Chapter 11: The Cardiovascular System A&P Spring 2017

I. Anatomy of the Heart Size, Location and Orientation a. 14cm long 1. Size (of average adult) a. 14cm long b. 9cm wide 2. Location a. Located within the mediastinum i. cavity between the lungs b. Base (top) just below 2nd rib c. Apex (pointed bottom) between 5th & 6th rib

3. Orientation a. base (top) points toward right shoulder b 3. Orientation a. base (top) points toward right shoulder b. apex (bottom) points toward the left hip

B. Coverings and Walls of the Heart 1. Pericardium a. Membrane that covers the heart b. 2 layers i. Fibrous pericardium ii. Serous pericardium (also 2 layers) - Parietal layer - visceral layer

2. Pericardial Cavity a. Space between the parietal and visceral layers b. Contains serous fluid c. Reduces friction between the membranes as the heart moves

3. Wall of the heart (3 layers) a. Outer epicardium i 3. Wall of the heart (3 layers) a. Outer epicardium i. membrane that covers the outside ii. also called visceral layer b. middle myocardium i. made of cardiac muscle ii. thickest layer c. Inner endocardium i. membrane that lines the inside

C. Heart Chambers and Great Vessels 1 C. Heart Chambers and Great Vessels 1. Heart is divided into 4 hollow chambers a. 2 upper chambers called atria i. receive blood returning to heart b. 2 lower chambers called ventricles i. contract to force blood out of the heart

2. Each chamber has a great vessel attached a 2. Each chamber has a great vessel attached a. Superior & Inferior Vena Cava i. attached to the right atrium ii. bring deoxygenated blood back from the body b. Pulmonary trunk i. attached to the right ventricle ii. Branches into two pulmonary arteries iii. Push deoxygenated blood to the lungs

c. Pulmonary veins i. attached to left atrium ii c. Pulmonary veins i. attached to left atrium ii. Bring oxygenated blood back from the lungs d. Aorta i. attached to the left ventricle ii. Push oxygenated blood to the body

D. Heart Valves & Septum 1. Atrioventricular Valves (A-V Valves) a D. Heart Valves & Septum 1. Atrioventricular Valves (A-V Valves) a. Tricuspid Valve i. between right atrium and ventricle ii. Has 3 “cusps” that prevent backflow of blood b. Bicuspid Valve i. between the left atrium and ventricle ii. A.K.A. The Mitral Valve

2. Semilunar Valves a. Pulmonary Semilunar Valve i 2. Semilunar Valves a. Pulmonary Semilunar Valve i. between the right ventricle and pulmonary trunk ii. tricuspid b. Aortic Semilunar Valve i. between the left ventricle and aorta

3. The Septum a. Wall-like structure b 3. The Septum a. Wall-like structure b. Separates left and right atria and ventricles c. blood from the right side NEVER mixes with blood from the left side

E. Circulation Systems 1. Pulmonary circulation a. Right Ventricle b E. Circulation Systems 1. Pulmonary circulation a. Right Ventricle b. Pulmonary Trunk/Arteries c. Lungs d. Pulmonary Veins e. Left Atrium

2. Systemic Circulation a. Left Ventricle b. Aorta c. Body d 2. Systemic Circulation a. Left Ventricle b. Aorta c. Body d. Superior & Inferior Vena Cava e. Right Atrium

F. Cardiac Blood Supply 1. Heart has its own arteries and veins a F. Cardiac Blood Supply 1. Heart has its own arteries and veins a. provide nourishment to the tissues of the heart 2. Coronary Arteries a. branches of the Aorta b. Supply oxygenated blood 3. Cardiac Veins a. branches of the Coronary Sinus b. remove deoxygenated blood

II. Physiology of the Heart Conduction System of the Heart Cardiac muscle cells contract independently Unlike skeletal muscle which must be stimulated by nerve cells Atrial muscle cells contract faster than ventricular muscle cells A control system is required to keep the pumps coordinated

2. Intrinsic conduction system helps regulate heart activity a 2. Intrinsic conduction system helps regulate heart activity a. System sends impulses throughout the heart muscles i. impulses cause muscles cells to contract b. impulses are sent in one direction i. from atria to ventricles c. System sets the basic rhythm i. heart beats about 75 times per minute

Bell Ringer How many times (approximately) does the heart beat each minute? Does the nervous system intrinsically cause the heart to beat?

