Blood unit 2 Flashcards
Blood
Continusouly regenerating connective tissue
Moves gases, nutrients, wastes, and hormones
Arteries
transport blood away from heart
Veins
transport blood toward heart
Capillaries
allow exchange between blood and body tissues
Blood components
Erythrocytes (red blood cells)
Leukocytes (white blood cells)
Platelets
Plasma
Erythrocytes
Red blood cells
ransport respiratory gases
◦ Small, flexible formed elements
◦ Lack nucleus and cellular organelles; packed with hemoglobin
◦ Have biconcave disc structure; single file through capillaries
◦ Transport oxygen and carbon dioxide between tissues / lungs
Leukocytes
white blood cells
defend against pathogens
Platelets
help form blood clots
Plasma
fluid portion of blood
Contains plasma proteins and dissolved solutes
Primary functions of blood
- Transportation
◦ Transports formed elements, dissolved molecules, gasses and ions - Protection
◦ Leukocytes, plasma proteins, and other molecules protect against pathogens
◦ Platelets and certain plasma proteins protect against blood loss - Regulation of body conditions
◦ Body temperature
◦ Blood absorbs heat from cells and heat is released a skin in blood vessels
◦ Body pH
◦ Blood absorbs acids and bases from body cells, acting as a buffer
◦ Buffer: Can accept and donate H+ ions maintaining a pH in a solution
◦ Fluid balance
◦ Water is added to blood from GI tract and lost through urine, skin, respiration
◦ Fluid is exchanged between blood and interstitial fluid – driven by osmotic pressure
Color of blood
depends on degree of oxygenation
◦ Oxygen-rich blood is bright red
◦ Oxygen-poor blood is dark red
Volume
about 5 liters in adult
Viscosity
blood is 4–5 times thicker than water
◦ Depends on amount of dissolved and suspended substances relative to amount of fluid
◦ Viscosity increases if erythrocyte number increases
◦ Viscosity increases if amount of fluid decreases
Plasma concentration of solutes
Determines the direction of osmosis across capillary walls
Temperature
◦ Blood is 1°C higher than measured body temperature
◦ Warms tissues as it moves through
Blood pH
◦ pH between 7.35 and 7.45
◦ Crucial to maintain protein shape
Centrifuged blood
◦ Plasma (55%)
◦ Straw-colored liquid at top of tube
◦ Buffy coat
◦ Very thin (1%) middle layer with gray-white color
◦ Leukocytes and platelets
◦ Erythrocytes (44%)
◦ Lower, red layer
Hematocrit
Percentage of RBCs in sample
Blood smear
Thin layer of blood placed on microscope slide and stained
◦ Erythrocytes are most numerous
◦ Pink, anucleate, biconcave discs
◦ Transport O2 and CO2
◦ Lifespan: ~120 days
Leukocytes
◦ Larger than erythrocytes
◦ Varied in form, noticeable nucleus
◦ Immune cells
◦ Lifespan: Varies from hours to years
Platelets
◦ Small fragments of cells
◦ Hemostasis
◦ Lifespan: ~8-10 days
Composition of blood plasma
◦ Composed of
◦ Water (92%)
◦ Plasma proteins (7%)
◦ Dissolved molecules and ions (1%)
◦ Similar composition to interstitial fluid, but plasma has higher protein concentration
colloid osmotic pressure
◦ Pulls fluid back in to the vessels
◦ Prevents loss of fluid from blood as it moves
through capillaries
◦ Helps maintain blood volume and blood pressure
Plasma proteins
Albumins (58%)
Globulins (37%)
Fibrinogen (4%)
Regulatory proteins (<1%)
Blood also contains:
◦ Cations: Sodium, potassium, calcium, and hydrogen
◦ Anions: Chloride, bicarbonate, and phosphate
◦ Dissolved electrolytes, nutrients, gases and waste products
Albumins
◦ Exert greatest colloid osmotic pressure
◦ Act as carrier proteins for some lipids, hormones,
and ions
Globulins
◦ Smaller alpha-globulins and larger beta-globulins
◦ Transport some water-insoluble molecules,
hormones, metals, ions
◦ Gamma-globulins (immunoglobulins or antibodies)
◦ Part of body’s defenses
Fibrinogen
◦ Aids in blood clot formation
◦ Following trauma converted into insoluble fibrin
strands
◦ Serum is plasma clotting proteins removed
Regulatory proteins
Includes enzymes and hormones
Hemopoiesis
production of formed elements
◦ Occurs in red bone marrow
Hemocytoblasts
stem cells for formed
elements
◦ Produce two different lines:
◦ Myeloid line forms erythrocytes, all
leukocytes except lymphocytes, and
megakaryocytes
◦ Lymphoid line forms only lymphocytes
Colony-stimulating factors (CSFs)
stimulate hemopoiesis
◦ Growth factors / hormones responsible for the division and maturation of hemopoietic stem cells
