The Cardiovascular System: The Blood

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Chapter 19

• The Cardiovascular System The Blood

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What is blood?

• Blood is a connective tissue composed of a liquid
  extracellular matrix called plasma. It has cells
  and cell fragments dissolved in it.
• The cardiovascular system is made up of blood,
  the heart, and blood vessels.

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Functions of Blood

• Transportation
• O2, CO2, metabolic wastes, nutrients, heat
  hormones
• Regulation
• helps regulate pH through buffers
• helps regulate body temperature
• helps regulate water content of cells
• Protection from disease loss of blood
• Hematology is study of blood and blood disorders

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Physical Characteristics of Blood

• Thicker than water and therefore flows more
  slowly than water
• Feels sticky
• Temperature of 100.4 degrees F
• pH 7.4 (7.35-7.45)
• 8 of total body weight
• Blood volume
• 5 to 6 liters in average male
• 4 to 5 liters in average female

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Techniques of Blood Sampling

• Venipuncture
• Most common method
• sample taken from vein with hypodermic needle
  syringe
• Finger or heel stick
• Used by diabetics to monitor blood sugar
• Used to test blood of infants
• Arterial stick used to determine oxygen levels

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COMPONENTS OF BLOOD

• Blood consists of 55 plasma and 45 of cells.
• Blood plasma consists of 91.5 water and 8.5
  solutes.
• Principal solutes include nutrients, enzymes,
  hormones, respiratory gases, electrolytes, and
  waste products.

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Blood Cells

• Red blood cells, 40 ( erythrocytes )
• White blood cells, 20 ( leukocytes )
• neutrophils, eosinophils, basophils
• lymphocytes T cells, B cells, and natural
  killer cells
• monocytes
• Platelets, 30 (special cell fragments)

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Hematocrit

• Hematocrit is the percentage of total blood
  volume occupied by RBCs.
• Anemia
• not enough RBCs or not enough hemoglobin
• Can be due to leukemia, iron deficiency, or B12
  deficiency
• Vitamins or injections of iron can treat anemia
• Polycythemia
• too many RBCs (over 65)
• dehydration, blood loss (including menstruation),
  blood doping in athletes (common in professional
  cycling to increase O2 supplies to the blood,
  muscles, and lungs)

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Formation of Blood Cells

• Most blood cells types need to be continually
  replaced
• die within hours, days or weeks
• process of blood cells formation is hematopoiesis
  or hemopoiesis
• In the embryo
• occurs in yolk sac, liver, spleen, thymus, lymph
  nodes red bone marrow
• In adults
• occurs only in red marrow of flat bones like
  sternum, ribs, skull pelvis and ends of long
  bones

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Red Blood Cells or Erythrocytes

• Contain oxygen-carrying protein hemoglobin that
  gives blood its red color
• 1/3 of cells weight is hemoglobin
• Biconcave disk 8 microns in diameter
• increased surface area/volume ratio
• flexible shape for narrow passages
• no nucleus or other organelles

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RBC Life Cycle

• RBCs live only 120 days
• wear out from bending to fit through capillaries
• no repair possible due to lack of organelles
• Worn out cells removed by macrophages in spleen
  liver

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Erythropoiesis Production of RBCs

• Erythrocyte formation, called erythropoiesis,
  occurs in adult red bone marrow of certain bones.
• It takes 1-2 days for a mature red blood cell to
  be formed and released into the blood stream.

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Hemoglobin

• Each RBC has 280 million hemoglobin molecules
• Each one can bind 4 molecules of oxygen (to the
  iron at the center of the molecule).
• Hemoglobin removes CO2 from the blood
• Hemoglobin also regulates blood pressure by
  regulating nitric oxide in the blood

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WHITE BLOOD CELLS

• Leukocytes (WBCs) have a nucleus but do not have
  hemoglobin.
• Granular leukocytes include eosinophils,
  basophils, and neutrophils based on the straining
  of the granules.
• Agranular leukocytes do not have cytoplasmic
  granules and include the lymphocytes and
  monocytes.

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WBC Physiology

• Less numerous than RBCs
• 5000 to 10,000 cells per drop of blood
• 1 WBC for every 700 RBC
• Leukocytosis is a high white blood cell count
• microbes, disease, strenuous exercise,
  anesthesia, cancer or surgery
• Leukopenia is low white blood cell count
• radiation, shock or chemotherapy
• Only 2 of total WBC population is in circulating
  blood at any given time
• rest is in lymphatic fluid, skin, lungs, lymph
  nodes spleen

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Neutrophils (Granulocyte)

• The most abundant WBC
• 60 to 70 of circulating WBCs
• First cells to migrate to the site of bacterial
  infection or cancer formation.
• Also involved in healing injuries
• release lysozymes which destroy/digest bacteria
• release defensin proteins that act like
  antibiotics poke holes in bacterial cell walls
  destroying them
• release strong oxidants (bleach-like, strong
  chemicals) that destroy bacteria

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Eosinophils (Granulocyte)

• 2 to 4 of circulating WBCs
• Combat parasites and infections
• Fight allergies and asthma

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Basophils (Granulocyte)

• Less than 1 of circulating WBCs
• Store histamine and can contribute to allergic
  reactions
• Also contain heparin, which prevents blood from
  clotting too quickly

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Lymphocyte (Agranulocyte)

• 20 to 25 of circulating WBCs
• The main soldiers in the immune system battles
• B cells
• destroy bacteria and their toxins
• turn into plasma cells that produces antibodies
• T cells
• attack viruses, fungi, transplanted organs,
  cancer cells some bacteria
• Natural killer cells (NKC)
• attack many different microbes some tumor cells
• destroy foreign invaders by direct attack

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Monocyte (Agranulocyte)

• 3 to 8 of circulating WBCs
• Stored in the spleen
• Produce macrophages which attack bacteria
• Destroy microbes and clean up dead tissue
  following an infection

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PLATELETS

• Platelets help stop blood loss from damaged
  vessels by forming a platelet plug.
• Their granules also contain chemicals that
  promote blood clotting.

