06-Dec-15
BONE MARROW
Prof Dr Waqas Hameed
What would happen if you had no Bones
• Floppy as a Bean Bag
• Could you stand up ?
• Could you walk ?
• Puddle of skin and guts on the floor
Bone Marrow - Types
• Red Marrow
• At birth all marrow is red
• Yellow marrow
• Due to deposition of fat
• ADULTS
• End of Long Bones
• Skull bones
• Rib cage
• Sternum
• Ileac crest
Red Marrow
Yellow Marrow
• Birth → 4th yr
All bones contain Red Marrow
• 10 → 14 yrs
patch of yellow marrow appears in distal ends
• By 20 yrs
red marrow replaced by yellow marrow except
upper end of femur & humerus
• By 70 yrs
half the ribs & sternum – yellow marrow
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Functions of Bone Marrow
Haematopoietic (hemopoietic) function
Destruction of RBC’s
Storage function
- Iron in the form of Ferritin
Reticulo-endothelial function
Immunological function
Osteogenic function
Connective tissue function
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Blood:
Tissue consisting of
variety of cells
suspended in a fluid
medium called
Plasma
Red blood cells
Total Blood vol:
5 litres
Depends upon:
ERYTHROCYTES
•Age
•Weight
•Height
•Sex
Red Blood Cells ( ERYTHROCYTES )
• Simplest Cell – Biconcave cell
• No Nucleus
• Count
♂
5 million/cmm
5 × 106/µL
5 × 1012/Liter
♀
4.8 million/cmm
4.8 × 106/µL
4.8 × 1012/Liter
Shape
Biconcave /
Dumble shaped
Surface area –
helps in gas exchange
Biconcave
Protein –
Spectrin in cytoskeleton
H2O content
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Size
7 – 8 µm ( 7.2 µm )
thickness – 2.2 µm
Surface Area
120 µm2
Volume
85 fl (1 fl = 10-15 l)
Life Span
120 days
Normal Levels Types and Functions of
Hemoglobin
ß
97%
2%
<1%
Composition
• Water
60 – 70%
• Solids
30 – 40%
- Hemoglobin
- Other proteins
- Inorganic substances
Physiological Variations in RBC
count
Diurnal Variation
- about 5% in 24 hrs
- ↓ in sleep / ↑ in evening
Muscular Exercise
- temporary ↑
Altitude
- ↑ at high altitude
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Physiological Variations in RBC count
contd.
↑ External Temperature
SPECTRIN Protein
↓ O2 Tension of Arterial Blood
Adrenaline inj. & Excitement
Absence of Nucleus - Advantages
• Gives RBC biconcave shape
• Cell vol. change without increasing tension on
cell memb.
• Can withstand change in osmotic pressure &
resist hemolysis
• 7.5% ↑ in vol. in Venous blood
• Easy ‘Folding’ – when passing through capillaries
• Hemoglobin distributed in thin layer
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