Circulatory System Circulatory System The function of the

Circulatory System

Circulatory System • The function of the circulatory system is to move materials around the body – Gases, nutrients, wastes, hormones, etc. • The circulatory system is composed of – Blood - fluid that carries stuff – Vessels - a place for the blood to travel – Pump - the heart pushes the blood through the vessels

The Heart • Made of muscle • 4 chambers – Right atrium • Receives oxygen-poor blood from body – Right ventricle • Sends oxygen-poor blood out to lungs – Left atrium • Receives oxygen rich blood from lungs – Left ventricle • Sends oxygen rich blood out to rest of body

The Heart • Valves – Prevent blood from flowing backwards when the heart relaxes • Septum – Wall between right and left side of heart – Prevents oxygen-poor blood from mixing with oxygen-rich blood

The Heart 1. 2. 3. 4. 5. 6. 7. 8. 9. Oxygen poor blood enters heart from body into right atrium Oxygen poor blood then moves into right ventricle Oxygen poor blood then moves out of right ventricle and goes to the lungs Blood picks up oxygen at the lungs Oxygen rich blood then goes back to the heart and enters the left atrium Oxygen rich blood moves into the left ventricle Oxygen rich blood then moves out of the left ventricle and goes out to the rest of the body In the rest of the body, blood drops off oxygen and picks up carbon dioxide and wastes The oxygen poor blood then returns to the heart

The Heart • Pulmonary circulation – Blood moving from heart to the lungs and back to the heart • Systemic circulation – Blood moving from the heart and to the rest of the body and back to the heart • Having these 2 circulations keeps the blood under HIGH pressure

The Heart • The heart muscle contains its own pacemaker (SA node) that tells the heart when to beat • The right and left atria contract first – Pushes blood into ventricles • Then the ventricles contract – Pushes blood out to lungs and to the rest of the body

Blood vessels • • • Arteries – Carry blood away from heart – Thick muscular walls squeezes the blood through Veins – Carry blood to heart – Thin walls but have valves to keep blood from flowing backwards Capillaries – Connect arteries to veins – Where oxygen and nutrients are dropped off and wastes are picked up – Very thin walls – Pass very close to all of the cells in your body

Blood pressure • The force of blood on the walls of your arteries • Blood pressure is given with two numbers • Normal is 120/80 • The first number is the systolic pressure – Pressure when the ventricles CONTRACT • The second number is the diastolic pressure – Pressure when the ventricles relax

Circulatory System Problems • High blood pressure – Weakness the heart and blood vessels – Increases risk for heart attack and stroke • Atherosclerosis – Plaque buildup on walls of arteries – Can lead to heart attack or stroke • Statistics – Half of us will die from cardiovascular disease • Prevention – Diet, exercise, no smoking

Blood • • Blood is the fluid that transports stuff around your body Has 4 parts – Plasma • Mostly water • Contains gases, nutrients, hormones, wastes, etc. – Red blood cells • These are the cells that carry oxygen • Hemoglobin is the protein in RBCs that grabs on to oxygen – White blood cells • Fight infection – Platelets • Involved in clotting

The kidneys and liver • Kidneys – All blood goes through the kidneys – Many dangerous wastes are removed there • Excreted in the form of urine – Salt and water balance is maintained by the kidneys • Liver – All blood goes through the liver – The liver processes or stores nutrients – The liver cells also detoxify the blood