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Lecture 06: Blood
Human Biology
24
Biology
Undergraduate 1
04/16/2011

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Term
Blood Functions
Definition
  • Transport of nutrients and waste products to an from tissue
  • Regulates body temperature and pH
  • Self-healing, forms clots in wounds
  • Fights infections
  • BAlood is composed of "formed elements" and plasma (liquid)
  • Most people have 5-6 L of blood in their bodies
Term
Blood Composition
Definition
  • 45% cells & platelets
  • 55% plasma:
    • 91% water
    • 7% proteins (albumins, globulins, fibrinogen)
    • 2% other solutes (ions, nutrients, waste products, gases, hormones, vitamins)
Term
Hematocrit
Definition
  • Proportion by volume of red blood cells in blood
  • Varies by oxygen requirements of individuals
  • Atheletes often train at high altitudes with limited oxygen to lower hermatocrit
  • High for people that require more oxygen, lower for people that don't
Term
Plasma
Definition
  • Plasma albumin is the most abundant plasma protein
    • Maintains osmotic balance
    • Acts as buffers, regulating pH
    • Transports molecules, including bilirubin
  • a and b globulins are carrier proteins that bind to hormones, fatty acids, and ions
  • Fibrinogin & prothrombin inactive precursors to proteins that form clots
  • Glucose and amino acids circulate in blood as nutrients to cells
  • Antibodies also circulate in blood
    • Members of general family of proteins called gamma globulins
Term
Red Blood Cells (Erythrocytes)
Definition
  • Produced in red bone marrow
  • Destroyed in liver adn spleen when too old
    • Erythrocytes are turned over relatively quickly ~ 12o days
  • Don't have nuclei (reason they're shaped the way they are, biconcave disks), therefore they can't reproduce
  • About the same size the diameter of capillaires
Term
Red Blood Cells (Erythrocytes): Hemoglobin
Definition
  • Packed with Hemoglobin molecules
  • Hemoglobin = the oxygen carrier molecule
  • Most O2 carried in the body becomes attached to Hemoglovin, doesn't dissolve much in water
  • Composition of hemoglobin
    • An iron complexed in a "porphyrin ring" with a heme group (a molecule with protein) in the middle
    • A tetramer
  • Gives cells their red color
  • Hemoglobin also carries some CO2 at low O2
Term
Nuber of RBC's in Circulation Depends on O2 Concentration in Blood
Definition
  1. There is a reduced O2-carrying ability of blood
  2. The kidney secretes erythropoitein
  3. Erytropoitein stimulates the red bone marrow to produce more RBCs
  4. There is an increased O2-carrying ability of blood
Term
Anemia
Definition
  • The decreased ability of the blood to carry O2
  • Decreases the number RBC's
  • Reduces the hemoglovin content of RBC's
  • Prescence of abnormal hemoglovin in RBC's
  • Leads to fatigue, shortness of breat, high heart rates
  • Causes
    • Excessive bleeding, tumors in bone marrow, malaria reduces RBC number
    • Iron, Cu, B-12 deficience - causes reduced Hemoglobin production
Term
White Blood Cells (Leukocytes)
Definition
  • White blood cells have a nucleus
  • Produced in bone marrow like RBC's
    • Myeoblasts, monoblasts, and lymphoblasts produce white blood cells
  • Helps to prevent diseases
  • Are mobile, leukocytes can squeeze through groups between endothelial cells in capillaries in case of infection
Term
White Blood Cells (Leukocytes): Granular Leukocytes
Definition
  • Have prominent granules
  • Eosinophils, Basophils, Neutrophils
  • Names come from histology, science of using dyes to identify cells & cell functions
  • Have strange-shaped nuclei
Term
Granular Leukocytes: Neutrophiils
Definition
  • Most common
  • First to respond (esp. to inflammation)
  • Phagocytotic (ingest harmful bacteria)
  • mult-lobed
Term
Granular Leukocytes: Eosinophils
Definition
  • Mast cells
  • Antigen  antibody complexes
  • Phagocytotic
Term
Granular Leukocytes: Basophils
Definition
  • Least common
  • Mast cell
  • Stores histamine
  • Inflammatory response
Term
Leukocytes: Monocytes
Definition
  • Agranular
  • Large phagocytotic cells that consume worn out RBC's and microbes
  • Can be found outside the bloodstream "lurking" in connective tissue
  • Now called macrophages
Term
Leukocytes: Lymphocytes
Definition
  • Specialized for immunity
  • Although in bloodstream, are mainly in lymphoid organs
  • Not phagocytotic
  • Types
    • T-lymphocytes: cell mediated immunity
    • B-lymphocytes
      • humoral mediated immunity, secretes antibodies
      • plasma cells derive fromethem and produce antibodies
Term
WBC-Related Disorders: Leukemia
Definition
  • WBC's may become cancerous
  • Divide uncontrollably
  • WBC's crowd out stem cells that produce RBC's and plateletes
  • Cancerous WBC's are not effective in fighting infection
  • Acute leukemia - inherited childhood disease
  • Treatment
    • Irradiation will kill bone marrow stem cells to prevent production of more cancerous WBCs. Then will attempt to kill canceous cells. Bone marrow transplants are then necessary to restore function.
