Blood Flashcards
What is blood?
A special connective tissue
What is the origin of blood?
Mesenchymal cells
What is the function of blood?
1) nutrient and oxygen delivery
2) waste and carbon dioxide removal
3) immune protection
4) circulation contributes to temperature regulation
What are the components in blood?
Erythrocytes
Leukocytes
Thrombocytes
Plasma
What are erythroctes involved in?
02 and C02 exchange
What are leukocytes used for?
immune responses
What is the function of thrombocytes?
Blood clotting
What is plasma ?
proteinaceous solution in which erythrocytes, leukocytes and thrombocytes circulate in
What are the advantages of a biconcave shape for erythrocytes?
1) Provides maximum surface to volume ratio for optimal gas exchange
2) Provides for flexibility for maneuvering through capillaries
What is the average life span of erythrocytes?
120 days
What constitutes a “worn out” erythrocyte?
1) probably due to a diminishing efficiency of cell surface ion pumps
2) loses ability to regulate volume and subsequently swells
3) eventually removed by splenic macrophages
What is hemoglobin?
1) iron-containing heme groups conjugated to globin
2) when rbc’s are removed, iron is recycled and the rest is excreted as bilirubin
What is carbonic anhydrase?
facilitates C02 uptake in tissues anq C02 discharge in the lungs
Are there nucleus and organelles in erythrocytes?
No, expelled during erythropoiesis
What is the surface chemistry of erythrocytes?
cell membrane glycolipids and glycoproteins involved in ABO blood typing
What is anemia?
1)any significant decrease in blood concentration of hemoglobin due to:
• reduction in total number of circulating erythrocytes
• reduction in hemoglobin content in each individual erythrocyte
2) reduced oxygen carrying capacity leaves person chronically tired
What is polycythemia
1) any significant increase in circulating erythrocyte number
2) increases viscosity of blood and hence workload on heart
What is a reticulocyte?
immature erythrocyte found in peripheral blood, contains some residual RNA
What are thrombocytes derived from?
Megakaryocytes
How much of the total body platelets circulate the body at one time? and how many are left in the spleen?
2/3 circulate the body
1/3 are in red pulp of spleen
What is the maximum circulation time for platelets?
about 10 days
What do thromboytes contain?
Various clotting factors
Platelet derived growth factor (promotes proliferation of fibroblasts and smooth muscle cells )
Serotonin (vasoconstrictor)
Do thrombocytes have a nucleus?
No nucleus is present in these fragments of cytoplasm
How do circulating platelets adhere to vascular wall components of damaged endothelium?
1) via integrins (IMP’s with binding specificity for fibronectin)
2) fibronectin is a tissue matrix protein that binds to collagen
When multiple platelets adhere to a damaged site it is known as?
Platelet aggregation which forms a platelet plug and eliminates further blood loss
What does serotonin do?
release causes vasoconstriction by smooth muscle cells and reduces blood loss from damaged vessel
What is fibrinogen converted to and where?
Converted to fibrin and on the surface of activated platelets
What replaces the early platelet plug?
An insoluble fibrin mass (thrombus)
what is the function of Platelet derived growth factor (PDGF)?
1) Release causes proliferation of smooth muscle and fibroblasts
2) step in repairing the damaged wall components
WHat is thrombocytopenia?
Platelet deficiency leading to easy bleeding subsequent to minor. trauma
What are leukocytes?
White blood cells
Where are leukocytes found?
Peripheral blood but greatest activity is in connective tissues
What is diapedesis?
process whereby a wbc leaves the circulatory system and enters CT
What are the Granular leukocytes?
Neutrophils
Eosinophils
Basophils
What are the agranular leukocytes?
Lymphocytes
Monocytes
What are neutrophils?
1) typically has a multilobed nucleus (usually 3 - 5 lobes)
very fine, pale pink staining cytoplasmic granules
~ contain hydrolases and anti-bacterial enzymes
2) Other organelles are sparse
3) aboundant amounts of glycogen are present for anaerobic metabolism
What is the function of neutrophils?
1) circulate in peripheral blood about 10 ho
2) these cells are phagocytic
first line of defense agai~st bacteria
3) respond to chemotaxms
What are Eosinophils?
1) nucleus usually is bi-lobed
3) intermediate sized, reddish-orange cytoplasmic granules.
What is the function of eosinophils
these are phagocytic cells with a particular affinity for antigen-antibody complexes
these cells also typically increase in number in certain:
~ parasitic diseases
~ allergic conditions
~ adverse drug reactions
What are basophils?
Usually bi-lobed nucleus and contain large, deeply basophilic cytoplasmic granules, contain cell surface receptors for IgE antibodies
What is the function of basophils?
may become involved in systemic allergic responses
~ antigen-lgE interaction with surface receptor triggers granule release
~ may ultimately lead to death
these cells are also mildly phagocytic
related to a tissue cell with similar function (mast cell)
What is a lymphocyte?
