Circulating Blood - Downing Flashcards
What is circulating blood made of?
- Specialized connective tissue
- cells
- intracellular materials
What cells are in circulating blood?
- Erythrocytes (RBCs)
- Leukocytes (WBCs)
- Platelets
- Hemoconia or “dust” (broken down endothelial cells)
- Chylomicrons (lipoprotein, fatty-like material)
What things make up the intracellular material of circulating blood (plasma or fluid component)?
- Water (90%)
- Proteins (7%)
- albumin, globulins, fibrinogen
- Inorganic Salts (0.9%)
- Cl-, HCO3-, PO4-, Ca2+, Na+, K+
- Organic Compounds (2.1%)
- amino acids, vitamins, hormones, lipids, carbohydrates, etc.
What does circulating blood (connective tissue) first develop from?
Embryonic tissue mesenchyme
What is the difference between Plasma vs. Serum?
- Plasma clots (has fibrinogen)
- Serum does not clot (no fibrinogen)
- Serum lacks the protein fibrinogen and some other clotting factors
What is the function of erythrocytes?
Transport of O2 and CO2
What is the shape of an erythrocyte dependent on?
spectrin-ankyrin-actin interaction
What is the cytoplasm of an erythrocyte composed of?
- 2/3 Water
- 1/3 Hemoglobin
- 0/3 Organelles (1%)
- no nucleus, no golgi, no centrioles, no lysosymes, no RER
What distinguishes Type A Blood?
- Antigen A present
- Antibodies to Antigen B
What distinguishes Type B Blood?
- Antigen B present
- Antibodies to Antigen A
What distinguishes Type AB Blood?
- Antigens A & B present
- No antibodies present
- Universal Acceptor
What distinguishes Type O Blood?
- Neither antigens A nor B present
- Antibodies to A and B
- Universal Donor
What is the life span of erythrocytes?
120-130 days
What is the life span of thrombocytes (platelets)?
8-10 days
What are platelets derived from?
Megakaryocytes in the bone marrow
What is the function of platelets?
Clotting mechanism
- Platelets aggregate → trap other platelets, RBCs, proteins, etc.
- Form Platelet Plug
- Clot results
What is the inner central region of a platelet called? Peripheral region?
- Central region = GRANULOMERE
- Azurophilic granules
- Peripheral region = HYALOMERE
- Microtubule hula hoops
What are the two types of Leukocytes (WBCs)?
-
Granulocytes
- have specific granules in cytoplasm
- non-mitotic cells in the blood stream and after leaving the vascular system
- Neutrophils, Eosinophils, Basophils
-
Agranulocytes
- lack specific granules in cytoplasm
- can reproduce by mitosis after leaving the vascular system
- Lymphocytes, Monocytes
What does diapedesis mean?
The process by which WBCs leave the vascular system.
What are Neutrophils (PMNs) characterized by?
- Multi-lobed nucleus
- Specific granules in the cytoplasm
- Most abundant leukocyte
- 50-70% of differential count
What types of granules are contained in Neutrophils?
- Azurophilic (primary) granules (20%)
- lysosomal enzymes
- Neutrophilic (specific/secondary) granules (80%)
- Bactericidal substances: lysozyme, lactoferrin
- Tertiary granules
- Gelatinase - break down gelatin & collagen to help leukocyte migrate through connective tissue
What is the function of Neutrophils?
- First line of cellular defense
- migrate to sites of infection
- phagocytose bacteria, foreign objects, etc.
- cells eventually die (martyr) - become pus
What are the two killing mechanisms of Neutrophils?
- Enzymatic
- Phagosome + granules
- Formation of reactive oxygen compounds
- O2- = superoxide
- HOCl = hypochlorous acid
- MPO = myeloperoxidase
What percentage of a differential count are Neutrophils?
50-70%
What percentage of a differential count are Eosinophils?
1-4%
What morphological features characterize Eosinophils?
- Bi-lobed nucleus
- Golgi & mitochondria
- Cytoplasm
- 2 types of granules
- Specific granules
- Azurophilic granules
- 2 types of granules
What is the function of Eosinophils?
