{"id":1844,"date":"2014-10-24T04:56:04","date_gmt":"2014-10-24T04:56:04","guid":{"rendered":"https:\/\/courses.candelalearning.com\/apvccs\/?post_type=chapter&#038;p=1844"},"modified":"2016-09-18T11:35:09","modified_gmt":"2016-09-18T11:35:09","slug":"bone-tissue-and-the-skeletal-system","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/chapter\/bone-tissue-and-the-skeletal-system\/","title":{"raw":"Bone Tissue and the Skeletal System","rendered":"Bone Tissue and the Skeletal System"},"content":{"raw":"<div>\r\n<h1><img style=\"font-size: 14px;line-height: 1.5em\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/18\/2014\/07\/19181203\/600_Child_Looking_at_Bones.jpg\" alt=\"This photo shows a boy looking at a museum exhibit that contains two fossilized crocodile skeletons embedded within a large boulder. The skull, spine and forelimbs of one of the crocodiles are visible.\" width=\"600\" \/><\/h1>\r\n<\/div>\r\n<div id=\"m46290\">\r\n<div id=\"m46290-fig-ch06_00_01\" title=\"Figure\u00a06.1.\u00a0Child Looking at Bones\"><address><strong>Figure\u00a05.1.\u00a0Child Looking at Bones<\/strong><\/address><address>Bone is a living tissue. Unlike the bones of a fossil made inert by a process of mineralization, a child\u2019s bones will continue to grow and develop while contributing to the support and function of other body systems. (credit: James Emery)<\/address><address>\u00a0<\/address><\/div>\r\n<h2>Introduction<\/h2>\r\nBones make good fossils. While the soft tissue of a once living organism will decay and fall away over time, bone tissue will, under the right conditions, undergo a process of mineralization, effectively turning the bone to stone. A well-preserved fossil skeleton can give us a good sense of the size and shape of an organism, just as your skeleton helps to define your size and shape. Unlike a fossil skeleton, however, your skeleton is a structure of living tissue that grows, repairs, and renews itself. The bones within it are dynamic and complex organs that serve a number of important functions, including some necessary to maintain homeostasis.\r\n\r\n<\/div>\r\n<div title=\"6.1.\u00a0The Functions of the Skeletal System\" xml:lang=\"en\">\r\n<div>\r\n<div>\r\n<h2 id=\"m46341\">The Functions of the Skeletal System<\/h2>\r\n<\/div>\r\n<\/div>\r\n<strong><em>Bone<\/em><\/strong><a id=\"id642625\"><\/a>, or\u00a0<strong><em>osseous tissue<\/em><\/strong><a id=\"id642639\"><\/a>, is a hard, dense connective tissue that forms most of the adult skeleton, the support structure of the body. In the areas of the skeleton where bones move (for example, the ribcage and joints),\u00a0<strong><em>cartilage<\/em><\/strong><a id=\"id642654\"><\/a>, a semi-rigid form of connective tissue, provides flexibility and smooth surfaces for movement. The\u00a0<strong><em>skeletal system<\/em><\/strong><a id=\"id642669\"><\/a>\u00a0is the body system composed of bones and cartilage and performs the following critical functions for the human body:\r\n<div>\r\n<ul>\r\n \t<li>supports the body<\/li>\r\n \t<li>facilitates movement<\/li>\r\n \t<li>protects internal organs<\/li>\r\n \t<li>produces blood cells<\/li>\r\n \t<li>stores and releases minerals and fat<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div title=\"Support, Movement, and Protection\">\r\n<div>\r\n<h3 id=\"m46341-fs-id1828191\">Support, Movement, and Protection<\/h3>\r\n<\/div>\r\nThe most apparent functions of the skeletal system are the gross functions\u2014those visible by observation. Simply by looking at a person, you can see how the bones support, facilitate movement, and protect the human body.\r\n\r\nJust as the steel beams of a building provide a scaffold to support its weight, the bones and cartilage of your skeletal system compose the scaffold that supports the rest of your body. Without the skeletal system, you would be a limp mass of organs, muscle, and skin.