1. Cardiovascular System Notes: Physiology of the Heart

2. Interesting Heart Fact Capillaries are so small it takes ten of them to equal the thickness of a human hair.

3. Review What are the 3 parts of the cardiovascular system? heart – blood – blood vessels What do arteries do? Take blood AWAY from the heart What are the 3 layers of an artery? What do veins do? Bring blood TOWARD the heart What do veins have that arteries don’t? VALVES – (veins & arteries both have the same layers except the muscular layer is smaller) Tunica externa /connective tissue (elastin) – tunica media/smooth muscle – tunica intima/endothelium

4. What exchanges material between blood and the body’s cells? CAPILLARIES How big are they? microscopic in size What is the outer membrane of the heart called? Pericardium What is the function of the pericardium? (there are 3) 1.protection 2. anchors heart to other structures 3.provides lubrication for heartbeat

5. What are the 3 layers of the heart wall? 1.Epicardium – outside layer 2.Myocardium – middle layer (cardiac muscle) 3.Endocardium – inner layer What are the 4 chambers of the heart? 1.Right Atria 2.Left Atria 3.Right Ventricle 4.Left Ventricle What does the septum do? Divides the heart into right and left sides

6. What is the function of the right atria? receives blood from inferior & superior vena cava (oxygen poor) What is the function of the left atria? receives blood from pulmonary veins (oxygen rich blood from the lungs) What does the function of the left ventricle ? receives blood from left atria & pumps it to the body (through the aorta) What is the function of the right ventricle? receives blood from the right atria and pumps it to the lungs (through the pulmonary arteries)

7. Where is the tricuspid valve located? between right atria and right ventricle Where is the bicuspid (mitral) valve located? between left atria and left ventricle Where is the pulmonary semilunar valve located? between pulmonary artery and right ventricle Where is the aortic semilunar valve located? between aorta and left ventricle

8. PHYSIOLOGY OF THE HEART The Conducting System (electric) 1. Sinoatrial Node (SA) PACEMAKER OF HEART – starts each heartbeat located in wall of right atrium made of specialized myocardial cells sends impulse to both atria, causing them to contract called an intrinsic conduction or “nodal” system of specialized tissue

9. 2. Atrioventricular Node (AV node) located at base of right atrium – receives impulse from SA node SA Node AV Node

10. Atrioventricular Bundle Location: middle of septum Direction of Heart Beat impulse from AV node goes down bundle to base of heart it then travels up the sides of the ventricles through the PURKINJE NETWORK causing the ventricles to contract from the bottom up Atrioventricular Bundle

11. RATE OF HEART BEAT Factors affecting heart rate age, sex, physical activity, temperature, thought processes, chemicals (natural and otherwise) rate high at birth (100 – 140 bpm) – then declines steadily until average is reached (70 – 80 bpm) heart rate faster in females – slower in trained athletes

12. CARDIAC CYCLE the events of one complete heartbeat length of cycle (heartbeat) is about 0.8 sec atria contract at the same time – as they relax, the ventricles contract SYSTOLE contraction of ventricle DIASTOLE relaxation of ventricle Cardiac Output amount of blood pumped out of each side of the heart in 1 minute heart rate X stroke volume

13. PULSE & BLOOD PRESSURE Pulse expansion & contraction of an artery as the left ventricle contracts normal is 70 – 80 bpm (there are exceptions to this) pulse can be found at many sites on the body

14. Blood Pressure pressure blood exerts on the inner walls of blood vessels Measuring BP BP is a measure of the systolic pressure (ventricles contracting) OVER the diastolic pressure (ventricles relaxing) Example: 110/70 is in normal range Factors affecting BP nervous system, blood volume (kidneys), temp, chemicals, diet, exercise

15. The Electrocardiogram (EKG or ECG) amplifies electric current of heart producing distinct wave patterns

16. P wave depolarization of atria QRS Complex depolarization of ventricles T wave repolarization of ventricles P wave QRS Complex T wave