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CARDIOVASCULAR SYSTEM The blood, heart and blood vessels Blood The heart beats by the third week after conception. Blood allows transport of oxygen, nutrients and waste Hemopoeisisblood cell formation, occurs in the bone marrow Blood Functions Transports dissolved gases Distributes nutrients Transports wastes Transports enzymes and hormones Regulates pH and electrolyte composition of interstitial fluids Clotting prevents fluid loss Defends against toxins and pathogens (WBCs) Regulates body temperature Blood Composition (blood is connective tissue) Plasma-ground substance-watery with dissolved proteins, is sticky and resists flow Formed elements--RBCs, WBCs, Platelets Plasma + formed elements = whole blood Blood Volume: 5-6 L adult male 4-5 L adult female hypovolemic hypervolemic normovolemic Plasma = 55% of blood volume Formed elements = 45% of blood volume Red Blood Cells/RBCs/Erythrocytes Function-Transport oxygen and carbon dioxide Structure- flat, circular, no nucleus. Can’t repair or reproduce. Breaks down in 120 days. Made in red bone marrow Hematocrit (hct)= percentage of whole blood taken up by formed elements Hemoglobin (hgb)= Oxygen carrying protein in RBCs, makes RBCs red, contains iron Anemias O2 carrying ability of blood is decreased. Signs and symptoms: weakness, lethargy, pale skin and mucous membranes Iron Deficiency Anemia- too little iron coming in or too much lost (bleeding). RBCs can’t make functional hemoglobin, therefore blood can carry less oxygen. Iron Rich Foods Red meats Liver Dark green leafy vegetable Whole grains Dried fruits (raisins, prunes) Sickle Cell Anemia Sickle Cell Anemia-affects a small proportion of the African-American population. (1 out of every 500 births). Caused by defective hemoglobin. Lots of O2- the RBCs look normal but, when O2 is given up RBCs get stiff and curved and are easily damaged. The ‘sickled’ RBCs get stuck in the small capillaries leading to pain and organ damage. Treatment: blood transfusion, drugs – no cure Anemias Hemorrhagic Anemia- caused by severe bleeding-leads to low blood volume with low hemoglobin and hematocrit Aplastic Anemia- bone marrow doesn’t make new RBCs. Fatal without bone marrow transplant Pernicious Anemia- RBCs don’t mature because of lack of vitamin B12. Requires supplementation by injection- B12 not absorbed well through digestive system. Blood Types Agglutinogens-antigens (substances that can make the body produce antibodies) on the surface of RBCs 3 important agglutinogens: A, B, Rh Blood Types ABO Types Type A- has agglutinogen A-40% of American population Type B –has agglutinogen B-10% of American population Type O-has NO agglutinogens- 46% of the American population Type AB- has both agglutinogens-4% of the American population Blood Types If the wrong type of blood is given to a person, the agglutinogens in the person's blood will attack the donor blood and cause agglutination (clumping) and hemolysis (breakdown of RBCs) which causes transfusion reaction and death! Type A can take Type A or Type O blood Type B can take Type B or Type O blood Type AB can take Type A, B,or O blood(universal recipient) Type O can only take Type O blood (universal donor) Rh Factor Rh agglutinogen (Rh factor) Rh+ has the RH agglutinogen Rh- does not have the Rh agglutinogen 75% of U.S. population is Rh+ Hemolytic disease of the newborn (Rh compatibility)- erythroblastosis fetalis. Rhogam given to Rh- moms to protect future Rh positive babies White Blood Cells/WBCs/Leukocytes 2 Classes Granulocytes—(look like granules in cytoplasm) neutrophils, eosinophils, basophils Agranulocytes— (have no granules)monocytes, lymphocytes Typical WBC count is 5,000-10,000 leukocytes per microliter of blood Leukemia Usually WBC count is > 100,000 Abnormal WBCs will proliferate. Immature and abnormal WBCs get into blood stream in large numbers, can invade tissues and organs These cells use LOTS of energy and replace normal cells in the bone marrow RBCs decrease (resulting in anemia), platelets decrease (resulting in decreased clotting ability,) untreated