\r\n\r\nBones also facilitate movement by serving as points of attachment for your muscles. While some bones only serve as a support for the muscles, others also transmit the forces produced when your muscles contract. From a mechanical point of view, bones act as levers and joints serve as fulcrums (<a title=\"Figure\u00a06.2.\u00a0Bones Support Movement\" href=\"#m46341-fig-ch06_01_01\">Figure\u00a05.2<\/a>). Unless a muscle spans a joint and contracts, a bone is not going to move. For information on the interaction of the skeletal and muscular systems, that is, the musculoskeletal system, seek additional content.\r\n<div id=\"m46341-fig-ch06_01_01\" title=\"Figure\u00a06.2.\u00a0Bones Support Movement\">\r\n<div>\r\n<div><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/18\/2014\/07\/19181206\/617_Bone_Support_Movement.jpg\" alt=\"This photo shows a man exercising on a leg press machine at a gym.\" width=\"290\" \/><\/div>\r\n<\/div>\r\n<address><strong>Figure\u00a05.2.\u00a0Bones Support Movement<\/strong><\/address><address>Bones act as levers when muscles span a joint and contract. (credit: Benjamin J. DeLong)<\/address><address>\u00a0<\/address><\/div>\r\nBones also protect internal organs from injury by covering or surrounding them. For example, your ribs protect your lungs and heart, the bones of your vertebral column (spine) protect your spinal cord, and the bones of your cranium (skull) protect your brain (<a title=\"Figure\u00a06.3.\u00a0Bones Protect Brain\" href=\"#m46341-fig-ch06_01_02\">Figure\u00a05.3<\/a>).\r\n<div id=\"m46341-fig-ch06_01_02\" title=\"Figure\u00a06.3.\u00a0Bones Protect Brain\">\r\n<div>\r\n<div><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/18\/2014\/07\/19181207\/618_Bones_Protect_Brain.jpg\" alt=\"This illustration shows how the cranium protects and surrounds the brain. Only the outline of the cranium is visible, which is made transparent to show how the brain sits in the skull. There is a small amount of space between the brain and the cranium but the top and sides of the brain are completely protected by the cranial bones. The bottom of the brain extends below the cranial bones, with the base of the cerebellum seated just above the roof of the mouth. The medulla extends to the bottom of the skull where it meets with the spinal cord.\" width=\"250\" \/><\/div>\r\n<\/div>\r\n<address><strong>Figure\u00a05.3.\u00a0Bones Protect Brain<\/strong><\/address><address>The cranium completely surrounds and protects the brain from non-traumatic injury.<\/address><address>\u00a0<\/address>\r\n<div><\/div>\r\n<h3>Mineral Storage, Energy Storage, and Hematopoiesis<\/h3>\r\n<\/div>\r\n<\/div>\r\n<div title=\"Mineral Storage, Energy Storage, and Hematopoiesis\">\r\n\r\nOn a metabolic level, bone tissue performs several critical functions. For one, the bone matrix acts as a reservoir for a number of minerals important to the functioning of the body, especially calcium, and potassium. These minerals, incorporated into bone tissue, can be released back into the bloodstream to maintain levels needed to support physiological processes. Calcium ions, for example, are essential for muscle contractions and controlling the flow of other ions involved in the transmission of nerve impulses.\r\n\r\nBone also serves as a site for fat storage and blood cell production. The softer connective tissue that fills the interior of most bone is referred to as bone marrow (<a title=\"Figure\u00a06.5.\u00a0Head of Femur Showing Red and Yellow Marrow\" href=\"#m46341-fig-ch06_01_04\">Figure\u00a05.5<\/a>). There are two types of bone marrow: yellow marrow and red marrow.\u00a0<strong><em>Yellow marrow<\/em><\/strong><a id=\"id643012\"><\/a>\u00a0contains adipose tissue; the triglycerides stored in the adipocytes of the tissue can serve as a source of energy.\u00a0<strong><em>Red marrow<\/em><\/strong><a id=\"id643026\"><\/a>\u00a0is where\u00a0<strong><em>hematopoiesis<\/em><\/strong><a id=\"id643040\"><\/a>\u2014the production of blood cells\u2014takes place. Red blood cells, white blood cells, and platelets are all produced in the red marrow.