Interstitial lamellae fill in between osteons. Circumferential Lamellae - Layers of bone matrix that go all the way around the bone. Each osteon consists of concentric layers, or lamellae , of compact bone tissue that surround a central canal, the haversian canal. The haversian canal contains the bone's blood supplies. Near the surface of the compact bone , the lamellae are arranged parallel to the surface; these are called circumferential lamellae.
What is the structure of a bone? Basic Bone Structure. Bones are organs composed of hard living tissue providing structural support to the body — it's scaffolding. It is a hard matrix of calcium salts deposited around protein fibers. Minerals make bone rigid and proteins collagen provide strength and elasticity. What are bone cells called? Bone is composed of four different cell types; osteoblasts, osteocytes, osteoclasts and bone lining cells.
Osteoblasts, bone lining cells and osteoclasts are present on bone surfaces and are derived from local mesenchymal cells called progenitor cells. What is the function of spongy bone? Spongy bone, also called cancellous or trabecular bone, provides structural support and facilitates movement of the joints and limbs.
Spongy bone is light and porous and found in most parts of the body and in other bones that do not typically endure large volumes of mechanical stress. What are the 5 main bone types? There are five types of bones in the skeleton: flat, long, short, irregular, and sesamoid. Let's go through each type and see examples. What is the function of lamella? Grana function in the light reactions of photosynthesis.
Lamella: A sheet like membrane found within a chloroplast of an autotrophic cell. They act as a type of wall at which chloroplasts can be fixed within, achieving the maximum light possible. Figure 1. The inner layer of bones consists of spongy bone tissue. The small dark ovals in the osteon represent the living osteocytes. Whereas compact bone tissue forms the outer layer of all bones, spongy bone or cancellous bone forms the inner layer of all bones.
Spongy bone tissue does not contain osteons that constitute compact bone tissue. Instead, it consists of trabeculae , which are lamellae that are arranged as rods or plates. Red bone marrow is found between the trabuculae.
Blood vessels within this tissue deliver nutrients to osteocytes and remove waste. The red bone marrow of the femur and the interior of other large bones, such as the ilium, forms blood cells. Figure 2. Trabeculae in spongy bone are arranged such that one side of the bone bears tension and the other withstands compression.
Spongy bone reduces the density of bone and allows the ends of long bones to compress as the result of stresses applied to the bone. Spongy bone is prominent in areas of bones that are not heavily stressed or where stresses arrive from many directions. The epiphyses of bones, such as the neck of the femur, are subject to stress from many directions. Imagine laying a heavy framed picture flat on the floor.
You could hold up one side of the picture with a toothpick if the toothpick was perpendicular to the floor and the picture. Now drill a hole and stick the toothpick into the wall to hang up the picture. In this case, the function of the toothpick is to transmit the downward pressure of the picture to the wall. The force on the picture is straight down to the floor, but the force on the toothpick is both the picture wire pulling down and the bottom of the hole in the wall pushing up.
The toothpick will break off right at the wall. The neck of the femur is horizontal like the toothpick in the wall. The weight of the body pushes it down near the joint, but the vertical diaphysis of the femur pushes it up at the other end.
Due to the strong nature of compact bone, compared to spongy bone, it is the preferred tissue for strength. Spongy bone is used for more active functions of the bones, including blood cell production and ion exchange. What is the structure of compact bone? Compact bone consists of closely packed osteons or haversian systems. The osteon consists of a central canal called the osteonic haversian canal, which is surrounded by concentric rings lamellae of matrix. Between the rings of matrix, the bone cells osteocytes are located in spaces called lacunae.
What are the functions of haversian systems? The haversian canals surround blood vessels and nerve cells throughout bones and communicate with bone cells contained in spaces within the dense bone matrix called lacunae through connections called canaliculi.
What makes compact bone? Compact bone, also called cortical bone, dense bone in which the bony matrix is solidly filled with organic ground substance and inorganic salts, leaving only tiny spaces lacunae that contain the osteocytes, or bone cells.
Both types are found in most bones. What is the end of the bone called? The end of the long bone is the epiphysis and the shaft is the diaphysis. When a human finishes growing these parts fuse together. The outside of the flat bone consists of a layer of connective tissue called the periosteum.
How is Trabeculae formed? Formation of woven bone As the spicules continue to grow, they fuse with adjacent spicules and this results in the formation of trabeculae. When osteoblasts become trapped in the matrix they secrete, they differentiate into osteocytes. As growth continues, trabeculae become interconnected and woven bone is formed. Where do you find compact bone?
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