1. Chapter 18 – Cardiovascular System

2. Heart About the size of your fist Weighs 8-10 oz
The heart has 4 chambers
2 atria
2 ventricles
The left and right side of the heart are separated by the SEPTUM

3. Heart Tissue Epicardium – outer layer of tissue
Myocardium – muscle layer
Endocardium – inner lining of chambers

4. Pericardium
Sac-like structure surrounding and protecting the heart; contains fluid to reduce friction

6. Movement through the Vessels

7. Arteries (Leaving the heart)
Arteries take blood AWAY from the heart
Arteries must be strong, yet flexible, to withstand pressure from the heart
Largest artery leading from the heart is the AORTA
Arteries branch into smaller vessels known as arterioles

8. Capillaries (Leaving the heart)
Arterioles branch into smaller vessels known as capillaries
Blood cells must travel single file
Because the walls of capillaries are so thin, oxygen and carbon dioxide can pass through the walls

9. Venules and Veins (Towards the heart)
Once capillaries release oxygen and gain CO2, blood goes to venules.
Venules then lead to larger vessels known as veins
Veins eventually push blood back into the heart
Veins have thinner walls due to lack of pressure
Valves are able to keep blood from moving backwards

13. Two Circuits Pulmonary Circuit – carries blood to and from the lungs
Systemic Circuit – carries blood to and from all body tissues

16. PATHWAY OF BLOOD Abbreviations: RA = Right Atrium RV = Right Ventricle
LA = Left Atrium
LV = Left Ventricle

17. PATHWAY OF BLOOD
1. Deoxygenated blood enters the RA through the Superior and Inferior Vena Cava

18. PATHWAY OF BLOOD
2. Blood pumps from the RA through the Tricuspid valve into the RV

19. PATHWAY OF BLOOD
3. Blood pumps from the RV through the Pulmonary Valve into the Pulmonary Artery

20. PATHWAY OF BLOOD
4. Blood flows from the Pulmonary Artery to the lungs to become oxygenated.

21. PATHWAY OF BLOOD
5. Oxygenated Blood returns from the lungs through the Pulmonary Veins into the LA.

22. PATHWAY OF BLOOD
6. Blood pumps from the LA through the Mitral Valve into the LV.

23. PATHWAY OF BLOOD
7. Blood passes from LV through the Aortic Valve into the Aorta.

24. PATHWAY OF BLOOD
8. Blood pumps from Aorta to send oxygen to the rest of the body.

25. What is Blood Pressure?
The measure of pressure that blood exerts on the walls of the arteries
Measured using a Sphygmomanometer 

27. Blood Pressure Numbers
Systolic (top number) - measures pressure in arteries when the heart beats (ventricles contracting)
Diastolic (bottom number) - measures pressure in arteries between heartbeats (when the heart muscle is resting and refilling with blood).

28. Heart Rate Number of heart beats per minute (bpm)
Average HR is ~70 bpm

29. Intrinsic Conduction System
Nodes are heart tissue that stimulate cardiac muscle to contract
Impulse runs from base to apex

31. Parts of the Conduction System
Sinoatrial (SA) node
“Pacemaker” of the heart
Located in right atrium
SA can increase rate when stimulated by drugs, fever, or sympathetic NS (exercise, stress, emotion, etc)
Atrioventricular (AV) node
Between atria and ventricles

32. Stages of Contraction Sinoatrial (SA) Node fires and atria contract
Impulse travels to Atrioventricular (AV) Node, then through Bundle of His, then through bundle branches and Purkinje fibers, causing ventricles to contract
Heart muscle repolarizes and prepares to contract again