Animals have a firm and rigid network called the skeleton. This framework supports the weight of the animal’s body. The skeleton tone provides a surface for muscle attachment and also gives the body its shape. There are two types so skeletons; endoskeleton and exoskeleton. The exoskeleton is found in arthropods. The endoskeleton is a characteristic feature of all vertebrates. Endoskeleton is made up of living tissues that are the bones. There are different types of bones in the animal’s body. They contain mineral salts (calcium phosphate), specialized cells, and collagen fibers. Bones are classified according to their shapes; flats bones, long bones, sutural bones irregular bones, sesamoid bones, and short bones.
Flat bones are broad and found in areas where wide muscle attachment and extensive organ protection is required. They include; scapulae, ribs, the roof of the skull, and sternum. Long bones are long and have a shaft and two ends. These bones are filled with red bone marrow. They include; tibia, ulna, radius, and femur. Sutural bones vary in size; are small, flat, and irregular in shape. Mostly they are found between the flat bones of the skull. Irregular bones have complex shapes, flat, short, and have ridged surfaces. They include hip bones, most skull bones, and the vertebrae. Sesamoid bones fat, small and have a sesame shape. They grow inside tendons and can be found near joints such as at the knees, feet, and hands.
Functions and Importance of Bones in the Body
Movement
Bones are joined together by bones. various types of joints allow varying degrees of movement. movable joints are found at various parts of the body. The joint is filled with a fluid known as synovial fluid for lubrication. Synovial joints are the ball and socket joint and the hinge joints. In the ball and socket joint, one bone has a round head while the other has a cavity where the head of the first bone fits easily and moves freely. This makes the bones to be able to move in all directions (Muscolino, 2014). Examples of this kind of joints include the hip and shoulder joints. In the hinge joint, the cavities in one bone permit the condyles of another bone to fit and articulate allowing movement in one direction. These joints are found at the phalanges, elbow, and knees. Bones are held together by a ligament to restrain the movement of bones and thus restricting movement. Bones transmit the force of muscle contractions to bring about movement. Muscles are attached to bones through tendons. Bones act as a lever when the muscles contract while the joints form a pivot point. Changes in the joints, bones, and joints affect movement (Muscolino, 2014). Bones and muscles interactions contribute to an extensive range of movements that the body makes. The sternum in flying vertebrates is modified to form a keel that provides a large surface area for attachment of pectoral muscles. This enhances efficient flying.
Protection
Flat bones protect the internal organs from mechanical injury by covering them. These bones provide shield-like protection and also provide surface area for muscle attachment. The skull is made up of many flat bones joined together to form the cranium which encloses and protects the brain. The skull is segmented into the brain cage and the facial bones. The brain cage protects the brain and stocks the middle and inner ear structures. The facial bones form the nasal cavity, orbits, support the teeth of both jaws, and encloses the eyeballs. Adults have the mandible which is the moveable bone of the skull (Rommel, Pabst & McLellan, 2009). The rib- cage encloses the thoracic cavity protecting the delicate organs such as the heart and lungs. The cage provides a protective cage of partial rigid bones between the lungs and the heart and around the lungs. Due to his weight, the rib cage is efficient in providing protection, allowing inspiration and expiration, and enabling the chest wall to move. The sternum also protects the thoracic cavity. The sternum also protects the organs in the thoracic cavity. The vertebral column protects the head, neck, body, and spinal cord (Rommel et al., 2009). The vertebral column extends from the neck to the tail. The cervical vertebrae protect the head from whiplash damage that damages the connecting tissue and the bone. This damage is brought about by snapping the head back at a high speed. The lumbar vertebrae protect the spinal cord from injuries resulting from the stress of lifting and carrying heavy things. The sacral vertebrae also protect the spinal cord by bearing the weight of the body and spreading it to the legs through the pelvic girdle. The pelvic girdle protects the bladder, reproductive organs in females, and part of the intestines.