1) nucleus is large and spherical and is very densely heterochromatic
usually only a thin rim of bluish cytoplasm is seen peripheral to the nucleus
What is the functions of lymphocytes?
85 % are T lymphocytes - differentiate in the thymus? - involved in cell-mediated immunity 15% are B-lymphocytes - differentiate in the bone marrow involved in antibody-mediated immunity precursor to plasma cell
What are monocytes?
1) Largest diameter of all leukocytes (3 RBC)
2) nuclear morphology is variable (“fat horseshoe” to “lumpy-bumpy blob”)
- chromatin is much less dense than lymphocyte chromatin
3) abundant pale blue-gray cytoplasm visible
4) contains typical complement of organelles
What is the function of monocytes?
1) direct circulating precursor of macrophage
2) limited capacity for phagocytosis in the circulating form
What is hematopoiesis?
Blood development
Do most types of blood cells divide?
No, they are highly differentiated and do not divide
Where are new blood cells made?
Bone Marrow
Where are old and worn out blood cells removed?
Spleen
What happens to monocytes that stay in bone?
They typically become osteoclasts
What happens to monocytes that typically stay in the blood?
They remain as monocytes
What is the cell origin of hematopoietic tissues?
Mesenchymal cells
What is myeloid tissue?
1) red bone marrow
2) source of most peripheral blood cells
3) hematopoietic tissue
What is lymphoid tissue?
1) spleen, thymus, lymph nodes
2) source of some lymphocyte differentiation
3) hematopoietic tissue
What happens at 3 weeks gestation regarding blood?
Blood islands form (pockets of red blood cells are forming around yolk sac)
What happens at 6 weeks gestation regarding blood?
liver erythropoiesis begins
What happens at 5 months gestation regarding blood?
bone marrow begins producing platelets and leukocytes
What happens at 7 months gestation regarding blood?
bone marrow now begins erythropoiesis as well
What happens at birth regarding hematopoiesis?
1) bone marrow accomodates all normal blood cell production
2) liver and spleen may participate in times of excessive blood loss
What happens during growth regarding hematopoiesis?
1) hematopoietic capacity of bone marrow exceeds even emergency requirements
2) hematopoietic marrow (red marrow) occupies less of total marrow space
What happens during skeletal maturity regarding hematopoiesis?
1) red marrow is limited to vertebrae, ribs, skull, pelvis and proximal femur
2) remaining marrow spaces fill with fat (yellow marrow)
- these still retain a hematopoietic potential if needed
What is a pluripotential stem cell?
1) True stem cell
2) capable of regenerating entire hierarchy of blood cell types
3) does so by giving rise to multipotential stem cells
4) also self renews through cell division to create self-sustaining pool of stem cells
What are multipotential stem cell?
1) Committed stem cell
2) still overtly undifferentiated but slightly more committed
3) CFU-L-gives rise to lymphocytic differentiation
4) CFU-GEMM -gives rise to all the other cell lineages
- granulocytic, ~rythrocytic, monoblastic, megakaryocytic
- single CFU may not give rise to both lines of cell differentiation
What is the difference of multipotential stem cells and pluripotential stem cells?
Multipotential stem cells are undifferentiated like pluripotential cells but the multipotential cell can only give rise to some blood cell elements but unable to do the entire hierarchy which pluripotential stem cells can make
What is a hematopoietic stem cell?
Specific stem cell that is the FIRST identifiable cell in each lineage
What do lymphoblasts make?
lymphocytes
What do proerythroblast make?
Erythrocytes
What do myeloblasts make?
granulocytes
What do monoblast make?
monocytes
What do Megakaryoblast make?
thrombocytes
What is the key development of red blood cells?
Proerythroblast (no hemoglobin)
Reticulocyte (has some RNA left)
Erythrocyte
What are the important changes occuring during erythropoiesis?
1) decreasing cell size
2) hemoglobin content increases
• cytoplasm changes from being basophilic (due to many ribosomes) to being acidophilic (due to hemoglobin)
3) gradual loss of organelles
4) condensation and extrusion of the nucleus
What is granulopoiesis?
Development of neutrophils, eosinophils and basophils
What are the key development of granulopoiesis?
Myeloblast (spherical) Band cell (sausage or rod-shaped like structure) Mature granulocyte (pinches off into 2 lobes)
What are the important changes occuring during granulopoiesis?
1) transition from spherical to rod-shaped to lobed nucleus
2) development of specific granules for each granulocytic lineage
• granules are first seen at myelocyte stage
• granules are identifiable for each granulocyte at metamyelocyte stage
