The document summarizes the structure and function of the cardiovascular system. It describes the layers of the heart wall, the flow of blood through the heart and cardiac cycle, regulation of the heart rate, structure and types of blood vessels, factors affecting blood pressure, and clinical applications related to the cardiovascular system.

1. CHAPTER 13: CARDIOVASCULAR SYSTEM

2. Structure of the Heart - covered by the pericardium which is a sac surrounding the heart - it is made up of 3 layers - produces serous fluid to decrease friction

3. Wall of the Heart 3 Layers 1. Epicardium - provides protection - deep part contains fat along blood vessels 2. Myocardium - thickest layer – mostly cardiac muscle tissue - forces blood out of the heart chambers - contains many capillaries & nerve endings

4. 3. Endocardium - contains Perkinje fibers – specialized nerve fibers used during the heart beat

6. Flow of blood through the heart          

7. Blood supply to the heart a) coronary artery - supplies blood to heart muscles b) cardiac veins - takes blood away from heart muscles – empties into the coronary sinus The cardiac cycle movie

8. Actions of the Heart Cardiac Cycle - consists of the atrias contracting (atrial systole) followed by the contracting of the ventricles (ventricular systole) followed by a brief relaxation of the heart (diastole) Heart Sounds - lubb - ventricles contracting - tricuspid and bicuspid valves closing - dupp - ventricular relaxation - pulmonary & aortic valves closing

9. Cardiac Conduction System - specialized cells initiate and conduct impulses through the myocardium SA node AV node AV bundle Perkinje fibers

10. 1. Sinoatrial node (SA node) - start impulses with no connection to nervous system - stimulates atrias to contract - a.k.a. the pacemaker 2. Atrioventricular node (AV node) - causes a delay in signal - impulse passes into AV bundle - causes impulse speed to increase - separates into perkinje fibers - ventricles contract - force blood out of ventricles

11. Electrocardiogram (ECG or EKG)  recording of electrical changes during cardiac cycle Cardiac conduction movie

12. P wave – impulse spreading from SA node to AV node - atria depolarize QRS Complex – spreading of impulse from AV node to ventricles - ventricles depolarize T wave – ventricles repolarize

14. Regulation of the Cardiac Cycle - depends on: physical exercise body temp concentration of various ions - when heart rate needs to be changed, the cardiovascular center in the medulla oblongata sends impulses to the SA node - secretes ACH (  heart rate) - secretes norepinephrine (  heart rate

15. Blood Vessels Structure a. tunica externa tunica externa - outer most layer - contains elastin and collagen fibers

16. b. tunica media tunica media - middle layer - contains the muscles to allow for vasoconstriction and vasodilation

17. c. tunica interna tunica interna - inner layer - primarily simple squamous epithelium  the endothelium - prevents blood clotting by providing a smooth surface

18. 1. Arteries - have thick muscular walls - carry blood away from the heart 2. Arterioles - little arteries - help to regulate blood flow to capillaries

19. 3. Capillaries - wall is made up of endothelium  1 cell thick - found near every living cell - high metabolic tissues have a greater density of capillaries - functions in gas exchange and filtration

20. 4. Venules - small veins - drain blood from capillaries 5. Veins - carry blood toward the heart - have thinner walls than arteries (less muscle) - act as a blood reservoir - contains valves to prevent the backflow of blood

21. Blood Pressure  the hydrostatic pressure exerted by blood on the walls of blood vessels - there is a high bp in the arteries and low bp in the veins - must have a pressure difference in order for blood to flow

22. Factors Affecting Blood Pressure 1. Blood volume -  volume =  bp -  volume =  bp 2. Blood vessel radius -  radius =  bp -  radius =  bp - the radius can be affected by physical activity, overall health, stress, hormones

23. 3. Blood viscosity - the “thickness” of the blood - due to decrease water or anemia  viscosity =  bp 4. Total blood vessel length -  length =  bp 5. Heart action - heart forces blood into arteries -  force =  bp

24. - stroke volume – amt. of blood discharged from ventricles - ~ 70 mL - cardiac output – amt. of blood discharged from ventricles per minute - ~5,040 mL Measuring Blood Pressure - measured with a sphygmomanometer - systolic pressure – maximum pressure - diastolic pressure – minimum pressure

25. Clinical Applications asystole – failure of the myocardium to contract sinus rhythm – the normal cardiac rhythm regulated by the SA node myocardial infarction – death of the heart muscle tissue (heart attack)

26. heart murmur – a valve does not close properly causing some blood to leak “backward” to the previous chamber hypertension – high blood pressure

27. spider veins – a milder form of varicose veins varicose veins – enlarged, dilated veins that are seen through the skin

28. aneurysm – a sac that forms in a blood vessel due to a weakened artery atherosclerosis – deposit of fatty materials (plaque) on the walls of blood vessels