Structure And Function Of Bone Marrow Pdf
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- Bone Marrow
- Bone Marrow: Structure and Function
- Bones: All you need to know
- Bone Structure and Function
Bones are more than just the scaffolding that holds the body together. Bones come in all shapes and sizes and have many roles. In this article, we explain their function, what they are made of, and the types of cells involved. Bones have many functions. They support the body structurally, protect our vital organs, and allow us to move.
Also, they provide an environment for bone marrow , where the blood cells are created, and they act as a storage area for minerals, particularly calcium. At birth, we have around soft bones.
As we grow, some of these fuse. Once we reach adulthood, we have bones. The largest bone in the human body is the thighbone or femur, and the smallest is the stapes in the middle ear, which are just 3 millimeters mm long. Bones are mostly made of the protein collagen , which forms a soft framework. The mineral calcium phosphate hardens this framework, giving it strength. Bones have an internal structure similar to a honeycomb, which makes them rigid yet relatively light. Compact cortical bone: A hard outer layer that is dense, strong, and durable.
It makes up around 80 percent of adult bone mass. Cancellous trabecular or spongy bone: This consists of a network of trabeculae or rod-like structures.
It is lighter, less dense, and more flexible than compact bone. Bones are not a static tissue but need to be constantly maintained and remodeled. There are three main cell types involved in this process. Osteoblasts: These are responsible for making new bone and repairing older bone. Osteoblasts produce a protein mixture called osteoid, which is mineralized and becomes bone.
They also manufacture hormones, including prostaglandins. Osteocytes: These are inactive osteoblasts that have become trapped in the bone that they have created. They maintain connections to other osteocytes and osteoblasts. They are important for communication within bone tissue. Osteoclasts: These are large cells with more than one nucleus.
Their job is to break down bone. They release enzymes and acids to dissolve minerals in bone and digest them. This process is called resorption. Osteoclasts help remodel injured bones and create pathways for nerves and blood vessels to travel through.
The marrow is responsible for making around 2 million red blood cells every second. It also produces lymphocytes or the white blood cells involved in the immune response. Bones are essentially living cells embedded in a mineral-based organic matrix. This extracellular matrix is made of:. Inorganic components , including hydroxyapatite and other salts, such as calcium and phosphate. Collagen gives bone its tensile strength, namely the resistance to being pulled apart.
Hydroxyapatite gives the bones compressive strength or resistance to being compressed. Bones provide a frame to support the body. Muscles, tendons, and ligaments attach to bones. Without anchoring to bones, muscles could not move the body. For instance, the skull protects the brain, and the ribs protect the heart and lungs. Cancellous bone produces red blood cells, platelets, and white blood cells. Also, defective and old red blood cells are destroyed in bone marrow.
Storing minerals: Bones act as a reserve for minerals, particularly calcium and phosphorous. Detoxification: Bones can absorb heavy metals and other toxic elements from the blood. Endocrine function: Bones release hormones that act on the kidneys and influence blood sugar regulation and fat deposition. Calcium balance: Bones can raise or reduce calcium in the blood by forming bone, or breaking it down in a process called resorption. Long bones: These are mostly compacted bone with little marrow and include most of the bones in the limbs.
These bones tend to support weight and help movement. Short bones: Only a thin layer of compact bone, these include bones of the wrist and ankle.
Flat bones: Usually bones that are thin and curved. They consist of two outer layers of compact bone and an inner layer of spongy bone. Flat bones include most of the bones of the skull and the sternum or breastbone. They tend to have a protective role. Sesamoid bones: These are embedded in tendons, such as the patella or kneecap.
They protect tendons from wear and stress. Irregular bones: As their name implies, these are bones that do not fit into the first four categories and are an unusual shape. They include the bones of the spine and pelvis. They are often protecting organs or tissues. Remodeling allows the body to fix damaged sections, reshape the skeleton during growth, and regulate calcium levels.
If one part of the skeleton is put under increased stress over time, for instance, during sport or exercise, the sections of bone under most pressure will become thicker in response. Remodeling is under the control of several hormones, including parathyroid hormone, calcitonin, vitamin D , estrogen in women, and testosterone in men.
Osteoporosis is a bone disease where there is a reduction in bone mineral density. This increases the risk of fractures occurring. Osteoporosis is most common in women after the menopause. However, it can happen in premenopausal women and men. Osteoporosis occurs either when removal or resorption of bone happens too quickly, new bone is formed too slowly, or for both reasons.
It can be caused by having inadequate calcium, a vitamin D deficiency, consuming excessive alcohol, or smoking tobacco. Although they get less attention than other body parts, bones are more than just a protective scaffold on which the human body is built.
