Ch 14 Blood Flashcards
What is blood tissue composed of?
red cells, white cells and platelets in a fluid matrix called plasma
Where is blood tissue located?
within blood vessels
What is the function of blood tissue?
transport gases, nutrients and wastes
What is a normal blood hematocrit?
45% cells and 55% plasma
What can affect blood volume?
size, changes in fluid and electrolyte compisition, and amount of adipose tissue
What is serum?
plasma minus clotting proteins
What are the formed elenments in blood?
erythrocytes, platelets, leukocytes
What is the normal plasma volume?
40 ml/kg of body weight
What is plasma?
The liquid in which peripheral blood cells are suspended
What is plasma composed of?
water, electrolytes such as Na and Cl (0.9%), 7% plamsa proteins (such as albumin, fibrinogen, globulins), hormones, fats, amino acids, vitamins, carbohydrates, and lipo proteins
What percentage of the total blood volume do erythrocytes occupy?
about 40-45% (30 ml/kg body weight)
What percentage of the total blood volume do leukocytes and platelets ocupy?
about 1-2%
What percentage of the body is blood?
8%
What percent of the blood is plasma?
55%
What percentage of the blood is formed elements?
45%
Breakdown the makeup of plasma into perecentages
7% proteins, 91% water, 2% other solutes
Breakdown the makeup of plasma proteins into percentages
albumins 58%, globulins 38%, fibrinogen 4%
What are the other solutes present in plasma?
ions, nutrients, waste products, gases, regulatory substances
How many platelets are in the formed elements of blood?
250-400 thousand per cubic mm
How man leukocytes are in the formed elements of blood?
5-9 thousand per cubic mm
How may erythrocytes are in the formed elements of blood?
4.2-6.2 million per cubic mm
Breakdown the makeup of leukocytes in percentages
60-70% neutrophils, 20-25% lymphocytes, 3-8% monocytes, 2-4% eosinophils, 0.5-1% basophils
Where are blood cells produced?
in bone marrow
Where do blood cells stem from?
hemocytoblasts into various cell lines based on stimulation from colony stimulating factors
What are bioconcave disks that contain one thrd oxygen carrying hemoglobin by volume?
red blood cells
How is oxyhemoglobin formed?
when oxygen combines with hemoglobin, it’s bright red
What do red blood cells discard during development?
their nuclei
What is the size of a mature human RBC?
~ 7-8 micrometers in diameter
What does the bulk of the cytoplasm of a RBC consist of?
hemoglobin (90-95% dry weight)
In addition to the nucleus, what else does a mature RBC lose?
golgi apparatus, centrioles, ER and most of its mitochondria
Why is a RBC in the shape of a bioconcave disk?
to acheive a maximum surface area to cytoplasmic volume ratio
What shape do RBCs assume in capillaries?
a cup shape
What is a RBC enclosed in?
bilayered cell membrane
What is the purpose of the bilayered cell membrane?
it is flexible and elastic enough to allow the cell to move through capillaries
What purpose do specrtin and actin serve in a RBC?
they are peripheral proteins that have a cytoskeletal function
What is the surface area of a RBC?
~128 square micrometers, so on average a person has ~ 3840 square micrometers of RBC membrane area for respiratory exchange
Describe the structure of hemoglobin
four globular protein subunits which each contain a single heme molecule, a porphyrin rins surrounding a single ion of iron
What is a reticulocyte?
a less mature erythrocyte
What do reticulocytes contain?
residual ribonucleoprotein particles that put a bluish hue to the cell on Romanowsky staining
What is the purpose of methylene blue in reticulocytes?
it can be used to identify the ribosomal reminants in reticlocytes
What is the frequency of reticulocytes?
1-2% of RBCs, after ~1 day in peripheral blood, they’re indistinguishable from mature RBCs
What is the function of erythrocytes?
to provide an environment for the iron containing respiratory pigment heme, which is complexed to 2 alpha and 2 beta globulin chains comprising the hemoglobin molecule
What is the major physiologic role of hemoglobin?
oxygen and CO2 transport
What is the purpose of the enzymes present in erythrocytes?
they participate in the glycolytic and hexose monophosphate biochemical pathways
What is the typical red blood cell count for males
4.6 -6.2 million cells per mm3
What is the typical red blood cell count for females?
4,5-5.1 million cells per mm3
What does the number of RBCs measure?
the blood’s oxygen carrying capacity
What is anisocytosis?
abnormalities in RBCs
What are erythroplastids?
erythrocytes
What are the characteristics of poikilocytes?
crenated, sickling cells
What is the life span of a mature erythrocyte?
~120 days in circulation
What happens to the surface area as a RBC ages?
the surface area decreases relative to cytoplasmic volume resulting in a sphere form which is more rigid and is ultimately trapped in splenic cords
What is the first step in RBC destruction?
with age, RBCs become increasingly fragile and are damaged by passing through narrow capillaries
What is the second step in RBC destruction?
macrophages in the liver and spleen phagocytize damaged RBCs
What is the third step in RBC destruction?
hemoglobin from the decomposed RBCs is converted into heme and globin
What is the fourth step in RBC destruction?
heme is decomposed into iron and biliverdin
What is the fifth step in RBC destruction?
iron is recycled into new hemoglobin or stored in the liver
What is the sixth step in RBC destruction?
some biliverdin is converted into bilirubin
What is the seventh step in RBC destruction?
biliverdin and bilirubin are excreted in bile as bile pigments
What is the first step in RBC production?
in the embryo and fetus, RBC production occurs in the yolk sace, liver and spleen. In adults it’s in red bone marrow
What is the second step in RBC production?
hemocytoblasts give rise to erythroblasts that also reproduce and give rise to many new cells
What is the third step in RBC production?
nuclei are pinched off
What is the fourth step in RBC production?
new RBCS are called reticuloytes at this stage they leave the bone marrow and enter the bloodstream
What is the fifth step in RBC production?
average life span of RBC is ~120 days
What is the sixth step in RBC production?
the total number of RBCs remains relatively constant due to a negative feedback mechanism utilizing the hormone erythropoietin, which is released in response to low oxygen levels detected in the kidneys and liver