1. The Cardiovascular System
Chapter 30 Section 3-4

2. Key Vocabulary Atrium-the 2 small chambers at the top of the heart.
Venticle-the 2 large chambers at the bottom of the heart.
Valve-flaps of tissue that prevent blood from flowing backward.
Pacemaker-collection of cells that stimulates the pumping action of the heart.
Pulmonary Circulation-collection of blood vessels that carries blood between the heart and the lungs.
Systemic Circulation-collection of blood vessels that carries blood between the heart and the rest of the body, except for the lungs.

3. Key Vocabulary
Blood Pressure-the force which blood pushes against the wall of an artery.
Systolic Pressure-the amount of pressure on the walls of an artery when the left ventricle contracts to pump blood through the body.
Diastolic Pressure-the pressure in the artery when the left ventricle relaxes.

4. The Heart and Circulation
Your heart beats around 100,000 times a day, and moves blood around close to 96,000 km of blood vessels.
That’s ¼ of the distance to the moon.
Cardiac muscle tissue can pump continuously without getting tired.
By age 70 your heart will have made 2.5 billion heart beats.

5. The Heart and Circulation
The largest structures in your heart are the 4 chambers: The 2 atria and the 2 ventricles.
A thick wall of tissue called the septum separates the ventricles.
Heart valves open when the chambers contract and close when they relax.

6. The Heart and Circulation
When one chamber fills with blood it contracts and moves the blood out of that chamber.
Because the heart is small and has a great amount of force it has a very powerful pumping action.
The heart regulates itself really well.
It listens to the signals of the brain
If you increase exercise it will adjust and pump faster.

7. The Heart and Circulation
The heart beat is made up of 2 parts: The atria contract and then the ventricles contract. “Lub Dub”
The contraction starts in the Right Atrium at a place called the sinoatrial (SA) node.
It’s the pacemaker of the heart.
Once the electrical impulse is made it contracts the atria and moves down through the fibers to the atrioventricular (AV) node. Then both ventricles contract.
If there is serious damage to the SA node it can be replaced by an artificial pacemaker.

8. The Heart and Circulation

9. The Heart and Circulation
So how does blood flow through the heart?
Oxygen poor blood comes in through the right atrium.
It moves into the right ventricle and into the pulmonary artery, which takes it to the lungs.
The lungs take out the CO2 and fills the blood with O2.
The oxygen rich blood comes into the left atrium.
It moves into the left ventricle and into the aorta where it goes to the rest of the body.

10. The Heart and Circulation

11. The Heart and Circulation
Blood flows through two different circulation systems:
Pulmonary
Systemic
Pulmonary circulation is only when blood moves between the heart and lungs.
Systemic circulation is when the blood moves through the rest of the body.

12. The Heart and Circulation
As our bodies oxygen needs change, sensors in the walls of major arteries signal the brain stem to this change.
The medulla lets the respiratory system know if it needs to go faster or slower.
When our heart rate and respiration rate are matched with the needs of our body we are in a state of balance.

13. The Heart and Circulation
When the body is in an environment of extreme cold the circulation systems help protect major organs by making sure that these organs remain at a constant temperature.
If we are exposed to this extreme cold for too long your body takes the blood from your arms and legs and moves them to your core to keep you head and torso warm.

14. Blood Vessels and Transport
The body’s circulatory system has 3 types of blood vessels:
Arteries
Veins
Capillaries
Arteries are strong and flexible because the blood they carry from the heart is at a higher pressure.
Veins are thinner and are under less pressure.
Capillaries are the smallest vessels.

15. Blood Vessels and Transport
Arteries have 3 layers to them.
The inner most layer is made of endothelium and coated with a protein to keep blood from clotting.
The middle layer is a thick layer of smooth muscle.
The outer layer is connective tissue and elastic fibers.
The fibers allow the walls to expand and contract.

16. Blood Vessels and Transport
Veins have larger diameters and thinner walls.
They have valves in them to prevent blood from moving backwards.
Skeletal muscle movement help move blood through the veins and back to the heart.
Sitting for too long makes it harder for blood to move upward.

17. Blood Vessels and Transport
Capillaries are made of epithelium and are very thin.
Allows materials to enter and exit the blood as quickly as possible.
Areas that are high in activity have capillary beds so that a lot blood can be moved into and out of these areas.

18. Blood Vessels and Transport

19. Blood Vessels and Transport
A normal resting blood pressure for a young adult is 120/70 mm Hg
The top number is the systolic pressure which is the amount of pressure on the walls of an artery when the left ventricle contracts.
The bottom number is the diastolic pressure which is the pressure on the artery when the left ventricle relaxes.
Blood pressure relies on how elastic and unblocked the arteries are and on the strength of the contraction.

20. Blood Vessels and Transport
If your arteries are less elastic and have blockages the blood flow is reduced so your heart has to work harder.
Heart works harder = Higher blood pressure.
Natural things like exercise and strong emotions can raise your blood pressure, but when your done it goes back down.

21. Blood Vessels and Transport
People with hypertension (permanent high blood pressure) are living with a risk of heart attack and stroke.
Heart attack is when the arteries to the heart muscle are damaged or blocked.
A stroke happens when the blood flow to the brain is interrupted.