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The Cardiovascular System image (Pathology Connection: (Systemic Blood…

- - - - Is the size of your fist, located slightly left of center of chest
      - Base is proximal to your head while apex is distal
      - Although heart is one single organ, it is easier to understand if you think of it as two pumps working together
        
        Right side collects blood from body and sends it to lungs; left side collects blood from lungs and sends it to rest of bod
      - The outer layer of the heart (visceral pericardium) is also know and the epicardium
        
        The middle layer of the heart wall is the myocardium
        
        The endocardium is what the inside of the heart is lined with.
      - The heart is surrounded by a serous membrane called the pericardium
        
        Inside the pericardium is the parietal layers
        
        The visceral layer is fused to the heart surface
        
        The pericardial cavity is between the layers
      - There are four chambers in heart
        
        Two chambers on left side are separated from two chambers on right side by wall called septum
        
        Wall between upper, smaller chambers (atria) is interatrial septum
        
        Wall between two larger chambers (ventricles) is interventricular septum
        
        Right atrium (locations are based on patient perspectives) is collecting chamber where blood is returned to heart after trip around body
        
        Two large veins that return blood to right atrium are superior and inferior vena cavae
        
        Blood travels from right atrium, through one-way atrioventricular valve called tricuspid valve, and into right ventricle
        
        When right ventricle is full of blood, heart contracts; tricuspid valve prevents backflow of blood into right atrium so blood flows through pulmonary semilunar valve to pulmonary arteries
        
        Right pulmonary artery goes to right lung, left pulmonary artery goes to left lung where vessels get smaller and smaller, eventually ending in capillaries around each air sac (alveolus); blood then returns to heart via left and right pulmonary veins
        
        Pulmonary veins return blood to left atrium
        
        Once left atrium is full, blood flows through atrioventricular valve, called mitral valve, and into left ventricle
        
        Left ventricular pressure increases as it fills, and when heart contracts forcing mitral valve closed, blood is ejected through aortic semilunar valve to ascending aorta, and then out to rest of body
      - Heart muscles have an amazingly blood rich environment because a
        
        Portion of newly oxygen enriched blood leaving heart is diverted from aorta by right and left coronary arteries
        
        Arteries continuously divide into smaller branches forming web of interconnections, known as anastomoses, in order to consistently supply heart muscle with rich supply of blood
        
        Regular aerobic exercise increases density of these blood vessels and the number of anastomoses also increases as do the number of their locations
        
        Important for those with blockage of coronary arteries b/c may have an alternate route of travel to prevent muscle damage
        
        Right coronary artery provides blood for right ventricle, posterior portion of interventricular septum, and inferior parts of heart
        
        Left coronary artery provides blood to left lateral and anterior walls of left ventricle, and portions of right ventricle and interventricular septum
    - - Blood Vessels can be broken further down
        
        Arteries carry blood away from heart, branch into smaller vessels called arterioles, which become capillaries, where nutrients are exchanged; capillaries become venules, that enlarge and become veins
        
        Carotid artery; largest arteries (side of neck) that take blood from heart to head
        
        Veins differ from arteries because they carry blood toward heart, have valves, and have thinner walls; they are more numerous and have larger capacity
        
        Jugular veins –largest veins that take blood from your head to the heart
- - - - The circulatory system has four main functions:
        
        Pump materials throughout the body
        
        Designed specifically to carry blood to various parts of the body
        
        The movement of materials facilitates the delivery of vital materials like O2 and nutrients to the cells of the body and remove cellular waste
        
        Return excess fluid (often in the form of lymph) to general circulation
- - - - Condition in which right side of heart can’t move blood efficiently
      - Develops because of heart muscles chronically working harder than normal; muscles on right side become too large, preventing efficient pumping
      - Heart may have to work harder in cases of: polycythemia (thick blood due to elevated RBC levels); constricted pulmonary vessels; both situations may develop in association with certain lung diseases
      - Cor pulmonale occurs in 85% of patients with COPD
      - Pathophysiology
        
