Week #5 (4/18-4/20) Warm Up – Mon, 4/18: - Finish Pig Dissections Have out:  1 piece of paper with Name, Per & Date labeled “How to take Blood Pressure” Pick up:  Cardiac Output, Blood Pressure & Pulse notes Agenda: 1.Cardiac Output, Blood Pressure & Pulse notes 2.How to Take Blood Pressure Homework: 1.Pig Heart Dissection Lab Abstract (3D) – Mon, 4/25 2.Heart/Circulation Quiz –Fri, 4/22 (Earth Day!) Anatomy Fun Fact: In 1929, German surgeon Werner Forssmann ( ) examined the inside of his own heart by threading a catheter into his arm vein & pushing it 20 inches into his heart, inventing cardiac catheterization, a now common procedure.

How Does the Heart Know to Beat? Heart Conduction System

The Heart: Conduction System Intrinsic conduction system (nodal system) Heart muscle cells contract, without nerve impulses, in a regular, continuous way Special tissue sets pace Sinoatrial node = SA node (“pacemaker”), is in R atrium Atrioventricular node = AV node, is at junction of atria & ventricles Atrioventricular bundle = AV bundle (bundle of His), is in interventricular septum Bundle branches are in interventricular septum Purkinje fibers spread within ventricle wall muscles

Heart Contractions Contraction is initiated by the sinoatrial node (SA node) Sequential stimulation occurs at other autorhythmic cells (pacemaker cells) Force cardiac muscle depolarization in 1 direction—from atria to ventricles Once SA node starts the heartbeat Impulse spreads to AV node Then atria contract At AV node, the impulse passes through the AV bundle, bundle branches & Purkinje fibers Blood is ejected from ventricles to aorta & pulmonary trunk as ventricles contract

The Cardiovascular System Pulse, Blood Pressure & Cardiac Output

Pulse (Heart Rate)  Pulse  Pressure wave of blood  Monitored at “pressure points” in arteries where pulse is easily palpated  Pulse averages 70–76 beats/min at rest  Also known as “heart rate”

Regulation of Heart Rate  Increased heart rate  Sympathetic NS  Crisis  Low blood pressure  Hormones  Epinephrine  Thyroxine  Exercise  Decreased blood volume  Decreased heart rate  Parasympathetic NS  High blood pressure or blood volume  Decreased venous return

Variations in Heart Rate  Tachycardia— rapid heart rate  “tach” - swift over 100 beats/min  Bradycardia— slow heart rate  “brady(s)” - slow less than 60 beats/min

The Heart: Cardiac Cycle  Atria contract simultaneously  Atria relax, then ventricles contract  Systole = contraction  Ventricles contract, pushing blood out  Diastole = relaxation  Atria refilling with blood  Blood flowing from atria into ventricles

Blood Pressure  Measurements by health professionals are made on the pressure in large arteries  Systolic—pressure at peak of ventricular contraction  Diastolic—pressure when ventricles relax  1 st - systolic  2 nd - diastolic  Ex: 120/80 mm Hg  Pressure in blood vessels decreases as distance from heart increases…WHY? Comparison of Blood Pressures in Different Vessels Blood Pressure videoBlood Pressure video ~ 2 mins.

Measuring Arterial Blood Pressure Figure 11.20a How to Take Blood Pressure

Blood Pressure Variations  Blood pressure  Affected by age, weight, time of day, exercise, body position, emotional state  Normal human 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

Blood Pressure: Effects of Factors  Neural factors  Autonomic NS adjustments (sympathetic division)  Renal (kidney) factors  Regulation by altering blood volume  Renin—hormonal control  Temperature  Heat has a vasodilating effect  Cold has a vasoconstricting effect  Chemicals/drugs  Various substances can cause increases or decreases  Diet

Factors Determining Blood Pressure Figure 11.21

Week #5 (4/18-4/20) Warm Up – Mon, 4/18: - Finish Pig Dissections Have out:  1 piece of paper with Name, Per & Date labeled “How to take Blood Pressure” Pick up:  Cardiac Output, Blood Pressure & Pulse notes Agenda: 1.Finish Cardiac Output, Blood Pressure & Pulse notes 2.Heart/Circulation Quiz 3.Work on Final Exam Homework: 1.Pig Heart Dissection Lab Abstract (3D) – Mon, 4/25 2.Heart/Circulation Quiz –Today (Earth Day!) Anatomy Fun Fact: In 1929, German surgeon Werner Forssmann ( ) examined the inside of his own heart by threading a catheter into his arm vein & pushing it 20 inches into his heart, inventing cardiac catheterization, a now common procedure.

The Heart: Cardiac Output  Cardiac output (CO)  Amount of blood pumped by each ventricle of heart in 1 min  Heart rate (HR)/pulse  ~75 beats/min  Starling’s law of the heart—the more the cardiac muscle is stretched, the stronger the contraction  Changing HR is most common way to change CO

Cardiac Output Regulation Figure 11.8

The Heart – Blood Pressure Active Reading Read QUIETLY through the passage on blood pressure. Answer the 2 short answer questions in COMPLETE SENTENCES & the multiple choice question based on what you read. When finished, turn your wkst in.