Bone Composition and Cells

Bone is a constantly expanding tissue in the body to which muscles are bound and which allows us to walk freely. It is composed of a protein called collagen and a mineral called calcium, all of which play distinct roles. Proteins provide a flexible structure, and calcium makes the bones sturdy, resulting in the bone’s ability to withstand pressure. The two kinds of bones are cortical, which is dense, and trabecular, which is delicate and forms the bone’s inner section. The cortical is composed of an osteon, which is cylindrical in form and through which blood vessels and nerves travel. The blood vessels enable the circulation of calcium and other nutrients in the bone. The spongy trabecular tissues contain bone matrix laying parallel to each other which is composed of cells responsible for the bone formation which are osteocytes and osteoblasts (Crampton).

The osteoclasts cell is responsible for the breakdown of bone tissue to release calcium. It breaks down the bone by releasing acids and enzymes to dismantle the bone and release minerals into the bloodstream. After breakdown, the cell osteoblast replaces the bone tissue, and the process of born formation begins.

B. Importance of Bone Remodeling

It is the continuous process of replacing old and mature bone tissue with new ones by removal of old tissues from the skeleton and developing new ones. The process is made up of three steps; beginning of bone dissolution and assimilation, transition to bone formation and the process of bone formation. The bone wears out and tear on a daily basis because of work, strain and other forms of stress hence the need for constant repair and replacement.

Bone remodeling is also an essential process in maintaining calcium equilibrium in the bone and help in shaping the general skeleton in growth. Replacement of bone in early development and from birth is 100%, but as we age, the replacement reduces significantly up to 10% in adults. The numerous replacement of bone tissues in early development is vital in ensuring complete bone development to prevent future bone related problems.

C. Problems Associated with Bone Remodeling

Bone replacement tends to reduce significantly as age increases leading to its lack of density, becoming fragile and susceptible to breaking and fractures. Improper use or lack of bone maintenance stimulus can also lead to a reduction in bone formation and replacement. As a result of low bone mass problems such as osteoporosis, osteopetrosis, rickets, renal osteodystrophy, and Paget’s disease occur (Feng and McDonald).

Osteoporosis is brought about by deteriorating of bone structure and low mass leading to its susceptibility to fractures. This disorder affects both men and women in their advanced age with an increased bone loss in women after menopause. With this problem, even the slightest fall can cause breakage or bone fractures, and it will take longer for replacement and healing. Paget’s disease of bone is a disorder of bone remodeling characterized by increased born resorption leading to more bone turnover. This condition increases with an advance in years, therefore, affecting older people more. Rickets is the deficiency of vitamin D in the body which contributes significantly to bone loss. It affects children and even adults such that in children, lack leads the bone to be deformed and fragile and in adults, it leads to osteoporosis.

Question 2

Sensory receptors

Thermoreceptors are distinct cells of the nervous system with the ability to detect variations in temperature, either cold or hot. Its location throughout the skin enables sensory reception in the whole body. The detection of heat is high because heat receptor is closer to the surface, unlike cold receptors which are more rooted in the skin dermis. Thermoreceptors help the body sense temperature changes for an appropriate response. In case of too much heat, sweating will result as a way of a cooling the body. When in cold, shivering will result in generation of heat warm the body. The thermoreceptors are essential to runners for regulating their body temperature.

Mechanoreceptors are situated on the skin and are designed to detect the feeling of touch and can also sense the difference in pressure. A nociceptor is a type of sensory receptor which recognizes any painful stimulation in the body. It works by signaling the spinal code and the brain of impending threat for appropriate remedy to be taken. The pain receptors are located all over the body and nerve endings and are essential in the reception and transmission of pain stimulations to the brain. This nociceptor and pain receptor are used by runners for early detection of any form of injury. The photoreceptor is located in the retina and is responsible for light detection. They are of two types, the rod and cones each with its own role with rods being responsive to changes in light and dark, movement and shape. Phasic and tonic receptors are located in the nerve endings are responsible for how we react to stimulus. Phasic receptors react faster to stimuli while tonic receptors, on the other hand, respond slower to stimuli and is sustained for longer before full adaptation.

Works Cited

Crampton, Linda. “Osteoblasts, Osteoclasts, Calcium, and Bone Remodeling.” 12 March 2017. Owlcation . https://owlcation.com/stem/Osteoblasts-Osteoclasts-Calcium-and-Bone-Remodeling. 27 November 2017.

Xu Feng, Jay M. McDonald. “Disorders of Bone Remodeling.” 13 February 2013. PubMed Central CANADA. http://pubmedcentralcanada.ca/pmcc/articles/PMC3571087/. 27 November 2017.