RBCS

Question 1

describe the shape of RBCs

Answer 1

biconcave disc shaped terminally differentiated structures , with thick periphery of 2.6 and thin center of 0.8

Question 2

describe the shape of RBCs in slow circulation in small vessels or blood smear

Answer 2

adhere to each other like a pile of coins forming rouleaux appearance which isn’t permanent ( why ) . this rouleax appearance occurs due to high surface tension .

Question 3

causes of biconcave appearance are :

Answer 3

1. molecular structure of the cell membrane .
2. colloidal Hb complex inside cells : a change in chemical composition of Hb filling the RBCs can change their shape .

Question 4

illustrate abnormal shapes of RBCs

Answer 4

1. crenation : RBCs in hypertonic solution (2% NaCl ) become shrunken ( smaller with notched outline ) due to loss of water .
2. spherocytosis : RBCs in hypotonic solution ( distilled water ) first become swell then spherical and rupture leaving remnant of cell membrane called ghosts .
3. poikilocytosis : abnormal shape of RBCs in certain diseases as in sickle cell anemia ( cell appear as sickle or crescent)

Question 5

illustrate the normal and abnormal size of RBCs

Answer 5

normal: diametre range 6-9 with mean 7.5
abnormal: microcyte< 6
macrocyte >9
great variation in diameter is called an isocytosis

Question 6

a blood film stained with Leishman stain may show :

Answer 6

1. normochromic RBCs : normal pale center with normal amount of Hb
2. hypochromic : less amount of Hb than normal

Question 7

normal RBCs are non……….enclosed …….. filled with ……and lacking ……

Answer 7

nucleated - sacs -Hb - organelles.

Question 8

energy requirement are met by …….

Answer 8

1. soluble enzymes for glycolysis .
2. hexose monophosphates shunt which produce ATP

Question 9

RBCs are surrounded by ……
most of the membrane proteins are ……
they include ……

Answer 9

lipoprotein cell membrane
integral membrane proteins
ion channel ( band 3 protein - glycophorin A )

Question 10

outer surface covered by ……..

Answer 10

carbohydrate rich glycocalyx containing glycosylated extracellular domain of the integral protein .

Question 11

inner surface associated with….

Answer 11

several peripheral cytoskeleton proteins e.g, spectrin , actin , ankyrin

Question 12

importance of cytoskeleton

Answer 12

stabilizes the membrane
maintain biconcavity of RBCs
provide cell flexibility required for passage through the capillaries

Question 13

histological adaptational characters:

Answer 13

1.cytoskeleton meshwork reinforces erythrocytes’ membrane and determine the shape of erythrocytes
2. biconcave surface gives very high surface to volume ratio for gas exchange
3. absence of nucleus and more organelles give more space for Hb
4. RBCs have no mitochondria , they contain enzymes for glycolysis needed for anaerobic respiration

Question 14

hereditary spherocytosis cause and morphology

Answer 14

cause : abnormal arrangement of the cytoskeleton of the RBCs ( spectrin , ankyrin )
morphology : RBCs become sphere shaped , fragile and easily destroyed leading to hemolytic anemia