17 April, 2013
How Are Nutrients Absorbed Into Bones?
Nutrition plays a pivotal role in the development and maintenance of bone health. Bones are highly vascularized, porous organs that receive oxygen and nutrients through a network of pores interconnected by thin channels that are embedded in bones. The efficient transport of nutrients within these microsystems is vital in keeping bones strong and healthy.
Compact bone forms the hard, exterior layer of bone. If you viewed it under a microscope, you would see that it is filled with tiny passages, or canals, for nerves and blood vessels. These blood vessels constantly supply essential nutrients such as calcium, phosphorus, vitamin D, magnesium, potassium, fluoride, protein and several other vitamins and minerals necessary for bone formation and metabolic processes.
Spongy bone is lightweight yet strong, and is found mostly at the ends of bones and joints. It is honeycomb-shaped and filled with open sections called pores that contain bone marrow, nerves and blood vessels transporting nutrients to and from the bone.
How Nutrients Enter Bone
Compact bone is composed of special cells called osteocytes that are lined up in rings around canals. Together they form structures called osteons. These are like thick tubes aligned in the same direction inside the bone, similar to a bundle of straws, with blood vessels located in the center receiving vital nutrients and oxygen while removing waste products. A central canal in each osteon contains blood vessels that branch off and connect to other tiny perforating canals, carrying nutrients that penetrate the compact bone to its outer surface.
Nutrients are transported from the central canal into the rest of the osteon through the lacunar-canalicular systems. Small tunnels, called canaliculi, connect the central canals with pores distributed within the osteon called lacunae. Here is where the osteocytes connect to one another and the central canal to receive nourishment via the canaliculi.
Calcium and Vitamin D are the two most important nutrients for building strong, dense bones when you are young and for maintaining bone density as you age. Vitamin D is required to absorb calcium and without it, you may lose bone mass, lower your bone density and increase your chances of breaking bones as you get older. You should avoid consuming too much protein and sodium in your diet as they are thought to contribute to an increase in calcium excretion and accelerate mineral leaching from bone.
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- Innerbody.com: Haversian System
- Society for Industrial and Applied Mathematics: Transport of Nutrients in Bones
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- Journal of Biomedical Engineering: Experimental Determination of the Permeability in the Lacunar-Canalicular Porosity of Bone
- Docstock.com: Nutrient Transport in Lacunar-Canalicular System of Cortical Bone
- IOP Science: Investigation of Nutrient Transport Mechanisms in the Lacunae-Canaliculi System
- National Institute of Arthritis and Musculoskeletal and Skin Diseases: Calcium and Vitamin D: Important at Every Age
- Jupiterimages/Comstock/Getty Images