The osteocytes in spongy bone are nourished by blood vessels of the periosteum that penetrate spongy bone and blood that circulates in the marrow cavities.
As the blood passes through the marrow cavities, it is collected by veins, which then pass out of the bone through the foramina. In addition to the blood vessels, nerves follow the same paths into the bone where they tend to concentrate in the more metabolically active regions of the bone. The nerves sense pain, and it appears the nerves also play roles in regulating blood supplies and in bone growth, hence their concentrations in metabolically active sites of the bone.
Watch this video to see the microscopic features of a bone. A hollow medullary cavity filled with yellow marrow runs the length of the diaphysis of a long bone.
The walls of the diaphysis are compact bone. The epiphyses, which are wider sections at each end of a long bone, are filled with spongy bone and red marrow. The epiphyseal plate, a layer of hyaline cartilage, is replaced by osseous tissue as the organ grows in length.
The medullary cavity has a delicate membranous lining called the endosteum. The outer surface of bone, except in regions covered with articular cartilage, is covered with a fibrous membrane called the periosteum. Flat bones consist of two layers of compact bone surrounding a layer of spongy bone. Bone markings depend on the function and location of bones.
Articulations are places where two bones meet. Projections stick out from the surface of the bone and provide attachment points for tendons and ligaments. Holes are openings or depressions in the bones. Bone matrix consists of collagen fibers and organic ground substance, primarily hydroxyapatite formed from calcium salts. Osteogenic cells develop into osteoblasts. Osteoblasts are cells that make new bone. They become osteocytes, the cells of mature bone, when they get trapped in the matrix.
Osteoclasts engage in bone resorption. Compact bone is dense and composed of osteons, while spongy bone is less dense and made up of trabeculae. Blood vessels and nerves enter the bone through the nutrient foramina to nourish and innervate bones. Which of the following are only found in cancellous bone? The area of a bone where the nutrient foramen passes forms what kind of bone marking?
If the articular cartilage at the end of one of your long bones were to degenerate, what symptoms do you think you would experience? If the articular cartilage at the end of one of your long bones were to deteriorate, which is actually what happens in osteoarthritis, you would experience joint pain at the end of that bone and limitation of motion at that joint because there would be no cartilage to reduce friction between adjacent bones and there would be no cartilage to act as a shock absorber.
In what ways is the structural makeup of compact and spongy bone well suited to their respective functions? The densely packed concentric rings of matrix in compact bone are ideal for resisting compressive forces, which is the function of compact bone. The open spaces of the trabeculated network of spongy bone allow spongy bone to support shifts in weight distribution, which is the function of spongy bone.
Skip to content Bone Tissue and the Skeletal System. Learning Objectives By the end of this section, you will be able to: Identify the anatomical features of a bone Define and list examples of bone markings Describe the histology of bone tissue Compare and contrast compact and spongy bone Identify the structures that compose compact and spongy bone Describe how bones are nourished and innervated.
Gross Anatomy of Bone The structure of a long bone allows for the best visualization of all of the parts of a bone Figure. Anatomy of a Long Bone. A typical long bone shows the gross anatomical characteristics of bone. The periosteum forms the outer surface of bone, and the endosteum lines the medullary cavity. The surface features of bones depend on their function, location, attachment of ligaments and tendons, or the penetration of blood vessels and nerves.
Bone Cells. Four types of cells are found within bone tissue. Osteogenic cells are undifferentiated and develop into osteoblasts. When osteoblasts get trapped within the calcified matrix, their structure and function changes, and they become osteocytes. Osteoclasts develop from monocytes and macrophages and differ in appearance from other bone cells. Compact and Spongy Bone The differences between compact and spongy bone are best explored via their histology.
Compact Bone Compact bone is the denser, stronger of the two types of bone tissue Figure. Diagram of Compact Bone. Spongy Cancellous Bone Like compact bone, spongy bone , also known as cancellous bone, contains osteocytes housed in lacunae, but they are not arranged in concentric circles.
Muscles, ligaments, and tendons may attach to the periosteum. Bones are classified by their shape. They may be long like the femur and forearm , short like the wrist and ankle , flat like the skull , or irregular like the spine. Primarily, they are referred to as long or short.
There are bones in the human skeleton. The bones include:. This includes the head, facial, hyoid, auditory, trunk, ribs, and sternum. This includes arms, shoulders, wrists, hands, legs, hips, ankles, and feet. Bones give shape and support for the body. They give protection to some organs.
Bone also serves as a storage site for minerals. And soft bone marrow in the center of certain bones is where blood cells are formed and stored. This type of blood cell is within the bone. Skip to content Main Navigation Search. Dictionary Articles Tutorials Biology Forum. Soils Nutrients in the soil are essential to the proper growth of a land plant.
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