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what is another name for WBC?
leukocytes
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Characteristically, how are WBCs and RBCs different?
WBCs have nuclei and do not contain hemoglobin
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there are 2 classifications of WBCs. They are:
Granular and Agranular
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What does granular and agranular mean?
it depends on whether they contain conspicuous chemical filled cytoplasmic granules (vesicles) that are made visible by staining when viewed thru a light microscope
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What are the granular leukocytes?
neutrophils, eosinphils, and basophils
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what are the agranular leukocytes?
lymphocytes and monocytes
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What do monocytes and granular leukocytes develop from?
a myeloid stem cell
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What do lymphocytes develop from?
a lymphoid stem cell
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What large, uniform-sized granulated cells stain red orange with acidic dyes?
eosinophils
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Describe an eosinophil
The granules usually do not cover or obscure the nucleus, which most often has 2 lobes connected by a thick strand of chromatin
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the round variable sized granules that stain blue purple with basic dyes
basophil
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describe the basophil
the granules commonly obscure the nucleus, which has 2 lobes
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describe neutrophil
the granules are smaller, evenly distributed and pale lilac in color; the nucleus has 2 to 5 lobes, connected by very thin strands of chromatin.
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What happens to neutrophils as the cells age?
the number of nuclear lobes increases because older neutrophils have several differently shaped nuclear lobes
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What are the several differently shaped nuclear lobes of the neutrophils?
polymorphonu-clear leukocytes (PMNs), polymorphs, or polys
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What are younger neutrophils usually called?
bands, because their nucleus is more rod shaped
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Do agranular leukocytes contain granules?
yes, but they are NOT visible under a light microscope because of their small size and poor staining qualities
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Describe the nucleus of a lymphocyte.
it is round or slightly indented and stains darkly
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describe the cytoplasm of a lymphocyte
it stains sky blue and forms a rim around the nucleus
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Why do we care about the differences of size between the small and large lymphocytes?
because an increase in the number of large lymphocytes has diagnostic significance in acute viral infections and in some immunodeficiency diseases
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there are 3 kinds of lymphocytes:
T lymphocytes (T cells)
B lymphocytes (B cells)
natural killer (NK) cells
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Describe a monocyte
The nucleus of a monocyte is usually kidney shaped or horseshoe shaped, and the cytoplasm is blue gray and has a foamy appearance.
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what are the color and appearance of the monocyte due to?
very fine azurophilic granules, which are lysosomes
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What happens with monocytes when blood transports them from the blood into the tissues?
they enlarge and differentiate into macrophages
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Monocytes can become 2 kinds of macrophages:
fixed macrophages and wandering macrophages
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define fixed macrophages
they reside in a particular tissue
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define wandering macrphages
they roam the tissues and gather at sites of infection or inflammation
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Usually, how long do WBCs live?
in a healthy body some can live for several months or years, but most live only a few days
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Do we have more or less WBS than RBC? About how many?
less
5000-10,000 per milliliter of blood; outnumbered by RBCs 700:1
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what is leukocytosis?
an increase in the number of WBCs above 10,000..it is a normal protective response to stresses such as invading microbes, strenuous exercise, anesthesia and surgery
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What is leukopenia?
an abnormally low level of white blood cells. It is never beneficial and may be caused by radiation, shock and certain chemotherapeutic agents
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Once pathogens enter the body, what is the general function of the WBCs?
to combat them by phagocytosis or immune responses
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How do WBCs accomplish phagocytosis?
many WBCs leave the bloodstream and collect at sites of pathogen invasion or inflammation. Once leukocytes and monocytes leave the bloodstream, they never return to it.
