Circulatory System

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					                                   THE BLOOD CIRCULATORY SYSTEM
                                           Cardiac - Vascular - Blood



                                       HEART STRUCTURE & PHYSIOLOGY
  I.   Components
               A. Blood — a fluid medium whose major function is for exchange of materials between the
                     external environment and body cells; also functions for protection
               B. Blood vessels — represent the channels for flow of the blood
               C. Heart — this serves as the pump of life; it is the pump for circulation of the blood


 II.   The Heart: Structures & Special Tissue — the heart itself is located in the mediastinum (the central
       region of the chest) between the second and fifth intercostals spaces; the base of the heart is at the
       second space, it is the flattened portion; the apex is the pointed end and it rests on the diaphragm, in the
       fifth space; 60% of the heart is in the left quadrant of the chest; essentially the heart is a double pump
       bound into a single organ
A. Right side — is concerned with pulmonary circulation, pumping blood to the lungs for gas exchange;
    contains deoxygenated blood
B. Left side — is concerned with systemic circulation (implies that it sends blood to all body
               parts); contains oxygenated blood
                      1. the two sides function simultaneously, as blood goes to the lungs, it also goes to the
                          other parts of the body; return occurs simultaneously also
C. General Anatomy of the Heart — the heart is contained in the pericardium, which is a fibroserous sac that
    surrounds the entire heart; the outer component of the sac is fibrous connective tissue (which protects the
    heart, anchors it to surrounding structures and prevents overfilling of the heart with blood); the inner
    component is serous membrane, referred to as parietal pericardium; the potential space between parietal and
    visceral pericardiums contains a small amount of serous fluid, which prevents friction during contraction
    and relaxation
D. Walls of the Heart
                     1. the outermost layer is called the epicardium, it is a visceral pericardium
                     2. the middle layer is called the myocardium, it is the thickest layer, it is composed of
                         cardiac muscle tissue, in which the branching muscle cells are tethered to one another by
                         connective tissue fibers arranged in spiral or circular bundles that link all parts of the

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                                                                                   AP 2 – Blood Circulatory System

                      heart together, this fibrous skeleton of the heart reinforces the myocardium internally
                      and anchors the cardiac muscle fibers and prevents stretching the vessels and valves
                  3. the innermost layer is called the endocardium, this is simple squamous epithelium
                      (referred to as endothelium) resting on a thin connective tissue layer, it lines the
                      chambers and covers the fibrous skeleton of the valves, it is continuous with the
                      endothelial linings of the blood vessels leaving and entering the heart
E. Chambers of the Heart
                         1. the two smaller, upper chambers are the atria, which are receiving chambers for
                            blood returning to the heart that function to direct blood to their respective
                            ventricles
                         2. the two larger, lower chambers are the ventricles, ventricles are discharging
                            chambers that make up most of the volume of the heart, the R ventricle pumps
                            deoxygenated blood into pulmonary circulation and the L ventricle pumps
                            oxygenated blood into systemic circulation, this chamber is somewhat larger than
                            the R because it bears the greater burden of work; the ventricles are separated by
                            the interventricular septum
F. Valves of the Heart — function to provide one-directional blood flow, which ensures that
               backflow does not occur and allows sufficient cardiac output
                     1. atrioventricular valves (aka cuspids) are located between the atria and ventricles
                         and function to direct blood from the atria to their respective ventricles, on the R is
                         the tricuspid valve and on the L is the bicuspid (mitral) valve, the cuspids are
                         composed of an upper portion that is endocardium, chordae tendineae that are thin
                         collagenous cords of tissue that extend into the ventricles, and papillary muscles that
                         are elevations in the walls of the ventricles and function to anchor the chordae
                         tendineae during contraction, thus keeping the AV valves closed during ventricular
                         contraction
                     2. semilunar valves are located between the ventricles and the arteries that arise from
                         them, unlike the AV valves, semilunar valves are simply flaps of endothelium that
                         open into the arteries, on the R is the pulmonary semilunar valve and on the L is the
                         aortic semilunar valve; when the atria contract, the cuspids open and the semilunars
                         remain closed; when the ventricles contract, the cuspids close and the semilunars
                         open