        Healthy left side of heart continues to pump blood normally
        
        Unhealthy right side of heart cannot keep up
        
        Blood begins to back up in systemic veins, causing
        
        Engorged liver and spleen
        
        Swollen ankles, feet, and hands
        
        Distended neck veins
    - - Heart failure
        
        Formerly called congestive heart failure
        
        Usually a left sided heart problem but can include the right sided failure as well
        
        Condition where heart cannot move blood efficiently;
        
        Pumping action of heart cannot overcome an increased system blood pressure
        
        Left side to weak to pump effectively
        
        Blood backs up into veins
        
        Increased pressure in veins allows fluid to leak from vessels and into tissues
        
        Possible causes include muscle damage after a heart attack, resulting in inefficient pumping
        
        In right-sided heart failure, left side is pumping normally, but right side cannot keep up
        
        Blood backs up in systemic veins
        
        Fluid starts to leak out into tissue
        
        Symptoms may include enlarged liver, spleen, and carotid arteries as well as swelling of feet, ankles, and/or hands
        
        In left-sided heart failure, right side is pumping normally but left side cannot keep up
        
        Blood begins to back up in lungs (pulmonary veins)
        
        Fluid leaks out of vessels into lung tissue, resulting in pulmonary edema
        
        Symptoms can include shortness of breath, wet-sounding cough, and hypoxia
        
        Can be treated with medications
        
        Agents that increase rate and force of heart contraction
        
        Diuretics that rid system of excess fluid
    - - Condition caused by inadequate or absent blood flow to area of heart muscle
        
        Ischemia: inadequate flow of oxygenated blood flow to the heart
        
        Does not permanently damage heart, but results in chest pain called angina pectoris
        
        Pain to the chest, radiate to the left shoulder, arm , neck, and jaw; nausea , diaphoresis, and dyspnea
        
        Can be treated with nitroglycerin, which dilates coronary blood vessels and improves blood flow
      - Myocardial infarction (MI) Also called heart attack
        
        Infarct: tissue damage and death that results from completely blocked blood flow
        
        May result from blood clot in coronary blood vessels (coronary thrombosis)
        
        Can cause permanent damage to heart if tissue death (necrosis) occurs because cardiac muscle cannot repair itself
        
        Symptoms:
        
        Chest pain or heaviness
        
        Pain in the left shoulder, arm, neck, or jaw
        
        Nausea
        
        Heartburn
        
        Generalized weakness
        
        Clammy sweaty feeling
        
        Shortness of breath
        
        Dizziness
        
        Anxiety
        
        MI– Dx & Tx
        
        Getting prompt diagnosis and treatment is sometimes difficult because:
        
        Some patients experience little or no pain; called silent MI
        
        Some patients (especially women) exhibit “non-traditional” signs and symptoms, like jaw pain
        
        Patients may misattribute symptoms to another medical condition, like indigestion or a pulled muscle
        
        If heart attack suspected, call 911 immediately and take aspirin; aspirin is mild anti-coagulant, and can help keep blood flowing around heart, minimizing damage
        
        Medical diagnosis may include measurement of various enzymes and proteins, substances released in bloodstream when cardiac muscle cells die
        
        Measurements used to diagnose:
        
        CK-MB: special kind of creatine kinase found in heart muscle cells; enzyme can be detected in blood within 2-6 hours of MI
        
        Lactate dehydrogenase (LDH): increases in blood approximately 12 hours after heart attack
        
        Troponin I and II: increases in blood approximately 4-6 hours after MI
        
        Some substances can remain elevated in blood for several days after MI
        
        Monitoring blood levels of substances can be important in diagnosing MI
  - - - Lifestyle changes that overcome at risk behaviors like a lack of exercise or improper diet, and smoking
  - - - Any blood vessel is susceptible, but aorta, coronary arteries, and cerebral arteries particularly susceptible
      - Some treatments include:
        
        Lifestyle changes, medications that control cholesterol, antiplatelet medications, anticoagulants, and blood pressure medications
      - Plaque composed mostly of cholesterol; build up can block blood flow
    - - Coronary angioplasty: procedure where balloon-tipped catheter threaded up to large plaque; when in proper position, balloon is inflated, squishing plaque to side and increasing blood flow
      - Intracoronary stent placement: stents are wire devices that hold blood vessel open after angioplasty; can prevent re-occlusion of blood vessel
      - Coronary artery bypass graft (CABG): surgical procedure where healthy blood vessels from another part of body are used to replace clogged coronary arteries
  - - - Types of dysrhythmias
        