3. Parts of the Conduction System a. Sinoatrial (SA) Node i 3. Parts of the Conduction System a. Sinoatrial (SA) Node i. located in the right atrium b. Atrioventricular (AV) Node i. located between the atria and ventricles c. Atrioventricular (AV) Bundle i. “Bundle of His” ii. Located in the interventricular septum d. Purkinje fibers i. spread throughout the walls of the ventricle

B. Cardiac Cycle and Heart Sounds 1. Terms a. Systole i B. Cardiac Cycle and Heart Sounds 1. Terms a. Systole i. means Contraction b. Diastole i. means Relaxation c. Cardiac Cycle i. events of one complete heartbeat

2. Cardiac Cycle Steps a. Atrial Systole i. Atria contract ii 2. Cardiac Cycle Steps a. Atrial Systole i. Atria contract ii. A-V Valves open iii. Semilunar Valves closed

b. Ventricular Systole i. Ventricles contract ii. A-V Valves close iii b. Ventricular Systole i. Ventricles contract ii. A-V Valves close iii. Semilunar Valves open

c. Complete Diastole i. Whole heart relaxed ii. A-V Valves re-open iii. Semilunar Valves close

Atrial Systole; Ventricular Diastole Atrial Diastole; Ventricular Systole Atrial & Ventricular Diastole

3. Heart Sounds a. Lub-Dub i 3. Heart Sounds a. Lub-Dub i. Each part of the sound is actually valves in the heart closing b. Lub: i. A-V Valves between the atria and ventricles closing c. Dub i. Pulmonary and Aortic valves between the ventricles and arteries closing

C. Cardiac Output (CO) 1. Cardiac Output Definition a C. Cardiac Output (CO) 1. Cardiac Output Definition a. The amount of blood pumped out by each ventricle in 1 minute b. CO = Heart Rate X Stroke Volume i. Heart Rate = # beats/minute ii. Stroke Volume = volume of blood pumped/beat c. CO = HR (75 beats/min) X SV (70mL/beat) i. CO = ? (L/min)

Bell Ringer List the 3 steps of the cardiac cycle (in your own words). What causes the “Lub-Dub” sound of the heart? What is the body’s natural pacemaker? What is the mathematical formula for cardiac output?

2. Factors Modifying Basic Heart Rate a. Neural Controls i 2. Factors Modifying Basic Heart Rate a. Neural Controls i. Neurons from the Sympathetic division can stimulate the SA and AV nodes to increase heart rate ii. Neurons from the Parasympathetic division can decrease heart rate

b. Hormones and Ions i. Epinepherine can increase heart rate ii. Low levels of calcium can decrease or even stop the heart c. Physical factors i. age, gender, exercise and body temperature can influence heart rate

III. Anatomy of Blood Vessels Tunics (walls) of blood vessels Tunica Intima Inner layer Capillaries consist of only this layer Tunica Media Middle layer Made of smooth muscle Tunica Externa Outer layer Protective cover

B. Arteries, Veins and Capillaries 1. Arteries a B. Arteries, Veins and Capillaries 1. Arteries a. Walls are much thicker than veins i. must be able to expand as blood is forced in from the heart b. Carry blood away from the heart

2. Veins a. thinner walls because of lower pressure b 2. Veins a. thinner walls because of lower pressure b. carry blood toward the heart c. larger veins have valves i. prevents backflow of blood ii. Needed because veins travel against gravity

3. Capillaries a. vessels that connect arteries and veins b 3. Capillaries a. vessels that connect arteries and veins b. gases and products are exchanged here i. O2 and nutrients go from blood to cells ii. CO2 and waste go from cells to blood c. form HUGE networks all over the body

IV. Physiology of Circulation Blood Pressure Measure of the amount of force blood is exerting on the arteries Systolic Blood Pressure Measurement during ventricular contraction Maximum pressure Diastolic Blood Pressure Measurement during ventricular relaxation Minimum pressure

B. Variations in Blood Pressure 1. Hypotension a. Low blood pressure i B. Variations in Blood Pressure 1. Hypotension a. Low blood pressure i. Systolic below 100 b. Usually not a bad thing but… i. Sudden hypotension can be a warning sign of circulatory shock

2. Hypertension a. High Blood Pressure i. BP of 140/90 or higher b 2. Hypertension a. High Blood Pressure i. BP of 140/90 or higher b. Called the “silent killer” i. over time it can strain the heart ii. Can also damage the arteries