The skeletal system

Tag: 上海夜生活男人好去处

first_imgThe human skeleton is composed of 206 bones. The skeleton is the framework of the body, without it the body would be shapeless. The bones are shaped according to their function. Bones may be: – Long, as in the arm and legs. – Flat, as the sternum and scapula. – Short as in the ankles and wrist. – Irregular, as in the vertebrae. – Round, as in the patellae. The bones of the arms, legs, shoulders and pelvis make up the appendicular skeleton. The bones of the skull and face and the auditory ossicle, vertebrae, ribs and sternum, make up the axial skeleton. BONE GROWTH Bones develop in the growing foetus through a process called ossification. The skeleton is completely formed by the end of the third month of gestation (pregnancy). After birth, bone growth proceeds from the epiphyseal plates (growth plates). Growth proceeds from the end towards the centre of the bone. When the bone has reached its full size and growth ceases the epiphyseal growth centres are replaced by bone cells. Longitudinal (length) bone growth and ossification usually continue in girls until about age 15 and age 16 in boys. However, bones continue to mature and develop their final shape until about 21 years of age. The whole growth process is controlled by hormones. If there is too much growth hormones the cartridge in the plates grows too fast and results in gigantism, while too little hormone leads to dwarfism. Bone formation and resorption are caused by the actions of osteoblasts and osteoclast. Osteoblast make new bones and at the same time cells called osteoclast break it down. Exercise causes osteoblast to work harder. But, extreme training, especially with weights at young age, can result in problem with bone deformity. Bones get more fragile as you age and can get weak and break easily (osteoporosis), especially in women. FUNCTIONS OF BONES There are five principal functions of bones. – Support the body, enabling you to stand erect. – Protect the internal organ and tissues. – Assist movement by coordination with muscles and joints. – Provide storage areas for minerals. – Serve as sites for formation and development of blood cells in the bone marrow (haematopoiesis). JOINTS A joint is where two or more bones meet (articulate). There are more than 100 joints in the body. Joints are divided into three types based on the amount of movement they allow. – Fixed or immovable joints (fibrous): In these, bones are fused together by tough fibres. These types of joints are found in areas requiring strength. Examples are the joints between the plates of the cranium (skull) and the fused joints in the sacrum. – Slightly movable joints (cartilaginous): In these, a small amount of movement can occur. The bones are linked by cartilage. Cartilage is a tough but flexible cushion of tissue that stops the bones from knocking together (friction) and can also compress a little to allow slight movement. Slightly movable joints are found between most of the vertebrae in the vertebral column and the joint between the ribs and sternum. – Freely movable joints (synovial): All freely movable joints share features which prevents friction between moving bones. One of the main features is the presence of synovial fluid between the moving bones. The bones are held together by slightly elastic fibres called ligaments, which allows the bones to move; any damage to the ligament results in the joint losing some of its strength and stability. Joints work smoothly together when we perform sporting activities. They must be capable of their full range of movement in order to work well. The demands of sport put severe stress on joints. Therefore, it is essential to warm-up before an activity and cool down after the activity. Joints can be injured as a result of impact, internal forces or a mixture of both. Examples sprains, torn ligament and dislocation. (More next week on the skeletal system). NUTRIENTS AND BONE GROWTH The most important nutrients for growth are: – Proteins – build cells and repair damaged tissues. Found in milk, cheese, eggs, fish, pulses and nuts. – Vitamins – Vitamin D helps with the absorption of calcium and is found in milk, fish, liver and eggs. The body also makes it with sunshine. – Minerals – calcium which gives strong bones and teeth and is found in milk, cheese fish and green vegetables.last_img read more


Tag: 上海夜生活男人好去处

first_imgThe axe officially fell on Tuesday — Salmon ports from Eureka to Gold Beach will remain off limits for recreational salmon fishing this year. Because of the historically low numbers of adult Klamath River fall Chinook, a lingering effect of five years of drought water mismanagement and poor ocean conditions, the PFMC reaffirmed their decision to officially close recreational salmon fishing within the California and Oregon KMZ areas.Fisheries to our south, which have far less impact on the …last_img


Tag: 上海夜生活男人好去处

first_imgA trade group representing manufacturers, retailers and installers of photovoltaic (PV) systems has published a short guide for homeowners who want to buy or lease a system.The Solar Energy Industries Association’s Residential Consumer Guide to Solar Power offers a summary of the three options homeowners have for getting into solar: buying a system outright, leasing a system, or signing a power purchase agreement in which they buy power produced from a system on their property at a set rate.Publication of the guide comes at a time of heady growth for residential PV in the U.S. Solar electricity still makes up a very small percentage of power consumed in the U.S., but installations are expanding rapidly. Not only are prices for solar panels continuing to fall, making an outright purchase much more attractive than in the past, but homeowners also can reap many of the benefits of solar without upfront payments by leasing a system.But rapid growth also has brought some problems. Earlier this year, a dozen members of Congress asked two federal agencies to look into complaints that consumers can be hoodwinked by deceptive sales practices. In a letter to the Federal Trade Commission, Republican House members said some solar leasing companies might be overstating savings and understating risks.In addition, other reports suggest solar leases can complicate and even kill pending real estate sales as buyers balk at existing contract terms. Know what you’re getting intoThe SEIA draws parallels between buying or lease a solar system and weighing the options for car ownership. Its pamphlet suggests that homeowners do their homework before making a decision so they know how much electricity they use, whether the roof on their house is suitable for a solar installation, and how much they can comfortably spend.It recommends that homeowners approach solar energy as they would any other major decision about home ownership: get multiple bids, research the potential installer, and study potential tax consequences and financial incentives.The pamphlet doesn’t offer much detail beyond a bare-bones explanation of how a system works, but it does include several links for additional information.“Consumer protection is an issue of highest priority and is vital to solar’s future growth across America,” SEIA President and CEO Rhone Resch said in a written statement.last_img read more


Tag: 上海夜生活男人好去处

first_imgThe doping scandal has taken a dangerous turn. A former SAI doctor, who exposed how doping was rampant at National Institute of Sports, has been beaten up at Patiala. Dr Sajib Nandi had recently revealed to Headlines Today how the authorities at NIS Patiala were hand in glove in the doping scandal. Nandi was beaten up at the entrance of NIS Patiala and dragged out of the campus by the security guards as he was set to meet Justice Mudgal, who is probing the doping scam. Nandi told Headlines Today, “I’m filing report with the police shortly. The NIS director is a corrupt person.” Unfortunately, this is not the first time that Nandi has been attacked in his attempt to cleanse the system. Back in 2002 too, he was beaten up as he tried to expose the authorities’ role and involvement in doping at Patiala. Recently, Punjab deputy chief minister Sukhbir singh Badal has taken action on the chemist shops in Patiala selling banned drugs. While raids were conducted on the shops, the state government was getting ready to cancel licences of all those found guilty of selling banned drugs. On July 5, Headlines Today had exposed how performance enhancing drugs were openly sold over the counter at chemist shops around NIS in Patiala. The expose had come amid the dope stink involving eight athletes, including golden girl Ashwini Akkunji. Headlines Today special investigation team went shopping and found no checks in place here to control the sale of banned drugs. NIS Patiala has a tarnished history dating back to 2001, when syringes and steroid strips were found in its hostels. An inquiry was ordered into the functioning of NIS by the Sports Authority of India in 2003.  Though no action has yet been taken, the report is believed to contain proof of sustained irregularities in anti-doping procedures and a nexus between NIS authorities, federation coaches and SAI officers.advertisementlast_img read more