        Flutter: coordinated, but extremely rapid contraction of heart chamber (flutter can sometimes reach rates of 300 contractions per minute)
        
        Fibrillation: rapid, uncoordinated contraction of cardiac muscle cells
        
        Heart block: condition where electrical signaling between atria and ventricles is delayed or completely blocked; results in atria and ventricles contracting out of sync with one another
      - Treating dysrhythmias
        
        Pacemaker: surgically implanted device that electrically stimulates heart, triggering contraction
        
        When dual leads are implanted, atrial and ventricular contractions can both be coordinated
        
        Some pacemakers trigger every heart beat; others work only when heart does not send electrical impulse on its own
        
        Defibrillation: device that applies electric current to all of cardiac muscle at once; in cases of life-threatening arrhythmias, this can be used to “jump start” heart back into normal rhythm
  - - - Secondary polycythemia: chronic low levels of oxygen cause body to produce more erythrocytes to transport more oxygen
        
        Usually seen with persons who have lung disease or they live in high altitudes
      - Primary polycythemia: can be due to bone marrow cancer
    - - Anemia: decreased numbers of RBCs or abnormal or deficient amount of hemoglobin
        
        Possible causes: bone marrow dysfunction; low level of iron or vitamins; improper formation of RBCs
        
        Common symptoms: pale skin, mucous membranes, and nail beds; fatigue and muscle weakness; shortness of breath, and/or chest pain
        
        Iron-deficiency anemia- caused by low dietary iron causing insufficient Hgb production. Affects women, children, ad adolescents. Tx prescribing iron supplements and increasing amount of green leafy veggies
        
        Aplastic anemia- bone marrow does not produce enough blood cells. Typically a side effect of of drug or radiation therapy that treats diseases like cancer
    - - Sickle cell anemia: inherited condition (found mainly with African Americans) in which RBCs and hemoglobin molecules cannot form properly
        
        RBCs are crescent-or sickle-shaped and tend to rupture
        
        As cells are destroyed, body is stimulated to produce more RBCs, resulting in immature cells due to high production rate
        
        Patients may suffer from increased clotting and impaired ability to carry oxygen because ruptured cells clog up small vessels. high numbers of RBCs thicken blood
  - - - Corticosteroids and anticancer medication
  - - - Usually inherited from mom to son that occurs because of a missing clotting factor
    - - If count is low enough, even routine acts of moving can lead to bleeding
      - Causes include liver dysfunction, decreased levels of vitamin K, radiation exposure, and bone marrow cancer
    - - Thrombus formation
        
        Rough surface on lining of blood vessel may allow platelets to begin “sticking,” forming clot called thrombus
        
        Thrombus in coronary artery can partially or totally block blood flow to portion of heart, causing heart attack (coronary thrombosis)
        
        Area of myocardium affected as well as how big the clot the is, determines severity of attack
        
        The bigger the clot, the bigger the blockage is and then it is a bigger area of the heart that gets affected
      - Embolus formation
        
        Part of thrombus can break off and travel; this is called embolus
        
        Embolus will eventually get stuck in small vessel; will partially or completely block vessel and affect blood flow
        
        Cerebral embolus would cause stroke; pulmonary embolus would affect oxygenation
        
        Risk factors for unwanted clots
        
        Slow blood flow, as seen in bedridden people; people sitting for long periods in plane, car, or bus
        
        Women who smoke and use oral contraceptives are at increased risk
        
        People on certain types of chemotherapy are also at increased risk
        
        Treatments and preventions for abnormal clot formation
        
        Aspirin and heparin can be taken to decrease risk of clot formation
        
        Streptokinase is “clot buster” that can break up existing clot
  - - - May be caused by a congenital defect, disease, or injury, familial tendency for abdominal aneurysm
      - This weakened area may balloon
      - Often no symptoms, but when aneurysm continues to expand it can rupture, causing hemorrhage
      - If it is in a major artery, an individual can bleed out in a matter of minutes
      - Found on X-ray/US
      - Surgical intervention can remedy the situation if detected early
    - - Often a sufficient blood flow to the legs during rest and minimal exertion but when activity increases the…
        
        Plaque interferes with blood flow, and then then the blood supply to the legs is less then the demand and can cause leg cramping
      - Treatments may include cleaning out clogged vessel or replacing it
      - What about the feet??
        