\r\n<div id=\"m46341-fig-ch06_01_04\" title=\"Figure\u00a06.5.\u00a0Head of Femur Showing Red and Yellow Marrow\">\r\n<div>\r\n<div><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/18\/2014\/07\/19181210\/619_Red_and_Yellow_Bone_Marrow.jpg\" alt=\"This photo shows the head of the femur detached from the rest of the bone. The compact bone at the surface of the head has been removed to show the spongy bone beneath. Rather than being solid, like the compact bone, the spongy bone is mesh like with many open spaces, giving it the appearance of a sponge. A circle of yellow marrow is located at the exact center of the spongy bone. The red marrow surrounds the yellow marrow, occupying most of the interior space of the head.\" width=\"380\" \/><\/div>\r\n<\/div>\r\n<address><strong>Figure\u00a05.5.\u00a0Head of Femur Showing Red and Yellow Marrow<\/strong><\/address><address>The head of the femur contains both yellow and red marrow. Yellow marrow stores fat. Red marrow is responsible for hematopoiesis. (credit: modification of work by \u201cstevenfruitsmaak\u201d\/Wikimedia Commons)<\/address><\/div>\r\n<\/div>\r\n<\/div>","rendered":"<div>\n<h1><img decoding=\"async\" style=\"font-size: 14px;line-height: 1.5em\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/18\/2014\/07\/19181203\/600_Child_Looking_at_Bones.jpg\" alt=\"This photo shows a boy looking at a museum exhibit that contains two fossilized crocodile skeletons embedded within a large boulder. The skull, spine and forelimbs of one of the crocodiles are visible.\" width=\"600\" \/><\/h1>\n<\/div>\n<div id=\"m46290\">\n<div id=\"m46290-fig-ch06_00_01\" title=\"Figure\u00a06.1.\u00a0Child Looking at Bones\">\n<address><strong>Figure\u00a05.1.\u00a0Child Looking at Bones<\/strong><\/address>\n<address>Bone is a living tissue. Unlike the bones of a fossil made inert by a process of mineralization, a child\u2019s bones will continue to grow and develop while contributing to the support and function of other body systems. (credit: James Emery)<\/address>\n<address>\u00a0<\/address>\n<\/div>\n<h2>Introduction<\/h2>\n<p>Bones make good fossils. While the soft tissue of a once living organism will decay and fall away over time, bone tissue will, under the right conditions, undergo a process of mineralization, effectively turning the bone to stone. A well-preserved fossil skeleton can give us a good sense of the size and shape of an organism, just as your skeleton helps to define your size and shape. Unlike a fossil skeleton, however, your skeleton is a structure of living tissue that grows, repairs, and renews itself. The bones within it are dynamic and complex organs that serve a number of important functions, including some necessary to maintain homeostasis.<\/p>\n<\/div>\n<div title=\"6.1.\u00a0The Functions of the Skeletal System\" xml:lang=\"en\">\n<div>\n<div>\n<h2 id=\"m46341\">The Functions of the Skeletal System<\/h2>\n<\/div>\n<\/div>\n<p><strong><em>Bone<\/em><\/strong><a id=\"id642625\"><\/a>, or\u00a0<strong><em>osseous tissue<\/em><\/strong><a id=\"id642639\"><\/a>, is a hard, dense connective tissue that forms most of the adult skeleton, the support structure of the body. In the areas of the skeleton where bones move (for example, the ribcage and joints),\u00a0<strong><em>cartilage<\/em><\/strong><a id=\"id642654\"><\/a>, a semi-rigid form of connective tissue, provides flexibility and smooth surfaces for movement. The\u00a0<strong><em>skeletal system<\/em><\/strong><a id=\"id642669\"><\/a>\u00a0is the body system composed of bones and cartilage and performs the following critical functions for the human body:<\/p>\n<div>\n<ul>\n<li>supports the body<\/li>\n<li>facilitates movement<\/li>\n<li>protects internal organs<\/li>\n<li>produces blood cells<\/li>\n<li>stores and releases minerals and fat<\/li>\n<\/ul>\n<\/div>\n<div title=\"Support, Movement, and Protection\">\n<div>\n<h3 id=\"m46341-fs-id1828191\">Support, Movement, and Protection<\/h3>\n<\/div>\n<p>The most apparent functions of the skeletal system are the gross functions\u2014those visible by observation. Simply by looking at a person, you can see how the bones support, facilitate movement, and protect the human body.