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Circulatory System- Blood

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What are the functions of blood?
-Transports all necessary fluids, gases, chemicals, nutrients, and wastes throughout the body
- Protection; WBCs, antibodies, and platelets
- Regulation of fluid and buffering
What are the properties of blood?
- Viscosity
- Osmolarity
What is Viscosity?
Resistance to flow
What is Osmolarity?
Total molarity of dissolved particles
- sodium ions, protein, and RBCs
High Osmolarity - causes fluid absorption into blood, raises BP
Low Osmolarity - causes fluid to remain in tissues, may result in edema
What are the three major categories of plasma proteins?
-Albumins (most abundant; contributes to viscosity and osmolarity, influences blood pressure, flow, and fluid balance)
- Globulins (antibodies; provide immune system functions such as gamma globulins are antibodies)
- Fibrinogen( precursor of fibrin threats that help form blood clots)
what is plasma?
a solution of water and solutes
What is formed elements?
-RBCs: carry oxygen and some carbon dioxide
-WBCs: important in immunity, allergic responses, antibody production and inflammation
- Platelets: essential for hemostasis
What is Serum?
Remains after plasma clots; Fibrinogen is NOT in serum
What is are nitrogenous compounds?
(Nonprotein)
-amino acids
-nitrogenous wastes (urea)
What the function of Erythrocytes (RBCs)?
- Gas transport (major function); increased surface area and volume ratio no nucleus or mitochondria
- Carbonic anhydrase (CAH); produces carbonic acid from CO2 and water; important role in gas transport and pH balance
What is a hematocrit?
% of whole blood composed of RBCs
Why are RBCs and Hemoglobin lower in women?
-adrogens stimulate RBC production
-periodic mestrual losses
-hematocrit inversely proportional to percent body fat
Hemopoiesis
the production of new blood cells,
-stimulated by a # of chemical messengers in response to alterations in body homeostasis
Where are plasma proteins made by?
mostly in the liver; except globulins produced by plasma cells
What does the bone marrow produce?
RBCs, WBCs, and platelets
Hemopoietic
tissues where new blood cells are produces
yolk sac
produce stem cells; colonize fetal bone marrow,liver, spleen and thymus
Spleen is involved?
with WBC production
Erthrocyte Homeostasis
Negative feedback control
- drop in RBC count causes kidney hypoxemia
- EPO production stimulates bone marrow
- RBC count increases in 3-4 days
What stimulates erythropoiesis?
-low levels of O2
- increase in exercise
- loss of lung tissue in emphysema
What are the nutritional needs for erythrocyte production?
- Iron (for hemoglobin production)
- Vitamin B12 and folic acid
- Vitamin C and copper (cofactors for enzymes synthesizing RBCs
EPO
stimulates the development of the proerythroblast into an erythroblast
Hemoglobin
a protein that consists of four polypeptide chains called globins.
Each heme group, bound to iron, can then bind to an oxygen molecule
How many oxygen molecules can a one hemoglobin bind to?
One hemoglobin molecule can bind to a maximum of 4 oxygen molecules.
What is polycythemia?
an excess of RBCs
Primary polycythemia
Cancer of erthropoietic cell line in red bone marrow
RBC count is high as 11
Secondary polycythemia
from dehydration, emphysema, high altitude, or physical conditioning
What is globin?
a polypeptide
What is Anemia and causes of it?
Inadequate erthropoiesis or hemoglobin synthesis (decreased production)
- kidney failure and insufficient erythropoietin
pernicious anemia
- inadequate vitamin of B12 from poor nutrition or lack of intrinsic factor
Hemorrhagic anemias
loss
Hemolytic anemias
increased destruction; Body destroying RBCs
Sickle-cell Disease- homozygous
Hereditary Hb 'defect'
-recessive allele modifies hemoglobin structure
- individual has shortened life
Sickle-cell trait
heterozygous for HbS - individual has resistance to malaria
Leukocytes (WBCs)
responsible for defense from microorganisms and other pathogens.
What are the 2 types of Leukocytes?
- Grandulocytes (Neutrophils, Eosinophils, Basophils)
- Agranulocytes (lymphocytes, monocytes)
Neutrophils
Increases in bacterial infections
-phagocytosis of bacteria
-release antimicrobial chemicals (hydrogen peroxide)
Eosinophils
Increase in parasitic infections or allergies
-phagocytosis of antigen-antibody complexes, allergens and inflammatory chemicals
-release enzymes to destroy parasites
Basophils
Increase in chicken pox, sinusitis, diabetes
-secrete histamine
-secrete heparin
Lymphocyes
Increase in diverse infections and immune responses
- destroy cancer cells
- "present" antigens to activate other immune cells
- coordinate actions of other immune cells
- secrete antibodies and provide immune memory
Monocytes
increase in viral infections and inflammation
- differentiate into marcrophages
- phagocytize pathogens and debris
- "present" antigens to activate other immune responses
Leukopenia
Low WBC count
causes: radiation, poisons, infectious diseases
effects: elevated risk of infection
Leukocytosis
High WBC count
Causes: infection, allergy and disease
Differential count -distinguishes % of each cell type
Leukemia
Cancer of hemopoietic tissue
-myeloid and lymphoid- uncontrolled WBC production
- acute and chronic- death in months or 3 years
Effects: normal cell % disrupted; impaired clotting
Platelets
Responsible for hemostasis; aid in vascular constriction, platelet plug formation, and coagulation.
-phagocytize bacteria
-chemically attract neutrophils and monocytes to sites of inflammation
thrombopoiesis
Production of platetes
Megakaryoblasts
(started out as Stem cells)
-repeatedly replicate DNA w/o dividing cytoplasm
-forms gigantic cell called megakaryocyte
Megakaryocyte
Infoldings of cytoplasm splits off cells fragments that enter bloodstream as platelets
Hemostasis
homeostatic mechanism that prevents the loss of blood due to trauma or other damage to blood vessels
What are the 3 stages of Hemostasis?
1. Vascular Spasm
2. Platelet Plug
3. Coagulation
Vascular spasm
promote the prompt constriction of a broken blood vessel.
-pain receptors (short duration-minutes)
-smooth muscle injury(longer duration)
-platelet release serotonin (vasoconstrictor)
-provides time for other two-clotting pathways
Platelete Plug Formation
Endothelium smooth, coated with prostacyclin
-broken vessel exposes collagen
-platelet pseudopods stick to damaged vessel and other platelets- pseudopods contract an draw walls of vessel togethere forming a platelet plug
- Platelets degranulate releasing serotonin (vasoconstrictor), ADP (attracts and degranulates more platelets), Thromboxane A
- positive feedback cycle is active until break in vessel is sealed
Clotting
conversion of plasma protein fibrinogen into insoluble fibrin threads to form framework of clot
Coagulation
-clotting
-Procoagulants (clotting factors) are present in plasma
-extrinsic pathway: factors released by damaged tissues begin cascade
-intrinsic pathway: factors found in blood begin cascade (platelet degranulation)
Hemophilia
Genetic lack of any clotting factor affects coagulation
- Sex-linked recessive
- physical exertion causes bleeding and excruciating pain
Embolism
clot traveling in a vessel
Thrombosis
abnormal clotting in unbroken vessel- likely to occur in leg veins of inactive people
Pulmonary embolism
clot may break free, travel from veins to lungs
Infraction
occurs if clot blocks blood supply to an organ
Thrombus
inappropriate clot inside vessel