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              G.      Blood Vessels associated with the heart - the heart has its own circulatory system because
                      It must be healthy enough to pump blood to the entire body; it needs the most oxygenated
                      blood and is the first organ to receive blood from the aorta
                      1.   Arteries — carry blood away from the heart; in most cases, this blood is oxygenated
                           (the exception is with pulmonary circulation)
                              a. aorta (a.) — arises from the L ventricle and supplies both coronary and
                                   systemic circulation
                              b.   pulmonary trunk (a.) — arises from the R ventricle and supplies pulmonary
                                   circulation; this vessel branches into a R and L side and sends deoxygenated
                                   blood to the lungs for gas exchange
                              c.   R coronary a. — branches from the ascending aorta; It splits into the
                                   marginal a. (which supplies the R ventricle) and the posterior interventricular
                                   (or descending) a. (which supplies the posterior walls of the ventricles)
                              d. L coronary a. — branches from the ascending aorta; it splits into the
                                   circumflex a. (which supplies the L atrium) and the anterior interventricular
                                   (or descending) a. (which supplies the anterior walls of the ventricles)
                      2.   Veins — return blood to the heart; in most cases, this blood is deoxygenated (the
                           exception is with pulmonary circulation)
                               a. superior vena cave (v.) — collects blood from above the diaphragm;
                                   empties into the R atrium
                               b. inferior vena cave (v.) — collects blood from below the diaphragm; empties
                                   into the R atrium
                               c. pulmonary v. — send oxygenated blood into the L atrium great cardiac v. —
                                   collects blood from the anterior walls of the heart; empties into the coronary
                                   sinus v.
                               d. middle cardiac v. — collects blood from the posterior walls of the heart;
                                   empties into the coronary sinus v.
                               e. coronary sinus v. - collects blood from the great cardiac and middle cardiac
                                   v. and empties into the R atrium
H. Impulse Conducting System of the Heart — this consists of specialized cardiac muscle tissue that is
   capable of transmitting electrical impulses for synchronized contracting of the heart itself; cardiac muscle
   tissue is the only muscle tissue that does not require input from the nervous system for contraction; the

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    muscle fibers of the heart are short, fat, branched, and interconnected; associated with this muscle are
    intercalated discs, which contain structures (desmosomes and gap junctions) that prevent adjacent cells from
    separating during contraction and allow ions to pass from cell to cell, transmitting a
               depolarizing current across the entire heart and allowing the myocardium to function as a single,
               coordinated unit; action potential is initiated by autorhythmic cells in the sinoatrial node, in the
               atrioventricular node, in the bundle of his, and in the Purkinje fibers
                     1.   Sinoatrial node — located in the right atrial wall, below the entrance of the superior
                          vena cava; this cell mass generates impulses about 75 times a minute; this node initiates
                          atrial contraction; no other region in the myocardium has a faster depolarization rate, so
                          this area sets the pace for the entire heart (thus, the SA node also is known as the
                          pacemaker.); this pace is the sinus rhythm
                     2. Atrioventricular node — located in the inferior wall of the interatrial septum
                          immediately above the tricuspid valve; the impulse is slowed at this node to allow the
                          atria to complete contraction before the ventricles contract; this node conducts impulses
                          more slowly than other parts of the system; once through this juncture, the impulse
                          spreads rapidly throughout the rest of the heart
                     3. Bundle of His — located in the superior part of the interventricular septum; this bundle
                          is the only electrical connection between the atria and ventricles; this bundle splits into
                          R and L branches that run along the interventricular septum toward the apex of the
                          heart
                     4. Purkinje Fibers — long strands of barrel-shaped cells located in the inferior
                          interventricular septum, then turning into the lateral ventricular walls; these fibers allow
                          ventricular depolarization followed by contraction; they also excite the papillary
                          muscles, allowing them to contract before the ventricles .




