Histology 2: Blood

Question 1

What is the composition of blood?

Answer 1

55% plasma, 45% formed elements (cellular components)

Question 2

What does the buffy coat consist of?

Answer 2

Concentrated white blood cells and platelets

Question 3

What are four features of Erythrocytes (red blood cells)

Answer 3

• Live for 120 days before becoming too deformed to effectively carry oxygen
• Born in the bone marrow (red bone marrow needs iron, globin, vitamin B12 and erythropoietin to make red blood cells)
• Leaves bone marrow through small blood vessels → capillaries → arterioles/venules → blood vessels of increasing diameter
• Undergoes death and components are phagocytosed and recycled. Usually occurs in the spleen, but can occur in the liver.
• 7-9 microns in diameter
• Biconcave dish shape
• Enucleated (RBCs undergo extrusion and lose their nucleus to maximize haemoglobin and O2 carrying potential)

Question 4

What are four features of Eosinophils?

Answer 4

• Bi-lobed nucleus
• Orange/red lysosomal granules containing hydrolytic enzymes and histaminase
• Number increase in parasitic infections, chronic infections and allergic reactions
• Exhibit a sluggish amoeboid movement through capillary walls into tissue spaces (using pseudopodia extrusions)
• Phagocytose antibody-antigen complexes
• Life span of 8-12 days

Question 5

What are four features of basophils?

Answer 5

• 1% of all WBC
• Very numerous granules (containing histamine and heparin) that almost obscure the nucleus
• Have a role in allergy control
• Life span of a few hours to a few days

Question 6

What are four features of neutrophils?

Answer 6

• Multi-lobed nucleus
• Most numerous of all WBC
• Very phagocytic and ingest bacterial particulate matter such as carbon by using its amoeboid action
• Characterized by multi-lobed nucleus and granules of alkaline phosphatase and bactericidal proteins
• Life span of 6 hours – a few days

Question 7

What are four features of monocytes?

Answer 7

• Very large cells with kidney shaped nucleus
• Relatively clear cytoplasm containing a few lysosomal granules
• Can pass from blood through capillary walls into tissue spaces and loose connective tissue
• A monocyte that enters tissue are called macrophages (name changes depending on tissue)
• Life span of months

Question 8

What are four features of lymphocytes?

Answer 8

• Most numerous of non-granular WBCs. 20-30% of all circulating WBC in the body
• Nucleus fills almost the whole cell, thin ring of cytoplasm containing a few granules
• Can mount an immune response by direct cellular attack or production of antibodies
• Life span of hours-years