Peripheral Blood Flashcards
1
Q
Proteins in plasma
A
- Albumin (major component): maintains osmotic pressure of blood, plays a role in transport of water-insoluble substances
- Gamma globulins (immunoglobulins): antibodies
- Fibrinogen: necessary for the formation of fibrin during blood clotting
- Complement proteins: inflammation and destruction of microorganisms
- Other solutes: electrolytes, nitrogen substances, nutrients, gases, hormones, enzymes
2
Q
Layers of centrifuged blood
A
- Lowest layer: RBCs, ~45% of blood volume. Hematocrit - % of blood volume occupied by RBC
- Middle Layer (buffy coat): ~1% of blood volume, white/gray in color, has leukocytes and platelets
- Upper layer: blood plasma, ~50% of blood volume, yellowish translucent supernatant
3
Q
Structure of erythrocytes
A
- Biconcave discs without nuclei (large surface to volume ratio)
- Diameter 6.5-8.0 um
- Bind eosin deeply around periphery
4
Q
Factors influencing the ability of RBCs to change shape
A
- Geometry (biconcave shape)
- Cytoplasmic viscosity (intracellular hemoglobin concentration)
- Properties of plasma membrane (3 layers)
5
Q
Membrane skeleton of RBCs
A
- Network of peripheral proteins
- Attached to cytoplasmic side of lipid bilayer
- Spectrin, actin, and protein 4.1
- Influences deformability of membrane
- Stabilize membrane against shearing forces
6
Q
Hemoglobin
A
- constitutes about 1/3 of cell weight
- responsible for viscosity
- globular chromoprotein
7
Q
Hemoglobin A1 (HbA1)
A
- major form of hemoglobin in adults (95%)
- consists of 2 alpha and 2 beta chains
8
Q
Hemoglobin A2 (HbA2)
A
- minor form of hemoglobin in adults (5%)
- consists of 2 alpha and 2 delta chains
9
Q
Hemoglobin F (HbF)
A
- Produced during the intrauterine period
- Consists of 2 alpha and 2 gamma chains
10
Q
Hemoglobin S (HbS)
A
- Single nucleotide mutation in DNA coding for beta chains (glutamic acid –> valine)
- Leads to sickle cell disease: RBC are inflexible and have reduced life span, can lead to anemia and can increase blood viscosity
11
Q
Function of RBCs and number of cells
A
- Transportation of gases: O2 from alveoli to tissues and CO2 from tissues to alveoli
- Males: 4.1-6 x10^6/ul
- Females: 3.9-5.5 x 10^6/ul
- Number influenced by altitude
12
Q
Life span of RBC
A
- Survive in circulation for about 120 days
- Senescent RBCs are removed by macrophages
13
Q
Reticulocytes
A
- RBCs recently released from bone marrow
- Contain small amount of ribosomal RNA (stains bright blue, appears as a net-like cytoplasmic structure)
- Make up ~1% of circulating RBCs
- Useful indicator of rate of RBC production (good for anemias, bone marrow regen. etc.)
14
Q
How do leukocytes leave blood vessels?
A
Through diapedesis - either between cells or through cells
15
Q
Classification of leukocytes
A
- Granulocytes: neutrophils, eosinophils, basophils
- Agranulocytes: lymphocytes and monocytes
16
Q
Number of leukocytes
A
- 6,000-10,000/ul (7,500) Relative frequencies: - Neutrophils 60-70% - Eosinophils 2-4% - Basophils 0-1% - Lymphocytes 20-30% - Monocytes 3-8%
17
Q
Structure of neutrophils
A
- 12-15um in diameter
- nucleus has 2-5 lobes (variably shaped)
- heterochromatic nucleus
- no nucleoli
- salmon-pink cytoplasm (from specific granules)
- 2 types of granules (80% specific/20% azurophilic)
18
Q
Cytoplasm of neutrophils
A
- Few mitochondria
- Small Golgi
- Poorly developed RER
- Few free ribosomes
- Considerable glycogen
19
Q
Functions of neutrophils
A
- Phagocytosis and killing of bacteria
- Formation of superoxide (O2) anions
- Netosis: release a net capable of trapping microbes
- Release microvesicles with antibacterial activity
- Production of cytokines
Neutrophils for pus when they die from these processes
20
Q
Phagocytosis function of neutrophils
A
- Neutrophils are motile and display chemotaxis (move in response to env. chemicals)
- Pseudopodia surround bacteria forming phagosomes
- Specific granules form with phagosome, discharge contents
- lysozyme hydrolyzes glycosides in bacterial cell wall
- lactoferrin is an iron binding protein - Azurophlic granules fuse with phagosome forming secondary lysosome: enzymes hydrolyze bacteria in small molecules
21
Q
Structure of eosinophils
A
- 2-4% of leukocytes
- 12-15 um in diameter
- Nucleus is bilobed
- Large eosinophilic specific cytoplasmic granules (no azurophilic)
- Cyto. granules are most striking feature - crystalline core, contain hydrolytic enzymes
22
Q
General function of eosinophils
A
- Phagocytosis
- Secretion