III.   Physiology of the Heart

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A. Cardiac Cycle — consists of the rhythmic contractions of the atria followed by contraction of the
   ventricles, followed by the relaxation of the entire heart; one such cycle is equivalent to a heartbeat
       1. systole — the period of contraction
            a. atrial contraction lasts 0.1 sec and ventricular contraction lasts 0.3 sec
            b. during atrial contraction the cuspid valves open and the semilunar valves close and
              during ventricular contraction the semilunar valves open and the cuspid valves close.


       2. diastole — the period of relaxation
            a. both atria and ventricles are relaxed
            b. diastole lasts 0.4 sec
            c. all valves closed
       3. systole plus diastole equals a heartbeat; the average time of the heartbeat is 0.8sec
       4. heart rate is the number of heartbeats per minute; the average heart rate is 75 beats per
           minute.
B. Cardiac Output — refers to the amount of blood ejected into the arteries from each ventricle per
   minute; the formula to determine cardiac output is: CO = (HR) (SV), where HR is heart rate and SV
   is stroke/volume (or the amount of blood ejected from each ventricle per heart beat); cardiac output
   averages 5L of blood per minute
       1. Cardiac Output is dependent on three factors:
            a. Preload — the Frank-Starling Law of the Heart states that control of stroke/volume is
                based on the degree of stretch of cardiac muscle cells just before they contract; there is
                a length-tension relationship
            b. Contractility — relates to the strength of the contraction; increased calcium entry into
                the cell and increased sympathetic stimulation increase contractility; increased
                hydrogen ion and increased potassium ion channel blockers decrease contractility (and
                ease the workload on the heart)
            c. Afterload - the backpressure exerted on the semilunar valves by arterial blood




C. Control of Heart Contractions — the heart has a natural impulse system, but it is regulated by the

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   ANS
       1. cardiac centers are located in the medulla oblongata; the sympathetic centers stimulate the
           heart and the parasympathetic centers inhibit the heart
       2. stress, exercise, fever, and certain hormones (epinephrine/norepinephrine and thyroxine) all
           serve to increase the heart rate
       3. blood ion concentrations also affect the heart
            a. increased calcium ion increases the intensity of the contraction
            b. increased hydrogen ion .decreases the intensity of the contraction; rising hydrogen ion
                   levels hinder the cardiac cells' ability to produce the Al? they need to pump calcium
                  ion into the extracellular fluid; this causes the gap junctions (normally open) to close,
                  which may impair the pumping activity of the heart
            c. increased potassium ion decreases the intensity of the contraction; may also decrease
                  the heart rate; excessive potassium ion interferes with depolarization by lowering the
                   resting potential and may lead to heart block and cardiac arrest
            d.     increased sodium ion decreases the intensity of the contraction; may also decrease the
                  heart rate; too much sodium ion inhibits transport of calcium ion into the cardiac cells,
                  thus blocking heart contraction
D. Blood Pressure — measures the systolic/diastolic rate; the systolic reading measure the force of
   ventricular contractions and the diastolic reading is a measure of arterial resistance to blood flow;
   note that the systolic reading is determined by the diastolic measure because ventricular contractions
   must overcome the resistance of the arteries
   1. "normal" blood pressure is 120/80 (note that the new standard is 110/70); to take blood pressure
       properly, the patient should sit on a chair with a back to it and should have his feet flat on the
       floor, the patient also should sit quietly for several minutes before blood pressure is taken; if
       these procedures are not followed, the systolic reading may read as much as 14 points too high
   2. hypertension is noted when the systolic reading is 130 and/or the diastolic reading is 90
   3. a combined reading of 60/40 may indicate shock (when in the presence of other mitigating
       factors)
   4. note that the point differential between the systolic and diastolic readings should be between 30
       and 40 points


   5. common causes of hypertension are:

