Transcript The Blood - Dr. Annette M. Parrott

The Blood
Functions of Blood
• Transportation
– O2, nutrients, waste, hormones, heat
• Regulation—maintain homeostasis of body
fluids
– Regulate pH, body temperature, maintain fluid
volume
• Protection
– Clotting prevents loss of fluids
– White blood cells protect against disease
– Blood proteins protect against disease
Physical characteristics and
volume
• Salty and metallic tasting
• More dense than water
• Slightly alkaline, pH between 7.35 and
7.45
• Temperature ~ 38o C or 100.4o F
• Makes up 8% of body weight
• Volume in adult males is 5-6 L and in
females 4-5 L
• Only fluid tissue in the body
Blood components
• Blood plasma 55%
• Formed elements 45%
– RBCs—measurement is hematocrit 14% + 5%
– Leukocytes and platelets
Blood plasma
• Includes over 100 different dissolved
solutes
Formed Elements
Hematopoiesis
• Occurs in the red bone marrow from
hemocytoblast/ hematopoietic stem cell
• Specialization based on receptors that
respond to …hormones
Erythrocyte structure
• Flexible structure, large surface
area
• Lack a nucleus and other
organelles.
• 33% of weight is hemoglobin
molecules.
• Other proteins include
antioxidants and those to maintain
RBC shape (spectrin)
Erythrocyte function
• Dedicated to carry respiratory gas
Regulation of RBCs
Erythropoietin (EOP) glycoprotein hormone
produced by kidneys to liver
Dietary needs to produce RBCs
• Iron, AAs, lipids, and carbohydrates.
• Iron is absorbed from the diet
– 65% found in hemoglobin
– The rest stored in liver, spleen and bone marrow
• Iron is toxic and requires transferrin as a
transporter
• Some iron is lost in feces and menstrual blood
• Vitamin B12 and folic acid are necessary for
DNA synthesis
Fate and death of RBCs
• RBCs have a lifespan of 100 to 120 days
• Age makes them less flexible and the
hemoglobin begins to degenerate.
• Old RBCs get trapped in the small capillaries
of the spleen
• Macrophages destroy and digest RBCs
– Heme and globin are separated
– Globin broken down into a.a.s
Heme bilirubinurobilinogenstercobilin
Bloodliverintestineanus
Erythrocyte Imbalances
• Anemia  reduced O2 carrying capacity of the
blood
• Insufficient number of RBCs:
– Hemorrhagic - due to blood loss associated with an
injury, undiagnosed bleeding ulcer, etc.
– Hemolytic - due to blood loss due to transfusion
reactions & certain bacterial and parasite infections
– Aplastic - due to destruction or inhibition of red marrow
by drugs, ionizing radiation or certain bacterial toxins.
Erythrocyte Imbalances
• Anemia  reduced O2 carrying capacity of the
blood
• Low hemoglobin content:
• Iron Deficiency - inadequate intake or
absorption of iron, forms microcytes.
• Pernicious - dietary deficiency of Vitamin B12 or
inadequate production of intrinsic factor for
absorption of Vitamin B12 , forms macrocytes
Erythrocyte Imbalances
• Anemia  reduced O2 carrying capacity of the
blood
• Abnormal Hemoglobin in RBCs
• Thalassemias- one globin chain is
absent/faulty
• Polycythemia-excess of erythrocytes
increasing blood viscosity
Erythrocyte Imbalances
• Polycythemia - abnormally high number
of RBCs (8 - 11 million/mm3). Increases
blood viscosity & blood pressure.
• most often the result of bone marrow
cancer.
• Lecuopenia - abnormally low number of
WBCs (less than 5,000/mm3).
• drugs, steroids & anti-cancer agents.
Leukocytes Structure
• WBCs have a nucleus and other organelles.
• WBCs can undergo diapedesis using amoeboid
motion when in the tissues
• Use chemical chemotaxis to follow trail to
infection or damaged tissue.
