Blood and Hematopoiesis Flashcards
Blood is a
Connective tissue
Total blood volume
~5-6 L or ~8% total body weight
- Delivery of O2 and nutrients to cells
- Transport of wastes and CO2 from cells
- Transport of hormones and other regulatory substances
- Maintenance of homeostasis by acting as buffer and participating in coagulation and thermoregulation
- Protective role via transport of immune cells and immune components
Functions of blood
What does blood deliver to cells
O2 and nutrients
What does blood transport from cells
Waters and Co2 from cells
Acts as buffer and participating in coagulation and thermoregulation
Maintenance of homeostasis
defined as cells in an extracellular matrix
Connective tissue
Provide the transportation system for blood through the body.
Heart and blood vessels
Acts as a double pump for the system
Heart
Provide distribution pathways
Blood vessels
Main 3 functions of blood
- Distribution
- Regulation
- Protection
absorbs and distributes heat around body; brings it to surface of the skin to cool
Bloods role in thermoregulation
blood acts as the reservoir fort the body’s
Alkaline reserve of bicarbonate atoms
CO2 carried in blood is transported as
Bicarbonate ions (70%)
How does blood prevent blood loss
Coagulation
What causes blood clots
platelets and plasma proteins
What is blood composed of
- Formed elements
- Plasma
Formed elements of blood
- Cells
- Cell fragments
Where do the formed elements of blood arise from?
Hemtopoietic stem cells
Cells in the blood
- Erthryocytes (RBS)
- Leukocytes
Are RBC true cells?
NO
What are cell fragments
Thrombocytes (plasma)
Protein-rich, fluid extracellular matrix
Plasma
Volume of packed red blood cells in a sample of blood
Hematocrit
How is hematocrit measured?
Centrifuging blood sample and calcutating perfectage of tube volume
Percentage of tube volume occupied RBCs as compared to whole blood
How hematocrit is measured
What is the relative volume of RBC in hematocrit?
45%
What is the relative volume of Plasma in hematocrit?
55%
What is the relative volume of buffy coat in hematocrit?
1%
What is in buffy coat?
Leukocytes and platelets
Normal hematocrite in males
39-50%
What is the normal hematocrite in females
35%-45%
What are the components of plasma?
- Water
- Plasma proteins
- Other solutes
Give percentages of plasma components
Water- >90
Plasma proteins 7
Other solutes 1
What is solvent for a variety of colutes in plasma
Water
Helps maintain homeostasis (providing optimal pH and osmolarity)
Water
- Albumin
- Globulins
- Fibrinogen
Plasma proteins
Electrolytes, non-protein nitrogen substances (i.e., waste materials), nutrients, blood gases, regulatory substances
Solutes in plasma
What makes up half of the plasma proteins?
Albumin
Where are plasma proteins made?
In the liver
Exerts concentration gradient; helps maintain osmotic pressure
Albumin
Acts as carrier protein, for substances such as hormones, metabolites, and drugs
Albumin
antibodies secreted by plasma cells
Immunoglobulins (γ-globulins)
produced by liver; help maintain osmotic pressure and serve as carrier proteins
Nonimmune globins (α- and β-globulins)
- Soluble
- Via series of cascade reactions, transformed into insoluble protein fibrin which helps form blot clots
Fibrinogen
drop of blood placed directly on slide and spread thinly over surface with edge of another slide
Blood smear
Produces monolayer of cells
Blood smear
Blood smear is air dried and stained with
Wright’s stain
Mixture of methylene blue (basic), azures (basic), and eosin (acidic)
Wrights stain
devoid of typical organelles
Anucleate cells
What type of cells are Erythrocytes?
Anucleate cells
Bind and deliver O2 (99%) to tissues and bind CO2 (30%) to remove from tissues
RBC
What shape are RBC
Biconcave
Diameter of RBC
7.8 um
What is important of the shape of a RBC
It maximizes surface area - important for gas exchange
Where does production of RBC occur?
Red bone marrow
Production of RBC
Erythropoiesis
Life span of a RBC
120 days
Rate of release of RBC
2 million/sec
specialized protein involved in binding, transporting, and releasing O2 and CO2
Hemoglobin
- Four polypeptide chains of globin (α, β, δ, γ)
- Four iron-containing heme groups
Structure of hemoglobin
What does iron bind to in hemoglobin
One O2 molecule
Each hemoglobin protein binds to
4 O2 molecules
What is the most common type of hemoglobin composed of?