        If smaller arteries are involved , the blood supply may be insufficient to the toes and feet so you have a decrease ability to heal well
        
        If plaque affects smaller arteries, blood flow to toes and feet may be inadequate
        
        Can lead to difficulty healing, gangrene infection, and tissue necrosis
        
        Surgical amputation of affected area may be necessary
    - - Etiology: inflammatory process that produces pericardial effusion, trauma, rupture of heart or aorta into pericardium
      - Signs and symptoms: pain possible, tightness/fullness in chest, possible frank dyspnea, loss of consciousness if extreme
      - Diagnostic tests: patient examination/history, radiological studies
      - Treatment: medical treatment, removal of offending fluid if no rapid improvement
    - - Etiology: result of blood leaking backward due to faulty heart valve or narrowed valve opening
      - Signs and symptoms: abnormal sound of blood flow in heart
      - Diagnostic tests: auscultation, with ultrasonic confirmation
      - Treatment: correction of condition creating abnormal murmur
    - - Etiology: various connective disease disorders, sometimes coronary artery disease
      - Signs and symptoms: possibly asymptomatic, murmur, fatigue, palpitations, dyspnea, increased chance for clot development
      - Diagnostic tests: auscultation, echocardiography, radiologic studies, cardiac catheterization, stress testing
      - Treatment: medication, possible valve reconstruction/ replacement if severe
    - - Etiology: rheumatic fever, congenital origin, aging process
      - Signs and symptoms: murmur, possible fatigue, chest pain, dyspnea, lower PaO2, pulmonary edema, syncope
      - Diagnostic tests: auscultation, cardiac catheterization, echocardiography, radiologic studies, stress test
      - Treatment: possible valve replacement, medication
- - - - Nodal cells, or pacemaker cells, are specialized cells that not only create electrical impulse, but create impulses at regular interval
        
        Nodal cells are connected to each other and to conducting network
        
        Nodal cells are divided into two groups, sinoatrial node and atrioventricular node
        
        Sinoatrial (SA) node
        
        Located in wall of right atrium, near entrance of superior vena cava
        
        Generates electrical impulse at approximately 70–80 impulses per minute
        
        Once electrical impulse is generated at SA node, it travels to AV node; there is a bit of signal delay, allowing atria to fill with blood before contraction occurs
        
        Once charge hits AV node, it travels through AV bundle or bundle of His
        
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        Atrioventricular (AV) node
        
        Located at point where atria and ventricles meet
        
        Generates electrical impulse at rate of 40–60 beats per minute
        
        Sinoatrial node sends impulse to atrioventricular node before AV node can send signal
        
        However, atrioventricular node acts as backup if sinoatrial node fails to fire, resulting in slower heartbeat because AV node fires fewer impulses per minute
        
        Heart rate not always 70–80 beats per minute (bpm)
        
        While SA node sets heart rate at rest, many other factors change heart rate
        
        Autonomic nervous system (sympathetic and parasympathetic) has direct connection to SA and AV nodes, as well as heart wall
        
        Sympathetic division can release neurotransmitters that increase heart rate and force of contraction (inotropism)
        
        Parasympathetic division can release neurotransmitter via vagus nerve(cranial nerve X) to decrease pulse and force of contraction
        
        Ions, hormones, and body temperature can alter heart rate
        
        Epinephrine increases heart rate
        
        Fever increases heart rate due to increased metabolic rate of the cardiac muscle cells
        
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        Altered levels of sodium, potassium, or calcium (electrolytes) can alter heart activity; low potassium can lead to weak heartbeat, while high calcium can prolong heart muscle contractions to point where heart can stop beating
        
        Age, sex, and exercise can all impact heart rate; normal female heart rate is 72–80 while normal for males is 64–72
        
