Feb 04, · Bones are made of four main kinds of cells: osteoclasts, osteoblasts, osteocytes, and lining cells. Notice that three of these cell type names start with 'osteo.' This is the Greek word for bone. When you see 'osteo' as part of a word, it lets you know that the word has something to do with bones. Made mostly of collagen, bone is living, growing tissue. Collagen is a protein that provides a soft framework, and calcium phosphate is a mineral that adds strength and hardens the framework. This combination of collagen and calcium makes bone strong and flexible enough to withstand stress.
Bonerigid what are bones made out of tissue consisting of cells embedded in an abundant hard intercellular material. The two principal components of this material, collagen and calcium phosphate, distinguish bone from such other hard tissues as chitinenameland shell. Bone tissue makes up the individual bones of the human skeletal system and pf skeletons of other vertebrates. The functions of bone include 1 structural support for the mechanical action of soft tissues, such as the contraction of muscles and the expansion of lungs, boness protection of soft organs and tissues, as by the skull3 provision of a protective site for specialized tissues such as the blood-forming system bone marrowand 4 a mineral reservoir, whereby the endocrine system regulates the level of calcium and phosphate in the circulating body fluids.
Bone is found only in vertebratesand, among modern vertebrates, it is found only in bony fish and higher classes. Although ancestors of msde cyclostomes and elasmobranchs had armoured headcases, which served largely maade protective function and appear to have been true bone, modern cyclostomes have only an endoskeleton, or inner skeletonof noncalcified cartilage and elasmobranchs a skeleton of calcified cartilage. Although a rigid endoskeleton performs obvious body supportive functions for land-living vertebrates, it is doubtful that bone offered any such mechanical advantage to the teleost bony fish in which it first appeared, for in a supporting aquatic environment great structural rigidity is not essential for maintaining body configuration.
The sharks and rays are superb examples of mechanical engineering efficiencyand their perseverance from the Devonian Period attests to the suitability of their nonbony endoskeleton. If modern vertebrates, true bone is found only in oit capable of controlling the osmotic and ionic composition of their what are bones made out of fluid environment.
Marine invertebrates exhibit interstitial fluid compositions essentially the same as that of the surrounding seawater. Early signs of regulability are seen in cyclostomes and elasmobranchs, but only at or above bpnes level of true bone fishes does the composition of the internal body fluids become constant.
The mechanisms involved in this regulation boens numerous and complex and include both the kidney and the gills. Fresh and marine waters provide abundant calcium but only traces of phosphate; because relatively high levels of phosphate are characteristic of the body fluids of higher vertebrates, it seems likely that a large, readily available internal phosphate reservoir would confer significant independence of external environment on bony vertebrates.
With the emergence of terrestrial forms, the availability of calcium regulation became equally ouh. Along with the kidney whar the various component glands of the endocrine systembone has contributed to development of internal fluid homeostasis —the maintenance of a constant chemical composition.
This was a necessary step for the emergence of terrestrial vertebrates. Furthermore, out of the buoyancy of water, structural rigidity of bone afforded mechanical advantages that mde the most obvious features of the modern gones skeleton. Article Introduction Evolutionary origin and significance Chemical composition and physical properties Bone morphology Four types of cells in bone Vascular supply and circulation Remodeling, growth, and development Bone resorption and renewal Types of bone formation Physiology of bone Calcium and phosphate equilibrium Physiological and mechanical controls Hormonal influences Nutritional influences Show more.
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Aug 04, · The main component of bone is bone matrix, which is a mixture of a fibrous protein called collagen and carbonated hydroxyapatite, an inorganic compound mostly made of calcium and phosphate. The combination of fibrous collagen and crystallized calcium makes bones hard and rigid and adds tensile strength. In children, the ends and edges of bones are mostly flexible cartilage, . Bone, rigid body tissue consisting of cells embedded in an abundant hard intercellular material. Bone tissue makes up the individual bones of the skeletons of vertebrates. Its two principle components are collagen and calcium phosphate.
Bone marrow: the tissue in the middle of bones that creates red and white blood cells Osteoclast: cells in your body that break down bone material in order to reshape it. Osteocyte: a star shaped bone cell with long branching arms that connect it to its neighboring cells. Osteon: tube shaped structure in bones with an open space for blood vessels, veins, and nerves in the center. Platelet: a small cell fragment without a nucleus that helps stop blood the flow of blood when the body is injured.
Have you ever seen fossil remains of dinosaur and ancient human bones in textbooks, television, or in person at a museum? It's easy to look at these and think of bones as dry, dead sticks in your body, but this couldn't be further from the truth. Bones are made of active, living cells that are busy growing, repairing themselves, and communicating with other parts of the body.
Lets take a closer look at what your bones do and how they do it. The skeleton of an adult human is made up of bones of many different shapes and sizes. Newborn babies are actually born with many more bones than this around , but many bones grow together, or fuse, as babies become older.
Some bones are long and thick, like your thigh bones. Others are thin, flat, and wide, like your shoulder blades. The adult human skeleton has bones. Click on the image to see a larger version. Support: Like a house is built around a supportive frame, a strong skeleton is required to support the rest of the human body.
Without bones, it would be difficult for your body to keep its shape and to stand upright. Protection: Bones form a strong layer around some of the organs in your body, helping to keep them safe when you fall down or get hurt. Your rib cage, for example, acts like a shield around your chest to protect important organs inside such as your lungs and heart.
