1. Cardiovascular System
Anatomy and Physiology

2. Cardiovascular System
Consists of heart—pump
System of blood vessels --transport

3. Cardiovascular System
Heart is covered by the pericardium
This is like a thin membranous sac for protection

4. Cardiovascular System
Heart has four chambers: 2 atria on top and 2 ventricles on the bottom
Atria are receiving chambers
Ventricles are pumping chambers, and have thicker walls

6. Cardiovascular System
Heart is also divided into right and left
Blood on the right side does not mix with blood on the left side
Blood which enters the right atrium goes on to the right ventricle
Enters left atrium; leaves left ventricle

7. Cardiovascular System
Blood entering the right side of the body is coming from the veins of the body and is low oxygen
It is sent from the right ventricle to the lungs

8. Cardiovascular System
Blood entering the left side of the heart has come from the lungs and is oxygenated
It is sent from the left ventricle through the arteries to all parts of the body

9. Cardiovascular System
Valves separate the atria from the ventricles
On the right side, it is the tricuspid valve
On the left side, it is the bicuspid valve
They close to prevent flow when it should be sealed off

12. Label the Heart

13. Pulmonary vs Systemic
The pulmonary circuit goes from the right atrium to the right ventricle
And then to the lungs, returning to the left atrium

14. Pulmonary vs Systemic
Systemic circulation goes from the left atrium into the left ventricle
And then to all body parts (oxygenated)

15. Initiating the Heartbeat
The “pacemaker” system
Involves specialized pockets of heart tissue which can initiate impulses
The first pocket is called the S-A (sinoatrial) node

16. S-A node Initiates the heartbeat Is located in the right atrium
Causes both atria to contract (small contraction to send blood into ventricles)
Impulse also travels on fibers to the next specialized pocket

17. A-V Node
The A-V node (atrioventricular) receives the impulse from the S-A node
Located in the septum where the atrium meets the ventricle
Impulse is relatively slow, allowing time for the ventricles to fill

18. A-V Node passes it on
From the A-V node, the impulse goes to the A-V bundle (also called the Bundle of His)
From there is branches into Purkinje fibers that enclose both ventricles

19. The Big Push
When all the cardiac muscle cells receive the impulse, the ventricles contract together and powerfully.
This is systole

20. Steps in Order SA node AV node AV bundle Bundle branches
Purkinje fibers

21. Replacement
If the SA node fails to keep a regular rhythm, an artificial pacemaker can be inserted.

22. ECG Electrocardiogram Sometimes called EKG
Recording of electrical changes
Records the electrical impulses of action potentials

25. The Blood Vessels Arteries lead away from the heart
Arteries branch into arterioles (smaller arteries,) then into tiny capillaries
Capillaries merge together to form venules (small veins)
Venules merge to become larger veins which return blood to the heart

26. Arteries Strong Elastic Able to withstand the pumping pressure
Three layers in the wall—one layer contains smooth muscle

27. Arteries
The muscle allows the artery to constrict (reduce diameter) and dilate (increase diameter)
This is important in maintaining body temperature

28. Capillaries Smallest diameter
Connect the smallest arterioles with the smallest venules
The wall is only one layer thick—very thin!
Exchange of materials occurs here

29. Veins Venules merge to form larger veins
Walls have three layers, but much thinner
Less muscle and elastic tissue
Collapse when empty

30. Artery and Vein Comparison

31. Veins Contain valves to prevent back flow
Valves open
Contain valves to prevent back flow
Most valves are in veins of the limbs
Harder to return blood from these parts, due to low pressure
Valves closed

32. Valves
Valves

33. Veins
By the time blood gets to the veins, it has little force behind it.
It’s hard to get blood back to the heart
Valves help, but also skeletal muscle movement and respiration help

34. Blood Pressure
Force blood exerts against the walls of the blood vessels.
Primarily in the arteries, since they are subject to the most force
Can feel a pulse in arteries

35. Blood Pressure
Systolic pressure is the pressure during ventricular contraction
Diastolic pressure is the pressure during ventricular relaxation
A blood pressure reading is expressed as
systolic pressure
diastolic pressure

36. Blood Pressure A normal blood pressure reading is 120/80.
Generally, lower is better
Hypertension may result in heart enlargement, heart attack, atherosclerosis, stroke
Exercise, controlling weight, limiting sodium, reducing stress, and medication are treatments for high blood pressure

37. Blood Pressure Factors affecting blood pressure include:
Amount of blood pumped by the left ventricle and how often
Blood volume
Peripheral resistance
Blood viscosity