Topic 20 - Blood : erythrocytes and platelets (morphology and function)

Question 1

Erythrocytes(red blood cells)

Morphology

Answer 1

Cell shape: maintained by spectrin at internal surface of membrane.
•Non-nucleated and biconcave: dogs, cows, and sheep.
•Shallow concavity: horse and cat.
•Flat: pigs and goats.
•Size: 7 mm the largest (in dogs) 4.1 mm the smallest (in goat)

Question 2

Erythrocytes(red blood cells)
origin
fine structure
lifespan

Answer 2

• red bone marrow
• mature erythrocytes lack nucleus and cell organelles. Contains hemoglobin, some enzymes, and electrolytes in water.
• last 4 months, destroyed in spleen.

Question 3

Erythrocytes(red blood cells)

Abnormalities

Answer 3

• Poikilocytosis: variation in shape (goat, deer)
• Rouleaux formation: erythrocytes adhering to one another, forming chains.
• Howell-Jolly bodies: small, round, pyknotic DNA fragments (nucleic remnants).
• Reticulocyte: immature red blood cells with residual ribosomes

Question 4

Thrombocytes (platlets)

• morphology
• nr
• originates from:
• func:
• blood clotting:

Answer 4

• colorless anucleate corpuscles, thin biconvex discs. Size: 2-3 mm.
• 150.000-300.000/ml
• from megakaryocytes
• provide blood clotting.
• thromboplastin transforms prothrombin into thrombin, and thrombin transforms fibrinogen into fibrin.