Structure and Function of Skull

The overall structure of the skull and It's function

The skull is a structure of bones that forms vertebrates head. It holds the face structure and offers a shielding cavity for the brain. The human skull is made of two parts: the mandible and the cranium. In human, the two parts are the viscerocranium and the neurocranium. The skull makes up the anterior most constituents of the skeleton and is a product of cephalisation and many sensory structures such as ears, eyes, mouth and nose. Skull functions include: protecting the brain, fixing ears position to enhance sound localisation and correcting the distance between the two eyes to enable stereoscopic vision (Colleran et al., 2010). (101words)

The Pectoral girdle and its functions

The pectoral girdle or the shoulder girdle is a group of bones found in the appendicular skeleton connecting to the arm on every side. It is composed of scapula and clavicle. Unlike pelvic girdle which is to the lower limb, the pectoral girdle is to the upper limb. The girdles form the appendicular skeleton parts that fix the appendages to the skeleton. The muscular connection allows for shoulder girdle mobility unlike the girdle of the compact pelvic, this is because weight bearing does not always involve the upper limb, its stability is being sacrificed to ensure greater mobility (Darias et al.,2011). (101words)

The Synovial joint and how it works.

Naming of components:

1-Partellar ligament 2-Articular cartilage 3-Synovial layer 4-Soft tissue 5-Joint cavity 6-Synovial membrane 7-Fibrous membrane

A synovial joint exists between bones that are moving against one another such as limbs joints (hip, elbow, knee and shoulder). Characteristically, it contains a joint cavity that has been filled with fluid. Other joints provide close to no movement, these include joints of the fibrous and fibrous cartilaginous (Dahdul et al., 2012).

Properties and fuctions of cartilage, tendons and ligaments

Cartilage: It is a smooth and gristly substance that covers the bones surface. It operates as a shock absorber thereby reducing friction effect as the bones move.

Tendons: These are connective tissues found in the joint made up of tough bands. They assist in transmiting force the muscle and the bone.

Ligaments: They are made of similar materials as tendons. They connect bone to bone. They specifically designed to assist in stabilizing the joints and offer a structure for the bones.

How it works:

When a joint is moved, bones tend to glide against each other and with no or little friction. This kind of easy motion is due to the boney surfaces that have been buffered by the slick articular cartilage layer. The synovial fluid is majorly made to provide lubrication and cushion for the joints. The synovial joint membrane produces hyaluronic acid and albumin that the provide stickiness and viscosity nature to the synovial fluid. Additionally, synovial fluid offers nutrients to the cartilage and gets rid of waste from the cartilage (McGee et al.,2009). When the joint is put at rest, the cartilage tends to absorb the synovial fluid, and when the joint is put into use then the synovial fluid is discarded from the cartilage, just the same way water is squeezed out from a sponge, Consequently, the use of joint is important since it facilitates the circulation of the synovial fluid throughout the joint. (309 words)

Characteristics, structure and function of smooth, striated and cardiac muscles.

Every muscle cell is designed for various functions that are required by specific body parts. Muscle tissues shorten or contract thereby producing movement of external and internal body parts. Smooth muscles are made up of spindle, elongated shaped cells are often involved in voluntary motions. Contraction or motion of the involuntary muscle are those movements that cannot be controlled consciously. The nucleus is located at the centre and the striation does not occur in smooth muscle cells. These kinds of cells are distributed in the whole body. Muscles that are created from these cells include those that are present in the blood vessel wall, the digestive system and the urinary bladder (Viceconti et al., 2012). In skeletal muscles, the movement is allowed by getting attached to the body bones. Skeletal muscle regulates voluntary movement which can be controlled consciously. Skeletal muscles are composed of cylindrical fibres which are present in the system of locomotives. The nucleus of every cell and the cells are striated (Al-Khayat et al 2013). Cardiac muscles are quadrangle and roughly shaped. They have one central nucleus. Branching fibre network is formed by the cells. The muscles are involuntary and cross-striated. They are normally found in the heart (Aagard et al., 2010). (205 words)