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Platelet (Thrombocyte) Anatomy

• Disc-shaped cell fragment with no nucleus
• They are produced in the bone marrow and live 5
  to 9 days in the blood stream before being
  recycled by the spleen and liver.

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Bone Marrow Transplant

• Bone marrow transplant replaces diseased marrow
  with healthy marrow.
• Patients diseased marrow is destroyed by cancer
  or disease.
• Healthy marrow is supplied by a donor or the
  patient. It is removed (painfully) by sticking a
  needle into the hipbone.
• Risks to recipient include
• Infection due to decreased WBC
• T cells might attack new bone marrow
• Must take immunosuppressant drugs for life

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Cord-Blood Transplant

• Stem cells are taken from the umbilical cord and
  frozen
• This method offers several advantages over marrow
  transplant.
• Easy to obtain
• More abundant
• Are not rejected by patient
• Dont transmit infections
• Can be stored, frozen, forever

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Hemostasis

• Stoppage of bleeding in a quick localized
  fashion when blood vessels are damaged
• Prevents hemorrhage (loss of a large amount of
  blood)
• Methods utilized
• vascular spasm
• platelet plug formation
• blood clotting

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Vascular Spasm

• Damage to blood vessel produces stimulates pain
  receptors
• Small blood vessels are contracted which reduces
  blood flow to the injury site

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Platelet Plug Formation

• Steps in the process
• (1) platelet adhesion (2) platelet release
  reaction (3) platelet aggregation

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Platelet Adhesion

• Platelets stick to exposed collagen underlying
  damaged cells in vessel wall

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Platelet Release Reaction

• Platelets activated by adhesion
• Extend projections to make contact with each
  other
• This decreases blood flow to injury site

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Platelet Aggregation

• Activated platelets stick together and activate
  new platelets to form a mass called a platelet
  plug
• Plug reinforced by fibrin threads formed during
  clotting process

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Clot Retraction Blood Vessel Repair

• The plug stops the bleeding, then
• Edges of damaged vessel are pulled together
• Fibroblasts endothelial cells repair the blood
  vessel

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Blood Clotting

• Blood drawn from the body thickens into a gel
• gel separates into liquid (serum) and a clot of
  insoluble fibers (fibrin) in which the cells are
  trapped
• If clotting occurs inside the body, it is called
  a thrombosis
• Having vitamin K in your diet can help prevent
  blood clotting

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Blood Groups and Blood Types

• RBC surfaces are marked by antigens, which
  determine blood type

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ABO Blood Groups

• Blood types in humans are
• display only antigen A -- blood type A
• display only antigen B -- blood type B
• display both antigens A B -- blood type AB
• display neither antigen -- blood type O
• Type O is the universal donor
• Type AB is the universal receiver

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RH blood groups

• Antigen was discovered in blood of Rhesus monkey
• People with Rh agglutinogens on RBC surface are
  Rh.
• Most people are Rh
• If an Rh - woman is pregnant and the baby is Rh,
  the mothers body may reject the pregnancy she
  must take anti-rejection drugs and be closely
  monitored.

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DISORDERS HOMEOSTATIC IMBALANCES

• Anemia
• Sickle-cell
• Hemophilia
• Disseminated intravascular clotting
• Acute leukemia
• chronic leukemia

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Anemia Not Enough RBCs

• Symptoms
• oxygen-carrying capacity of blood is reduced
• fatigue, cold intolerance paleness
• Types of anemia
• iron-deficiency lack of absorption or loss of
  iron
• pernicious lack of intrinsic factor for B12
  absorption
• hemorrhagic loss of RBCs due to bleeding
  (ulcer)
• hemolytic defects in cell membranes cause
  rupture
• thalassemia hereditary deficiency of hemoglobin
• aplastic destruction of bone marrow
  (radiation/toxins)

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Sickle-cell Anemia

• Genetic defect in hemoglobin molecule
• RBC is deformed
• sickle-shaped cells rupture easily causing
  anemia clots
• Found among populations in malaria belt
• Mediterranean Europe, sub-Saharan Africa Asia

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Hemophilia

• Inherited deficiency of clotting factors
• bleeding spontaneously or after minor trauma
• subcutaneous intramuscular hemorrhaging
• nosebleeds, blood in urine, articular bleeding
  pain
• Treatment is transfusions of fresh plasma or
  concentrates of the missing clotting factor

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Disseminated Intravascular Clotting

• Life threatening paradoxical presence of blood
  clotting and bleeding at the same time throughout
  the whole body
• Associated with infections, hypoxia, low blood
  flow rates, trauma, hypotension hemolysis
• Clots cause necrosis leading to multisystem organ
  failure

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Leukemia

• Acute leukemia
• uncontrolled production of immature leukocytes
• crowding out of normal red bone marrow cells by
  production of immature WBC
• prevents production of RBC platelets
• Chronic leukemia
• accumulation of mature WBC in bloodstream because
  they do not die