leads to death! Can be acute (short and severe) or chronic (lasts a long time) Leukemia (cont.) Acute can be caused by radiation exposure or virus. Chronic can be caused by chromosomal abnormalities or immune system malfunction There are very effective treatments for some types, but not for others. Acute lymphoid leukemia if detected early and treated85-90% of patients in remission more than 5 years. Acute myeloid leukemia- only 10-14% are in remission five years Treatments include bone marrow transplants, radiation, chemotherapy Need to isolate patient to protect them from infection Platelets/Thrombocytes or Megakaryocytes Thrombocytes (clotting cells) or megakaryocytes (big nucleus cells)— found in bone marrow—make platelets Platelets are really cell fragments—packets of enzymes, not cells New platelets constantly replace old platelets Too few platelets = thrombocytopenia Too many platelets = thrombocytosis Platelets/Thrombocytes or Megakaryocytes Functions Transport chemicals needed for clotting Plug holes in damaged blood vessels Shrink clots so healing can take place Hemostasis (hemo=blood, stasis=halt) stops blood flow so healing can start 5 steps 1. Vascular phase-local vasoconstriction makes vessels smaller at site of injuryhappens immediately and lasts for 30 min. 2. Platelet phase-platelets attach to site and plug the hole (within seconds of injury) 3. Coagulation phase- starts 30 sec. to several min. after injury. Coagulation = blood clotting Hemostasis 4. Clot retraction- platelets contraction and cause clot to get smaller 5. Fibrinolysis- (lysis=destruction) clot dissolves Clotting Abnormalities Hemophilia- inherited disorder causing excessive bleeding- inadequate production of clotting factors. 80-90% of victims are male. Usually a clotting factor VIII is lacking. Transfusions of Factor VIII come from the pooled blood of many donors. Sometimes blood clots within the vessels when it shouldn’t: Thrombus =stationary clot Embolus=clot moving through circulation The Heart Heart = pump Beats about 100,000 times daily Circulatory system: heart, hollow blood vessels and blood Arteries: efferent—carry blood away from heart Veins: afferent—return blood to heart The Heart Capillaries-tiny blood vessels that connect the smallest veins Pulmonary Circuit- takes blood to and from the lungs Systemic Circuit-takes blood to and from the rest of the body (except the lungs) Heart Chambers 2 Atria(atrium is singular) (atrium =chamber) function of atria is to collect blood 2 Ventricles-function of ventricles is to pump the blood Heart Chambers Right atrium- takes blood away from the body (systemic circulation) and pumps it into the right ventricle Right Ventricle- pumps blood into the pulmonary circuit Left atrium-takes blood from the lungs (pulmonary circuit) then pumps blood into the left ventricle Left ventricle-pumps blood out to the body(systemic) Every time the heart beats, both ventricles contract pumping out equal amounts of blood Superficial Anatomy of the Heart Size- size of one’s fist about the center of the thoracic cavity, enclosed by mediastinum (divider between the 2 plueral cavities wt. about 11 oz. (300g) Pericardial cavity-encases the heart (lined by pericardium) Base- (top) connected to the great vessels Apex- tip of heart Valve=tissue folds allow blood to flow only one way through heart Right pulmonary artery Aorta Left pulmonary artery Superior vena cava Left pulmonary veins Right pulmonary veins Inferior vena cava Apex Deoxygenated blood Oxygenated blood Left atrium Pulmonary valve Right atrium Tricuspid valve Right ventricle Aortic valve Bicuspid/ Mitral valve Left ventricle Blood Flow Heart Wall 3 layers Epicardium / Pericardium Myocardium Endocardium Epicardium (Pericardium) Outer, protective covering Double layer membrane (or sac) that helps decrease friction during heart beats- prevents tissue damage Myocardium Muscle layer, layers that wrap around atria and ventricles Endocardium Inner layer- lines chambers of heart Smooth layer of cells that line inside of the heart. Allows blood to flow smoothly Diseases and Disorders