Granular leukocytes
• Neutrophils
• multilobed nucleus, inconspicuous granules
• Phagocytize bacteria & some fungi
• Produced in bone marrow by myeloblasts
• Eosinophils
• bilobed nucleus, red granules
• Destroy parasitic worms & immune complexes
• Produced in bone marrow by myeloblasts
• Basophils
• lobed nucleus, purple-black granules
• Cause vasodilation by release of histamines
• Produced in bone marrow by myeloblasts
Agranular leukocytes
• Lymphocyte
– B lymphocytes - Humoral Immunity (antibodies)
– T lymphocytes - Cellular Immunity
– Produced in lymphatic tissues
• Monocytes
– Differentiate into macrophages in tissues.
– Provide defense against viruses & intracellular
bacteria in chronic infections.
– Produced by monoblasts in lymphatic tissues.
Production of leukocytes
• Leukopoiesis is stimulated by interleukins
and colony-stimulating factors (CSFs)
• Pluripotent stem cells have the capacity to
differentiate into several types of cells.
– Myeloid stem cells
– Lymphoid stem cell
Leukocyte Imbalances
• Leukopenia—low WBC count
• Leukemia—unchecked growth of a single
unspecialized clone. Abnormally high numbers of
immature WBCs that are mitotic & unspecialized
– Acute leukemia occurs if it derives from blast-type
cells
– Chronic leukemia occurs if it derives from later
stages
– Bone marrow is compromised and defense system
becomes nonfunctional
• Infectious mononucleosis derives from excessive
numbers of agranulocytes (Epstein-Barr virus)
Platelets
• Under the influence of thrombopoietin,
myeloid stem cells develop into
megakaryocytes (huge cells).
• These cells fragment into 2-3K particles.
• They have a very short life of 5- 9 days.
Hemostasis
• Damaged blood vessels
require a rapid,
localized and controlled
hemostatic response to
reduce blood loss.
– Vascular
spasm/constriction
– Platelet plug formation
– Blood clotting/
coagulation
Platelet plug formation: platelet adhesion
Platelet plug formation: platelet release
action
Platelet plug formation: platelet
aggregation
Stages of clotting
• Extrinsic (s) and intrinsic
(min) pthwys make
prothrombinase.
• Prothrombinase & Ca2+
Catalyze prothrombin 
thrombin
• Thrombin & Ca2+ converts
soluble fibrinogen insoluble
fibrin (thread of the clot)
• Thrombin activates factor
XIII which stabilizes &
strengthens threads
Hemostasis Animation
Thromboemolitic Disorders
• Thrombus clot in an unbroken vessel
• Ebolus an abnormal object moving through a blood
vessel, Clot, air bubble, lipid droplet, thrombus, etc.
• Disorders
– Embolisms (pulmonary, cerebral, cardiac)
– Artherosclerosis
– Inflammation
• Treatment
– Aspirin
– Heparin
– Warfarin
Bleeding disorders
• Thrombocytopenia—low platelet levels
• Impaired liver function
– Vitamin K
• Hemophilia
– Deficiency of factor VIII (antihemophilic
factor)
– Deficiency of factor IX
– Lack of factor XI
ABO blood typing
• Based on two
glycolipid
antigens, A and
B.
• Blood has
agglutinogens
(antibodies)
that react to A
or B antigens.
Blood groups and blood types
Rh blood groups
Hemolytic
disease of
newborn
(HDN)
Transfusion reactions
• Agglutination clogs blood capillaries
• Clumped cells will rupture and be
phagocytized by macrophages
• Hemoglobin is released into the blood
• Oxygen carrying is disrupted
• Blood flow is impaired
• Hemoglobin passing into kidney tubules
causes cell death and renal shutdown
Diagnostic blood tests
• Lipidemia is characteristic of those with
heart disease
• Erythrocyte morphology can detect
anemias
• Differential white blood cell count
– High eosinophil indicates allergies or parasitic
infection
• Platelet count (thrombocytopenia)
• SMAC is blood chemistry profile
• CBC provides information on the formed
elements
Resources
• Heart Anatomy Tutorial:
• Hematopoiesis Overview:
• BodySmart Blood & Bloodcells