- Potential role in asthma
- Other (mammary gland development, transplant rejection, demyelinating diseases)
23
Q
Phagocytosis function of eosinophils
A
- kill larvae of parasites that invade tissues
- dispose of antigen-antibody complexes
- granules fuse with phagosomes
- hydrolytic enzymes digest phagocytized material
24
Q
Secretory function of eosinophils
A
- Release of granule contents into extracellular space
- Inactivate mediators of inflammation (histamine, SRS-A)
- Synthesize lipid mediators of inflammation (leukotriene C4 and platelet activating factor)
- Produce a variety of cytokines: promote survival/enhance activity of eosinophils
25
Potential role of eosinophils in asthma
- Bronchoconstriction
- Excess mucus secretion
- Inflammation
- Airway remodeling (increased smooth muscle, collagen in ECM, goblet cell metaplasia)
26
Structure of basophils
- 0-1% of leukocytes
- 12-15um in diameter
- Nuclei are less segmented than neutrophils or eosinophils
- Large azurophilic granules frequently obscure nucleus
- Granules are rich in heparin, histamine, and SRS-A
27
Function of basophils
- Role in inflammation
- Immediate hypersensitivity reactions
- -> certain antigens stim plasma cells to produce IgE (anaphylaxis), IgE attaches to cell surface of basophils, rxn may be local or wide spread
- Delayed hypersensitivity rxns: take longer to develop (12-18 hrs)
- Produce eosinophilic chemotactic factor
28
Size and structure of small lymphocytes
- Intensely staining spherical nucleus
- Thin rim of cytoplasm
- 6-8um diameter
- Most frequent size in peripheral blood
29
Size and structure of medium lymphocytes
- Larger and less heterochromatic nucleus
- More abundant cytoplasm
- 8-10um in diameter
30
Size and structure of large lymphocytes
- Cells activated by specific antigens
- More diffuse nucleus
- Cytoplasm contains more organelles
- 10-18um in diameter
- SOme have large azurophilic granules
31
Function of B lymphocytes (humoral immunity)
- 10-15% of circulating lymphocytes
- Differentiate into plasma cells which produce antibodies
- Have immunoglobin molecules on cell surface (antigen receptors)
- Undergo mitosis after antigenic stim., some become memory B cells
32
Function of T lymphocytes (cell-mediated immunity)
- 70-80% of circulating lymphocytes
- Require antigen presenting cells
- Some activated T cells differentiate into cytotoxic T cells (CD8+), Helper T cells (CD4+), or suppressor (regulator) T cells
33
Cytotoxic T lymphocytes
- CD8+
- Capable of killing foreign or viral infected cells
- Recognize other cells that have foreign antigens on their surface, lyse and induce apoptosis in target cells
34
T Helper Cells
- Assist B cells and T cells in their response to antigens
- Produce lymphokines
- Specific target for HIV
35
Supressor (regulator) T Cells
- Suppress or dampen the response to foreign antigens
- May suppress immune response to self molecules
- May block anti-tumor responses of cytotoxic T cells
36
Large granular lymphocytes (Natural Killer cells)
~ 5% of circulating lymphocytes
- Have neither B nor T cell surface molecules
- Have large azurophilic granules
37
NK cell functions
1. Kill virus infected cells
2. Kill malignant cells
3. Production of cytokines that influence host's immune response
38
Structure of monocytes
~4% of circulating leukocytes
- 12-20um in diameter
- Variable shaped, euchromatic nucleus
- Abundant cytoplasm with man small azurophilic granules and vacuoles
- Nucleolus often observable
- Full complement of cytoplasmic organelles
39
Functions of monocytes
1. Phagocytosis of bacteria and tissue debris
2. Concentrate/process antigens for presentation to lymphocytes (APCs)
3. Fusion to form osteoclasts
4. Formation of giant cells (chronic inflammation)
5. Production of cytokines that help regulate hematopoesis
6. Immune surveillance of endothelial cells (??)
40
Structure of blood platelets (thrombocytes)
- Small cytoplasmic fragments of megakaryocytes
- 2-4um in diameter
- 250,000/ul normal count
- Non-nucleated
- Central darkly staining granulomere
- Peripheral less intensely staining
- Usually appear in clumps
- Produced by megakaryocytes in bone marrow
41
Functions of blood platelets
- Seal off breaks in blood vessels
- Blood coagulation
- Maintain integrity of epithelium
- Role in inflammation associated with rheumatoid arthritis by increasing vascular permeability
- Role in tissue repair/regeneration?
- May inhibit angiogenesis and tumor growth by releasing thrombospondin-1?
