1. The Cardiovascular System Chapter 9

2. The Cardiovascular System
Includes:
Heart
Blood vessels
Blood (and blood circulation)

3. The Heart Straddles the midline Dorsal to the sternum
Base is cranodorsally
Apex is ventrally to the left

4. The Heart
Acts as a pump to circulate blood throughout the body to nourish tissues and remove waste products.
Made of cardiac muscle (involuntary; striated)
Size varies with species
Located in the thoracic cavity

5. The Pericardium Membrane that covers the heart Composed of:
Fibrous pericardium (external layer)
Tough, fibrous sac surrounding serous layers
Serous pericardium (inner layers)
Parietal layer – lines the pericardium
Visceral layer – (a.k.a. – epicardium) – covers the surface of the heart

6. The Pericardium
The pericardial space is the space between the two serous layers of the pericardium
This space contains pericardial fluid
Pericardial fluid prevents friction between the heart and the pericardium when the heart beats

8. Layers of the Heart Heart wall has 3 Layers:
Epicardium – outer; visceral layer
Myocardium – middle layer; muscle layer
Endocardium – innermost layer; lines chambers and valves

10. LAYERS OF THE HEART:

11. Chambers of the Heart There are 4 chambers within the heart:
2 craniodorsal chambers = atria
2 caudoventral chambers = ventricles
The heart is divided into right and left sides.
Interatrial septum divides atria
Interventricular septum divides ventricles

12. Chambers of the Heart Atria receive blood and ventricles send blood.
Atria have thin walls and ventricles have thick walls.
The right side of the heart receives blood from body and sends it to the lungs to pick up O2.
The left side of the heart receives oxygenated blood from lungs and sends it to the tissues.

13. Valves of the Heart
Atrioventricular valves (AV valves) lie between each atria and ventricle.
Mitral valve – Left side; called bicuspid valve because it only has two flaps/cusps.
Tricuspid valve – Right side; has three flaps
Flaps are attached to ventricular wall by chordae tendineae.

14. Valves of the Heart
Semilunar valves (half-moon shaped) prevent backflow of blood from arteries into ventricles.
Aortic semilunar valve is a 3-flapped valve between left ventricle and aorta.
Pulmonary semilunar valve is located between right ventricle and pulmonary artery.

15. Valves of the Heart

17. Valves of the Heart

21. Blood Circulation: Systemic
Left ventricle
Aorta
Arteries
Arterioles
Capillaries
Venules
Veins
Right atrium

22. Blood Circulation: Pulmonary
Right atrium
Right ventricle
Pulmonary artery
Lungs
Arterioles
Lung capillaries
Lung venules
Pulmonary veins
Left atrium
Left ventricle

23. Blood Circulation

24. Blood Vessels
Arteries carry oxygenated blood away from the heart back to the body.
Walls are thick and muscular
***Exception = pulmonary artery***
Veins transport deoxygenated blood back to the heart.
Walls are thin and elastic
Valves prevent backflow of blood
***Exception = pulmonary vein***

25. Blood Vessels
As arteries branch out and become smaller, they become arterioles.
Arterioles branch and become smaller into capillaries.
Capillaries have very thin walls and distribute O2 to tissues while picking up CO2
Capillaries branch into larger structures called venules which empty into larger structures called veins which return blood to the heart.

26. Blood Vessels

27. Drop that beat!!! Autonomic Nervous System:
Parasympathetc: mainly supply the SA & AV Nodes, slows the heart rate, reduces impuse conduction
Sympathetic: acts on the SA & AV nodes to increase the heart rate and impulse condction

29. CONDUCTION SYSTEM of electrical impulses
SINOATRIAL NODE is the pacemaker of the heart and where the heartbeat originates and the rate is regulated
located in the RA
The impulses make the atria contract and force blood into the ventricles
ATRIOVENTRICULAR NODE is in the right atrium near the lower portion of the interatrial septum
the electrical impulse from the SA node affects the AV node, which then transmits the impulse to the
ATRIOVENTRICULAR BUNDLE (BUNDLE OF HIS)
this is located in the interventricular septum
the ventricles now contract as the impulse is carried
throughout the ventricles via the PURKINJE FIBERS

30. The Cardiac Cycle
Atria contract in unison; ventricles contract in unison
As one group contracts, the other relaxes.
Atrial contraction sends blood into ventricles through bicuspid and tricuspid valves.
While this is occurring, the semilunar valves close
Ventricles relax at this time

31. The Cardiac Cycle
Ventricular contraction sends blood through the semilunar valves and into the aorta and pulmonary artery.
While this is occurring, the bicuspid and tricuspid valves close
The atria relax, allowing blood to enter from the vena cava and pulmonary veins.

32. The Cardiac Cycle Systole Diastole
Part of the cardiac cycle associated with contraction of ventricles and atria and ejection of blood into the arteries.
Diastole
Part of the cardiac cycle associated with relaxation of atria and ventricles and filling of the chambers with blood.