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                  a. increased amounts of blood, which makes the heart work harder
                  b. increased blood viscosity, commonly due to increased red blood cells or dehydration
                  c. status of the arteries — atherosclerosis is the narrowing of the artery due to cholesterol
                      induced lipid build up on the walls of the artery; arteriosclerosis is the loss of elasticity
                      of the artery, which causes increased resistance to blood flow
II.   Heart Disorders
      A. Valvular Disorders
         1. stenosis — which refers to the narrowing of the heart valve (often due to scar tissue around the
            valve caused by infection of the endocardium), which may affect cardiac output
         2. valvular insufficiency (or murmur) — implies improper closure of a valve, which results
            in a backfiow or regurgitation of blood, which affects cardiac output and oxygenation of the.
            blood
      B. Heart Rate Irregularities
            1. Tachycardia — an increased heart rate, usually above 100 beats per minute
            2. Bradycardia — a decreased heart rate, usually below 60 beats per minute
            3. Arrhythmia — an irregular heartbeat; the most common are fibrillations (which are
                unsynchronized, rapid, and weak contractions); atrial fibrillations are the lesser life-
                threatening, usually caused by a defect in the SA node, may be corrected through the
                insertion of an artificial pacemaker, prolonged atrial fibrillations could lead to abnormalities
                in ventricular contraction; ventricular fibrillations are the more serious condition, in this
                condition there is little or no pumping of the blood out of the ventricles, this causes cardiac
                arrest within minutes
      C. Oxygenation
             1. coronary occlusion — a partial blockage in one or more of the coronary arteries so that
                 blood flow-is obstructed to some degree
             2. coronary infarction (heart attack) — caused by complete blockage of a coronary artery;
                 leads to death of the myocardial tissue supplied by the obstructed vessel (no oxygen to the
                 tissue); note that even heafthy individuals with no cardiovascular disease can suffer a heart
                 attack Ifs clot is formed or thrown into a vessel
             3. angina pectoralis (literally, pain in the pectoral muscles) — due to a temporary deprivation
                 of oxygen; most commonly occurs with stress or exercise in individuals with pre-existing
                 coronary artery disease; nitrate-based medication, which dilates blood vessels, alleviates this

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                                                                                   AP 2 – Blood Circulatory System

                   condition
       D. Inflammation of Cardiac Tissue
              1. endocarditis — inflammation of the endocardium (often due to an .untreated Strep
                  infection); could lead to stenosis
              2. myocarditis — inflammation of the myocardium
              3. pericarditis — inflammation of the pericardium, which could lead to an increase in
                  pericardial fluid, which can affect the pumping ability of the heart
       E. Congestive Heart Failure (CHF) — occurs when the pumping efficiency of the heart is so low that
          blood circulation is inadequate to meet tissue needs; may be due to atherosclerosis, multiple
          myocardial infarcts, dilated cardiomyopathy (flabby ventricles), or persistent high blood pressure;
          each side may fail independently of the other, if the left side fails, pulmonary congestion occurs
          (blood vessels in the lungs become engorged, their pressure increases, fluid leaks into the lung
          tissue, edema occurs, the patient suffocates)


                                              BLOOD VESSELS

I. Arterial — carry blood away from the heart, blood is primarily oxygenated
       A. Arteries — fewer in number, thicker walled, more elastic, largest lumen
       B. Arterioles — branches from arteries, greater in number, thinner walled, smaller lumen


II.    Venous — carry blood to the heart, blood is primarily deoxygenated
       A. Veins — fewer in number, thicker walled, larger lumen; must move blood against gravity, which
            requires valves, a larger lumen, and collapsibility '
       B. Venules — merge together to form veins, greater in number, smaller in size


III.   Capillaries— unlike arteries and veins, these vessels are microscopic; most numerous of all vessels,
       thinner walled, present between arterioles and venules; function for the exchange of materials between
       the blood and surrounding tissue


IV.    Layout — human blood vessels form a closed system, which means that the blood is contained in
       channels; advantages of a closed system are that it keeps a one-directional blood flow and that it keeps
       pressure at an increased level, which allows for a more rapid blood flow