Support
Bones shape and provide support to the bodies. Although the bones are light, they are strong enough to support the body’s weight. Long bones located in the appendicular skeleton provides a framework to support the body weight. This helps in facilitating movement. These bones include; the girdles and the limbs attached to them. Bones in the lower limbs include; the fibula, tibia, femur, phalanges, and metatarsals. Those in the upper limbs include the radius, ulna, humerus, metacarpals, and phalanges (Zelzer, Blitz, Killian & Thomopoulos, 2014). The lower limbs support the body when we stand. Therefore, the points, bones, and muscles translate to the lower limb to offer stable support. Locomotor activities require necessitates the lower limb so as to support the weight of the arms, head, and trunk as the body is pushed forward. As the limbs swing forward, one limb supports the other and thus creating a repetitive movement pattern. Upper body weight is supported by the large bones of the limbs. Short bones support the ankles and the limbs and thus providing support and hence facilitating movement (Muscolino, 2014). The cervical vertebrae support the head and thus allowing head movement; turning and nodding. The lumbar vertebrae have a large and broad centrum to support the weight of the body to withstand the strain of movement (Zelzer et al., 2014). At the lower end of the thoracic cavity, the sternum and the rib-cage offer surfaces for attachment of the back and the abdomen. This helps in supporting the ribs and the ribs and thus bringing about movements of the rib-cage during breathing in mammals.
Production of Red Blood Cells
Lungs receive oxygen through inhalation, blood then collects this oxygen and transports it throughout the body. As blood is being transported to the heart, it collects carbon (iv) oxide and takes it] back to the lungs. The red blood cells are manufactured in the bone marrow and carry oxygen from the lungs. The bone marrow is found in the cancellous bone which looks sponge-like and is compact inside. Bone marrow is of two types; red and yellow bone marrow. Red bone marrow is found in the center of the bones e.g. ribs. It produces blood cells. Yellow bone marrow contains fat and is found in long bones in the hollow centers e.g. thigh bones. Bones with a high concentration of red marrow are responsible for blood cell formation. These include; pelvis, spine, sternum, ribs, and upper parts of legs and arms. The bone marrow contains stem cells (hemocytoblasts) which produce platelets, a certain type of white blood cells, and red blood cells (Muscolino, 2014). The formation of red blood cells from a stem cell takes about 2 days. When the stem cells mature, cell division occurs and more stem cells are created which develop into blood cells. After maturation, there is the presence of hemoglobin and the nucleus in the blood cells becomes smaller. Later, the nucleus is lost and the red blood cells are introduced into the bloodstream in the bone marrow. The formation of red blood cells in the bone marrow increases when blood is lost from the circulation. this continues until the number of red blood cells circulating is reinstated. Nutrients are required for this process since some nutrients are the building blocks of red blood cells (Muscolino, 2014). Iron is which is a component of hemoglobin is needed for the production of blood. Destruction of red blood cells or hemorrhage increases the production of red blood cells in the bone marrow. Red blood cells transport oxygen to the body’s tissues, white blood cells fight infection. Platelets aid in blood clotting in presence of a cut.
Storage of Minerals
Bones are a reservoir for minerals in their matrix. The minerals are stored in the matrix in form of hydroxyapatite which comprises phosphate and calcium. Since the body gets calcium from the food we eat or from supplements, if it’s not enough in the diet the body doesn’t absorb enough calcium. This makes the bones weak or not grow properly. Collagen makes up the soft framework of the bone while hydroxyapatite enhances strength and hardens the framework. Bones store 85%of phosphorous and 99% of calcium (Teti & Zallone, 2009). The level of calcium should be maintained within a narrow range. The red bone marrow stores and releases minerals. The potassium stored helps in maintain the normal blood pressure, keeping skin healthy, and aids in muscle contraction.
Storage of Fat
Fat cells found in the bone marrow are known as Bone Marrow Adipose Tissue (BMAT). This adipose tissue rises during the starvation period. The adipose tissue stores energy to use during food unavailability. There are two types of bone marrow; the red bone marrow and the yellow marrow. The yellow bone marrow is made up of adipose tissue (Teti & Zallone, 2009). This tissue is stored in the adipocytes of the yellow marrow tissue to be released as a source of energy. The bone marrow adipose tissue is sensitive to metabolic conditions and increases when there is a negative energy balance. increase in bone marrow storage when there is insufficient energy means that the fat confers recovery from starvation. When the bone marrow adipose tissue increases due to constraint in the functioning of the bone marrow, then there is no impact on the surrounding bones (Zofkova, 2018). The stored adipose tissue contributes to systemic and skeletal metabolism. Storage of the adipose tissue in the bone marrow increases with age. Red bone marrow also stores fats.