◦ Secreted in response to a decrease of formed elements in the blood or other changes in blood homeostasis
◦ Target hemocytoblasts
Erythropoiesis
red blood cell production
◦ Hemocytoblast differentiates in to myeloid stem cell
◦ Multi-CSF differentiates stem cell to a progenitor cell
Leukopoiesis
production of leukocytes
◦ Involves maturation of granulocytes, monocytes, lymphocytes
Granulocytes
Myeloid stem cell (multi-CSF)
Progenitor cell (GM-CSF)
Myeloblast (G-CSF)
Granulocyte
How are they made: Monocytes
Myeloid stem cell (multi-CSF)
Progenitor cell (GM-CSF)
Monoblast (M-CSF)
Lymphocytes production
Lymphoid stem cell
T & B lymphoblasts
Thrombopoiesis
platelet production
◦ Results in 1000’s of platelets
◦ Blood flow “slices” off fragments
which are platelets
Myeloid stem cell (multi-CSF)
Hemoglobin
red-pigmented protein
◦ Transports oxygen and carbon dioxide
◦ Termed oxygenated when maximally loaded with oxygen
◦ Termed deoxygenated when some oxygen lost
Erythrocyte pt 2 lol
◦ Each hemoglobin molecule is composed of
four globins
◦ Two alpha chains and two beta chains
◦ Each chain has a heme group: a porphyrin ring
with an iron ion in its center
◦ Each hemoglobin can bind four oxygen
molecules
◦ Oxygen binds to iron
◦ Binding is fairly weak
◦ Rapid attachment in lungs and rapid detachment
in body tissues
◦ Carbon dioxide binds to globin protein
◦ Binding is fairly weak
◦ Attachment in body tissue and detachment in
lungs
Erythropoietin
EPO) controls erythropoiesis
◦ EPO - hormone produced by kidneys
◦ EPO secretion is stimulated by a decrease in blood oxygen
◦ Red marrow myeloid cells respond to EPO by making more erythrocytes and releasing
them into circulation
◦ The erythrocytes increase blood’s oxygen carrying capacity
◦ The increase in blood oxygen inhibits EPO release (negative feedback)
Testosterone
stimulates EPO production in kidney
◦ Males have higher testosterone and higher erythrocyte count
Environmental effects on EPO
Environmental factors such as altitude
influence EPO levels
o The low oxygen levels at high altitude
stimulate EPO production
o Increased erythropoiesis raises blood’s
oxygen carrying capacity and viscosity
Erythrocyte destruction
◦ Lacking organelles, erythrocytes cannot synthesize proteins for repairs
◦ Maximum life span is 120 days
◦ Old erythrocytes phagocytized by the liver or spleen
◦ Globins and membrane proteins are broken into amino acids
◦ Used by body for protein synthesis
◦ Iron from hemoglobin transported by transferrin protein to liver and recycled
◦ Bound to storage proteins: ferritin, hemosiderin
◦ Transported to red bone marrow as needed for
erythrocyte production
BILE
◦ Heme group (without the iron) is excreted
◦ macrophages convert into green pigment: biliverdin
◦ Further converted to yellow pigment: bilirubin
◦ Becomes part of bile (used in digestive system)
◦ Bilirubin converted to urobilinogen in small intestine
◦ May continue thorough intestine, be converted by bacteria to stercobilin, and be expelled from body as brown pigment in feces
◦ May be absorbed back into blood, converted to urobilin, and be excreted from
kidneys as yellow pigment of urine
◦ Liver bile small intestine feces or urine
Erythrocytes
ABO blood group
◦ Determined by presence or absence of A antigen and B antigen
◦ A and B antigens are membrane glycoproteins
◦ Type A - antigen A
◦ Type B - antigen B
◦ Type AB - both antigens
◦ Type O - neither antigen
Rh blood type
Presence or absence of Rh factor (antigen
D) on erythrocytes determines if blood
type is positive or negative
agglutination
◦ If someone receives an incompatible transfusion agglutination occurs
◦ Recipient’s antibodies bind to transfused erythrocytes and clump them together
◦ Can block blood vessels
◦ Can cause hemolysis, rupture of erythrocytes, organ damage
Leukocyte characteristics
◦ Defend against pathogens
◦ Contain nucleus and organelles, but not hemoglobin
◦ Motile and flexible—most not in blood (in tissues)
Diapedesis
process of squeezing through blood vessel wall
Chemotaxis
attraction of leukocytes to chemicals at an infection site
Granulocytes
type of leukocyte
have visible granules seen with light microscope
◦ Granules are secretory vesicles
◦ Neutrophils, eosinophils, basophils
Agranulocytes
type of leukocyte
have smaller granules that are not visible with light microscope
◦ Lymphocytes, monocytes
Neutrophils
Granulocyte
◦ Most numerous leukocyte in blood, multi-lobed nucleus
◦ Cytoplasm has pale granules when stained
