Chapter 12 Flashcards
Define the term Hematology
study of blood.
When blood is seperated by centrifugation, what are they two fluid compenents?
- plasma- complex mixture of water, proteins, carbohydrates, lipids, electrolytes and clotting factors
- Cellular components- RBC, WBC, and platelets.
Which organ is the principal site of blood cell formation
bone marrow
they contain precurors of developed cell lines [RBC, WBC and platelets], which multiple and mature.
Define the term hematopoiesis
the term given to the production of blood cells. `
what happens to bone morrow as peoeple age?
the number of bone caivities containing red marrow decrease but the increased size of the hemopoeitic marrow site found in the vertebare, sternum, ribs, skull and pelvic bones compensates.
what is the name of the stem cells that become commited to production of RBC
erythroblasts,
they undergo 4 miotic divisions eventially producing 16 RBC (erythrocytes). When releasted into the system its called retibulocyte.
What is the principal factor in the regulation of RBC production?
the hormone erythropoietin which is produced by the kidney. This hormone [ ] is ^ when O2 transport to the tissues is impaired, and it causes stem cells to commit to RBC line and increase rate of cell dividsion.
What is the life span of a normal RBC?
how does it die?
120 days,
it is removed by the reticuloendothelial system which is composed of spleen, liver, bone marrow and lymph nodes.
how are RBC’s destroyed in the bone morrow?
How are misshapen cells removed?
special cells called macrophages, they engulf or phacocytize the aging RBC in the bone marrow. the hemoglobin molecule is broken into iron, protoporphyrin and globin.
- by the spleen
When protoporphyrin undergoes further degradation, it eventually becomes what?
What happens to the iron?
bilirubin
reincorporated into newly synthesized heme or is store for future use.,
What is the most useful laboratory test for the evaluation of hematological processes and disorders?
the complete blood count. used as a diagnostic monitoring prognosis test treatment evaluation screening test.
The CBC consists of two parts, what are they and what to they include?
- hemogram
- WBC, RBC, HGB, HCT, (MCV, MCH, MCHC), PLT - second part
- WBC differential and RBC morphology
define leukocytosis and leukpenia
increased number of WBC and decreased number of wbc
name 3 causes of leukocytosis
- acute bacterial infection
- physical stimuli such as heat, cold, pain, sugery, malignancy
- emotional stimuli such as stress
What is leukemia?
elevated WBC count is permanently elevated and progresive
When is leukpnia seen?
with viral or rickettsial infection or with an overwhelming bacterial infection
what is anemia
a decrease in the number of circulating erythrocuts and/or the quality of these cells.
what causes anemia?
- decrease in RBC production or reduction in hemmoglobin level
- an increase in RBC destruction
- dietary insufficiencies
- actual blood loss
What is polycythemia?
increase in RBC
the oxygen-carrying capacity of blood is directly proportional to what?
the hemoglobin concentration rather than the number of RBC.
What causes decreased hemoglobin levels
anemia, hyperthyroidism, liver cirrhosis, severe hemmorhage, hemolutic reaction, and cancer.
When do you see increased hemoglobin level
polycythemia,
pulmonary disorders
congestive heart failyre
What is hematocrit?
is the volume of erythrocytes compared to the colume of whole blood in a sample.
it means to separate blood and is calculated as the height of the packed cells compared to the total height of the specimen after blood is centrifuged then is expressed in a percentage
How are the red blood cell indices (MCV, MCH, and MCHC) calculated?
determined from the same blood sample used for the RBC count, hemoglobin and hematocrit values.
they are used to define cell size and hemoglobin content.
When are microcytic cells seen?
in iron deficiency anemia and thalassemia
When do macrocytes apepar?>
liver disoders, alcoholism, folic acid and Vit 12 deficiencies.
What is MCH?
the average weight of hemoglobin in each individual RBC
What is MCHC?
a measure of the average concentration of hemoglobin in RC.
Define differential
in a blood sample 100 consectutive WBC are taken which contain the 5 types of normal leykocytes and any abN cells are collectected and compared as a percentage. The ration can help determine certain disorders
Define normocytes
normal sized erythrocytes,
they are uniform, circular, homogenous discs.
what are microcysts and macrocytes?
cells smaller than 6 mircons and cells larger than 8 microns.
Define the term Anisocytosis
describe an abnormal variation in cell size.
Define the term poikilocytosis
variation in red blood cells.
define the term schistocytes
cell fragments.
What should be considered by u/w when intepreting the CBC?
- couse of CBC results
- reason the test was done
- age of the results
- whether a dx has been made
- is there a pattern to the results over time?
What part of the CBC numbers should be analyzed with anemia hx?
hemoglobin, MCV and MCH.
Used to classify the anemia as normocytic, microcutic or macrocutic and normochormic of hypochornic
What are nomoccytic and normochromic anemias?
those with normal MCH and MCV values.
1. chronic disease, acute blood loss, and aplastic anemia anemias with decreased MCV and MCH are almost a