Every cell in body needs nutrients and oxygen

Every cell in body needs nutrients and oxygen to function Circulatory system- transports blood and other materials vital to the cells and carries away wastes

The circulatory system moves blood to all parts of the body Functions to transport O 2 and nutrients to body cells and carry oxygen poor blood and CO 2 back to the heart and lungs

Main parts of system are heart, blood, and blood vessels a. Heart- muscular pump b. Blood- circulates through a closed system 1). About 5 liters 2). Takes about 60 seconds for round trip

Blood vessels- three types 1). Arteries- carries blood away from heart (oxygen rich) 2). Veins- carries blood back to heart (oxygen poor) 3). Capillaries- smallest vessels where materials can diffuse into and out of cells

The tissues and structures of the heart make it an efficient pump Consists of four chambers a. Atrium- right and left sides (smaller chambers) b. Ventricles- right and left sides (larger chambers) c. Valves- flaps of tissue that prevent blood from flowing backwards

Blood flow in heart a. Oxygen poor blood enters right atrium and pumped into right ventricle b. Right ventricle pumps blood to lungs for gas exchange c. Returns to left atrium and pumped to left ventricle d. Left ventricle pumps blood to rest of body (this is the largest chamber)

The heart pumps blood through two main pathways • Pulmonary circulation – heart pumps oxygen-poor blood to the lungs, blood becomes oxygen-rich & returns to the heart • Systemic circulation – heart pumps oxygen-rich blood to body tissues & then the oxygen-poor blood returns to the heart

Blood Vessels and Transport • Arteries carry blood away from the heart – Must be strong & flexible to withstand the pressure of the heart pumping the blood through – Walls are made up of 3 thick layers of tissue

• Veins carry blood back to the heart – Larger in diameter and have thinner layers of tissue – Valves prevent the backflow of blood

• Capillaries allow materials to diffuse in and out of the blood quickly & easily – Very small in diameter – Made up of a single layer of tissue, sometimes only 1 cell layer thick

Factors that Affect Blood Flow Inner walls of blood vessels must be smooth and free of obstruction to allow for proper blood flow Factors that affect blood flow include: • Blood viscosity (thickness) • Blood clots • Diameter of blood vessels

Blood pressure- force with which blood pushes against wall of an artery (E. g. 120/70) • Blood pressure rises naturally with activity, stress, & strong emotions • Permanently high blood pressure (hypertension) can be a sign of circulatory disease and can lead to heart attack or stroke • Blood pressure can usually be lowered through proper diet & exercise • Low blood pressure (hypotension) can be caused by problems such as shock or capillary leak syndrome

Lifestyle plays a key role in circulatory disease 1. Increased risk of developing circulatory disease with: smoking, lack of exercise, excessive weight, long-term stress, diet high in saturated fats

2. Arteriosclerosis- artery walls become thick and inflexible 3. Artherosclerosis- blood flow partially or fully blocked by sticky material called plaque