Lecture 23: Blood Microstructure, Content (2/2) Flashcards
hematopoesis
formation and development of blood cells
very few starting cells produce massive numbers of mature cells
pleuropotent cell
undifferentiated cell, can give rise to all cell lineages
what influences hematopoetic stem cell differentiation
cytokein
are hematopoetic stem cells pleuripotent?
most evidence- only produce blood cells, not other organs, although some info says can make cardiac tissue
longest living blood cells?
red blood cells, 4 month survival
most abundant blood cell in body?
red blood cell, 1000x more than white cells
platelet function
clotting, stop bleeding
where is blood produced
bone marrow
yellow marrow
fat
red marrow
cellular tissue
megacaryocyte
largest cell in bone marrow, gives rise to platelets
survival time of granulocyte
< 10 hours
survival time of platelets
1 week
how many blood cells lost/replaced every day?
approximately 10 x 10^12
erythrocytes
RBC
carry oxygen
leukocytes
WBC
fight infection
thrombocytes
platelets
hemostasis - control bleeding
types of blood cells
erythrocytes, leukocytes, thrombocytes
types of blood plasma
electrolytes, proteins, lipids
electrolyte function
maintain tonicity
plasma protein function
albumin, globulins (antibodies), clotting factors- stop bleeding
plasma lipids function
serum
how much blood in avg person?
5L (70 cc/kg)
how blood cells differ from other cells
short life span (except lymphocytes, macrophages)
multiplicity of cell types
widely distributed throughout body (only liquid tissue in body)
bone marrow must respond quickly to emergent need for additional cells (7-8x)
hematopoetic stem cells maintained throughout life, through self-renewal process
how many blood cells produced daily?
10 trillion
erythroblast
immature RBC in bone marrow
nucleated (big -> small -> extruded) then cell enters peripheral blood
erythrocytes exhibit what kind of coloration on smear?
polychromasia- many colors
reticulocyte
newborn erythrocytes
count these in an anemic pt; if count is low, bone marrow problem; if have enough, problem is in peripheral blood
characteristic of normal small mature lymphocyte
has area of central pallor
shape of RBC
biconcave disc
why is RBC not a perfect sphere?
disc shape increases surface area:volume ratio
functions of RBC per shape
- increased SA means more gas exchange between oxygen to tissue, CO2 away from tissue
- deformability- must fit through smallest tiny capillaries in blood
structure of RBC membrane allows for what?
slippery; doesn’t adhere to endothelial cells, doesn’t aggregate
RBC membrane structural components
- lipid bilayer- slipper, impeded adherence
- integral membrane proteins- chloride-bicarbonate exchange (band 3)
- cytoskeleton proteins- maintain cellular shape, deformability, tensile strength
what don’t erythrocytes have?
organelles
what do erythrocytes use for anaerobic respiration/why?
no mitochondria
need G6PD, NADPH to reduce oxidants and maintain hemoglobin iron in reduced state for O binding
life span of erythrocyte?
120 days/300 miles
red cells most important function?
carry oxygen to tissues
most abundant protein in blood?
hemoglobin
most abundant protein in plasma?
albumin
structure of hemoglobin
2 alpha globin chains, 2 beta globin chains, 4 heme molcules w/ iron in center of each
function of hemoglobin
transports oxygen from lungs to tissues; transports CO2 from tissues to lungs
what causes sickle cells
defect in hemoglobin structure
what causes microcytic cells
red cells smaller than should be
iron deficiency causes it
what happens if RBC become spherocyte
pt becomes anemic because these RBC easily removable from circulation, get hemolized
megakaryocyte
big cell of bone marrow, see 3-4 in bone marrow aspirate
hyper diploid cell w/ a very large cytoplasm
why megakaryocyte so large?
undergoes special division where only nucleus divides - ENDOREDUPLICATION
how does megakaryocyte form
during platelet formation, cytoplasm breaks off into little pieces; leaves lung; enters bone marrow, breaks down further; becomes platelet
platelet clumping
in vitro artifact of megakaryocyte
causes incorrect CBC
characteristics of platelets
anuclear, 1-3u, 7-10 day life span, 150-400,000/ul, all organelles, electronic dense granules, microtubules, contractile proteins, membrane proteins
functions of platelets
first line defense at vascular injury site (adhesion, activation, aggregation)
platform for fibrin formation (clot)
mediate inflammation
mediate vascular constriction (serotonin)
mediate fibroblast proliferation (PDGF)
thrombocytopenia
too few platelets, results in bleeding in mucocutaneous locations like mucosa, lips, skin
types of WBC
leukocytes = WBC
neutrophil (55-65%, eosinophil (2-5%), basophil (1%), monocyte (3-8%), lymphocyte (20-25%)
2 groups of WBC
granulocyte (granules in cytoplasm), agranuloocyte
most numerous type of granulocyte?
neutrophil
most numerous agranulocyte?
lymphocyte
normal WBC count?
5-10 x 10^3 leukocytes/ul
most mature form of neutrophil in blood?
segmented neutrophil
neutrophil types
band, segmented
neutrophil life span
6 hours in blood; 1-5 days in tissues
proteins in neutrophils
actin, myosin
cytoplasmic granules in neutrophils
specific: lysozyme, alk phos;
non-specific: acid phos, lysozyme, myeloperoxidase
neutrophil function
motility (contractile proteins) - chemotaxins, released at site of tissue damage, attract PMNs to infected/inflammed tissue
endocytosis/phagocytosis
endotoxin mediates G-CSF, GM-CSF release from marrow stromal cells resulting in neutrophilia
what are released when infection/tissue damage occurs, that attracts neutrophils?
hemotaxins
how do neutrophils fight infection?
leave circulation, form pseudopoedia, engulf bacteria/damaged tissue and release phagosomes, break apart/kill bacteria, allow blood to wash away
leukocytosis
too many WBC
granulocytosis
too many granulocytes
what kind of disease is chronic myelogenous leukemia?
granulocytosis
eoisnophil characteristics
bipobed nucleus; specific granules
how long do eosinophils live?
circulate for several hours after leaving marrow; then enter skin, pulmonary or GI mucosa; may migrate into local secretions
what do eosinophils do?
phagocytize antigen-antibody complexes
what kind of receptors do eosinophils have?
receptors for IgE
when are there increased numbers of eosinophils?
allergy, parasitic infections
what do basophil granules contain?
heparin, histamine
what kind of receptors do basophils have?
receptors for IgE, produced by plasma cells in response to allergens; when bound, degranulation and release of histamine occurs
what do basophils do
mediate allergic responses
what are basophils precursors of?
tissue mast cells
what type of granules do monocytes have?
azurophilic granules, with lysosomal enzymes
what type of receptors do monocytes have?
Fc and Complement receptors on surface
how long do monocytes live?
differentiate into tissue macrophages -> live months to years
characteristics of monocytes
motile, phagocytic
lymphocyte function
effect immune response
T cell function
lymphocyte- cell mediated immunity
B cell function
lymphocyte- humor immunity
what percentage of blood leukocytes are monocytes?
3-8%
