Skeletal System
The skeletal system is consists of your bones. Without the skeleton you would basically be a pile of skin, muscle and organs. The skeleton is also vital for movement, as muscles pull and move bones that they are joined to, permitting movement.
You may be surprised to learn that bones have other vital functions. Inside bone is a substance called red bone marrow, which produces both red (for oxygen transport) and white blood cells (to fight infection). The skeletal system also contains a store of calcium and help controls blood sugar and fat, by releasing a hormone called osteocalcin. Yellow bone marrow is used to store energy in the form of fatty lipids. In these ways, the skeletal system can be linked to the respiratory system, the immune system, the circulatory system and the endocrine system!
There are 4 types of bone cell:
Osteoclast (word means bone-broken in Greek): large cells with many nuclei, which break bone down. This is important so that bone can be maintained – like removing damaged brick on a wall, to then replace it with new brick. Osteoclasts latch on to bone and then release enzymes (chemicals that speed up and allow some reactions to occur) that allow calcium and phosphate from the bone to be taken up by the osteoclast. These are then released by the cell and into the blood. Osteoclasts are regulated by hormones (from the endocrine system) such as parathyroid hormone (from parathyroid gland), calcitonin (from thyroid gland) and interleukin 6 (from t cells and macrophages of the immune system).
Osteoblast (word means bone-germ in Greek): are smaller than osteoclasts, have one nucleus and work to form bone. They produce a substance that is composed of collagen, called osteoid, which they work within to enrich the area with calcium phosphate. This hardens to form new bone, with the osteoblast inside, which then is termed an osteocyte. Other osteoblasts also fix to the surface of the new bone, to protect it and become lining cells. Osteoblasts enrich bone with minerals such as copper, sodium and zinc.
Osteocyte (word means bone-cell in Greek): as mentioned above, osteoblasts become osteocytes once it has made a chamber of bone around itself (called a lacuna). Osteocytes are linked to neighbouring osteocytes by channels called canaliculi, so that nutrients and waste can be exchanged. Osteocytes are involved with breaking down bone and also remaking bone, typically in response to stresses caused by physical activity, to make it stronger. It is thought that osteocytes have a role in controlling osteoclasts and osteoblasts.
Lining cells (word means… well…what it says!): as mentioned above, lining cells are osteoblasts which have become flattened and cover the bone to protect it from harmful chemicals. Lining cells are connected to each other by gap junctions and like osteocytes they exchange nutrients and waste through channels called canaliculi. Lining cells release calcium into the blood, if levels get low.
You may be surprised to learn that bones have other vital functions. Inside bone is a substance called red bone marrow, which produces both red (for oxygen transport) and white blood cells (to fight infection). The skeletal system also contains a store of calcium and help controls blood sugar and fat, by releasing a hormone called osteocalcin. Yellow bone marrow is used to store energy in the form of fatty lipids. In these ways, the skeletal system can be linked to the respiratory system, the immune system, the circulatory system and the endocrine system!
There are 4 types of bone cell:
Osteoclast (word means bone-broken in Greek): large cells with many nuclei, which break bone down. This is important so that bone can be maintained – like removing damaged brick on a wall, to then replace it with new brick. Osteoclasts latch on to bone and then release enzymes (chemicals that speed up and allow some reactions to occur) that allow calcium and phosphate from the bone to be taken up by the osteoclast. These are then released by the cell and into the blood. Osteoclasts are regulated by hormones (from the endocrine system) such as parathyroid hormone (from parathyroid gland), calcitonin (from thyroid gland) and interleukin 6 (from t cells and macrophages of the immune system).
Osteoblast (word means bone-germ in Greek): are smaller than osteoclasts, have one nucleus and work to form bone. They produce a substance that is composed of collagen, called osteoid, which they work within to enrich the area with calcium phosphate. This hardens to form new bone, with the osteoblast inside, which then is termed an osteocyte. Other osteoblasts also fix to the surface of the new bone, to protect it and become lining cells. Osteoblasts enrich bone with minerals such as copper, sodium and zinc.
Osteocyte (word means bone-cell in Greek): as mentioned above, osteoblasts become osteocytes once it has made a chamber of bone around itself (called a lacuna). Osteocytes are linked to neighbouring osteocytes by channels called canaliculi, so that nutrients and waste can be exchanged. Osteocytes are involved with breaking down bone and also remaking bone, typically in response to stresses caused by physical activity, to make it stronger. It is thought that osteocytes have a role in controlling osteoclasts and osteoblasts.
Lining cells (word means… well…what it says!): as mentioned above, lining cells are osteoblasts which have become flattened and cover the bone to protect it from harmful chemicals. Lining cells are connected to each other by gap junctions and like osteocytes they exchange nutrients and waste through channels called canaliculi. Lining cells release calcium into the blood, if levels get low.