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     A. types of circulation
        1. pulmonary
        2. systemic
        3. coronary
        4. fetal — umbilical veins carry oxygenated blood and umbilical arteries carry deoxygenated blood
        5. portal — implies, an extra. set of capillaries;-blood-must-go to a specific organ before returning
            to general circulation; venous portal circulation is found between the hypothalamus and the
            anterior pituitary and as the hepatic portal system, which means that blood from the digestive
            organs must go to the liver (via the portal vein) before returning to general circulation (the liver
            detoxifies, stores/converts/releases nutrients), the portal vein is formed by the merging of the
            splenic vein and the superior mesenteric vein


V.   Vessel Tissue
     A. tunica extema (adventitia) — the outermost layer, present in arteries (thinner layer) and veins
        (thicker layer) only, composed of fibrous connective tissue (primarily collagenous fibers) which
        provides strength and protection
     B. tunica media — the middle layer, present in arteries (thicker layer) and veins (thinner layer) only,
        composed of smooth muscle tissue (gives contractility) and elastic connective tissue (gives
        elasticity); this layer is non-collapsible in arteries and collapsible in veins (helps to move blood
        against gravity)
     C. tunica intema (intima) — the innermost layer, present in all three vessel types (it is the only layer
        of capillaries), composed of endothelium (simple squamous epithelium), functions to prevent friction
        between the blood and the vessel (in arteries and veins) and to allow for the exchange of materials
        between the blood and surrounding tissue (in capillaries only), this layer forms valves (similar to the
        semilunar valves in the heart) in veins (which helps to move blood against gravity, prevents
        backflow)




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                                                                                    AP 2 – Blood Circulatory System

                                                    BLOOD

  I.   Functions
          A. Transport - takes materials to the cell and takes cell wastes to their site of elimination
          B. Protection —
                   1. blood clotting, which provides protection via repair of the system
                   2. regulates pH through a system of buffers
                   3. heat regulation — blood is primarily water, which absorbs heat and carries it to the
                      body's surface for elimination
                   4. phagocytosis (which ingest foreign particles) and immunity (antibody formation)
                      through WBCs
          C. Interstitial fluid — blood is the source of this intercellular fluid


 II.   Composition: the 5L blood volume is divided into: Remember blood is connective tissue
          A. plasma — the fluid, non-living matrix component of blood; comprises 60% or 3L; part of the
              plasma is serum, which is plasma minus fibrinogen (the clotting factor)
          B. cellular components (living component) — the formed elements; comprise 2L


III.   Plasma
          A. Water, which is 90% of plasma
          B. Proteins, which are 8% of plasma; the major proteins are:
                   1. hormones (such as thyroxine}
                   2. enzymes
                   3. fibrinogen
                   4. globulins, sub-divided into alpha, beta, and gamma globulins; alpha and beta globulins
                       function to transport molecules in blood (hormones and lipids for example); gamma
                       globulins are the sum total of all antibodies present in the blood stream
                   5. albumin, which functions to maintain osmotic pressure in the blood vessel by attracting
                       water and to maintain blood volume; albumin is the most abundant protein
          C. Electrolytes, which make up 1% of plasma; the major electrolytes are:
                   1. calcium ions
                   2. potassium ions all are responsible for body structure and function
                   3. sodium ions
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                                                                                AP 2 – Blood Circulatory System

         D. Gases, which are oxygen and carbon dioxide)
         E. Nutrients)       comprise the final 1% of plasma
         F. Nitrogen-containing wastes)


