Blood: blood groups and components

Question 1

Describe the constituents of blood

Answer 1

• blood is composed of a clear, watery fluid called the plasma
• the plasma makes up 55% of the blood volume
  -plasma contains electrolytes, nutrients, plasma proteins and enzymes
• erythrocytes make up 45% of the cell fraction
• less than 1% of thrombocytes and leucocytes are in the blood

Question 2

Give a detailed description of erythrocytes

Answer 2

• they have a biconcave disk shape and a flexible membrane which allows them to squeeze through capillaries also increase surface area for gas exchange

-lack nucleus and organelle which allows more room for haemoglobin

-carries some carbon dioxide
-Hb is found in the cytosol of the cell

-membrane is made of certain glycolipids these are antigens responsible for differences in blood groups

-haemoglobin is a protein which carries oxygen

-live for 120 days due to wear and tear

Question 3

give a detailed description of leucocytes

Answer 3

-function in defence and immunity, identifies foreign or abnormal material and destroys it

-have a nucleus
-plasma membranes have major-histocompatibility antigens used for immunological purposes

different classifications of wbc:
granular (eosinophils, basophils and neutrophils) filled with granules

granular (lymphyocytes and monocytes) they develop into macrophages in tissues

Question 4

outline the procedure of erythropoiesis

Answer 4

• The process starts in the bone marrow as a pluripotent stem cell
• pluripotent stem cells differentiates into pro erythroblast
• synthesis of haemoglobin and ejection of the nucleus takes place =reticulocyte

-reticulocyte matures over 1-2 days after leaving the bone marrow
- erythrocyte if the matured cell

Question 5

what is erythropoiesis triggered by?

Answer 5

-juxtaglomerular cells of kidney detect low o2 levels
- secretion of erythropoietin into blood
-inc of maturation process speed in the bone marrow
-more rbc’s produced

Question 6

what two types of stem cells do pluripotent stem cells differentiate into?

Answer 6

differentiate into bone marrow as:

-myeloid stem cell
-lymphoid stem cell

Question 7

Give a detailed description of thrombocytes

Answer 7

-formed from fragments of megakaryocytes under the influence of thrombopoietin in red bone marrow
- disk shaped
-life span of 8-11days
- no nucleus
- cytoplasm is packed with granules containing substances essential for blood clotting, which causes haemostasis (cessation of bleeding).