1. The Circulatory System

2. Bringing It All Together The role of the circulatory system is basically to connect all of the other systems through transport. Our bodies are made of a number of specialized parts that all contribute something to the whole organism (you). It is essential to your health that the benefits of each body part are shared with the other parts and this is where the circulatory system comes into play. Through the circulation of blood, items from various parts of the body are shared with all of the other body parts. The blood carries a number substances in it that were put there by various body parts and delivers them throughout.

3. Parts of a Circulation System Any system of circulation has three essential components: 1.Pump – The heart is the pump that provides the force to move the blood. 2.Fluid – The blood is the fluid that is circulated throughout the body. 3.Vessels – Your blood vessels act as the pipes or channels through which the blood is moved within the body.

4. Components of Blood Your blood has four main components: 1.Red Blood Cells (Erythrocytes) – They carry oxygen from the lungs to the cells of the body. A protein called hemoglobin allows them carry O 2. Iron is a key part to the structure of hemoglobin. 2.White Blood Cells (Leukocytes) – They are in charge of immune response and protect you from foreign invaders called pathogens. 3.Platelets – These are cell fragments that respond to damaged blood vessels and heal them through blood clotting. 4.Plasma – The fluid part of blood. It carries dissolved substances and allows the blood to be moved. Plasma is 55% of your blood and the plasma itself is 90% water.

5. Components of Blood

6. Circulation Circuits?... Isn’t that like saying, “Allow myself to introduce…myself.” Your blood circulates through three different circuits or loops – each with its own job. 1.Pulmonary Circuit – Blood flow from the heart to the lungs and back to the heart. Oxygen must be loaded into the blood and sent back out to the body. 2.Systemic Circuit – Blood flow from the heart to the cells of the body and back to the heart. Oxygen in the blood gets used up and sent back to the heart for more oxygen. 3.Coronary Circuit – Blood flow from the heart to the muscle of the heart and back. The heart works very hard so it has coronary arteries that feed it blood full of nutrients and oxygen.

7. Circulation Circuits

8. The Heart The heart is the major organ of the circulatory system. It is a muscular organ about the size of your fist that works continuously to pump the blood throughout the body. The heart has several layers of muscle tissue in its make up: –Myocardium – The think muscular walls of the heart. –Endocardium – Tissue lining the inside of the heart. –Pericardium – The outer lining of the heart.

9. Chambers of the Heart We have a four-chambered heart. A chamber is a hollow compartment in the heart. The chambers of the human heart are named according to their position within the heart. The upper chambers are called atria (atrium for singular) while the lower chambers are the ventricles. We have two atria and two ventricles in our heart. We divide the pairs based on what side of the heart they are on – left or right. This means we have a right atrium and right ventricle and a left atrium and left ventricle.

10. The Heart

11. Blood Flow Through the Heart We will start with deoxygenated blood coming back to the heart through the vena cavas. 1.Blood enters the heart at the right atrium. 2.Blood goes through tricuspid valve into right ventricle. 3.Blood is squeezed up through pulmonary valve into the pulmonary arteries. 4.Blood goes through pulmonary arteries to the lungs, picks up O 2, and back to the heart via the pulmonary veins. 5.The oxygenated blood enters the heart through the left atrium and is squeezed down through the bicuspid valve down into the left ventricle. 6.The left ventricle squeezes blood up through the aortic valve and into the aorta and out to the rest of the body cells. 7.It gets used up and comes back to the heart through the vena cavas.

12. Blood Flow

13. Bump-Bump…Bump-Bump… The heart is controlled by the medulla oblongata – same part that looks after your breathing. The brain sends impulses down to the pacemaker, called the sinoatrial node (SA Node). It is located in the upper wall of the right atrium and it receives the impulses and causes the atria of the heart to contract. (First Bump!) Right after the SA node fires, the atrioventricular node (AV node) receives the impulse and it causes both ventricles to contract. (Second Bump!) The heart then takes a brief rest and then the cycle repeats itself. Bump-Bump…Bump-Bump…Bump-Bump…

14. Blood Pressure Blood pressure is the amount of force placed on the walls of the blood vessels as your blood is forced through them. Think of a garden hose…The more water you force through it, the harder the hose gets because there’s more pressure on the inner wall of the hose. Your blood pressure consists of two numbers (for two pressures): –Systolic pressure – The pressure placed on the vessels when the heart contracts. (High #) –Diastolic pressure – The pressure exerted on the walls of the vessels when the heart is at rest. (Lower #) A sphygmomanometer is the inflatable cuff thing used to measure blood pressure.

15. Blood Vessels Arteries – Carry blood away from the heart. Arterioles – Smaller arteries. Veins – Carry blood back to the heart. Venules – Smaller veins. Capillaries – Very small and thin vessel – the site of exchange between the blood and the cells of the body.

16. Artery vs. Vein ARTERIES Thicker muscular wall. No valves. VEINS Muscular wall but not as thick as artery. Vein valves – Help carry blood back up to heart – usually an uphill battle!

17. And That’s All I Got…