Term
WBC-Related Disorders: Infectious Mononucleosis, "Mono"
Definition
  • Viral disease transmitted via saliva
  • Infects lymphocytes
  • Symptoms: Fatigue, aches, sore throats, low-grade fever
  • Treatment: rest, lots of liquids
Term
Plateletes (Thrombocytes)
Definition
  • Cell fragments
  • Responsible in part for clotting
Term
Clotting
Definition
  • Capillaries are dmaged all the time because they are very thin (for diffusion) and get damaged sometimes when blood cells pass through
  • Clotting prevents catastrophic loss of blood
  1. Blood vessel is punctured
  2. Platelets congregate at puncture site and form a plug
  3. Plateletes and damged tissue cells release the protrhombin activator thromboplastin which initiates a cascade of enzymatic reactions: prothrombin --> thrombin --> fibrinogen --> fibrin threads
  4. Fibrin threads form and trap red blood cells, forming abarrier
  5. Actin cytoskeleton in plateletes contract, tighting up clot in close wound
  6. An inactive precursor plasminogen is incorporated into the clot when it forms, causing it to dissolve after a while.
  • Prothrombin & thrombin are produced in the liver
Term
Clotting Disorders
Definition
  • Thrombocytopenia
    • A disorder in which the number of platelets is too low due to not enough being made in the bone marrow or the increased breakdown of plateletes outside the marrow.
  • Leukemia may reduce platelet count
  • Radiation kills bone marrow stem cells, preventing the production of megakaryocytes --> platelets
  • Hemophilia
    • A genetic defect that prevents the liver from producing prothrombin and thrombin, clotting factors
    • Lack of clotting factors may also be due to liver damage from hepatitis, cancer, and alcholism
  • Thrombo-Embolism
    • Clots can break loose in the bloodstream and lodge in the blood vessels (thrombosis) serving the heart or the brain, causing heart attacks and strokes respectively
Term
Blood Types
Definition
  • Red blood cells may have one of a numer of antigens on their surface
  • Types of blood are defined by the type of glycoprotein on its surface: A, B, AB, or none (O)
  • Type O blood is name given to bloo
  • Rh Factor
    • Another blood antigen is the Rh antigen located on RBC's
    • 85% of people have this antigen and are called Rh+
    • 15% of people do not and are called Rh-
Term
Rh Factor
Definition
  • Another blood antigen is the Rh antigen located on RBC's
  • 85% of people have this antigen and are Rh+
  • 15% of people do not have this antigen and are Rh-
Term
Transfusions (Blood Typing)
Definition
  • Antigens are identified on the blood transfusion recepient and compared with antibodies found on the donor's blood.
  • If the antibodies in the donor blood can recognize the antigen on the recepient's blood (i.e. type ! blood and anti-A antibodies) then the blood will agglutinate (clump) and cause rejection.
  • Antigens bind to antibodies at it's variable region
  • Testing in vitro allows blood typing
Term
Hemolytic Disease of the Newborn (HDN)
Definition
  • If a father is Rh+ and the mother Rh-, it is possible for an unborn child to be Rh+.
  • If blood leaks across teh placenta from the fetus to the mother, Rh+ antigen int he child can caue the mother to produce anti-Rh+ antibodies.
  • Anti-Rh+ antibodies produced by the mother cross back across the placent a in either this pregnancy. The antibodies destory the baby's red blood cells.
  • RBC breakdown causes a rise in bilirubin in the child's blood stream, leading to mental retardation or death.
  • Avoiding HDN
    • Mother is given anti-RH+ antibody injections either midway in pregnancy or within 72 hr of giving birth to an Rh+ child. The idea is to destory any circulating fetal/newborn blood cells before they have a chance to cause the bother to develop her own antibodies.
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