Circulating Blood Flashcards
Erythrocytes
Lacks a nucleus in mammals, but nucleated in other forms (birds, etc.)
Lacks a Golgi, centrioles, lysosomes, RER
Very few or no mitochondria , resulting in anaerobic glycolysis and pentose phosphate pathways being important for energy production.
RBCs are 500-1000 times more numerous than leukocytes
A person with type B blood has _ antigens and antibodies against _.
A person with type B blood has B antigens and antibodies against A.
thrombocytes
Derived from megakaryocytes in the bone marrow, and represent membrane bound
fragments of the cell
No nucleus, but a fragment of the megakaryocyte
Contains a central granulomere and a peripheral hyalomere
Granulocytes vs Agranulocytes
- Granulocytes/polymorphonuclear
a. have specific granules in the cytoplasm
b. non-mitotic cells in the blood stream and after leaving the vascular system
c. three types:
i. neutrophils
ii. eosinophils
iii. basophils - Agranulocytes/mononuclear
a. lack specific granules in the cytoplasm
b. differ from granulocytes in that they can reproduce by mitosis after leaving the
vascular system
c. two types:
i. lymphocytes
ii. monocytes
Neutrophils
Characterized by having a many lobed nucleus and specific granules in the cytoplasm
Comprise 50-70% of differential count
C. Functions
1. Neutrophils serve as a first line of cellular defense against invasion of microorganisms. PMNs are chemotactically attracted by devitalized tissue, bacteria, and other foreign bodies and factors produced by antigen-antibody interactions with certain blood proteins (complement) and they migrate to the site of infection
2. Killing of bacteria is thus accomplished via two different mechanisms:
a. enzymatic (via fusion of specific and azurophilic granule contents with the
phagosome) which involves:
(1) phagocytosis of the foreign material, thus forming a phagosome,
(2) the specific granules fusing with the phagosome, inactivating the material,
(3) the azurophilic granules fusing with the phagosome, digesting the material,
and
(4) finally the digested material expelled from the cell.
b. via formation of reactive oxygen compounds within the phagosome
3. Neutrophils die and become the pus of an abscess.
- Not all bacteria destroyed by neutrophils. For example, the tubercle bacillus survives phagocytosis by the PMN, and must be contained by the macrophage which is derived from the monocyte
granules
(1) azurophilic or primary granules (20% of granules) (reddish-purple color)
i. 400-700 nm (0.4 μm) in diameter
ii. membrane bound granules containing lysosomal enzymes and
myeloperoxidase (peroxidase)
iii. appear early in cell development (promyelocyte stage) and progressively
decrease in number
(2) neutrophilic or specific or secondary granules (80% of granules) (lavender or lilac color)
i. less than 400 nm in diameter
ii. membrane bound granules containing alkaline phosphatase (hydrolases that function at a neutral or alkaline pH) and bacteriocidal substances
(lysozyme, lactoferrin)
iii. appear later in cell development (myelocyte stage) and progressively
increase in number
(3) tertiary granules
i. contain gelatinase; cathepsins; glycoproteins that can be inserted into the
plasma membrane (aid in the phagocytic processes)
Eosinophil
Comprise 1-4% of the differential count
c. specific granules
i. specific granules very large (0.5 to 1.5 um wide)
ii. granules eosinophilic due to the large amount of arginine in the protein
iii. crystalline structure in granule core seen with TEM (contains major basic
protein, eosinophilic cationic protein, and eosinophil-derived neurotoxin):
major basic protein and eosinophilic cationic protein are very effective agents in combating parasites
d. azurophilic granules
i. these are lysosomes and contain hydrolytic enzymes and peroxidase
ii. contents help in the destruction of parasitic worms and in the hydrolysis of
antigen-antibody complexes internalized by the eosinophils
C. Functions
1. Eosinophils leave the vascular system by diapedesis, and locate especially in the
connective tissue beneath the epithelium of the respiratory and gastro-intestinal tract.
