1. The Circulatory System 37-1

2. Circulatory and Respiratory together Interrelationships between the circulatory and respiratory systems supply cells throughout the body with the nutrients and oxygen they need to stay alive

3. Functions of the Circulatory System The human circulatory system consists of the heart, and series of blood vessels and the blood that flows through them. These structures transport nutrients and wastes throughout the body.

4. The Heart Your heart is found near the middle of your chest and is about the size of your closed fist. The myocardium is the powerful muscle found in your heart. its contractions pump blood through the circulatory system.

5. The heart is divided down the middle by the septum, dividing it into a left and right side Each side has two chambers The upper chamber that receives blood = atrium The lower chamber that pumps blood out = ventricle The heart has four chambers total, two atria and two ventricles

7. Circulation Through the Body Pulmonary circulation - the right side of the heart pumps blood from the heart to the lungs Carbon dioxide leaves the blood and oxygen is absorbed Blood then goes to the left side of the heart Systemic circulation – the left side of the heart pumps the oxygen rich blood to the body Cell absorb the oxygen and load the blood with carbon dioxide The blood then goes back to the right side of the heart

8. Circulation Through the Heart Blood enters the heart through the atria When the heart contracts the blood flow to the ventricles then leaves the heart and goes to the body or lungs Valves are connective tissue that are in between the atrium and the ventricle. They prevent the blood from flowing backwards

9. Heartbeat There are two networks of muscle fibers in the heart, one in the atria and one in the ventricles. When one is stimulated, they all get stimulated and contract as one On the right atrium is a small group of muscle cells called the sinoatrial node (pacemaker) which begins the muscle contraction.

10. The impulse starts in the atria and pushes the blood from the atrium to the ventricles When the impulse get to the ventricles they contract and push blood out of the heart Your heart can beat faster or slower based on how much oxygen your body needs

11. Blood Vessels When blood leaves the left side of your heart to go to the body it passes into the aorta The aorta is the first of a series of blood vessels that carry blood to the body Blood moves through 3 different types of blood vessels Arteries Capillaries Veins

12. Arteries Arteries carry blood from the heart to the tissues of the body All arteries (except the pulmonary artery) carry oxygen rich blood.

13. Capillaries Capillaries are the smallest blood vessels, they give the nutrients and oxygen to the tissues and absorb the carbon dioxide and other wastes the walls of the capillaries are only one cell thick and are sometimes so narrow, the blood cells have to travel single file to pass through them

14. Veins Veins bring the blood back to the heart Some large veins have valves to prevent blood from flowing in the wrong direction Exercise keeps them strong and prevents pooling of blood, called varicose veins

15. Blood Pressure When the heart contracts is makes a wave of fluid pressure in the arteries. The force of the blood on the arteries’ walls is know as blood pressure

16. Diseases of the Circulatory System High blood pressure (hypertension) forces the heart to work harder, which can weaken or damage the heart muscle and blood vessels Atherosclerosis is when fatty deposits called plaque build up on the inner walls of the arteries if there is a blockage in an artery supplying the heart with oxygen and nutrients that part of the heart of can become damaged This is known as a heart attack

17. Circulatory System Health Cardiovascular diseases are easier to prevent than cure Regular exercise, eating a balanced diet, and avoiding smoking all can help prevent cardiovascular disease