two α and two β chains
subclassified into two general groups based upon presence or absence of prominent specific granules within cytoplasm and the shape of their nuclei
Leukocytes
Two types of leukocytes
- Polymorphonuclear granulocytes
2. Mononuclear agranulocytes
Contain specific granules and have multilobed nuclei; also possess azurophilic granules
Polymorphonuclear Granulocytes
What type of WBC are polymorphonuclear granuloctyes
- Neutrophils
- Eosinophils
- Basophils
No specific granules and have rounded nuclei; do contain azurophilic granules
Mononuclear Agranulocytes
Types of Mononuclear Agranulocytes
- Lymphocytes
- Monocytes
Types of lymphocytes
- B lymphocytes
- T lymphocytes
- Natural Killer (NK) cells
Most numerous leukocytes
Neutrophils
Cytoplasm of neutrophils
Small faint lavender granues
Granule contents of neutrophils
- Lysozyme (specific granules)
- Peroxidases (azurophilic granules)
Nucleus of neutrophils
Darkish, several lobes
- First responders to infection
- Acute inflammation
- Phagocytose bacteria within tissues; accumulate as pus
Function of neutrophils
Comprise 1%-5% of leukocytes
Eosinophils
Cytoplasm of eosinophils
Large coarse acidophillic granules
Granule content of eosinophils
- Peroxidase
- Histaminase
- Arylsulfatase
Nucleus of Eosinophils
Llight, bilobed
Contribute to defense of parasitic infections (major role in defense against helminths (worms))
Eosinophils
Associated with allergies; release of histaminase & arylsulfatase moderates potentially harmful effects of inflammatory vasoactive mediators
Eosinophils
Chronic inflammation
Eosinophils
Least abundant leukocyte
Basophils
How his the cytoplasm of basophils?
Large coarse basophilic granules
Granule content of basophils
Histamine, serotonin, heparin sulfate
How is the nucleus of basophils?
Light, bilobed
- Involved in regulating immune response to parasites
- Role in allergies via release of vasoactive agents (e.g. histamine)
Basophils function
Comprise 26-28% leukocytes
Lymphocytes
Cytoplasm of lymphocytes
Narrow rim of blue cytoplasm
Nucleus of lymphocytes
Very dark, takes up all of the cell, round, slightly indented
Types of lymphocytes
- T lymphocytes
- B lymphocytes
- Natural Killer (NK) cells
Where do T lymphocytes mature?
Thymus
Adaptive immune cells; cell-mediated immunity
T lymphocytes
Adaptive immune cells; humoral immunity
B lymphocytes
What are B lymphocytes responsible for?
Production of antibodies
Innate immune cells; kill virally infected and malignant cells
Natural killer (NK) cells
How is the cytoplasm of monocytes
Gray (foamy) texture
How is the nucleus in a monocytes
darkish; large, off-center; oval, kidney, or horseshoe shaped
Differentiate into macrophages within body tissues
Monocytes
serve as phagocytic cells involved in antigen presentation
Monocytes as macrophages
Large cells within bone marrow
Megakaryocytes
Thrombocytes are
Platelets
Where are thrombocytes derived from?
Megakaryocytes
separate from peripheral margins of megakaryocyte forming thrombocytes (platelets)
Small bits of cytoplasm
Lifespan of thrombocyte
10 days
Small disc shaped structures
Thrombocytes
blot clot formation and repair of tears in blood vessel wall
Thrombocytes (platelets)
process of blood cell production and maturation
Hematopoiesis
to maintain constant level of the different blood cell types within blood
Purpose of hematopoiesis
Hematopoiesis of RBC
Erythropoiesis
HEmatopoiesis of white blood cells
Leukopoiesis
- Granulopoiesis
- Monocytopoiesis
- Lymphopoiesis
Forms of Leukopoiesis
Hematopoiesis of platelets
Thrombopoiesis
When is hematopoiesis initiated?