IV.   Formed elements (Cellular Components)
         A. Erythrocytes — red blood cells
                  1. the most abundant of all cellular components, more than 99%
                  2. anucleated — to make more room for hemoglobin
                  3. biconcave — to increase surface area for oxygen combination
                  4. - elastic to ease passage through capillaries
                  5. major component is hemoglobin (a cellular protein), which is an iron-containing
                         molecule that functions for oxygen transport
                  6. formed in myeloid tissue (red bone marrow), which is primarily present in flat bones
                         and the proximal ends of the extremities
                  7. life span is three to four months
                  8. destruction occurs in the spleen and liver. (the liver recycles the heme component of
                         the hemoglobin)
                  9. normal counts average 5 million per cubic ml of blood; that number is lower in
                         females due to
                         hormones (estrogen inhibits RBC formation and testosterone stimulates RBC
                         formation)
                  10. abnormal counts
                             a. Anemia: too low, a decrease in the numbers of RBCs or in the amount of
                                 hemoglobin present
                             b. Aplastic Anemia: d/ t a defect in the myeloid tissue
                             c. Sickle Cell Anemia: an increased rate of RBC destruction d/t the abnormal
                                 shape of the cells
                             d. Iron Deficiency Anemia: in which the amount of hemoglobin is reduced
                             e. hemorrhage, caused by blood loss
                  11. too high is called polycythemia
                              a. may be a temporarily normal occurrence when there is a decrease in
                                  atmospheric O2 (the body increases the numbers of RBCs to increase the O2).

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                                                                                 AP 2 – Blood Circulatory System

                             b. this occurrence is abnormal when there is a disease in the lungs (such as
                                 emphysema) and there is an insufficient gas exchange, which leads to
                                 increased blood viscosity (thus, increased BP and workload on the heart), a
                                 variety of circulatory problems, and increased blood clot formation (thicker
                                 blood causes more friction between the blood and the vessel walls); in some
                                 cases, the problem of polycythemia is alleviated by removing blood from the
                                 system
Blood Transfusions
            Concerned with blood types (blood groupings), which are dependent on antigens (agglutinogens)
             on the red blood cell membrane and on antibodies (agglutinins) in the plasma.of blood; both
             antigens and antibodies are proteins


            antigens are usually foreign substances that stimulate antibody formation in the individual in
             whom the antigen is introduced; antibodies are plasma proteins that are designed to destroy or
             inactivate the antigen — the two types of antibodies are innate, which are present from birth and
             acquired, which occur more commonly and which are formed during an individual's lifetime in
             response to the introduction of an antigen.


            Rh factors refer to an additional antigen on the red blood cell membrane
            a positive Rh factor indicates an antigen on the cell membrane
            a negative Rh factor indicates the absence of the antigen on the cell membrane
            a Rh + individual does not have acquired. antibodies
            a Rh- individual only acquires antibodies through exposure to the Rh antigen (which comes
             through transfusion or transfer from a Rh+ fetus — note that during the first Rh+ pregnancy
             there is some transfer of the Rh+ antigen to the mother during the shedding of the placenta, this
             is due to capillary breakage and the subsequent mix of blood; as a result, the Rh- mother forms
             anti-Rh antibodies, which is not dangerous to either the mother or newborn; with subsequent
             pregnancies there is a transfer of maternal Rh antibodies to the Rh+ fetus = these antibodies are
             transferred across the placenta — which results in clumping of the fetal RBCs and anemia d/t
             RBC destruction; as the number of Rh+ pregnancies increases, the number of problems with the
             fetus also increases; to prevent agglutination of the fetal RBCs, mothers now are given a
             RhoGam shot within 72 hours after birth or the termination of the pregnancy (the injection also is
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                                                                       AP 2 – Blood Circulatory System

   given at 28 weeks); the RhoGam shot contains anti-Rh antibodies; these pre-formed antibodies
   do not remain in the bloodstream, they simply destroy the antibodies formed in response to the
   positive blood; this shot must be given with each pregnancy