◦ Enter tissue spaces and phagocytize infectious pathogens
◦ Release enzymes that target pathogens
◦ Numbers rise dramatically in acute bacterial infection
Eosinophils
Granulocyte
◦ 1–4% of leukocytes, bi-lobed nucleus connected by thin strand
◦ Cytoplasm has reddish granules
◦ Phagocytize antigen-antibody complexes
◦ Increased numbers during parasitic worm infections and allergic reactions
Basophils
Granulocyte
◦ 0.5–1% of leukocytes, bi-lobed nucleus
◦ Cytoplasm has blue-violet granules with histamine and heparin
◦ Increased numbers during allergic reactions and inflammatory responses
◦ Release causes:
◦ Histamine
◦ Heparin
Lymphocytes
◦ Reside in lymphatic organs and structures
◦ 20–40% of blood leukocytes
◦ Dark-staining round nucleus
◦ Three categories:
◦ T-lymphocytes
◦ B-lymphocytes
◦ NK cells (natural killer cells)
Histamine
release causes increase in blood vessel diameter and capillary permeability
(classic allergy symptoms)
Heparin
inhibits blood clotting
T-lymphocytes
mount immune response
◦ Some can directly attack dangerous cells, some mark cells as being dangerous, some
release cytokines
B-lymphocytes
become plasma cells and produce antibodies
◦ Antibodies attack dangerous cells
NK cells
(natural killer cells) physically attack and poison abnormal and infected tissue
cells
Monocytes
◦ C-shaped nucleus
◦ 2–8% of blood leukocytes
◦ Take up residence in tissues
◦ Transform into large phagocytic cells,
macrophages
◦ Phagocytize bacteria, viruses, debris
◦ Numbers increase during chronic infection
◦ Ex. tuberculosis
Macrophages
monocytes that left the blood vessel
Differential count
measures amount of each type of leukocyte and whether any are immature in a count of 100 WBCs
Leukopenia
decreased leukocytes
◦ Increases risk of infection
◦ Leukocytosis
◦increased leukocytes
◦ Caused by recent infection or stress
Lymphocytosis
increased lymphocytes
◦ Caused by viral infections (e.g., mumps,
mononucleosis, COVID)
◦ Decreases associated with HIV, leukemia,
or other autoimmune disorders
Neutropenia
Less neutrophils
◦ May occur with anemia, drug or radiation therapies
Neutrophilia
more neutrophils
◦ Associated with bacterial infections, stress, tissue necrosis
Platelets
◦ Small, membrane-enclosed
cell fragments
◦ No nucleus
◦ Break off of megakaryocytes in red
marrow
◦ Important role in blood clotting
◦ Normally 150,000 to 400,000 per cubic
millimeter blood
◦ 30% stored in spleen
◦ Circulate for 8 to 10 days; then broken down
and recycled
Hemostasis
stoppage of bleeding
◦ Three overlapping phases
1. vascular spasm
2. platelet plug formation
3. coagulation
Vascular spasm
blood vessel constriction
◦ First phase in response to blood vessel injury
◦ Limits blood leakage
◦ Lasts from few to many minutes
◦ Platelets and endothelial cells release chemicals
that stimulate further constriction
◦ Greater vasoconstriction with greater vessel
damage
Hemostasis
Platelet plug formation
◦ When blood vessel damaged, a platelet
plug is formed
◦ Collagen fibers in vessel wall exposed
◦ Platelets stick to collagen
◦ Platelets develop long processes allowing
for better adhesion
◦ Many platelets aggregate and close off
injury
Coagulation
blood clotting
◦ Network of fibrin (insoluble protein) forms a
mesh
◦ Fibrin comes from soluble precursor fibrinogen
◦ Mesh traps erythrocytes, leukocytes, platelets,
plasma proteins to form clot
Intrinsic (contact activation) pathway
Initiated by platelets upon damage to inside of vessel wall
Extrinsic (tissue factor) pathway
Initiated by damage outside of vessel
Common pathway
Activated by extrinsic or intrinsic pathway
◦ Positive feedback leads to clot formation
◦ Clot stops once fibrin fills mesh
◦ Extra fibrin is destroyed by enzymes in the blood
Calcium is required at multiple phases in the clotting cascade
Clot Elmimation
Clot elimination includes clot retraction and fibrinolysis
Clot retraction
Actinomyosin (protein within platelets) contracts and squeezes serum out of developing
clot making it smaller
Fibrinolysis
◦ Degradation of fibrin strands by plasmin
◦ Begins within 2 days after clot formation
◦ Occurs slowly over a number of days
The sympathetic response to blood loss
◦ If greater than 10% of blood is lost
◦ Sympathetic nervous system increases vasoconstriction, heart rate, force of heart
contraction
◦ Blood redistributed to heart and brain
◦ Effective in maintaining blood pressure until 40% of blood lost
