 Arteries- elastic and stretchy, ability to withstand the high pressure of blood being pumped from the heart ◦ Arteries close to the heart are more elastic ◦ Arteries farther from the heart have more muscle to help maintain blood pressure ◦ Arterioles are the small branches of arteries that lead into the organs and tissues to the capillaries  Capillaries- very small vessels that connect arterial and venous circulation.  Veins-vessels that return blood to the heart ◦ Venules are the smaller branches that lead out of the tissues and organs to larger veins ◦ One-way valves prevent backward flow of blood

Non-Cellular  Water  Mineral ions: Na, Mg, K, Ca, Cl  Plasma proteins  Transported substances: sugar, fats, urea, hormones, Cellular  RBCs  Platelets  Leukocytes- WBC  Lymphocytes- T and B cells  Phagocytes  Other white cells

Relationship between blood, lymph, plasma, and tissue fluid Capillaries are very small and connect arterial and venous circulation and allow efficient exchange of nutrients and wastes between the blood and tissues. Fluid leaks out of the capillaries and bathes the tissues. This movement depends on hydrostatic pressure and solute concentrations This tissue fluid is returned to the circulatory system via the lymphatic system

 Deoxygenated blood travels to the right side of the heart, enters the vena cava (largest vein)  Deoxygenated blood enters the right atrium and moves into the right ventricle through the tricuspid valve  The right ventricle pumps blood pump the deoxygenated blood to the lung via the pulmonary artery  The oxygenated blood enters the heart via the pulmonary veins to the left atrium  Then moves to the left ventricle through the bicuspid valve.  The left ventricle then pumps oxygenated blood to the body via the aorta (largest artery)

 The center of the cardiovascular system  Weighs about 342 grams  Two atria and two ventricles  Found between the two lungs along the midline  Surrounded by a double layer pericardium made of connective tissue, it anchors the heart and prevents over-distension

 The heart pumps with alternate contractions  Systole contractions  Diastole relaxations  The pulse results from rhythmic expansion of the arteries as blood spurts from the left ventricle. Pulse rate corresponds to heart rate  Ventricles relax and blood flows into them during artrial systole  Artria relax as the ventricles contract and blood is pumped out of the heart

 6,000 quarts of blood are pumped a day.  The heart has an internal regulation, myogenic  The sinoatrial node is the hearts pacemaker  The rate is set by the node but is regulated by the medulla and is influenced by sensory information and changes to meet the needs of the body.

 Aortic aneurysm- ballooning of the wall of the aorta  Valve defects- unusual heart sounds (murmurs) can result when a valve does not close properly allowing backflow  Myocardial infarction- occurs when an area of the heart is deprived of blood and dies, can lead to heart failure  Atherosclerosis is the disease of the arteries caused by fatty deposits on the inner walls. ◦ The accumulation of plague narrows the vessels and increases blood pressure and reduces flow ◦ Aneurysm and thrombosis are the result of blood clotting within the vessels ◦ Results can be infarction, stroke, gangreneor