1. Cardiovascular System The Heart Chap. 12

2. The Cardiovascular system is comprised of the heart, blood vessels, & blood
The heart acts as a “pump”, creating pressure which causes blood to move through the blood vessels of the body, allowing O2 & nutrients to be distributed to, & wastes removed from, body tissues

3. Anatomical Features of the Heart
The heart lies within the mediastinum of the thoracic cavity
Hollow muscular organ with four internal chambers
(2) atria (lt. atrium & rt. atrium)- receive blood from ________
(2) ventricles (lt. ventricle & rt. ventricle)- pump blood into ___________
Superior aspect of heart is the “________”, where the blood vessels attach; Inferior is the “________”, which rests on the relaxed diaphragm

4. Pericardium The heart lies enclosed within pericardial membranes
Fibrous pericardium (pericardial sac) – outer layer of dense CT that protects & anchors
Serous pericardium – double layered membrane with “pericardial fluid” between
Parietal pericardium – lines the pericardial sac
Visceral pericardium – covers the heart; also known as the “____________”

5. Layers of Heart Wall Epicardium (a.k.a. visceral pericardium)
Myocardium
Endocardium
Fibrous pericardium (pericardial sac)

6. Cardiac Muscle Tissue
Figure 12.4

7. Because of the characteristics of cardiac muscle tissue & the arrangement of connective tissue (“fibrous skeleton”) within the heart, the heart basically has two functional units:
the myocardium of the atria (upper chambers) act as one functional unit
the myocardium of the ventricles (lower chambers) act as the other

8. This allows the atria to contract simultaneously (_________ ) while the ventricles are relaxed; then the ventricles contract simultaneously (__________) while the atria relax

9. External Features
Auricles
Coronary sulcus – contains the coronary sinus
Anterior interventricular sulcus – contains coronary vessels
Posterior interventricular sulcus – contains coronary vessels

10. Lt Atrium Rt Atrium SVC IVC Deoxygenated blood Interatrial septum
Coronary sinus (opening)
Deoxygenated blood
Interatrial septum
Pulmonary veins
Oxygenated blood
Rt Atrium
Lt Atrium
Pectinate muscles
Tricuspid valve
Bicuspid (mitral) valve
Chordae tendineae
Papillary muscle

11. Atrioventricular (AV) valves
Tricuspid
Bicuspid

12. Lt ventricle Rt ventricle Aorta Pulmonary artery Pulmonary trunk
Brachiocephalic trunk
Lt. common carotid artery
Lt. subclavian artery
Aorta
Aortic semilunar valve
Ligamentum arteriosum
Pulmonary semilunar valve
Pulmonary trunk
Pulmonary artery
Trabeculae carneae
Rt ventricle
Lt ventricle
Interventricular septum

13. Anatomy

14. Coronary Circulation
Myocardium receives oxygenated blood from the left & right Coronary arteries – branches off the ascending aorta
Deoxygenated blood is drained through Cardiac veins, which all eventually merge into the coronary sinus
Fig. 12.7

15. Conducting System
Intrinsic regulating system that generates “heartbeat”
comprised of functionally specialized “autorhythmic (conducting) cells” – which can spontaneously generate action potentials
Fig. 12.9

16. The electrical events that occur in the heart can be detected on the surface of the body
The resulting pattern of activity is known as an ECG (or EKG) - Electrocardiogram

17. Electrocardiogram (ECG)

18. The activity of the conducting system results in the contraction (systole) & relaxation (diastole) of the heart chambers
The change in volume (size) of the chambers results in changes in pressure within the heart – decreased volume  increased pressure & vice-versa.
Blood will flow through the chambers (and throughout the cardiovascular system) due to the differences in pressure (blood moves from high  low pressure)

19. Cardiac Cycle Average 75 cycles/minute
One complete “heartbeat” is referred to as a “Cardiac Cycle”
Average 75 cycles/minute
Each cycle lasts approx. 0.8 seconds
Continuous, repetitive cycle that can be “divided” into 3 phases for ease of understanding:
atrial diastole/ventricular diastole (0.4 sec.)
atrial systole/ventricular diastole (0.1 sec.)
atrial diastole/ventricular systole (0.3 sec.)

20. Cardiac Cycle atrial systole/ventricular diastole
START
atrial diastole/ ventricular diastole
“Lub”
atrial diastole/ventricular systole
“dupp”

21. Cardiac Output Important physiological measurement of cardiac function
Refers to the amount of blood ejected by the left ventricle each minute
C.O. = stroke volume X heart rate
stroke volume – ____________________
________________________________
heart rate – ________________________
_________________________________
average C.O. = 6000 ml/min (6 L/min)

22. Cardiac Output Cardiac output is primarily regulated by:
1. Blood volume reflexes – there is a direct relationship between blood entering the heart & amount ejected
increased venous return  atrial reflex (aka Bainbridge reflex)  increased heart rate (through increase in sympathetic activity)
increased venous return  ventricular reflex (aka Frank-Starling principle)  increased stroke volume

23. Cardiac Output
2. Cardiac center of M.O. – ANS input to SA node to increase/decrease heart rate & stroke volume
Cardiac center influenced by:
baroreceptors – detect blood pressure changes
chemoreceptors – detect oxygen/carbon dioxide concentrations
higher brain centers – ie. hypothalamus
3. Hormones – epinephrine/norepinephrine, thyroid hormones, glucagon, etc can increase heart rate & force of contraction