- 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
When does the differential count of eosinophils increase?
- parasitic infections
- major basic protein and eosinophil cationic protein bore holes in the pellicles ofparasitic worms, facilitating access of reactive oxygen compounds
- allergic conditions such as hay fever and asthma
What is the main location of Eosinophils?
Lamina propria of digestive and respiratory tracts
What morphological features characterize Basophils?
- Nucleus: irregular shape, s-shaped, difficult to see
- Cytoplasm: two types of granules
- Specific granules (large)
- Azurophilic granules (lysosomes)
What percentage of a differential count are Basophils?
0.5%
When does Basophil count increase?
- Increase in number along with other leukocytes with leukemia.
- Increase in number in smallpox, chicken pox, and sinus inflammations.
What is the function of Basophils?
- Antigens can bind to IgE molecules whose Fc portion is bound to Fc receptors on the basophil surface
- basophils release the specific granule contents into the extracellular spaces
- release of histamine causes smooth muscle contraction (in the bronchial tree), vasodilation of microcirculation, and leaking of blood vessels
- begin to produce and release leukotrienes
- similar effects to histamine, but actions are slower and more persistent
What percentage of a differential count are lymphocytes?
20-40%
Where are lymphocytes produced?
- Lymphatic nodules
- Lymph nodes
- Spleen
- Thymus
- Tonsils,
- Bone marrow
What percentage of circulating lymphocytes are B-lymphocytes?
15%
What is the fate of B-lymphocytes?
- Plasma cells: antibody production and humoral immune responses
- Memory cells: responsible for secondary immune responses
What morphological features characterize Lymphocytes?
- Most lymphocytes are small: 6-12 microns (90%)
- Nucleus
- spherical or slightly indented on one side
- chromatin is densely packed with a hill and valley pattern
- nucleolus present but not seen because of clumped chromatin
- Cytoplasm
- frequently appears as a thin rim
- many free ribosomes and polysomes, some azurophilic granules, Golgi, RER, and mitochondria
How do T-lymphocytes develop?
- originate embryological from the yolk sac and seed the thymus by way of the
- liver and bone marrow
- multiply and differentiate into T-lymphocytes in the thymus - each developing
- lymphocyte develops an individual antigenic specificity.
- activation of T-cells (needed for activation)
- appropriate antigen
- macrophages must process the antigen for presentation
What is the function of T-lymphocytes?
- cell mediated immunity
- assist in humoral immunity
What are the three types of T-lymphocytes?
(1) Cytotoxic T-cells
(2) T-helper cells
(3) T-suppressor cells
What are Null Cells?
Neither B- nor T-lymphocytes
ex. Natural Killer (NK) cells
What percent of a differential count are Monocytes?
2-8%
What morphological features characterize Monocytes?
- Large size: 12-20 microns in diameter
- Nucleus: indented, oval, kidney, or horseshoe-shaped
- Cytoplasm:
- vacuoles may or may not be present in the cytoplasm
- some azurophilic granules may be present (contain lysosomal enzymes)
- well-developed Golgi, some ribosomes and polysomes, mitochondria, and little RER
What is the function of Monocytes?
- Differentiate into macrophages in the connective tissues and other places
- Kupffer cells (liver)
- Microglial cells (CNS)
- Antigen presenting cells
- etc.
- 2nd line of defense against invading organisms
What is a monocytosis?
Increased monocyte count due to infectious and inflammatory diseases, tuberculosis, and leukemia.
What are Chylomicrons?
A. Found in the plasma
B. Consists of fat combined with plasma proteins
C. Can be visualized with the light microscope after eating a fatty meal
What is Hemoconia?
A. Best described as “junk” in the blood stream
B. Consists of broken down RBCs, endothelial cells, and ingested material not filtered out in the spleen
What are the components of lymph?
- Plasma
- carries carbonic acid but little oxygen
- Cells
- lymphocytes are chief element
- very few granulocytes
- presence in any significant numbers is usually pathological
What is the function of lymph?
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
