Review Sheet: Circulatory System

Structure of the Heart & Actions of the Heart

1. List the chambers of the heart.

Right atrium, left atrium, left ventricle, right ventricle.

2. What vessels bring blood to the right atrium?

The super vena cava, inferior vena cava, and the coronary sinus.

3. What vessels bring blood to the left atrium?

Pulmonary veins.

4. What is the function of the valves of the heart?

Controlling the flow of blood and stopping the blood from coming back.

5. What events make up the cardiac cycle?

The atria contracts and ventricle relaxes. Then the atria relaxes and ventricle contracts. Then both relax for a brief interval. This cycle is the cardiac cycle.

6. What produces the heart sounds heard with a stethoscope?

Vibration in the heart tissues with the valve closing. A heart beat, often said to sound like “lubb-dupp”, occurs when the valves in the heart tissue close. The “lubb” occurs during ventricle systole and the “dubb” occurs during ventricle diastole.

7. What structures can be assessed by the heart sounds?

If there is a murmur sound, the valvular cusps are not completely closing and blood is leaking.

8. Trace an impulse through the cardiac system.

SA Node, AV Node, Buddle of His, and Purkinje Fibers.

9. How is the heart affected by the following: potassium, calcium, and temperature?

An increase in potassium leads to a decrease in the heart rate. An increase in calcium leads to an increase in the heart rate while a decrease in calcium lead to a decrease in the heart rate. An increase in temperature increases the heart rate, while a decrease in temperature decreases the heart rate.

Blood Vessels

10. Describe the structure of arteries.

Arteries are strong elastic vessels that carry blood away from the heart under high pressure. Wall of the arteries consists of three layers. The 3 layers are the tunica interna, tunica media, and tunica extrema. Tunica interna, inner layer, is made of simple squamous epithelium. Tunica media is the middle layer. It has smooth muscle fibers that encircles the tube/thick layer elastic connective tissue. Tunica extrema is an outer layer that is made of relatively thin connective tissue.

11. How is the structure of arterioles different from that of arteries?

Arteries are strong elastic vessels that carry blood away from the heart under high pressure. Arterioles are vessels that subdivide into thinner tubes and branches.

12. What determines the density of capillaries within tissue?

Rate of metabolism within the tissue reflect the capillary’s density.

13. How is the distribution of blood in the capillaries regulated?

Precapillary sphincters regulate the distribution of blood.

14. What is blood pressure?

Force exerted by blood on the walls of vessels.

15. What cardiac events are related to systolic and diastolic arterial pressure?

Systolic is the maximum pressure due to ventricle contraction. Diastolic is low pressure due to ventricle relaxation.

16. What is a pulse?

Swelling of blood vessels due to pressure.

17. How does each of these factors influence blood pressure, heart action, blood volume, and peripheral resistance, and viscosity?

Heart action determines the rate of flow. Blood volume can affect the pressure. Less blood means a decreased flow. Peripheral resistance means more friction and a slower blood flow. Viscosity means the thicker the blood the increase in pressure.

18. Discuss the mechanical, neural, and chemical factors that affect cardiac output.

Mechanical: Longer the fibers the stronger the contraction.

Neural: Cardiac center in brain that sends impulses to the SA Node.

Chemical: Natural endorphins cause an increase in heart rate.

19. How is peripheral resistance regulated?

Peripheral resistance is regulated by alternating constriction and dilation of the blood vessels.

Path of Circulation

20. How do the pulmonary and systematic circuits differ?

Pulmonary pumps blood from heart to lungs. Systematic pumps blood from the heart to the body.