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- - - - Transports oxygen from lungs, nutrients from digestive system and fat cells, and hormones from endocrine glands to approximately 75 trillion cells in body
      - On return trip carries carbon dioxide and other waste products to kidneys, lungs, and other organs for removal
    - - Helps regulate variety of levels in body to help maintain homeostasis by ensuring pH (levels of acidity or alkalinity) and electrolyte values are within normal parameters for proper cell functioning
      - Helps to regulate body temperature by absorbing heat generated by skeletal muscles, spreading it throughout rest of body or releasing heat through skin
      - Helps regulate fluid balance of the body by taking in or giving up more fluid
    - - Helps protect us from invasion and infection by pathogens and toxins
      - Specialized white blood cells (WBC) and special proteins called antibodies function to prevent infection
  - - - Major components are plasma and formed elements
        
        Plasma is yellowish, straw-colored liquid that comprises about 55% of blood’s volume
        
        90% water; other 10% contains nutrients, salts, oxygen, hormones and other regulatory substances
        
        Plasma proteins are important group of dissolved substances that include albumin, which aids in keeping correct amount of water in blood; fibrinogen is substance needed for blood clotting, and globulins involve antibodies for protection from infection
        
        Formed elements include:
        
        Red Blood Cells (RBCs) or erythrocytes
        
        Red blood cells created by red bone marrow through a process called hemopoiesis because they lack nucleus to reproduce themselves
        
        Don’t confuse with hemolysis (this is the rupture of RBC which releases hemoglobin into the blood
        
        Can happen during a blood transfusion or during a blood test and skew a result. Also can happen when blood is drawn too fast (too must suction)
        
        Similar to doughnut in shape
        
        Perform two crucial functions:
        
        With aid of iron-containing red pigment called hemoglobin, transport oxygen
        
        On lesser scale, help to transport carbon dioxide from cells to lungs for removal
        
        White Blood Cells (WBCs) or leukocytes
        
        Basophils
        
        Eosinophils
        
        Lymphocytes
        
        Monocytes
        
        Neutrophils
        
        Leukocytes are guardians from invasion and infection
        
        Several different types, divided into two main types; each originate from different areas:
        
        Polymorphonuclear granulocytes originate from red bone marrow
        
        Mononuclear cells originate from lymphoid and myeloid tissue
        
        Leukocytes are guardians from invasion and infection
        
        Several different types, divided into two main types; each originate from different areas:
        
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        Mononuclear cells originate from lymphoid and myeloid tissue
        
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        Monocytes: found in higher than normal amounts when chronic infection occurs
        
        Thrombocytes or platelets aid in clotting
        
        Thrombocytes are also known as platelets
        
        Smallest formed elements and are responsible for blood’s ability to clot
        
        Platelets stick together and plug hole in blood vessel and can release substance called serotonin, which causes smooth muscle constriction and decreased blood flow
- - - - Arteries divide into smaller and smaller vessels, smallest of which are called arterioles
        
        Arterioles feed into capillaries that form capillary beds in body’s tissues, allowing oxygen and nutrients to infuse into cells and picking up carbon dioxide and waste products for removal
        
        Blood continues journey from capillaries to small vessels called venules
        
        Venules combine into veins, which eventually combine into great veins that empty back into heart
  - - - Tunica interna
        
        Tunica interna is innermost layer
        
        Composed of tightly packed layer of tissue made up of squamous epithelial cells that covers a layer of loose connective tissue
        
        Compacting of squamous epithelial cells makes for smooth surface so blood can easily pass through
      - Tunica media
        
        Tunica media is middle layer
        
        Thicker and composed mainly of smooth muscle, elastic tissue, and collagen
        
        By contracting or relaxing these muscles, layer actually controls diameter of vessel to meet certain needs of body at given time
        
        Sympathetic nervous system determines body’s need and blood vessel either vasoconstricts (smaller diameter, higher BP) or vasodilates (larger diameter, lower BP) to control blood supply as needed
      - Tunica externa
        