How actin and myosin move to cause contraction of the muscle

Actin is protein with a spherical shape. It forms the thin filament found in the muscle cells. The filaments are made of long chains composed of molecules. Every actin molecule contains a site of myosin bind where the myosin head is binded. For a contraction to happen, stimulation of the muscle must first occur in the form of an impulse from the neuron. The neuron of the individual motor and the fibres of the muscle stimulated are known as the motor unit. The neuromuscular junction is the muscle fibres and neuron axon motor it stimulates (Kaveh & Talatahri, 2010). When a motor unit muscle fibres are reached by an impulse, a reaction is stimulated in every sarcomere between the myosin filaments and the actin. This type of reaction results in contraction of the theory of living filament. The reaction formed due to impulse arrival of an impulse facilitate stimulation of the 'heads’ on a filament of the myosin to move forward and get attached to the filament of the actin and then pull them towards the sarcomere. This process simultaneously occurs in the sarcomeres and the resultant process is the shortening of the sarcomeres. (Darias et al., 2011). The troponin is a three-protein complex that is integral to the construction of the muscle. It is joined to the tropomyosin of protein in the actin filaments. The tropomyosin blocks the sites of the attachment for the myosin across heads when the muscle is relaxed. This prevents contraction. When the nerve impulse stimulates the muscle to contract, channels of calcium open in the reticulum of sarcoplasmic and allows calcium into the sarcoplasm. Some of the calcium is attached to troponin which leads to transformation in the muscle cell that push tropomyosin away so that the crossing bridges can get attached and produce contraction of the muscle (Narici & De Boer, 2011). (308words)

Effects of poor posture on muscle and skeletal system

Joint stress

The joint in the body is shielded by connective tissue designed to protect and cushion the joint during movement. The joint load being properties are reflected by the amount of connective tissue. A spine that has been misaligned results in weight loss or redistributed stress throughout the body. When joints are subject to excess stress, the result is long term pain or supportive connection tissue degeneration (Linari et al., 2015).

Misalignment

The ailments of the skeletal that result from the bad posture are due to misalignment in the spine. Poor posture disrupts the spine alignment of an individual by either triggering the formation of horizontal curvature or stressing one or more of the spinal curves. Poor alignment of the spine leads to disruption of the major muscles and bone this causing short term pain or structural damage (Darias et al., 2011). (151words)

Effects of poor lifting technique on the muscular and the skeletal system

Injury of the muscle

Poor posture while lifting weights can result in stress being subjected on the lower back muscles, and when there is a high demand for support a muscle is injured. A lot of stress can result in the formation of tears around the muscle, generally known as strain. It's common for injuries of the back. This kind of injury on the back can be very painful, making it hard to breathe properly. The strain on the back can often heal, however, it can take longer periods (Kaveh & Talatahri, 2010).

Disc injury

The intervertebral disc operates like a cushion and ball bearing between the bones in the spine. They consist of fibrous rings, that can break open, bulge or rupture when injured. Pain on the lower can be caused by disc injury that may radiate down to the leg (Al-Khayat et al 2013). (152 words.)

Osteoporosis

Osteoporosis is a condition that adversely affects bones thereby making them, more fragile, less dense and prone to fracture. Some individuals find it easy to develop osteoporosis as compared to others. Additionally, certain bones in the body are more likely to weaken by fracture and osteoporosis as compared to others. Human bones contain two structures: spongy bone and the cortical bone. Osteoporosis reduces bone density and the spongy bone structure, and cortical bone thinning. When bones of an individual are excessively thinned to appoint that osteoporosis is to be diagnosed, the soundness and physical structure of the body is changed. Specifically, the cortical bone gets thin and the spongy bone starts becoming less dense with larger spaces forming between struts bony structure which intern becomes thinner. Osteoporosis makes the body to become brittle and thin hence prone to have a fracture. The common sites of fracture caused by osteoporosis include the spine vertebrae and the bone of the thigh at the hip (Darias et al., 2011). People with osteoporosis may have a fracture due to light bump or minor fall out. A fracture can occur due to the compressed weakened bone. This happens during a simple bending motion while moving forward or uplifting or bending forward in osteoporosis. This kind of fracture often results in pain and mark spine curving with loss of height that can be observed in older people with osteoporosis. A fracture that occurs at the bone of the thigh can result to an inability to walk without being assisted for long periods, long period of nursing care and higher chances of dying during the year due to the fracture (Linari et al., 2015).