Carditis—general term for inflammation of the Heart Endocarditis-inflammation of the endocardium20-30% mortality rate-usually caused by blood clots that break away from the inner surface and go into the circulation as emboli leading to stroke, heart attack, kidney failure Diseases and Disorders Myocarditis- inflammation of the myocardium caused by bacteria, viruses or fungi. Usually results in increased heart rate leading to abnormal contraction of the heart Diseases and Disorders Pericarditis-inflammation of the pericardium. Can be caused by a variety of pathogens. Layers of the pericardium (epicardium) rub together leading to an increase in fluid which can restrict heart movement resulting in cardiac tamponade (excess fluid in pericardium leading to decreased effectiveness of heartbeat) Diseases an Disorders Coronary Artery Disease (CAD)- causes a decrease in coronary circulation leading to decreased oxygen in the heart muscle. Decreased circulatory supply=coronary ischemia(usually caused by partial or complete blockage of blood flow through the coronary arteries) CAD is progressive Primary Symptom=angina pectoris (angina=pain, pectoris=chest) Exertion or emotional stress can bring on pain Diseases and Disorders CAD treatment Reduce stress or find positive ways to deal with stress Decrease dietary fat Drugs-beta blockers (prevent sympathetic nervous system from stimulating heart muscle), nitroglycerin (vasodilator-transdermal patch or sublingual pill) Diseases and Disorders CAD treatment Cardiac Catheterization- catheter inserted until blocked place is reached and imaged Options: tool inserted to ream out artery and plaque suctioned out OR Balloon angioplasty- balloon in catheter is inflated pushing plaque against vessel walls OR Stent inserted to hold plaque against artery walls Coronary Bypass surgery- Part of a blood vessel (usually a vein) taken from another part of the body (chest or leg), grafted on to bypass blocked artery Myocardial Infarction Heart Attack! What happens? Treatment Risk factors Myocardial Infarction (heart attack) Cardiac muscle cells die from decreased oxygen. Tissue degenerates so there is an area of the heart that doesn’t function (infarct) Often caused by severe CAD- scar tissue that forms in damaged area causes heart to beat inefficiently. Heart beat can become irregular, blood vessels may constrict Most dangerous time after MI is the first hour after the attack (golden hour) -25% die before Medical help arrives. 65% of MI deaths in those under age 50 happen in the first hour Myocardial Infarction (heart attack) Treatment goals limit size of infarct Prevent further complications Increase circulation with vasodilators Increase Oxygen Decrease cardiac workload Eliminate source of blockage Risk Factors- Smoking, increased blood pressure, increased cholesterol, diabetes, obesity, sedentary life style, high stress, hereditary factors If a person has 2 of these, MI risk doubles The Heartbeat Normal heart rate 60- 100 beats per minute Bradycardia- slow heart rate, <60 bpm Treat with artificial pacemaker Tachycardia- fast heart rate, >100 bpm, Heart works too hard Ventricles don’t have time to fill with blood The Heartbeat Cardiac cycle- time of the start of one heart beat to the start of the next heart beat Systole- contraction phase. Heart is pumping/beating Diastole- relaxation phase, between beats Heart Sounds Stethoscope- instrument used to listen to heart sounds Auscultation- act of listening to sound with an instrument Electrocardiogram/ECG/EKG Record of electrical activity of heart. Gives info on the performance of different areas of the heart. The tracing looks different when the electrodes are placed in different areas Cardiac Arrhythmias Cardiac Arrhythmias—abnormal patterns of heart activity Heart block—damage to conductive pathways. Can cause skipped beats PVC—premature ventricular contractions Ventricular tachycardia (V-tach)— very rapid heart beat—can lead to Ventricular fibrillation (V-fib) (V-fib) heart quivering, not pumping blood—rapidly fatal unless defibrillation occurs Cardiac Arrhythmias Defibrillator—electric