        Tunica externa is outermost layer
        
        Due to composition of mostly fibrous tissue, job is to provide vessel support and protection
  - - - Arteries possess much thicker walls than veins because arteries are closer to heart and have to deal with higher pressures
      - Larger arteries contain complete sheets of elastic tissue, elastic laminae, in their middle walls to help deal with this increased pressure
      - Lumen in veins are larger than in arteries, and also contain valves that prevent backward flow of blood
      - Relaxation and contraction of muscles in body that surround veins help to “milk” blood toward heart
    - - Composed of only tunica interna, with diameter of only 0.008 mm (slightly larger than diameter of single red blood cell)
      - Allow easy movement of oxygen and nutrients through wall(it is only one cell in thickness) while carbon dioxide and wastes can move into blood
      - Each cell requires approximately 250 ml of oxygen, producing 200 ml of carbon dioxide every minute when body is at rest
      - Dozen of capillaries form a web, or network, or vessels called a capillary bed.
        
        Capillary beds are composed of two types of blood vessels:
        
        Vascular shunt, which is main road connecting the arteriole to venule
        
        True capillaries, which make actual exchanges with tissue cells
        
        True capillaries can be considered on and off ramps from and to vascular shunt
      - Precapillary sphincters are composed of smooth muscle and act as toll booths, either allowing or stopping blood flow as they contract and open
        
        Blood that is allowed through travels through true capillaries and to cells
        
        Otherwise blood travels through vascular shunt
- - - - What does this mean? Antigens are often proteins that make their way into our body through wounds, blood transfusions, ect…
    - - This is the basis of the immune response; so what happens?
        
        Antibodies will react with antigens that caused them to form, and antigens stick together in little clumps, called agglutination
    - - Type A, B, AB, & O (everyone has only one of these blood types, inherited from parents)
        
        Type A blood is very common; approximately 41% of American population has this type of blood
        
        “A” represents specific type of “self” antigen found on cell membrane of red blood cell
        
        Since this person was born with type A blood, no antibodies were created to fight it, so there are no anti-A antibodies, in his or her plasma, but there are anti-B antibodies
        
        Type B RBCs possess type B self antigens
        
        Plasma contains anti-A antigens. If person with type B blood was given type A blood, anti-A antibodies would attack donated red blood cells and destroy them because they see cells as foreign material; antibodies cause agglutination, resulting in serious harm and even death
        
        (these two types do not like each other)
        
        Type AB blood contain both A and B self antigens
        
        Has neither A or B antibodies in plasma
        
        Because there are no A or B antibodies, people with type AB blood are called universal recipients because they can accept any type of blood type transfusion
        
        Type O RBCs contain no A or B antigens, but its plasma contains both A and B antibodies
        
        Can be given to anyone
        
        Person with type O blood is labeled universal donor
        
        If you donate blood that has no A or B antigens, agglutination by anti-A and or anti-B antibodies in the receiver’s blood is prevented
        Type O can be given to anyone b/c it has no anit-A or anti-B antigens it can’t clump
        
        Rh Factor
        
        Special blood antigens were first found in blood of Rhesus monkeys, and labeled Rh factor
        
        Found in 85% of white and 88% of black population of United States have Rh antigen in their blood
        
        If individual has this antigen they are said to be Rh positive, if not they are Rh negative
        
        As result, people are either A, B, AB, or O negative or positive.
        
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- - - - Several substances in blood plug leaks
        
        Hemostasis, or stoppage of blood, is accomplished through chain of events
    - - When inner wall of vessel is damaged, underlying collagen fiber becomes exposed
        
        Platelets floating in blood begin to attach to that rough damaged site and create a plug
        
        Attached platelets release several chemicals (serotonin) which will cause blood vessels to spasm which decreases the blood flow to the area
        
        Within 15 seconds, blood clotting (coagulation) begins
        
        With help of calcium ions and 11 different plasma proteins (clotting factors), a chain reaction starts
        
        One of clotting proteins, prothrombin, produced by liver with help of Vitamin K, is converted to thrombin
        
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- - - - Decreasing blood volume (diuretics)
      - Vasodilating peripheral blood vessels (ACE inhibitors, angiotensin-converting enzyme inhibitors)
      - Slowing down heart rate (beta-blockers, calcium channel blockers)
  - - - Examples: statin medications (Zocor, Lipitor)