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Cardiovascular System Chapters 11, 12 Oxygen enters the cardiovascular system by diffusing from alveoli into blood cells in the capillaries, then binding to hemoglobin in red blood cells. Blood • Hematology- the study of blood, blood forming tissues, and the disorders associated with them. • Blood consists of 2 components. – Plasma (55%) • Water (92%). • Proteins (8%). – Formed Elements (45%) • Erythrocytes (99%)- red blood cells. • Leukocytes (<1%)- white blood cells. • Platelets (<1%)- a fragment of cytoplasm enclosed in a cell membrane. Characteristics of Blood • • • • • • 1 Drop of blood contains 250 million blood cells. Blood is denser than water. Blood temperature is about 100.4 °F. pH= 7.35-7.45. Blood is about 8% of total body weight. Blood volume in – Men is 5-6 liters (1.5 gallons). – Women is 4-5 liters (1.2 gallons). Hemoglobin • 280 million molecules of hemoglobin per red blood cell. • Hemoglobin- oxygen binding protein/pigment. – Globin protein that consists of 4 polypeptide chains. – Heme molecules are attached to each polypeptide chain. • Each heme contains an iron ion (Fe+2) that binds to oxygen. • Transports oxygen from the lungs to tissue cells and transports part of the carbon dioxide to the lungs. Hematocrit and Blood Disease • Hematocrit- percentage of blood occupied by cells. – Female normal range • 38-46% (aver.- 42%) – Male normal range • 40-54% (aver.- 46%) • Anemia- reduced RBCs or not enough hemoglobin. • Hemoglobinopathyblood disease. The Heart • Anatomy – Cone-shaped, the size of a closed fist (5 inches in length, 3.5 inches in width, 2.5 inches thick). – The heart has: • 2 atria (upper chambers). • 2 ventricles (lower chambers). • 4 valves. – The heart consists mostly of myocardium (cardiac muscle tissue). • Function – Pump blood. • About 3,600 gallons pumped per day. • Beats about 72 times per minute, over 100,000 times per day. The Heart- external The Heart- internal The Cardiac Cycle Atrial Systole Diastole Ventricular Systole Measuring Blood Pressure • Sphygmomanometer • Blood Pressure- a measure of arterial pressure in the brachial artery. – Systolic pressure= pressure during contraction (120 mm Hg). – Diastolic pressure= pressure during relaxation (80 mm Hg). The valves prevent backflow of blood Pulmonary valve Aortic valve Tricuspid valve Bicuspid (mitral valve) Normal Heart vs. Mitral Valve Prolapse Internal Conduction System • Sinoatrial node (SA, pacemaker). • Atrioventricular node (AV). • Atrioventricular bundle. • Purkinje Fibers. •HeartArteriesArteriolesCapillaries VenulesVeinsHeart Heart Heart Vein Artery Venule Capillary Arteriole Arteries vs. Veins • Each have the 3 layers. • The middle layer of an artery shows more smooth muscle. • The lumen is smaller in arteries. • Veins often contain valves. • Veins are blood reservoirs, and hold 65% of blood. Valve Smooth Muscle Artery Vein Capillaries are sites of exchange • Capillaries are microscopic, narrow vessels. – Substances are exchanged through the plasma membrane of the capillary. • Arterial end of capillary – Blood pressure forces fluid out of the capillary. • Venous end of capillary – Fluid is drawn back into the capillary by osmotic pressure. • Blood pressure – Decreases in capillaries. • Blood velocity – Decreases in capillaries due to greater surface area. Pulse- a pressure wave created by the ejection of blood from the left ventricle into the aorta. Drainage- the flow of blood back to the heart. • Accomplished by – Skeletal muscle contraction. – Valves in veins. – Respiratory movements. Atherosclerosis • Atherosclerosis- the buildup of lipids in the artery walls. (athero- yellow; sclerosis- hardening). • Buildup of fatty deposits (plaques), particularly LDLs (bad cholesterol), obstructs blood flow. • Leading cause of heart attacks (death of heart muscle cells) and strokes (death of brain cells). Balloon Angioplasty • A catheter and baloon are threaded into the coronary artery to the point of blockage. • The balloon is inserted into the blocked area and inflated. • Plaque is pushed to the artery walls. Coronary Bypass Surgery Lymphatic System Cardiovascular + Lymphatic = Circulatory System Lymphatic Components • Lymphatic vessels and ducts. • Lymph- fluid. • Lymphatic Organs – – – – – Red bone marrow Thymus Spleen Lymph nodes Diffuse lymphatic tissue • Tonsils, adenoids & Peyer’s patches. Function #1- Draining excess interstitial fluid & plasma proteins from tissue spaces. • About 85% of what exits the arterial end is reabsorbed by the venous end of the capillaries. • The 15% that doesn’t return is excess tissue fluid, it is absorbed by the lymphatic system. Lymph is returned to the bloodstream just above the heart in the brachiocephalic veins. Function #2- Transporting dietary lipids and vitamins from the GI tract to the blood. Function #3- Facilitating immune responses by recognizing microbes or abnormal cells and killing them directly or by antibodies. Basophil 1% Eosinophil 3% Lymphocyte 24% Neutrophil 66% Monocyte 6% White Blood Cells • Function- fight infection; defend against pathogens that invade the body. – Granular leukocytes • Neutrophils- phagocytosis and destruction of bacteria (pus). • Eosinophils- destroy worms, lessen the severity of allergies. • Basophils- release histamine, a chemical that attracts other white blood cells to the site of infection, causes blood vessels to dilate. – Agranular leukocytes • Lymphocytes – T cells- attack viruses, cancer cells, and transplanted tissue cells. – B cells- develop into plasma cells that secrete antibodies. – Natural killer cells- attack microbes and tumor cells. • Monocytes- develop into phagocytotic macrophages. Red Bone Marrow • Spongy bone- site of red and white blood cell production. – Stem cells in the marrow give rise to all formed elements. Lymph Node Anatomy • Bean-shaped organ, up to 1 inch long (125 mm), located along lymphatic vessels. • Scattered throughout body but concentrated near mammary glands, axillae, and the groin. • About 600 per human. Lymph Node Function • Lymph nodes filter lymph. • House macrophages that phagocytize debris, cancer cells, viruses, and bacteria. • House lymphocytes that mount attacks on pathogens. Spleen • Anatomy – 5 inch long organ between stomach and diaphragm. • Function – Destroy bacteria and viruses. The white pulp consists of mostly lymphocytes and macrophages. – Filter old and damaged red blood cells and pathogens from blood. The red pulp consists of mostly lymphocytes and macrophages. Thymus Gland • Large in infants (70 g), atrophied in adult (3 g). • 2 lobed organ. • Each lobule has a cortex and medulla. • The cortex is tightly packed with lymphocytes & macrophages. • Chief Function – Aid in the maturation of Tlymphocytes. Lymphatic Nodules • Lymphatic nodulesoval-shaped concentrations of lymphatic tissue. – Tonsils- form a ring around the throat where they protect against disease organisms that are inhaled or swallowed. – Peyer’s patcheskeep bacteria from breaching the wall of the ileum. Pharyngeal tonsil (adenoid) Palatine tonsil Lingual tonsil