Circulatory System -Cardiovascular

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Circulatory System-Cardiovascular Lymphatics-

• Chapters 17 - 19

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Chapter 17 - BLOOD

• Components
• Only fluid connective tissue
• Formed elements living cells
• Fluid matrix plasma
• Spun tube 45 RBCs, 1 buffy coat (WBCs,
  Platelets), 55 plasma

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• Characteristics
• Salty
• Alkaline (7.35 7.45 pH)
• Varied in color due to O2 content
• 5-6 L in males 4-5 L in females
• 8 of body weight

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• Functions (transportation /or protection)
• Distribution
• O2 and food nutrients
• Wastes to lungs kidneys
• Hormones from endocrine glands to target organs
• Maintains body temperature (absorbs distributes
  body heat)

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• Protection
• Maintains pH (reservoir for bicarbonate ions)
• Maintains fluid volume
• Prevents blood loss (through platelet action
  blood proteins)
• Prevents infection (through WBCs antibodies)

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• Formed Elements
• Erythrocytes (RBCs)
• Characteristics
• Lacks nucleus organelles
  bag of hemoglobin
  molecules 33 of RBC is hemoglobin
• 8 mm in diameter look like flat discs with
  depressed centers

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• Shape provides large surface area ideal O2
  transport
• Flexible due to spectrin (fibrous protein) which
  allows Rouleaux movement (stacking) when
  traveling through capillaries
• 8001 RBCs WBCs blood viscosity

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• 4.3 5.2 million cells/cc RBC count in women
• 5.1 5.8 million RBC count in men
• Number of cells correlates with viscosity more
  RBCs more viscous blood slower moving

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• Function
• Carry O2 through their contained hemoglobin
• Hemoglobin consists of globin protein bound to
  red heme iron pigment
• Each hemoglobin contains 4 ringlike heme groups

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• Each globin protein consists of 4 polypeptide
  chains each chain is bound to a heme group
• Each iron atom can combine with one O2
• Thus each hemoglobin can carry 4 O2s

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• Each RBC contains 250 million hemoglobin
  molecules transporting 1 billion O2s.
• Also carries CO2 on the globin so there is no
  competition for binding sites
• 20 of CO2 is carried this way

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• Production of RBCs
• In red bone marrow of long flat bones
• Arise from stem cells Hemocytoblasts which
  reside in bone marrow
• Hemocytoblast is transformed into a
  proerythroblast
• Proerythroblast give rise to early erythroblast
  (produce large amounts of ribosomes)

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• Early erythroblast transforms into late
  erythroblast as hemoglobin production increases
• Late erythroblast transforms into normoblast when
  hemoglobin content reaches 34

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• Nucleus ceases functions is ejected causing the
  center of cell collapse (thus the depressed
  center or disc shape)
• Normoblast transforms into reticulocyte (named
  for remaining rough ER)
• Up to this point takes 3-5 days

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• Reticulocytes enter circulation become mature
  erythrocytes in 2 days.
• Process is balanced between production
  destruction (about 2 million/sec) under hormonal
  control with adequate amounts of iron B
  vitamins.

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• Hormonal Control
• RBC production is directly linked to erythrocyte
  hormone (which is in system at low levels all the
  time to maintain production as basal levels)

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• Erythropoietin hormone is produced when kidney
  cells release REF (renal erythropoietin factor)
  in response to cell hypoxia. Hypoxia is due to
• Declining of RBCs due to hemorrhaging or
  excessive RBC destruction

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• Reduced availability of O2 due to altitude or
  pneumonia
• Increased O2 demands by tissues during exercise
• Its not the number of cells that controls
  erythropoietin, but the cells ability to
  transport O2

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• Erythropoietin stimulate red marrow to MATURE
  already committed cells at a faster rate than
  otherwise (1-2 days faster)
• Testosterone can stimulate kidneys to release REF
  (accounting for high RBC levels in men than
  women conversely those with kidney failure have
  RBC counts less than half of normal individuals

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• Dietary needs for erythropoietin production
• Need carbs, proteins, lipids, iron B-complex
  vitamins
• 65 of bodys iron supply is in hemoglobin, the
  rest is stored in liver, spleen and marrow
  (because free iron is toxic to tissues) as
  ferritin, hemosiderin, or transferrin