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Effect on the bone structure:

Bone is continuously undergoing the remodeling process where new bone is build up to replace the old bone that has been broken down. The osteoclasts get rid of old bone and produces calcium phosphate into the blood. Bones don't always get much weaker or stronger or smaller or bugger since the process often cancel each other at a faster rate. The development phases are usually ignored. Osteoclasts in osteoporosis is usually far much better than osteoblasts, and therefore the break down is faster than it is replaced and this results into pores in bone that has been weakened. Long bones such as radius, humerus, tibia and femur have a strong layer of dense bone known as cortical bone located outside with the lighter and spongey bone known as canollous bone. Remodelling occurs in both types of bone and therefore all are affected by osteoporosis (Darias et al., 2011).

Osteoporosis is most common among older people above 50years of age. If the bone formed is greater than the reabsorbed bone, then the amount of bone in the Skeleton increases, as this occurs at childhood. At the age of 30 years, the total bone being resorbed starts to become slightly greater than the total amount of bone formed, and for several years after this age, this partial imbalance results into a gradual loss of the density of the bone (Cosman et al., 2014). ( . (504words)

Reference

Dernell, W. S. (2011). Tumours of the skeletal system. In BSAVA manual of canine and feline oncology (pp. 159-177). BSAVA Library.

Narici, M. V., & De Boer, M. D. (2011). Disuse of the musculo-skeletal system in space and on earth. European journal of applied physiology, 111(3), 403-420.

Colleran, D., Schorer, S., & McAfee, P. (2010). U.S. Patent No. 7,854,752. Washington, DC: U.S. Patent and Trademark Office.

Darias, M. J., Mazurais, D., Koumoundouros, G., Cahu, C. L., & Zambonino-Infante, J. L. (2011). Overview of vitamin D and C requirements in fish and their influence on the skeletal system. Aquaculture, 315(1-2), 49-60.

Dahdul, W. M., Balhoff, J. P., Blackburn, D. C., Diehl, A. D., Haendel, M. A., Hall, B. K., ... & Segerdell, E. (2012). A unified anatomy ontology of the vertebrate skeletal system. PloS one, 7(12), e51070.

Manilay, J. O., & Zouali, M. (2014). Tight relationships between B lymphocytes and the skeletal system. Trends in molecular medicine, 20(7), 405-412.

Kaveh, A., & Talatahari, S. (2010). Optimal design of skeletal structures via the charged system search algorithm. Structural and Multidisciplinary Optimization, 41(6), 893-911.

Tidball, J. G., & Villalta, S. A. (2010). Regulatory interactions between muscle and the immune system during muscle regeneration. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 298(5), R1173-R1187.

Aagaard, P., Suetta, C., Caserotti, P., Magnusson, S. P., & Kjær, M. (2010). Role of the nervous system in sarcopenia and muscle atrophy with aging: strength training as a countermeasure. Scandinavian journal of medicine & science in sports, 20(1), 49-64.

Linari, M., Brunello, E., Reconditi, M., Fusi, L., Caremani, M., Narayanan, T., ... & Irving, M. (2015). Force generation by skeletal muscle is controlled by mechanosensing in myosin filaments. Nature, 528(7581), 276.

Al-Khayat, H. A., Kensler, R. W., Squire, J. M., Marston, S. B., & Morris, E. P. (2013). Atomic model of the human cardiac muscle myosin filament. Proceedings of the National Academy of Sciences, 110(1), 318-323.

Cosman, F., de Beur, S. J., LeBoff, M. S., Lewiecki, E. M., Tanner, B., Randall, S., & Lindsay, R. (2014). Clinician’s guide to prevention and treatment of osteoporosis. Osteoporosis international, 25(10), 2359-2381.