Ph Balance
Bones are dynamic connective tissues that are prone to regeneration and degradation. Bones store calcium, they deliver alkaline compounds to bring a balance in ph or keep it constant (Bushunsky & Krieger, 2015). While this is important, bone mass can be reduced due to this process leading to negative health impacts. Bones breakdown also regulates the acid-base balance because this breakdown leads to the release of calcium which is alkaline.
Detoxification
Bone tissue removes harmful, foreign, and heavy metals from the blood that gets in the body through the food supply, breathing, and beauty products. These toxins affect the body and the bones because they are acidifying (Teti & Zallone, 2009). An acidic environment causes degeneration of calcium from the bones and thus weakening them. After the bone tissue has removed all the harmful substances, they are removed from the body through excretion.
Sound Transduction
The vibrational energy of the sound waves is converted into electrical energy. Sound is conducted to the inner ear through the bones of the skull. This allows a person to perceive the audio content without blocking the ear canal (Muscolino, 2014). The sound is transmitted continuously as the waves vibrate the skull bone. Lower-frequency sounds are better conveyed than higher-frequency sounds hence, the difference between a recorded sound and a person’s voice.
Endocrine Regulation
Bone forming cells (osteoblasts) produces osteocalcin. Osteocalcin is a protein but also a hormone. This hormone leads the beta cells in the pancreas to produce more insulin. Osteocalcin leads fat cells to produce adiponectin hormone which increases insulin sensitivity (Zofkova, 2018). The presence of phosphate is vital in mineralization and bone growth. Its inadequacy leads to a dropping of osteomalacia levels and rickets. The Fibroblast Growth Factor-23 is released by the bones to reduce phosphate reabsorption.
Mineral Homeostasis
Bones maintain a balance of different minerals in the body. Excess minerals are stored and later released to the bloodstream when required to carry out vital activities in the body. Through homeostasis, the flow of calcium in and out of the bones is regulated (Teti & Zallone, 2009). Calcium in the extracellular fluid is regulated by the rate of its entry and the rate of its loss. Calcium enters the extracellular fluid through three ways; absorption in the intestines, reabsorption by the kidney, and through mineral release from bones (Zelzer et al., 2014). For the normal functioning of the blood, the right levels of calcium and other minerals are required. When the calcitonin levels in the blood are high, bones remove calcium from the blood plasma. Bones absorb some minerals and stores them in form of mineral salts when their levels in the blood are high making them hard. Calcium removal from the bones is inhibited. When the levels of minerals in the blood are low, the bones release back some minerals in the blood. This is regulated by parathyroid hormone and thus maintaining homeostasis (Teti & Zallone, 2009). Calcium and phosphorous levels in the blood are regulated by calcitriol to maintain a healthy skeletal system. The incorporation of calcium in the bones is stimulated by calcitonin. Low calcium levels in the blood cause osteoporosis. Calcium homeostasis prevents hypocalcemia and hypercalcemia thus maintain good health.
Muscle Attachment
Bones provide surfaces for attachment of skeletal muscles. These muscles vary in shapes; from tiny muscles in the ear to large muscles in the upper leg. Skeletal muscles are made up of fibers which are grouped in the connective tissue called tendons (Muscolino, 2014). These tendons are attached to the bones either direly or indirectly through the periosteum. This tissue protected and transports delicate muscle cells and allowing them to withstand contraction forces. Skeletal muscles aid in moving of body parts through the joint.
Conclusion
Bones form the skeleton that provides a framework for support of the body’s weight.it also gives the body its shape and provides a surface for muscle attachment to facilitate movement. The internal organs are also attached to or suspended from this framework. The bones work together so as to resist mechanical stress.
