blood cell types L5

Question 1

Plasma

Answer 1

blood without cell components

Question 2

Serum

Answer 2

plasma without clotting factors and fibrinogen

Question 3

Hematocrit

Answer 3

Rapid assessment of blood composition
percentage of the blood volume that is composed of red blood cells (RBCs)

Question 4

Bone Marrow

Answer 4

Children: bone marrow of most bones generate blood cells

Adult: Majority of blood cell production from bones of chest, base of the skull, spinal vertebrae and upper potions of limbs

Bone marrow of an adult weighs almost as much as the liver

Blood cells derived from hematopoietic stem cells (undifferentiated cells capable of producing the precursors of different blood cells)

Question 5

Platelets

Answer 5

Known as thrombocytes or platelets

Anucleate (no nucleus) cell fragment

Discoid fragments (shaped like a discus)

Progenitor cells: megakaryocytes, cells with multi-lobed nucleus

Question 6

Thrombopoietin

Answer 6

Thrombopoietin (c-mpl ligand), a hormone mainly produced by the liver that stimulates platelet production
Thrombopoietin (TPO) binds to platelets in circulation
If platelet counts are normal then free TPO level is low.
If platelet counts are low then free TPO level in serum is high so platelet production is stimulated.
Therefore, platelet levels regulate platelet production from megakaryocytes

Question 7

Platelet plug formation

Answer 7

1. Platelet Adhesion
   Site of blood vessel damage
   Endothelial cell layer disruption
   Exposure of the sub-endothelial layer and connective tissue collagen fibres
   Platelets adhere to collagen primarily via a second protein von Willebrand factor (vWF)
   vWF forms a bridge between the damaged blood vessel and the circulating platelet
   Triggers platelet activation and the secretion of signalling molecules
   Adenosine Diphosphate (ADP) and serotonin
2. Platelet Activation

Platelet activation leads to shape change, activation of the fibrinogen receptor (GP IIb/IIIa) and the release of electron dense granules (ADP and serotonin).

Activation of nearby platelets and fibrinogen receptor activation

3. Platelet Aggregation

Fibrinogen is a blood protein that plays an important role in platelet aggregation and blood clotting
Fibrinogen forms bridges between activated platelets by binding to the activated fibrinogen receptor
This forms the platelet plug
The platelet plug can completely seal small areas of damage to blood vessels
Activated platelets also release chemical mediators to trigger vasoconstriction

Question 8

Erythrocytes

Answer 8

Red Blood cells (RBCs)
Transport O2 and CO2
Contain haemoglobin (Hb)
Biconcave - high surface area to volume ratio
Membrane polysaccharides/proteins confers an individuals blood group

Question 9

Erythrocyte production

Answer 9

The production of erythrocytes is called erythropoiesis

Erythropoiesis occurs in the bone marrow

The production of erythrocytes (RBCs) is controlled by a hormone called erythropoietin (EPO)
produced by kidney (also liver but lesser extent)
controls erythrocyte (RBC) production in the bone marrow

Erythropoietin usually secreted in small amounts
Controlled by oxygen delivery to the kidneys
Decreased oxygen levels trigger EPO production
High altitude
Lung disease
Insufficient pumping of the heart
Anaemia

Question 10

Anemia

Answer 10

Decrease in the total number of erythrocytes (each having normal level of Hb)
Decreased concentration Hb per erythrocyte
Or a combination of both ie. a decreased number of erythrocytes and a decrease in Hb levels

Question 11

Granulocytes

Answer 11

Densely stained granules in cytoplasm

Can be called polymorphonuclear leukocytes due to the nucleus shape

Three types:- neutrophils, basophils and eosinophils

Neutrophil: phagocytic cells and important component of innate immunity

Eosinophil: important in defense to parasitic infections

Basophil: circulating immune cells that contain histamine, pathogenesis of allergic reactions, inflammation

Question 12

Innate Immunity

Answer 12

First line of defense against pathogens

Question 13

Adaptive Immunity

Answer 13

highly specific to the particular pathogen (antigen specific)
longer lasting protection

Question 14

Monocytes

Answer 14

Largest of the blood cells
Irregular, often lobed nucleus
Fine granules
Monocytes differentiate into macrophages

Question 15

Macrophages

Answer 15

Innate Immunity
detection, phagocytosis and destruction of bacteria
Macrophages can also present antigens to T cells and trigger inflammation by release signalling molecules called cytokines
Macrophage polarization into different subtypes

Question 16

Lymphocytes

Answer 16

Large nucleus, small numbers of granules containing lysosomal enzymes
B cell and plasma cell - antibody production
T helper cells - regulate antibody production, regulate & mediate immune reactions
Natural Killer (NK) cells - lyse target cells