The Cardiovascular System: The Heart 18

Coverings of the Heart: Anatomy & Physiology Pericardium – a double-walled sac around the heart Pericardial walls are separated by the fluid-filled pericardial cavity Protects and anchors the heart Prevents overfilling of the heart with blood Reduces friction

Layers of the Heart: The Heart Wall Epicardium – visceral layer of the pericardium Myocardium – cardiac muscle layer forming the bulk of the heart Endocardium – endothelial layer of the inner myocardial surface

Atria are the receiving chambers of the heart Atria of the Heart Atria are the receiving chambers of the heart Blood enters right atrium from superior and inferior vena cava and coronary sinus (vein from the heart) Blood enters left atrium from pulmonary veins From the lungs

Ventricles of the Heart Ventricles are the discharging chambers of the heart Right ventricle pumps blood into the pulmonary artery Left ventricle pumps blood into the aorta

Also called the interventricular septum The left and right side of the heart is divided by a tissue wall called the septum Also called the interventricular septum

How does the heart prevent blood from flowing backwards? 2/20 Open your notes to page 55. I will be checking for questions on page 54 Heart diagram: in space below diagram or on post it note Take out a sheet of paper for new notes. Page 57 Copy the EQ at the top of the page. EQ: How does the heart prevent blood from flowing backwards?

Heart valves ensure unidirectional blood flow through the heart Two types: atrioventricular and semilunar Atrioventricular (AV) valves lie between the atria and the ventricles: Tricuspid between the right atria and ventricle Bicuspid/mitral between the left atria and ventricle AV valves prevent backflow into the atria when ventricles contract

Semilunar valves prevent backflow of blood into the ventricles Heart Valves Semilunar valves prevent backflow of blood into the ventricles Aortic semilunar valve lies between the left ventricle and the aorta Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk (artery)

New EQ: copy the following: How is heart rate regulated and controlled?

Heart Physiology: Sequence of Excitation The brain sends a message to the Sinoatrial (SA) node The message is sent to the Atrioventricular (AV) node Impulse passes from atria to ventricles via the atrioventricular bundle (bundle of His) continued

Heart Physiology: Sequence of Excitation AV bundle splits into two pathways in the interventricular septum (bundle branches) Bundle branches carry the impulse toward the apex of the heart Purkinje fibers carry the impulse to the heart apex and ventricular walls

Be prepared to flip to page 56 so show me your questions on this page 2/21 Open your notes to page 54. I will be stamping for a summary on this page. Be prepared to flip to page 56 so show me your questions on this page Put the following EQ on a new sheet of paper (Pg 59) EQ: How is blood flow through the heart and the rest of the body measured?

Used to determine Blood Pressure Cardiac Cycle Cardiac cycle refers to all events associated with blood flow through the heart Systole – contraction of heart muscle Diastole – relaxation of heart muscle Usually associated with ventricle contraction Used to determine Blood Pressure (more in chapter 19)

The pulse measures the flow of blood in the arteries As blood flows through, the pressure of the blood causes the artery to expand Directly related to heart rate

Heart sounds (lub-dup) are associated with closing of heart valves First sound occurs as AV valves close and signifies beginning of systole Second sound occurs when SL valves close at the beginning of ventricular diastole

New EQ for a new page of notes(page 61) 2/22/19 Open notes to pages 56 and 58 for me to stamp summary and questions Copy the EQ on a new sheet of paper (page 61) EQ: What is the structure and function of the blood vessels?

The Cardiovascular System: Blood Vessels 19

Carry blood away from the heart Thick middle muscle layer arteries Carry blood away from the heart Thick middle muscle layer Must withstand more pressure

Carry blood back to the heart Thinner muscular layer veins Carry blood back to the heart Thinner muscular layer Contain valves to prevent back flow of blood

Capillaries- smallest blood vessels Walls consisting of a thin internal layer , one cell thick Allow only a single RBC to pass at a time contact tissues and exchange materials with the cells

Cardiac Cycle (review) Cardiac cycle refers to all events associated with blood flow through the heart Systole – contraction of heart muscle Diastole – relaxation of heart muscle Usually associated with ventricle contraction Used to determine Blood Pressure Do not copy

Determined by heart sounds BP Determined by heart sounds Pressure cuts off blood flow in artery Pressure is released and blood flow is restored Creates a thumping sound This is the systolic pressure Eventually the sounds go away when flow is restored to 100% This is the diastolic pressure Continued on next slide

BP Written as: Systolic / Diastolic Ex: 120 / 80

Alterations in Blood Pressure Hypotension – low BP in which systolic pressure is below 100 mm Hg or diastolic under 60 Hypertension – condition of sustained elevated arterial pressure of 140/90 or higher Acute elevation can be caused by fever, physical exertion, and emotional upset Chronic elevation is a major cause of heart failure/attack, vascular (blood vessel) disease, renal failure, and stroke