Cardiovascular Circuits & Heart Physiology 11b

How does blood flow through the heart and body?

Blood Flow Through the Heart & Body Pulmonary Circulation Blood flow through lungs Systemic Circulation Blood flow through body Coronary Circulation Blood flow through heart

Pulmonary Circulation Occurs in Lungs FUNCTION Add Oxygen to blood, remove Carbon Dioxide from blood Process Oxygen Poor blood leaves Right Ventricle through Pulmonary Arteries Oxygen Poor blood flows through lungs and becomes Oxygen Rich Oxygen Rich blood leaves lungs and enters Left Atrium through the Pulmonary Veins

Systemic Circulation Occurs in Body FUNCTION Process To deliver oxygen and nutrients to body cells and remove carbon dioxide and waste from cells Process Oxygen Rich blood leaves Left Ventricle through Aorta Oxygen Rich blood is delivered to cells all over the body and becomes oxygen poor Oxygen Poor blood enters the Right Atrium through the Superior and Inferor Vena Cava

Blood Flow through heart animation http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumping.html

How are the tissues and cells of the heart nourished How are the tissues and cells of the heart nourished? Don’t they need a lot of oxygen and nutrients?

Coronary Circulation FUNCTION: Process: Coronary arteries Nourish Heart cells Process: Coronary arteries Deliver Oxygen rich blood from the Aorta to heart cells Cardiac veins Oxygen Poor blood empties into the Right Atrium via the coronary sinus Slide 11.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Coronary Circulation

Quick Quiz Describe what happens in Pulmonary Circulation What is the purpose of Systemic Circulation? How are the heart tissues and cells nourished?

So, the heart pumps blood…how does it know when to pump?

The Heart: A hard working organ Your heart beats continuously Circulates your entire blood volume 1000 times in one day Pumps the equivalent of 6000 quarts in one day!

The Heart: Conduction System Intrinsic conduction system (nodal system) Heart muscle cells contract, without nerve impulses, in a regular, continuous way This means your heart can beat even if your brain is not working! Slide 11.13a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Conduction System Special tissue sets the pace Sinoatrial node Pacemaker Atrioventricular node Atrioventricular bundle Bundle branches Purkinje fibers Slide 11.13b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Heart Contractions Contraction is initiated by the sinoatrial node Sequential stimulation occurs at other autorhythmic cells Slide 11.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Heart Contractions Slide 11.14b Figure 11.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Quick Quiz What part of the heart initiates contraction? What does the Atrioventricular Node do?

The Heart: Cardiac Cycle Atria contract simultaneously Atria relax, then ventricles contract Systole = contraction of ventricles Diastole = relaxation of ventricles Slide 11.16 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Cardiac Cycle Cardiac cycle – events of one complete heart beat Mid-to-late diastole – blood flows into ventricles Ventricular systole – blood pressure builds before ventricle contracts, pushing out blood Early diastole – atria finish re-filling, ventricular pressure is low Slide 11.17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Filling of Heart Chambers – the Cardiac Cycle Figure 11.6 Slide 11.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Quick Quiz What is Systole? What is Diastole? Why do you think we measure heart contractions when the Ventricles contract?

The Heart: Cardiac Output 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 Slide 11.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Regulation of Heart Rate Stroke volume usually remains relatively constant Starling’s law of the heart – the more that the cardiac muscle is stretched, the stronger the contraction Changing heart rate is the most common way to change cardiac output Slide 11.20 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Regulation of Heart Rate Increased heart rate Sympathetic nervous system Crisis Low blood pressure Hormones Epinephrine Thyroxine Exercise Decreased blood volume Slide 11.21 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Regulation of Heart Rate Decreased heart rate Parasympathetic nervous system High blood pressure or blood volume Dereased venous return Slide 11.22 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cardiac Output Regulation Figure 11.7 Slide 11.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Quick Quiz What is Cardiac Output? Name 2 things that increase heart rate Name 2 things that decrease heart rate