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Bones: All you need to know. Medically reviewed by William Morrison, M. The structure of bones Bone cells Types of bone Bone remodeling What is osteoporosis? In a nutshell Bones are more than just the scaffolding that holds the body together. The structure of bones. Share on Pinterest. Bone cells. Share on Pinterest Electron microscope image of trabecular bone x magnification. Image credit: Sbertazzo. Types of bone. Bone remodeling.
Share on Pinterest Bone is constantly under construction. What is osteoporosis? In a nutshell. Resilience in the age of global crises: How can we cultivate it? Study reveals dietary factors associated with mental health. Related Coverage. Natural ways to potentially boost HGH.
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Bone Marrow: Structure and Function
Bone marrow is found in the medullary cavities — the centres of bones. The bone marrow is where circulating blood cells are produced — a process known as haematopoiesis. Bone marrow undergoing haematopoiesis is coloured red due to the presence of red blood cells, whereas bone marrow that is not undergoing haematopoiesis is yellow. The red marrow consists of long trabeculae beam-like structures within a sponge-like reticular framework. Spaces around this framework are filled with fat cells, stromal fibroblasts and blood cell precursors.
Bone, the material that makes vertebrates distinct from other animals, has evolved over several hundred million years to become a remarkable tissue. Bone is a material that has the same strength as cast iron, but achieves this while remaining as light as wood. The front leg of a horse can withstand the loads generated while this pound animal travels at 30 miles per hour. The upper arm is able to keep birds aloft through entire migrations, sometimes over 10, miles without landing. The antlers of deer, used as weapons in territorial clashes with other deer, undergo tremendous impacts without fracturing, ready to fight another day. In addition to its mechanical functions, the bone is a reservoir for minerals a "metabolic" function. It is very important to keep the blood level of calcium within a narrow range.
Bones: All you need to know
Bone marrow is a semi-solid tissue found within the spongy or cancellous portions of bones. In adult humans, bone marrow is primarily located in the ribs , vertebrae , sternum , and bones of the pelvis. Human marrow produces approximately billion blood cells per day, which join the systemic circulation via permeable vasculature sinusoids within the medullary cavity. Bone marrow transplants can be conducted to treat severe diseases of the bone marrow, including certain forms of cancer such as leukemia. Several types of stem cells are related to bone marrow.
Bone tissue is continuously remodeled through the concerted actions of bone cells, which include bone resorption by osteoclasts and bone formation by osteoblasts, whereas osteocytes act as mechanosensors and orchestrators of the bone remodeling process. This process is under the control of local e. An imbalance between bone resorption and formation can result in bone diseases including osteoporosis. Recently, it has been recognized that, during bone remodeling, there are an intricate communication among bone cells.
The bones of the skeletal system serve many important functions for the body, from giving your body support to allowing you to move. They also play an important role in blood cell production and fat storage.
Bone Structure and Function
Bone marrow is the soft, spongy tissue that is located in the medullary cavities centers of certain large bones. Healthy bone marrow is an essential part of the body, as it contains stem cells that produce blood cells and the cells that make up the immune system. The stem cells contained in the bone marrow can mature into several different kinds of cells, each of which has its own vital functions within the body. There are two types of bone marrow — red bone marrow myeloid tissue and yellow bone marrow fatty tissue.
From birth to early adolescence, the majority of our bone marrow is red marrow. As we grow and mature, increasing amounts of red marrow are replaced by yellow marrow. Bone marrow is separated into a vascular section and non-vascular sections. The major function of bone marrow is to generate blood cells. Hematopoietic stem cells , found in red marrow, are responsible for the production of blood cells. Red bone marrow contains hematopoietic stem cells that produce two other types of stem cells: myeloid stem cells and lymphoid stem cells. These cells develop into red blood cells, white blood cells, or platelets.
through the blood to assure a sufficient stem cell pool size in each bone marrow “sub-unit”). It should be recalled that the bone marrow functions as a physiological.
Yellow bone marrow
Bone marrow is a spongy substance found in the center of the bones. It manufactures bone marrow stem cells and other substances, which in turn produce blood cells. Each type of blood cell made by the bone marrow has an important job. Three very important types of white blood cells are essential to the proper functioning of the body's immune system, which fights infection:. Another source of bone marrow stem cells is the blood that circulates in the veins and arteries of all normal people. These stem cells are known as peripheral blood stem cells PBSC. Patients recovering from chemotherapy and healthy people who are treated with certain drugs that stimulate the growth of the bone marrow have relatively large numbers of PBSC in their blood.
Bones are more than just the scaffolding that holds the body together.
Michael Reese Hospital Chicago. This article is only available in the PDF format. Download the PDF to view the article, as well as its associated figures and tables. This is a well-written, up-to-date, concise text of bone marrow morphology structure and physiology function.
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