Your brain is another organ that needs a lot of protection. The thick bone layer of your skull protects your brain. For this purpose, being "thick-headed" is a very good thing.
Movement: Many of your bones fit together like the pieces of a puzzle. Each bone has a very specific shape which often matches up with neighboring bones. The place where two bones meet to allow your body to bend is called a joint.
How many different ways can you move your joints? Some bones, like your elbow, fit together like a hinge that lets you bend your arm in one specific direction. Other bones fit together like a ball and socket, such as the joint between your shoulder and arm. This type of joint lets you rotate your shoulder in many directions, or swing it all the way around in a circle like softball pitchers do.
The movement of our bodies is possible because of both joints and muscles. Muscles often attach to two different bones, so that when the muscle flexes and shortens, the bones move. This allows you to bend your elbows and knees, or pick up objects. A skeleton has plenty of joints, but without muscles, there is nothing to pull the bones in different directions. More than half of the bones in your body are actually located in your hands and feet.
These bones are attached to many little muscles that give you very exact control over how you move your fingers and feet. Blood Cell Formation: Did you know that most of the red and white blood cells in your body were created inside of your bones? This is done by a special group of cells called stem cells that are found mostly in the bone marrow, which is the innermost layer of your bones.
Storage: Bones are like a warehouse that stores fat and many important minerals so they are available when your body needs them. These minerals are continuously being recycled through your bones--deposited and then taken out and moved through the bloodstream to get to other parts of your body where they are needed.
Each bone in your body is made up of three main types of bone material: compact bone, spongy bone, and bone marrow. Cross section showing osteons. The large dark spots are passages for blood vessels and nerves. The little black spots are osteocytes. Compact bone is the heaviest, hardest type of bone.
It needs to be very strong as it supports your body and muscles as you walk, run, and move throughout the day. It makes up the outer layer of the bone and also helps protect the more fragile layers inside.
If you were to look at a piece of compact bone without the help of a microscope, it would seem to be completely solid all the way through. If you looked at it through a microscope, however, you would see that it's actually filled with many very tiny passages, or canals, for nerves and blood vessels. Compact bone is made of special cells called osteocytes. These cells are lined up in rings around the canals.
Together, a canal and the osteocytes that surround it are called osteons. Osteons are like thick tubes all going the same direction inside the bone, similar to a bundle of straws with blood vessels, veins, and nerves in the center. Looking at the osteons in bone A under a microscope reveals tube-like osteons B made up of osteocytes C.
These bone cells have long branching arms D which lets them communicate with other cells. Spongy bone is found mostly at the ends of bones and joints. Unlike compact bone that is mostly solid, spongy bone is full of open sections called pores. If you were to look at it in under a microscope, it would look a lot like your kitchen sponge.
Pores are filled with marrow, nerves, and blood vessels that carry cells and nutrients in and out of the bone. Though spongy bone may remind you of a kitchen sponge, this bone is quite solid and hard, and is not squishy at all.
The inside of your bones are filled with a soft tissue called marrow. There are two types of bone marrow: red and yellow. Red bone marrow is where all new red blood cells, white blood cells, and platelets are made. Platelets are small pieces of cells that help you stop bleeding when you get a cut. Red bone marrow is found in the center of flat bones such as your shoulder blades and ribs.
Yellow marrow is made mostly of fat and is found in the hollow centers of long bones, such as the thigh bones. It does not make blood cells or platelets. Both yellow and red bone marrow have many small and large blood vessels and veins running through them to let nutrients and waste in and out of the bone.
When you were born, all of the marrow in your body was red marrow, which made lots and lots of blood cells and platelets to help your body grow bigger. As you got older, more and more of the red marrow was replaced with yellow marrow. The bone marrow of full grown adults is about half red and half yellow. Bones are made of four main kinds of cells: osteoclasts, osteoblasts, osteocytes, and lining cells.
Notice that three of these cell type names start with 'osteo. When you see 'osteo' as part of a word, it lets you know that the word has something to do with bones. Osteoblasts are responsible for making new bone as your body grows.
They also rebuild existing bones when they are broken. The second part of the word, 'blast,' comes from a Greek word that means 'growth. Minerals are then added to osteoid, making it strong and hard.
When osteoblasts are finished making bone, they become either lining cells or osteocytes. Osteocytes are star shaped bone cells most commonly found in compact bone. They are actually old osteoblasts that have stopped making new bone. As osteoblasts build bone, they pile it up around themselves, then get stuck in the center. At this point, they are called osteocytes. Osteocytes have long, branching arms that connect them to neighboring osteocytes.
This lets them exchange minerals and communicate with other cells in the area. Lining cells are very flat bone cells. These cover the outside surface of all bones and are also formed from osteoblasts that have finished creating bone material. These cells play an important role in controlling the movement of molecules in and out of the bone.
Osteoclasts break down and reabsorb existing bone. The second part of the word, 'clast,' comes from the Greek word for 'break,' meaning these cells break down bone material. Osteoclasts are very big and often contain more than one nucleus, which happens when two or more cells get fused together. These cells work as a team with osteoblasts to reshape bones. This might happen for a number of reasons:. It's not completely understood how bone cells in your body are able to work together and stay organized, but pressure and stress on the bone might have something to do with it.
The smallest bone in the human body is called the stirrup bone, located deep inside the ear. It's only about 3 millimeters long in an adult. The longest bone in the human is called the femur, or thigh bone.
It's the bone in your leg that goes from your hip to your knee. In an average adult, it's about 20 inches long. Heller, H.