Early embryonic development
Phases of hematopoiesis
- Yolk- sac phase
- Hepatic phase
- Bone marrow phase
Hematopoiesis after birth
Red bone marrow
The monophyletic theory states that all blood cells are derived from a common
pluripotential stem cell: hematopoietic stem cell (HSC)
All blood cells are derived from a common pluripotential stem cell: hematopoietic stem cell (HSC)
Monophyletic theory
Capable not only of differentiating into all the blood cell lineages, but also capable of self-renewal
Pluripotential stem cell: hematopoietic stem cell (HSC)
What does HSC break into
HSC & Progenitor cells
In the bone marrow, descendents of the HSC can differentiate into 2 major colonies of mulitpotential progenitor cells:
- Common Myeloid Progenitor (CMP)
2. Common Lymphoid Progenitor (CLP)
-Start to get an idea or suggestion of what they will become
Blast cells
Cells that have a lot of mitosis
Blast cells
Only undergo some mitosis
Stem and progenitor cells
Only undergo mitosis to maintain their populations
Stem and progenitor cells
Under great mitosis producing only cells on their way to differentiation,
Blast cells
Undergo asymmetric mitosis
Stem and progenitor cells
Common myeloid progenitor differentiate into lineage-restricted progenitors
- Megakaryocyte/Erythrocyte
- Granulocyte/Monocyte
Previously called “colony-forming units-granulocyte, erythrocyte, monocyte, megakaryocyte” (CFU-GEMM)
Common myeloid progenitor cells
Previously called “colony-forming units-lymphoid”
Common lymphoid progenitor cells
Gives rise to T cells, B cells, and Natural Killer (NK) cells
Common lymphoid progenitor cells
Progenitor cells develop into
Precursor cells or blasts
Morphological characteristics begin to differentiate
Blast cells
Large amount of mitosis – but only produce cells on the way to differentiation
Blast cells
The higher the potentiality, the lower the
Mitotic rate
The lower the potentiality the higher the
Mitotic rate
Process of blood cell production and maturation
Hematopoiesis
to maintain constant level of the different blood cell types within blood:
Purpose of hematopoiesis
- Large cell (12-20μm); large, spherical nucleus with 1 to 2 nucleoli
- Cytoplasm shows mild basophilia (free ribosomes)
Proerythroblast
Development of erythrocytes within bone marrow
Erythropoiesis
dark-staining, condensed; inactive
Heterochromatin
HSC->CMP->MEP->ErP:
Note
- Nucleus 10-16μm in diameter; progressively more heterochromatic
- Cytoplasm strongly basophilic due to large numbers free ribosomes (polyribosomes) that synthesize hemoglobin
Basophilic Erythroblast
Free ribosomes that synthesize hemoglobin
Polyribosomes
- Cytoplasm displays both acidophilia (hemoglobin) and basophilia (ribosomes),gives overall gray/lilac color
- Nucleus becoming smaller; coarse heterochromatin granules - checkerboard pattern
Polychromatophilic erythroblast
- Small, compact, densely stained nucleus
- Eosinophilic cytoplasm (large amount of hemoglobin)
- No longer capable of cell division
Orthochromatic erythroblast (normoblast)
No longer capable of cell division
Orthochromatic erythroblast (normoblast)
- No nucleus
- Some polyribosomes still present, impart slight basophilia to eosinophilic cells
- Can be found within bloodstream (1-2% of total RBC count)
Polychromatophilic erythrocyte (reticulocyte)
- Granulopoiesis
- Monocytopoiesis
- Lymphopoiesis
Leukopoiesis
- Eosinophils
- Basophils
- Neutrophils
Granulopoiesis
-Monocytes
Monocytopoiesis
- B cells
- T cells
- NK cells
Lymphopoiesis
Can give us progenitor cells for each line; monocytes and all the granulocytes
GMP
Originate from common myeloid progenitor which differentiates into granulocyte/monocyte progenitors
Granulocytes and Monocytes
neutrophils, eosinophils, and basophils undergo similar morphologic maturation process:
Granulopoiesis
Follow granulopoiesis
myeloblast -> promyelocyte -> myelocyte -> metamyelocyte
-> (*band cell) -> mature cell
HSC -> CLP —> —> Lymphocytes
Lymphocytes
Derived from megakaryocytes via thrombopoiesis:
Thrombocytes (platelets)
Follow the formation of thrombocytes
HSC -> CMP -> MEP -> MKP -> Megakaryoblast -> Megakaryocyte -> Platelets
Megakaryoblast under goes successive _____ to become a platelet-producing megakaryocyte
Endomitoses
50 to 70μm in diameter; complex, multilobed nucleus and scattered azurophilic granules; polyploid cells (64N)
Megakaryocyte
Large cell (30μm diameter); nonlobed nucleus
Megakaryoblast
Where are megakaryocytes located?
Near sinusoids within bone marrow
Megakaryocytes send cytoplasmic extensions that break off as platelets
Platelets
Small bits of cytoplasm separated from peripheral regions of megakaryocytes by extensive platelet demarcation channels, lined by
Invaginations of plasma membrane
Cytoplasmic fragments partitioned, forming
Individual platelets
Represents areas where segmentation of platelets is occurring
“foamy” peripheral cytoplasm
Penetrate the sinusoidal endothelium; where platelets will pinch off
Proplatelets
Debate either invaginations of plasma membrane considered “fracture lines” for the release of platelets, but now represents a membrane reservoir that facilitates proplatelet elongation.
Platelet Demarcation Membranes
Where is bone marrow located?
Within medullary cavity and spaces of spongy bone
What does bone marrow consist of?
Sinusoids (sinusoidal capillaries and hematopoietic cords
Developing blood cells, megakaryocytes, macrophages, mast cells, adipocytes
Hematopoietic cords
Where do hematopoietic cells develop?
In clusters/nests located near sinusoids
Send sheetlike extensions into hematopoietic cords –> provide support for developing blood cells; stimulate differentiation of progenitor cells
Adventitial cells (reticular cells)
ratio of hematopoietic cells to adipocytes
Bone marrow cellularity
Number of hematopoietic cells _______ with age
Decreases
Bone marrow cellularity:
100 – age ± 10%