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• Iron loss is 1.7 mg and 0.9 mg per day in women
  and men respectively
• B-12 and folic acid are needed for DNA synthesis
  in immature RBCs

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• Destruction of RBCs
• Because they are anucleate, they cannot
  synthesize proteins, reproduce, grow, etc.
• Lifespan of 100-120 days
• Dying cells become trapped in capillaries of
  spleen and are engulfed by roaming phagocytes

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• Hemoglobin is degraded into billirubin and
  secreted in the bile by the liver
• Released iron is salvaged and recycled

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• Disorders (anemias or polycythemia)
• Anemias reduced O2 carrying ability of blood
  (really a symptom rather than a disease)
• Hemorrhagic anemia results from blood loss
  corrected by blood replacement

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• Hemolytic anemia erythrocytes are ruptured
  prematurely (hemoglobin abnormalities, blood
  mismatch, bacterial or parasitic infection,
  congenital defects in plasma membrane)

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• Aplastic anemia destruction or inhibition of
  red marrow (cancer and the drugs used to treat
  cancer can cause marrow to be replaced by
  connective tissue) blood transfusions are used
  until a bone marrow transplant can be performed

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• Iron deficiency anemia inadequate intake of
  iron-containing foods, impaired iron absorption
• Pernicious anemia deficiency in vitamin B-12,
  usually due to lack or intrinsic factor necessary
  to absorb B-12 from the diet

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• Thalassemia genetic in origin, RBC count is
  less than 2 million cells/cc, RBCs are small and
  delicate due to hemoglobin molecule abnormality

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• Sickle-cell anemia abnormal hemoglobin is spiky
  and sharp causing cells to become crescent
  shaped cells rupture prematurely causing vessels
  to dam up and cause clots.

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• Polycythemia excessive or abnormal increase in
  the number of erythrocytes. Viscosity is
  increased causing sluggish blood flow. Usual
  cause is bone cancer.

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• Secondary polycythemia normal in those living
  at high altitudes due to secretion of
  erythropoietin in response to reduced O2 levels.

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• Leukocytes (WBCs)
• 800 1 RBCsWBCs
• 4,000-11,000 WBC/cc (anymore leukocytosis)
• 1 of total blood volume
• Contain nuclei and organelles
• Protect from damage caused by viruses, bacteria,
  toxins, parasites, cancer

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• Display diapedesis (slip in and out of blood
  vessels) by amoeboid movement
• Can respond to chemical distress signals given
  out by damaged and dying tissues (positive
  chemotaxis)
• 2 major categories based on structural and
  chemical characteristics

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• Granulocytes lobed nuclei and stained granules
  appears grainy
• Neutrophils
• most numerous
• 2x RBC size
• ½ of WBC population
• 3-5 lobes, hard to see granules
• digest bacteria
• s elevate with staph, salmonella, systemic
  yeast, and appendicitis infections

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• Basophils
• Least numerous
• Slightly larger than RBCs,
• U or S shaped nucleus
• Few purple granules
• When found in tissues are called mast cells
• When bound to antibodies release heparin
  (anticoagulant) and histamine (vasodilator) to
  help WBC migration

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• Eosinophils
• 2x RBC size
• 1-4 of WBC population
• Nucleus is bi-lobed
• Large, coarse red granules
• Eat antigen-antibody complexes
• Elevation can indicate allergic reactions,
  parasitic worm or protozoan infections
• Reside in intestines, lungs and skin

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• Agranulocytes lack granules
• Lymphocytes
• 2nd most numerous
• Found in lymph tissue
• Small portion in bloodstream
• Immune cell (T and B cells) production
• Large, dark, purple nucleus which occupies most
  of the cell
• May have a thin rim of pale blue cytoplasm
• Act against virus infected cells and tumors

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• Monocyte
• Largest WBC
• Also called macrophages
• Gray-blue cytoplasm,
• dark blue-purple U or kidney shaped nucleus
• Elevation may indicate a chronic viral or
  bacterial infection such as leprosy or
  tuberculosis

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Monocyte
1
4
Basophil
Eosinophil
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2
Neutrophil
Lymphocyte
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• Production of WBCs
• Leukopoiesis hormonally triggered
• All arise from hemocytoblasts
• Some mature in the thymus gland others in the
  bone marrow