a. binding of histamine, leukotrienes, and eosinophil chemotactic factor (released by mast cells, basophils, and neutrophils) to eosinophil plasma membrane receptors results in the migration of the eosinophils to the site of the allergic reaction, inflammatory reaction, or parasitic worm invasion
- The differential count of eosinophils increases with parasitic infections (trichinosis,
schistosomiasis, ascaris)
a. major basic protein and eosinophil cationic protein bore holes in the pellicles of
parasitic worms, facilitating access of reactive oxygen compounds (e.g.
superoxides; hydrogen peroxide) to the parasite - Differential count increases in allergic conditions such as hay fever and asthma.
- Cells play a role in the phagocytosis and hydrolysis of antigen-antibody complexes.
- Eosinophils degrade chemical mediators such as leukotrienes and histamine released by mast cells and basophils, thus regulating local inflammatory responses
Basophil
Comprise about 0.5% of differential count
Functions 1. Increase in number along with other leukocytes with leukemia. 2. Increase in number in smallpox, chicken pox, and sinus inflammations. 3. Functions are appear to be involved in mediating allergic and inflammatory reactions (functions are similar to mast cells) a. antigens can bind to IgE molecules whose Fc portion is bound to Fc receptors on the basophil surface; this may cause the basophils to release the specific granule contents into the extracellular spaces (1) release of histamine causes smooth muscle contraction (in the bronchial tree), vasodilation of microcirculation, and leaking of blood vessels b. begin to produce and release leukotrienes (1) similar effects to histamine, but actions are slower and more persistent
Lymphocytes
Produced in lymphatic nodules, lymph nodes, spleen, thymus, tonsils, and bone
marrow, and endow the body with its immunological defense.
Comprise 20-40% of differential count
Two size categories: a. Small lymphocytes (1) comprise 90% of the lymphocytes (2) diameter of 6 to 12 μm b. Large lymphocytes (1) comprise 10% of the lymphocytes (2) diameter of 12 to 18 μm (3) significance of these cells is unknown, but may be partially differentiated plasma cell precursors (4) differ from small lymphocyte in that nucleus is slightly bigger, and there is slightly more cytoplasm and organelles (5) appear similar to monocytes, but smaller and nucleus is never kidney shaped
monocytes
Comprise 2-8% of the differential count
- Monocytes exhibit diapedesis (continually extend and withdraw pseudopodia) and
reach full development outside the blood stream where they are known as
macrophages. Macrophages fuse to form foreign body giant cells and osteoclasts; In the CNS the macrophages form microglia; in the liver, Kupffer cells; and in the lungs, alveolar macrophages. - Serve as the second line of defense against invading organisms. Found in areas of
chronic inflammation. - After leaving the vascular system, the macrophage (monocyte) plays a role along with the T-lymphocyte in the differentiation of the B-lymphocyte into the plasma cell, which produces immunoglobulins.
- Some macrophages are particularly good at processing and presenting antigen and are called antigen presenting cells
- Monocytosis - increased monocyte count due to infectious and inflammatory diseases, tuberculosis, and leukemia.
Be able to describe the differences between blood plasma, lymph plasma, and serum.
Lymph plasma
A. Carries carbonic acid, but very little oxygen
B. Intestinal lymphatics after a meal become filled with a large number of chylomicrons,
resulting in a white colored lymph known as chyle
C. Coagulates more slowly than blood, the fibrin forming a colorless clot
a. composition of plasma:
i. water - 90%
ii. proteins (albumin; globulins - alpha, beta, gamma; fibrinogen) - 7%
iii. inorganic salts (Cl-, HC03-, P04-3, Ca+2 Na+, K+) - 0.9%
iv. organic compounds (amino acids, vitamins, hormones, lipids,
carbohydrates, etc.) - 2.1%
b. plasma vs. serum
i. plasma clots, serum does not clot
ii. serum lacks the protein fibrinogen and some clotting factors
