Chapter 5: Blood Flashcards
(187 cards)
What is blood?
It is a special type of C.T. That circulates inside blood.
What is blood formed of?
Cells and an extracellular fluid matrix called plasma.
What is the composition of blood?
It is made of 45% blood cells (erythrocytes, leukocytes, and platelets) and 55% plasma.
Examination of the blood using a blood film.
A drop of blood is spread on a glass slide and left to dry in air.
Blood examination using staining
With a neutral stain (Eg. Leishmans stain) formed of a mixture of red acidic stain Eosin and blue basic stain methylene blue dissolved in methyl alcohol (fixative).
Erythros
Red
What are Red blood corpuscles?
Non-nucleated biconcave discs.
RBC’s shape
Top view: rounded.
Side view: biconcave, to increase surface area for the exchange of gases.
What is the reason behind abnormal shapes of the RBC’s?
It is due to changes either in the cell membrane or Hb content. They are more fragile and more prone to hemolysis causing anemia.
What are the types of abnormal shapes?
- Spherocytes: spherical.
- Ovalocytes: oval.
- Sickle cell: crescent.
- Poikilocytes: pear.
RBC’s size
Diameter: 6-9 micrometers in with an average of 7.5 (the median).
Thickness: 2.2 micrometers (edge) and 0.8 (center).
Abnormal sizes of RBC’s
Microcytes: less than 6 micrometers.
Macrocytes: more than 9 micrometers.
Anisocytosis: different sizes.
RBC’s LM
Unstained blood film: appear colored due to Hemoglobin.
Stained blood film: stained with leishmans stain, RBC’s are rounded, non nucleated and acidophilic (hemoglobin is a basic protein), with a pale center (1/3 of the diameter of RBC’s are Normochromic).
RBC rouleaux appearance
- RBC’s may adhere to each other resembling piles of coins.
- This process occurs in slow circulation (abnormal).
- Due to the surface tension caused by their biconcave surface.
- Reversible, no damage to cells.
Erythrocyte sedimentation rate (ESR)
The long chains of RBC’s sediment more easily. This is the mechanism for ESR, which increases non specifically due to inflammation.
RBC’s EM
- No nucleus
- No organelles
- Filled with hemoglobin: appears electron dense and homogeneous.
- Cell membrane is flexible
- Cytoskeleton (actin and spectrin): keeps stability of shape and membrane.
- Glycocalyx includes antigenic sites for blood groups (ABO) and RH factor.
Life span of RBC’s
120 days
Fate of RBC’s
Old RBC’s are phagocytosed by macrophages in the liver, bone marrow, and spleen. It is secreted as bile pigments while iron is reused to form new RBC’s.
Osmotic fragility of RBC’s
RBC’s maintain normal shape in plasma (isontonic solution: OP of 0.9% saline.
Crenation: if placed in hypertonic solution, they shrink and show notches.
Hemolysis: if placed in hypotonic solution, they swell, burst, and leak hemoglobin.
Remaining cell membrane is called Cell ghost.
How are RBC’s counted?
- Hemocytometer.
- Electronic counting instruments.
What is the number of RBC’s?
- Average number of RBC’s: 5 million/mm3
- Adult male: 5-5.5 million/mm3
Stimulators effect of male hormones on the bone marrow. - Adult female: 4.5-5 million/mm3
- Newborns: highest in newborns and decreases gradually.
Abnormalities in number
- Anemia
- Polycythemia
Anemia
Decreased number of RBC’s below 4 million/mm3 (oligocythemia) and/or decreased hemoglobin concentration.
What are types of anemia?
- Pernicious anemia.
- Sickle cell anemia.
- Aplastic anemia.