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• Disorders
• Leukemia white blood
• Abnormal WBCs which fail to respond to
  regulatory mechanisms
• Remain unspecialized

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• Enhanced ability to divide
• Impair or suppress normal bone marrow function
• Named according to cell type myelocytic or
  lymphocytic leukemias

lymphoblastic
promyelocytic
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• Infectious mononucleosis
• Viral (Epstein-Barr virus)
• Elevated monocytes and lymphocytes
• Leukopenia decreased number of WBCs usually
  due to chemotherapy

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• Platelets (Thrombocytes)
• Not true cells are fragments
• Anucleated
• Arise from stem cells, become megakaryocyte then
  fragment

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• 250,000 500,000 /cc
• Essential for clotting
• Degenerate in 10 days

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• Hemostasis (stopping blood flow)
• Vasoconstriction
• Constriction of blood vessels triggered by injury
  to smooth muscle wall of vessel, compression of
  vessel by escaping blood, chemicals released by
  platelets, pain receptors being stimulated

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• 20-30 minutes of reduced blood flow
• More efficient when vessel is crushed rather than
  blunt cut . Blunt cuts have less tissue damage
  and more profuse blood flow

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• Platelet Plug
• () charged platelet clings to the (-) charged
  collagen tissue under the endothelium
• Platelets develop swollen, spiky processes
• Platelet granules degenerate and release chemicals

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• This sets up a series of clotting events which
  calls more platelets to the injury site
• Aspirin inhibits plug formation
• Takes about 1 minute

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Plug Formation
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• Coagulation (blood clotting)
• Prothrombin ------gt thrombin
• Thrombin fibrinogen fibrin mesh
• 30 different factors involved each require Ca

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• Most are plasma proteins made in the liver
• Absence of any one of these factors results in
  the inability to coagulate blood (hemophilia is
  an example)
• Takes about 3-6 minutes

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COAGULATION
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• Clot Retraction
• Within 30 60 minutes, platelets shrink and pull
  fibrin fibers closer together, further sealing
  edges of wound

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• Fibrinolysis Clot disposal
• Within 2 days, plasmin enzyme (activated by
  healing endothelium and factors in the clot
  itself) will begin to eat away at the clot

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Fibrinolysis
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• Pathology
• Thrombus undesirable clot in an unbroken vessel
• Embolus thrombus that has broken free and is
  traveling in the circulatory system

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• Any roughening of vessel walls can exacerbate
  this (atherosclerosis, burns, inflammation,
  immobilization, etc)

Ruptured cholesterol plaque with thrombus
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• Thrombocytopenia decrease in the number of
  platelets, causes numerous, small, hemorrhages
  body wide (petechiae). Caused by anything that
  would destroy bone marrow (drugs, radiation).
  Diagnosed with a platelet count under 50,000/cc.
  Often need blood transfusions

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• Impaired Liver Function cant manufacture
  coagulants due to vitamin K deficiency,
  hepatitis, cirrhosis, etc

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• Hemophilia
• Type A lack Factor VIII 83
• Type B lack Factor IX
• Type C lack Factor X

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• Plasma
• 90 water
• 10 other stuff gases, hormones, nutrients,
  wastes, ions, proteins (albumin, clotting
  proteins, globulins), etc.

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• Transfusions
• Losses of 15 30 causes paleness and weakness
  more than 30 severe shock
• RBCs have specific antigens (flags) on their
  surface

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• Plasma has agglutinogens (soldiers) floating in
  it which attach to and clump foreign antigens
• Foreign blood will be agglutinated (clumped) and
  destroyed

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• Type A A antigens, Anti-B agglutinogens can
  receive A and O blood
• Type B B antigens, Anti-A agglutinogens can
  receive B and O blood

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• Type AB A B antigens, no agglutinogens can
  receive all blood types (universal recipient)
• Type O no antigens, Anti-A Anti-B
  agglutinogens can receive only O (universal
  donor)

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• Rh factor is another type of antigen
• Transfusion reactions can involve lowered oxygen
  carrying ability, blocked blood vessels, renal
  shut down from liberated hemoglobin in the
  system, fever, chills, nausea, vomiting

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Any Questions?