shock depolarizes entire myocardium at the same time—gives ventricles a chance to respond to normal electrical impulses within heart Blood Vessels Arteries Veins Capillaries Heart, arteries and capillaries have 30-35% of all body’s blood (~1.5L) Venous system has 65-70% of all body’s blood (~3.5L) Arteries common carotid subclavian brachiocephalic Carry blood away from heart Branch into arterioles Thicker, muscular walls axillary brachial renal abdominal aorta ulnar radial common iliac femoral popliteal Veins jugular subclavian brachiocephalic Carry blood toward heart Branch into venules Venous system has less pressure than arterial sys. Thinner walls axillary superior vena cava brachial hepatic portal inferior vena cava renal ulnar radial common iliac great saphenous femoral popliteal Capillaries The smallest blood vessels (10 billion in body) connect arterioles and venules The only vessels allowing gas, nutrient and waste exchange. Work together in capillary beds Diseases and Disorders Aneurysm-bulge in the weakened wall of a vessel (often an artery)-like a bubble in a tire. Can lead to catastrophic blow out. In the brain it can lead to stroke. In the aorta-the person can bleed out in seconds. Cause: usually chronic high blood pressure, can be linked to hereditary disorders (Marfan’s syndrome) Painless, often undetected Diagnosis: ultrasound, often found when having tests done for another condition Treatment: Decrease blood pressure with vasodilators, beta blockers or surgery if aneurysm is accessible Disease and Disorders Arteriosclerosis- artery walls get thick and tough. Leads to about ½ of all U.S. deaths each year. CAD (coronary artery disease) is a form of arteriosclerosis. Atherosclerosis Disease and Disorders Atherosclerosis- fatty plaque builds up on artery walls. Most common in elderly, especially males. Estrogen has a negative effect on plaque build up. Other factors- high blood pressure, high cholesterol, cigarette smoking, diabetes mellitus, obesity and stress. Treatment: decrease fat and cholesterol, stop smoking, check BP and lower if needed, check blood cholesterol, control weight, exercise, for severe cases; cardiac catherization and balloon angioplasty or stents Disease and Disorders Thrombus- stationary clot Embolus clot moving through circulation Blood Pressure Blood pressure=arterial pressure-force of blood against vessel walls Systolic pressure= peak pressure, pressure during ventricular systole. Pressure while heart is contracting Diastolic pressure=minimum pressure, pressure during ventricular diastole. Pressure between heart beats Measure using a Stethoscope and a Sphygmomanometer Hypertension-high blood pressure Hypotension- low blood pressure Normal-100-140/60-90 Treatment-quit smoking, exercise, decrease sodium, fat and calories in diet, medication Exercise and Cardiovascular System Benefits of regular exercise to cardiovascular system Increase heart size and cardiac output Decrease heart rate Decrease blood cholesterol Decrease blood pressure Helps decrease consequences of stress Could reduce heart attack chance by 1/2 Blood Loss and Shock Blood Loss: Immediate problemmaintain adequate BP and blood flow to peripheral tissues Long term problemrestore normal blood volume Blood Loss Shock Acute crisis situation – life threatening Low and falling blood pressure leads to too little blood flow. Therefore, tissues are starved for oxygen and nutrients Causes; hemorrhage, heart damage, external pressure on the heart, extensive peripheral vasodilatation Signs and symptoms- hypotension, cool and clammy skin, rapid and weak pulse, confusion, no urination and metabolic acidosis(lactic acid made in oxygen deprived tissues Aging and the Cardiovascular System Changes to the Blood- Hematocrit decreases Increased likelihood of venous thrombosis(usually in the legs) Changes to the HeartDecreased cardiac output decreased maximum heart rate and arrhythmias Increased atherosclerosis->decreased circulation Increased scar tissue Changes to the Vessels Some arteriosclerosis, arteries lose some elasticity Increase risk of stroke and heart attack