Blood Tissue Flashcards
How can a histological specimen of blood be prepared?
We can’t prepare blood like other tissue samples, so a blood smear is taken instead.
A drop of blood is put onto a slide, another slide is put in contact with the first, forming an angle of 30-45o. This is then put into contact with the blood drop, which will spread along the edge of the slide. Then the slide is pushed to ‘smear’ this drop over the slide.
If done correctly, a monolayer of blood over the slide will be obtained. This is then dried and stained.
Describe the shape of red blood cells.
They have a peculiar shape - forms a ring with almost a ‘hole’ in the middle. This is just a depression in the center of the cell.
Biconcave shape - thicker at the periphery and thinner in centre.
Describe the main features of red blood cells.
Not true cells as no nucleus or cytoplasmic organelles, only membrane and cytoskeleton.
Well-structured PM.
Formed in bone marrow and circulating to live about 4 months, they are destroyed in the liver and spleen.
Why are the central parts of red blood cells less stained?
Less cytoplasm present in the middle, much more hemoglobin on the edges which can bind more histological dyes compared to the middle.
Therefore the central part of red blood cells are less coloured than the periphery.
What is hemoglobin (give structure)?
A protein formed by 4 polypeptide chains (2 alpha and 2 beta) and heme groups containing Fe.
Binding of O to hemoglobin is reversible as it needs to be released.
Every RBC can contain up to 250 million hemoglobin molecules.
How is fetal hemoglobin different from adults?
Fetal hemoglobin is different from adult, as tension of O is lower for embryos. Therefore globin needs to have higher affinity for O.
Alpha hemoglobins always present. But gamma chains are present in fetal life as they have higher affinity for O. This is then replaced by red blood cells containing beta globins.
Describe the condition jaundice.
The replacement of gamma chains is responsible for physiological Jaundice in infants.
This is when there is massive destruction at the level of liver of red blood cells and the release and processing of hemoglobin with the accumulation of the catabolic products which gives the baby a yellow colour to the skin and especially the eyes.
If exchange between red blood cells containing different globins occurs suddenly, then usually the newborns are exposed to UV light to reduce jaundice.
Where is carbonic anhydrase contained?
Carbonic anhydrase is contained at the C terminals of one of the transmembrane proteins present in the PM of the red blood cells, called the Band 3 proteins.
Describe how CO2 is converted in the red blood cell.
In peripheral tissues, there’s production of CO2, which is converted by carbonic anhydrase together with water into HCO3- and H+.
This is released through the antiport into the plasma and taken up at the level of the lungs to convert back into CO2 and H2O to be exhaled at the level of the lungs.
Break down the % of CO2 present in various forms in the blood.
23% bound to hemoglobin.
70% in the form of HCO3- (bicarbonate ions) in the plasma.
7% free in the plasma.
How does the shape of red blood cells contribute to its function?
The biconcave shape is essential to its function as it increases surface to volume ratio.
How is the shape of red blood cells maintained?
Shape maintained by a highly specialized cytoskeleton underneath the PM, which confers to the cells elasticity.
Band 3 protein connected with globular protein called Ankyrin, which is connected to another filamentous protein called spectrin. Spectrin forms filaments interconnected the PM as well as actin filaments.
This structure is fundamental to maintaining shape and distortion of structure without the cell rupturing.
What happens to the cell if put into a hypertonic/hypotonic solution?
When put into a hyper/hypotonic solution, it will either expand or shrink due to concentration gradient of ions.
This can be used to study the cells.
Which part of the red blood cell do pathological conditions usually affect?
Pathological conditions can cause changes to membranes of RBCs to form different shapes.
What is hemolysis?
Most pathological conditions undergo hemolysis, which is a process through which the aged RBCs are destroyed.
When RBS age they lose elasticity, which remains trapped in the spleen capillaries and is eliminated there by macrophages.
During ageing, transmembrane proteins can break and change conformation. This is recognised by macrophages at the level of the liver and destroyed.
How can pathological conditions lead to hemolysis?
There can be pathological conditions that lead to this. This can be both acquired and hereditary conditions.
Instead of having a deformable sphere, they can have non-elastic spheres. So when they get into the microcirculation, they break and release their contents.
Describe what would happen if there are primary defects in spectrin and or ankyrin.
Both lead to a spectrin deficiency, which leads to a decreased protein density of the skeletal monolayer.
Parts of the lipid bilayer not supported by the skeleton are therefore released in the form of microvesicles.
Membrane surface area decreases - microspherocytosis.
The whole cell deformability decreases and is trapped in the splenic microcirculation.
What is G6PD?
G6PD is an important enzyme in the pentose phosphate pathway.
What is the function of G6PD?
G6PD is important for the production of NADPH which is an important reducing agent.
Describe a pathology related to G6PD.
A pathology of G6PD deficiency where women normally carry the disease, and men can inherit this disease.
This is very severe and leads to deaths if not recognized immediately.
What is anemia?
Decreased concentration of hemoglobin in the blood (less than 125 mg/ml men and 115 mg/ml in women).
- Decreased production of Hb/RBCs.
- Increased hemolysis of RBCs.
What is hemoglobinopathies?
Sickle cell anemia, point mutation in the hemoglobin beta chain gene (DNA: adenine replaced by thymine) that causes substitution for glutamine.
What is the order of the % of each type of white blood cell?
Neutrophil Lymphocyte Monocytes Eosinophils Basophils
What happens to red blood cells during hemoglobinopathies?
When RBC releases ?? in the periphery tissues, the hemoglobin binds together to form long chains that make the cell stiff, resulting in the formation of sickle structure.
They are very fragile so are prone to hemolysis.