B. Leukocytes — White Blood Cells
          1. Classes of WBCs are agranular (no granules in the.cytoplasm) and granular (granules
              in the cytoplasm)
                 a. Agranular — formed in bone marrow, but lymphocytes quickly migrate to
                     and proliferate in lymphoid tissue (tonsils, lymph glands), which are soft
                     tissue organs; these leukocytes have rounded nuclei
                         i. lymphocytes — the more abundant agranular WBC; they function in
                             the development of immune responses; they are the longest lived
                             WBC; they are the smallest WBC
                        ii. monocytes — occur with low frequency; they function in phagocytosis
                            (any phagocytic cell is short lived); they function in chronic infections;
                            these are the largest WBC
                 b. Granular - formed in myeloid tissue; these leukocytes have lobed nuclei
                        i. neutrophils — the most abundant granular WBC; they function in
                           phagocytosis; they function in acute (rapid onset, severe) infections
                       ii. eosinophils — these cells play a role in detoxification by phagocytosis
                           of toxic molecules (anything you are allergic to is toxic); they also play a
                           role in destroying parasitic worms
                      iii. basophils — these cells function in histamine production (which is
                           responsible for initiating inflammation, the body's defense mechanism
                           against infection) and in heparin production (which is an anti-dotting
                           agent)
          2. Function: Protection against infection via immunity and inflammation - Life span of
              leukocytes is varied, anywhere from hours to years
                      a. Normal Counts: 5,000to 10,000 per cubic ml of blood
                      b. Abnormal Counts
                           i. leukopenia (penia means deficient) —WBC count below 5000; the
                              danger of this low count is an increased susceptibility to infection.

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                                                                        AP 2 – Blood Circulatory System

                           ii. leukocytosis (cytosis means increased) — this is a moderate increase
                               in WBC counts (12000 — 20000); this increase occurs as a natural
                               response during an infection in an attempt to fight off the infection;
                               the increase is not across the board, it is usually of one type of cell or
                               another
                           iii. leukemia — this is an increase in WBC count above 200000; this
                               tends to destroy myeloid tissue, which affects RBC formation
                               (immature forms are released into the blood and these immature cells
                               cannot hold as much hemoglobin)
C. Thrombocytes (aka platelets)
           these are cell fragments that are released into the blood upon disintegration of precursor
            embryonic cells in myeloid tissue; these cells are seen as small clusters of purple
            fragments in the blood smear
           site of formation is myeloid tissue




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                                                                                  AP 2 – Blood Circulatory System

                                            BLOOD TYPING


   Blood typing is determined by the presence of an antigen (a protein marker) on the erythrocyte
    cell membrane. These antigens are responsible for stimulating the anti-body response.
   Antibodies (in the plasma) are proteins that accumulate is the plasma.shortly after birth; they
    function to destroy foreign antigens (anything that it sees as being a threat).
   The term agglutination is the clumping of erythrocytes that occurs as a transfusion. reaction,
    Agglutination causes hemoglobin (the oxygen carrying component of erythrocytes) to be released into
    the plasma. This release can cause symptoms that are as mild as a fever or as severe as the blood clotting
    and ultimately death.
   Another way of saying agglutinating antigens is agglutinogens.
   Another way of saying antibodies that cause agglutination is agglutinins.
   The most common blood type in the United States is 0 (45%), then A (39%), B (12%), AB (4%).
   Rh factor is another antigen on the erythrocyte. Someone who is Rh+ has six additional antigens
    on their erythrocyte cell membrane. Someone who is Rh- does not have these additional antigens.
              Rh- individuals become sensitized when exposed to Rh+ blood through one of two ways:
                   Through a transfusion
                   An Rh- female carrying a fetus that is Rh+. RhoGam is an injection given to the mother
                    carrying the fetus, it is a temporary anti-antibody,
   AB can receive blood from everyone (universal recipient).
   0 can give blood to everyone (universal donor).



                                        A-B-O Blood Typing
                      Antigens on            Antibodies in
Blood Type            Erythrocytes             Plasma               Can give blood to       Can receive blood
                    (Agglutinogens)          (Agglutinins)                                        from
     A                   A                    Anti-B                   A and AB                 A and 0
     B                   B                    Anti-A                   B and AB                 B and 0
    AB                A and B                  None                       AB                      All
    O                   None              Both Anti-A and                 All                      0
                                              Anti-B



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