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Compact bone is the denser, stronger of the two types of osseous tissue (Figure 6.3.6). It makes up the outer cortex of all bones and is in immediate contact with the periosteum. In long bones, as you move from the outer cortical compact bone to the inner medullary cavity, the bone transitions to spongy bone.
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- Overview
- Evolutionary origin and significance
The two principal components of bone are collagen and calcium phosphate, which distinguish it from other hard tissues such as chitin, enamel, and shell.
What are the major functions of bone tissue?
Bone tissue makes up the individual bones of the skeletons of vertebrates. The other roles of bone include structural support for the mechanical action of soft tissues, protection of soft organs and tissues, provision of a protective site for specialized tissues such as the blood-forming system (bone marrow), and a mineral reservoir.
Do bones contain calcium?
Bone contains 99 percent of the calcium in the body and can behave as an adequate buffer for maintaining a constant level of freely moving calcium in soft tissues, extracellular fluid, and blood.
Why is calcium important for bone health?
Bone is found only in vertebrates, and, among modern vertebrates, it is found only in bony fish and higher classes. Although ancestors of the cyclostomes and elasmobranchs had armoured headcases, which served largely a protective function and appear to have been true bone, modern cyclostomes have only an endoskeleton, or inner skeleton, of 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 efficiency, and their perseverance from the Devonian Period attests to the suitability of their nonbony endoskeleton.
In modern vertebrates, true bone is found only in animals capable of controlling the osmotic and ionic composition of their internal 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 the level of true bone fishes does the composition of the internal body fluids become constant. The mechanisms involved in this regulation are 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 significant. Along with the kidney and the various component glands of the endocrine system, bone 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 are the most obvious features of the modern vertebrate skeleton.
Britannica Quiz
Human Bones Quiz
Oct 30, 2023 · Definition. Bone is a living, rigid tissue of the human body that makes up the body's skeletal system. Structure. Cortical bone - outer layer. Bone tissue (cancellous bone) - inner layers. Medullary canal - contains either red (active) or yellow (inactive) bone marrow. Types of bones.
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Jan 26, 2024 · Bones are composed of two types of tissue. Compact (cortical) bone is a hard outer layer that is dense, strong, and durable. It makes up around 80% of adult bone mass and forms the outer layer of ...
- Bones support the body's structure and protect vital organs, but they also play a key role in blood cell production, the immune system, the storage...
- Following a varied diet with plenty of calcium, getting enough vitamin D, and exercising are important for bone health. Avoiding smoking and limiti...
- Various health problems can affect the bones. Signs of osteoporosis include a loss of height, an increasingly stooped posture, and fractures that h...
Sep 5, 2024 · Ultrastructure of Bone. Bone is a specialised type of connective tissue. It has a unique histological appearance, which enables it to carry out its numerous functions: Haematopoiesis – the formation of blood cells from haematopoietic stem cells found in the bone marrow. Lipid and mineral storage – bone is a reservoir holding adipose tissue ...
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May 13, 2022 · Figure 6.3.1 6.3. 1: Anatomy of a Long Bone.A typical long bone shows the gross anatomical characteristics of bone. The wider section at each end of the bone is called the epiphysis (plural = epiphyses), which is filled with spongy bone. Red marrow fills the spaces in the spongy bone.
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A bone is a rigid organ [1] that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, and enable mobility. Bones come in a variety of shapes and sizes and have complex internal and external ...
