1. The Circulatory System

2. Circulatory System Also known as the Cardiovascular System
Consists of:
Heart
Blood Vessels
Blood

3. Functions of the Circulatory System
Transports oxygen and nutrients to all body cells
Transports carbon dioxide and metabolic materials away from the body cells

4. Blood Vessels
Include:
Arteries
Veins
Capillaries

5. Arteries Blood Vessels that carry blood away from the heart
More muscular and elastic than the other vessels
Largest artery is the Aorta
Smallest branches are called arterioles
Join with capillaries
Contain oxygen rich blood except the Pulmonary Artery

6. Veins Blood vessels that carry blood back to the heart
Venules , the smallest branches of veins, connect with the capillaries
(join together and become larger veins)
The 2 largest veins: Superior Vena Cava and Inferior Vena Cava
Veins are thinner and less muscle tissue
Most contain valves which keep the blood flowing in one direction

9. Capillaries
Blood vessels that connect arterioles (smallest arteries) with venules (smallest veins)
Smallest blood vessels
Contain thin walls that allow oxygen and nutrients to pass through to the cells
Also, allow carbon dioxide and metabolic waste products to enter these vessels for removal from the cell

10. Heart Muscular, hollow organ functions as pump
Weighs less than one pound
Size of closed fist
Located in the mediastinal cavity, between the lungs, behind the sternum and above the diaphragm

11. Heart Facts
The heart contracts about 100,000 times each day to pump the equivalent of 2,000 gallons of blood through the body.
The human heart beats 35 million times in a year.
In a lifetime, the heart pumps around 1 million barrels of blood.

12. Layers of the Heart Three layers of tissue include:
Endocardium – smooth layer which lines the inside of the heart
Myocardium – thick, middle muscular layer
Pericardium – double layered membrane or sac that covers the outside of the heart
A lubricating fluid, pericardial fluid, fills the space
between the two layers. This fluid helps prevent friction
and damage to the membrane as the heart beats.

13. Septum
A muscular wall that separates the heart into a right side and a left side
Prevents blood from moving between the 2 sides
Upper part of the septum is called the interatrial septum
Lower part of the septum is called the interventricular septum

14. Heart Chambers The heart is divided into four parts, or chambers.
2 upper chambers are called atrias (atriums)
2 lower chambers are called ventricles

15. Blood Flow (Right Side of Heart)
The Right Atrium receives blood as it returns from the body cells via the Superior Vena Cava and Inferior Vena Cava.
The Right Ventricle receives blood from the Right Atrium and pumps the blood into the Pulmonary Artery, which carries the blood to the lungs for oxygen.

16. Blood Flow (Left Side of the Heart)
The Left Atrium receives oxygenated blood from the lungs via the Pulmonary Veins.
The Left Ventricle receives blood from the Left Atrium.
The blood is pumped into the Aorta for transport to the body cells.

17. Heart Valves
One way valves in the chambers of the heart keep the blood flowing in the right direction.

18. Heart Valves on Right Side
The Tricuspid Valve is located between the right atrium and the right ventricle (contains
3 cusps or leaflets).
The Pulmonary Valve is located between the right ventricle and the pulmonary artery (contain 3 cusps or leaflets).

19. Heart Valves on Left Side
The Mitral (Bicuspid) Valve is located between the left atrium and the left ventricle (contains 2 cusps or leaflets).
The Aortic Valve is located between the left ventricle and the aorta (2 cusps or leaflets).

20. Heart Valves
This three dimensional image shows the heart valves functioning. Look close at the 3D of the heart (on the right), the leaflets of the tricuspid and aortic valves are partly visible.
The 2 left images show the tricuspid and mitral valves (above) and aortic and mitral valves (below).

21. Cardiac (Heartbeat) Cycle
Even though the 2 sides of the heart are separated by the septum, these 2 sides work together in a cyclic manner.
The cycle consists of a brief period of rest called diastole, followed by a period of ventricular contraction, called systole.

22. Cardiac Cycle Start of a cycle Atria contracts
Blood pushed into ventricle
Atria relaxes
Blood enters from superior & inferior vena cava on right side and blood enters from pulmonary veins on left side
Atria filling, systole begins, and the ventricle contract
Contraction of ventricles pushes blood into pulmonary artery on right side and pushes blood into aorta on the left side

23. Beating Heart

24. Pulmonary Circulation
Blood on the right side of the heart is deoxygenated meaning it is very oxygen poor and high in carbon dioxide.
The blood enters the lungs via the pulmonary artery.
When the blood arrives in the lung, the carbon dioxide is released into the lungs, and then oxygen is taken into the blood (occurs in capillary beds in lungs) .
Once the blood returns to the heart on the left side, it is filled with oxygenated blood (oxygen rich).

27. Review
Right Side of Heart Left Side of Heart Deoxygenated Blood Oxygenated Blood (Oxygen Poor) (Oxygen Rich)

28. Blood Flow Through Right Side of Heart
Superior Vena Cava and Inferior Vena Cava
Right Atrium
Tricuspid Valve
Right Ventricle
Pulmonary Valve
Pulmonary Artery
To the Lungs
DEOXYGENATED BLOOD

29. Blood Flow Through Left Side of Heart
From Lungs
Pulmonary Veins
Left Atrium
Mitral (Bicuspid) Valve
Left Ventricle
Aortic Valve
Aorta
To the Body
OXYGENATED BLOOD

30. Conductive Pathway
Electrical impulses cause the cyclic contractions of the heart. These impulses start
in the atria and then move
down through the ventricles.
Sinoatrial (SA) Node – group of nerve cells in the right atrium. “Pacemaker” of the heart.
Atrioventricular (AV) Node –
group of nerve fibers between
the atria and ventricles.

31. Conductive Pathway
3) Bundle of His – group of nerve fibers in the septum.
4) Right Bundle Branch and Left Bundle Branch – nerve fibers that carry the impulse
down the ventricles.
5) Purkinje Fibers – a network of nerve fibers located throughout the ventricles.

33. Electrocardiogram
This electrical conduction pattern occurs approximately every 0.8 seconds.
The electrical impulses can be recorded on an electrocardiogram (ECG or EKG) and used to detect abnormal activity or disease.

34. EKG: Electrocardiogram

35. Arrhythmias
If something interferes with the normal electrical conduction pattern of the heart, then arrhythmias occur.
These abnormal heart rhythms can be life threatening.
Ventricular fibrillation (V-Fib) occurs when the ventricles contract without coordination which decreases blood output.
A defibrillator (device which shocks the heart with a electrical current) is used. After a successful shock, the SA node is able to regain control.

36. Heart Review