<\/p>\n<p>Just as the steel beams of a building provide a scaffold to support its weight, the bones and cartilage of your skeletal system compose the scaffold that supports the rest of your body. Without the skeletal system, you would be a limp mass of organs, muscle, and skin.<\/p>\n<p>Bones also facilitate movement by serving as points of attachment for your muscles. While some bones only serve as a support for the muscles, others also transmit the forces produced when your muscles contract. From a mechanical point of view, bones act as levers and joints serve as fulcrums (<a title=\"Figure\u00a06.2.\u00a0Bones Support Movement\" href=\"#m46341-fig-ch06_01_01\">Figure\u00a05.2<\/a>). Unless a muscle spans a joint and contracts, a bone is not going to move. For information on the interaction of the skeletal and muscular systems, that is, the musculoskeletal system, seek additional content.<\/p>\n<div id=\"m46341-fig-ch06_01_01\" title=\"Figure\u00a06.2.\u00a0Bones Support Movement\">\n<div>\n<div><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/18\/2014\/07\/19181206\/617_Bone_Support_Movement.jpg\" alt=\"This photo shows a man exercising on a leg press machine at a gym.\" width=\"290\" \/><\/div>\n<\/div>\n<address><strong>Figure\u00a05.2.\u00a0Bones Support Movement<\/strong><\/address>\n<address>Bones act as levers when muscles span a joint and contract. (credit: Benjamin J. DeLong)<\/address>\n<address>\u00a0<\/address>\n<\/div>\n<p>Bones also protect internal organs from injury by covering or surrounding them. For example, your ribs protect your lungs and heart, the bones of your vertebral column (spine) protect your spinal cord, and the bones of your cranium (skull) protect your brain (<a title=\"Figure\u00a06.3.\u00a0Bones Protect Brain\" href=\"#m46341-fig-ch06_01_02\">Figure\u00a05.3<\/a>).<\/p>\n<div id=\"m46341-fig-ch06_01_02\" title=\"Figure\u00a06.3.\u00a0Bones Protect Brain\">\n<div>\n<div><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/18\/2014\/07\/19181207\/618_Bones_Protect_Brain.jpg\" alt=\"This illustration shows how the cranium protects and surrounds the brain. Only the outline of the cranium is visible, which is made transparent to show how the brain sits in the skull. There is a small amount of space between the brain and the cranium but the top and sides of the brain are completely protected by the cranial bones. The bottom of the brain extends below the cranial bones, with the base of the cerebellum seated just above the roof of the mouth. The medulla extends to the bottom of the skull where it meets with the spinal cord.\" width=\"250\" \/><\/div>\n<\/div>\n<address><strong>Figure\u00a05.3.\u00a0Bones Protect Brain<\/strong><\/address>\n<address>The cranium completely surrounds and protects the brain from non-traumatic injury.<\/address>\n<address>\u00a0<\/address>\n<div><\/div>\n<h3>Mineral Storage, Energy Storage, and Hematopoiesis<\/h3>\n<\/div>\n<\/div>\n<div title=\"Mineral Storage, Energy Storage, and Hematopoiesis\">\n<p>On a metabolic level, bone tissue performs several critical functions. For one, the bone matrix acts as a reservoir for a number of minerals important to the functioning of the body, especially calcium, and potassium. These minerals, incorporated into bone tissue, can be released back into the bloodstream to maintain levels needed to support physiological processes. Calcium ions, for example, are essential for muscle contractions and controlling the flow of other ions involved in the transmission of nerve impulses.<\/p>\n<p>Bone also serves as a site for fat storage and blood cell production. The softer connective tissue that fills the interior of most bone is referred to as bone marrow (<a title=\"Figure\u00a06.5.