 Veins of the Systemic Circulation

Blood Pressure Measure of the force of blood How it is measured Using a sphygmanometer Temporarily stop arterial flow, then, when air is released, the first time blood flow is heard is the top number (systolic) Pressure during contraction The last time you hear the blood flow is the bottom number (diastolic) Pressure during relaxation Units: mmHg