Fundamentals of Blood and Red Blood Cells Flashcards
Blood has a cellular and extracellular component.
True or False?d
True
What colour is blood plasma?
Yellow
What % of blood is water?
92%
What do inorganic salts do in blood plasma?
Buffer the pH and contribute in osmotic balance and the regulation of the cell membrane potential
diagram of blood components
Haematocrit
% of red blood cells relative to the total blood volume
Platelet purpose?
essential for blood clotting
Platelets are not really cells but
rather cytoplasmic cell fragments of cellular precursors
Red blood cells have a characteristic shape ——, which allows them to
- “flexible disc”, biconcave shape
- Allows them to travel in vessels and narrow capillaries
- Large surface for gas exchange
Normal haematocrit in men and women
- Men: 46%
- Women: 42%
RBC characteristics
- no nucleus
- reduced number of organelles and cellular membrane structures
- short life span: 120 days in circulation
Older RBCS rupture easily and the debris left is degraded by
macrophages
What % of RBC volume is taken up by haemoglobin?
25%
RBC plasma membrane composition
is asymetrical with mainly negatively charged phospholipids (those with a terminal primary amino group) being located on the inner part of the lipid bilayer
Why is RBC membrane composition important?
for cell signaling communication
Biconcave shape of RBC achieved by?
Via a mesh-like network of the protein spectrum
What is the primary component of RBC cytoskeleton that interacts with cell membrane proteins?
Spectrin
Shape of spectrin?
Filamentous shape
Spectrin gene abnormalities cause
spherical and fragile RBCs
What are platelets released by?
Megakaryocytes
What do platelets contain?
Enzymes that initiate blood clotting
Blood clotting
- when vessels are damaged circulating blood platelets come in contact with collagen fibers, causing the platelets to swell and form a “sticky patch”, which begins the blood clotting cascade
- Clotting relies on inactivated precursor proteins (prothrombin, fibrinogen) that are produced by the liver and circulate in the blood. These are cleaved to thrombin and fibrin respectively, leading to the formation of a blood clot prior to the formation of scar tissue in wound healing.
Automate blood counts
Erythropoiesis
- from birth, the bone marrow is the site of haematopoiesis in humans
- erythropoiesis takes place in the haematopoeitic/red marrows, which is located within trabecular (spongy) bone at the end of long bones
RBC production equation and include numbers
RBC volume/ RBC life span
2250ml/120 days = 18.75 ml/day average production in a healthy adult
Erythropoetin
Reticulocytes
- when haemoglobin synthesis has been completed the erythroblast nucleus, that has been progressively condensing, gets expelled yielding the reticulocyte
- reticulocytes enter vascular circulation and mature in 1-3 days to erythrocytes
Normal levels of reticulocytes in blood circulation?
25-125 x10^9/L
What does an elevated number of reticulocytes indicate?
Active bone marrow response to blood loss or anaemia (compensation)
What cell is this??
Blood films stained with Romanowsky (Giemsa) stain that have an increased number of reticulocytes appear to have a blue tinge. This called polychromasia.
The blue tinge is due to high levels of RNA. As the cells mature towards erythrocytes the RNA is replaced by increased amounts of haemoglobin and the cell colour changes to a pink/red one that’s is characteristic of red blood cells.
HbA/adult haemoglobin structure
- consist of four subunits; two identical alpha chains and two identical beta chains
- four haeme groups bound to each of the subunits
HbF/ fetal haemoglobin structure
- consists of four subunits; two identical alpha chains and two identical gamma chains
- four haeme groups bound to each of the subunits