\u00a0Head of Femur Showing Red and Yellow Marrow\" href=\"#m46341-fig-ch06_01_04\">Figure\u00a05.5<\/a>). There are two types of bone marrow: yellow marrow and red marrow.\u00a0<strong><em>Yellow marrow<\/em><\/strong><a id=\"id643012\"><\/a>\u00a0contains adipose tissue; the triglycerides stored in the adipocytes of the tissue can serve as a source of energy.\u00a0<strong><em>Red marrow<\/em><\/strong><a id=\"id643026\"><\/a>\u00a0is where\u00a0<strong><em>hematopoiesis<\/em><\/strong><a id=\"id643040\"><\/a>\u2014the production of blood cells\u2014takes place. Red blood cells, white blood cells, and platelets are all produced in the red marrow.<\/p>\n<div id=\"m46341-fig-ch06_01_04\" title=\"Figure\u00a06.5.\u00a0Head of Femur Showing Red and Yellow Marrow\">\n<div>\n<div><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/18\/2014\/07\/19181210\/619_Red_and_Yellow_Bone_Marrow.jpg\" alt=\"This photo shows the head of the femur detached from the rest of the bone. The compact bone at the surface of the head has been removed to show the spongy bone beneath. Rather than being solid, like the compact bone, the spongy bone is mesh like with many open spaces, giving it the appearance of a sponge. A circle of yellow marrow is located at the exact center of the spongy bone. The red marrow surrounds the yellow marrow, occupying most of the interior space of the head.\" width=\"380\" \/><\/div>\n<\/div>\n<address><strong>Figure\u00a05.5.\u00a0Head of Femur Showing Red and Yellow Marrow<\/strong><\/address>\n<address>The head of the femur contains both yellow and red marrow. Yellow marrow stores fat. Red marrow is responsible for hematopoiesis. (credit: modification of work by \u201cstevenfruitsmaak\u201d\/Wikimedia Commons)<\/address>\n<\/div>\n<\/div>\n<\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-1844\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Chapter 6. <strong>Authored by<\/strong>: OpenStax College. <strong>Provided by<\/strong>: Rice University. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@7.1@7.1.\">http:\/\/cnx.org\/contents\/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@7.1@7.1.<\/a>. <strong>Project<\/strong>: Anatomy &amp; Physiology. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Download for free at http:\/\/cnx.org\/content\/col11496\/latest\/. <\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":74,"menu_order":1,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Chapter 6\",\"author\":\"OpenStax College\",\"organization\":\"Rice University\",\"url\":\"http:\/\/cnx.org\/contents\/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@7.1@7.1.\",\"project\":\"Anatomy & Physiology\",\"license\":\"cc-by\",\"license_terms\":\"Download for free at http:\/\/cnx.org\/content\/col11496\/latest\/. \"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1844","chapter","type-chapter","status-publish","hentry"],"part":1841,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/pressbooks\/v2\/chapters\/1844","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/wp\/v2\/users\/74"}],"version-history":[{"count":5,"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/pressbooks\/v2\/chapters\/1844\/revisions"}],"predecessor-version":[{"id":5159,"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/pressbooks\/v2\/chapters\/1844\/revisions\/5159"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/pressbooks\/v2\/parts\/1841"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/pressbooks\/v2\/chapters\/1844\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/wp\/v2\/media?parent=1844"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/pressbooks\/v2\/chapter-type?post=1844"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/wp\/v2\/contributor?post=1844"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/atd-herkimer-biologyofaging\/wp-json\/wp\/v2\/license?post=1844"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}