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Do lymphocytes come back to the bloodstream or stay out once they are out?
they come back and are continually recirculating
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How do the lymphocytes recirculate?
from blood to interstitial spaces of tissues to lymphatic fluid and back to blood
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How much of the total lymphocyte population is circulating in the blood at any given time?
only 2%
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If only 2% of the total lymphocyte population is circulating int he blood at a given time, where are the other lymphocytes?
in lymphatic fluid and organs such as the skin, lungs, lymph nodes and spleen
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WBCs leave the bloodstream by a process called...
emigration, formally known as diapedesis
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How is emigration done by WBCs?
they roll along the endothelium, stick to it, and then squeeze between endothelial cells
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What help WBCs stick to the endothelium?
molecules known as adhesion molecules
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Neutrophils and macrophages are active in what process?
phagocytosis
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what is phagocytosis
to ingest bacteria and dispose of dead matter
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What is chemotaxis?
When several different chemicals released by microbes and inflamed tissues attract phagocytes
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What substances provide stimuli for chemotaxis?
toxins produced by microbes; kinins, which are specialized products of damaged tissues and some of the colong stimulating factors (CSFs)
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Other than stimulat chemotaxis, what else do CSFs do?
enhanse the phagocytic activity of neutrophils and macrophages
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Among WBCs, what respond most quickly to tissue destruction by bacteria?
neutrophils
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After engulfing a pathogen during phagcytosis, what does a neutrophil do?
unleashes several chemicals to destroy the pathogen
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What are some of the chemicals used to destroy the pathogens?
the enzyme lysozyme, which destroys certain bacteria, and strong oxidants
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Monocytes take longer to reach a site of infection than ___, but they arrive in ___ numbers and destroy more ___
neutrophils
larger
microbes
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What do monocytes do when they arrive at the site of infection?
they enlarge and differentiate into wandering macrphages, which clean up cellular debris and microbes by phagocytosis after an infection
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What do the basophils do at the sites of inflammation?
they leave capillaries, enter tissues, and release granules that contain heparin, histamine, and serotonin
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What do heparin, histamine and serotonin do during the inflammatory reaction?
they intensify it an are involved in hypersensitivity (allergic) reactions
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What are similar in funtion to mast cells?
basophils
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What do eosinophils do?
leave the capillaries and enter tissue fluid; believed to release enzymes and other substances involved in inflammation during allergic reactions;also produce phagocytize antigen
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What would a high eosinophil count indicate?
an allergic condition or a parasitic infection
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What are the major soldiers in immune system battles?
lymphocytes
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What are B cells particularly effective in?
destroying bacteria and inactivating their toxins
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What are T cells good at?
They attack viruses, fungi, transplanted cells, cancer cells and some bacteria and are responsible for transfusion reactions, allergies and the rejection of transplanted organs
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What do the immune responses carried out by both B and T cells help do?
combat infection and provide protection against some diseases
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What do natural killer cells attack?
a wide variety of infectious microbes and certain spontaneously arising tumor cells
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What would a Dr order to detect infection or inflammation, determine the effects of possible poisoning by chemicals or drugs, monitor blood disorders and the effects of chemotherapy or detect allergic reactions and parasitic infections?
a differential white blood cell count
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What is a differential white blood cell count?
a count of each of the five types of white blood cells
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What would a high count of neutrophils indicate?; low count?
bacterial infection, burns, stress, inflammation
Radiation exposure, drug toxicity, vitamin B12deficiency, or systemic lupus erythematosus (SLE).
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What would a high count of lymphocytes indicate?; low count?
Viral infections, some leukemias
Prolonged illness, immunosuppression, or treatment with cortisol
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What would a high count of monocytes indicate?; low count?
Viral or fungal infections, tuberculosis, some leukemias, other chronic diseases
Bone marrow suppression, treatment with cortisol
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What would a high count of eosinophils indicate?; low count?
Allergic reactions, parasitic infections, autoimmune diseases.
Drug toxicity, stress
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What would a high count of basophils indicate?; low count?
Allergic reactions, leukemias, cancers, hyperthyroidism.
Pregnancy, ovulation, stress, or hypothyroidism.
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