Essential Questions What role does the heart play in maintaining homeostasis? How do changes in the cardiac cycle effect delivery of oxygen to cells? What does blood pressure and heart rate indicate? How do we determine if the cardiovascular system is functioning properly? 1

Systole/Diastole 2

Cardiac conduction System SA node -sinoatrial node, found in the right atrium. Regulates the heart beat between 60 and 100 bpm. PACEMAKER of the heart. AV node -atrioventricular node Atrial Systole- contracting atria, relaxing ventricles. Ventricular systole –contracting ventricles, relaxing atria Diastole- when the entire heart is relaxing 3 The Cardiac Cycle

Pulmonary valve closed Tricuspid and mitral valves open (a)(b) Aortic valve closed Atrial systole LA LV RV RA Ventricular diastole Pulmonary valve open Tricuspid and mitral valves closed Aortic valve open Atrial diastole Ventricular systole Valves and Contractions of the Heart

Due to vibrations in heart tissues as blood rapidly changes velocity within the heart. Heart sounds can be described as a "lubb-dupp" sound. First sound (lubb) -ventricles contract and A-V valves are closing Second sound (dupp)-ventricles relax and aortic and pulmonary valves are closing. Heart Sounds

An electrocardiogram (ECG) is a recording of the electrical changes that occur during a cardiac cycle. Electrocardiogram

(a) (b) 0 – Milliseconds S Q P T R Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Millivolts Electorcardiogram P wave -SA node sends signal to atria and they contract to send blood to ventricles QRS interval - ventricles depolarize and contract T wave -ventricles repolarize

ECG Principles

Blood pressure -force of blood against inner walls of blood vessels anywhere in the cardiovascular system. – As blood gets further and further from the left ventricle, blood pressure decreases. Pulse-The surge of blood that occurs with ventricular contraction and can be felt at certain points in the body. – Caused by the expansion and contraction of blood vessels Systolic pressure- During ventricular contraction, arterial pressure is at its highest. Diastolic pressure- When ventricles are relaxing, arterial pressure is at its lowest. Blood Pressure

Listen for the sounds from the brachial artery-1st loud tapping sound=systolic pressure. When sounds suddenly are muffled= diastolic pressure. Normal blood Pressure= 120/80 or less

Arteries -strong, elastic vessels adapted for carrying high-pressure blood which become smaller and give rise to arterioles. Arterioles-smaller and thinner than arteries and give rise to capillaries Capillaries are the smallest vessels where substances are exchanged with tissue cells. Venules-lead from capillaries and merge to form veins that return blood to the heart. Veins- contain one way valves so blood cannot flow backwards. Blood Vessels/Capillary Network

Fig13.17 Artery Vein One way Valve Lumen Endothelium of tunica interna Connective tissue (elastic and collagenous fibers) Tunica media Tunica externa (a)(b) Artery vs. Vein