Answer:
In case of a physical support there is a bone system involved, in case of the maintenance of the body weight there is wide spectrum of thyroid hormones as well as leptin and ghrelin, according to the recent studies.
Explanation:
There is a whole spectrum of physiological body systems involved in the maintenance of the body weight in humans, as well as metabolism. One of the most important hormones are thyroid hormones. According to the most recent studies, the major role there is an adequate function of the digestive system as well. The most important digestive-related hormones are leptin and ghrelin.
In case of the physical protection of the human body weight the major role have bones, cartilages and ligaments. All of the aforementioned structures support the human body organs and other structures. In case of skeleton, it has been estimated that it consists of 206 bones. In case of younger individuals, the human skeleton has a greater protective effect to other body systems. In case of bones, its main role is to have a rigid support for internal organs and other body structures. In that way, the body weight is is supported against the force of gravity. Additonaly, it provides a support for muscles to maintene their movements as ligaments bind to the distal and proximal parts of the corresponding bones. If we analyze the upper parts of skeleton, their promienent role is in the lifting and carrieng objects etc. The lower parts of the skeleton are involved in a variety of functions such as walking, runinng, playing sports etc.
In case of internal portions of skeleton, it is necessary to outline the major role of skeleton for example in the abdominal and peritoneal cavities. In these cases, the role of skeleton is to act protectively to the contained organs in those cavities. In case of bones themselves, they act as aa storage site for diverse minerals (calcium, phosphate etc. ). The bone marrow is a storage site for the production of blood components producing cells.
Thyroid hormones have an essential role in the body weight regulation. Their major role is through the regulation of the energy in the human body. Thyroid impairment (such as hyperthyroidism, hypothyroidism) may have a large impact on the changes in the body weight and basal metabolic rate.
The most important thyroid hormones studied in the context of the body weight regulation are free triiodothyronine (T3), free thyroxine (T4), total T3, total T4 and thyroid stimulating hormone (TSH). Thyroid hormones regulate the basal metabolic rate via increasing ATP production and regulation of the Na⁺/K⁺ and Ca₂⁺ concentrations and gradients.
Leptin and ghrelin are hormones that regulate energy balance. Leptin mediates a long-term regulation of energy balance. Leptin suppresses food intake and regulates energy expenditure.. In that way, leptin leads to weight loss. Leptin is a 6-kDa protein with helical structure, secreted from white adipocytes. The leptin receptors have a role similar to the cytokine receptor I class via transduction mechanisms. Leptin receptors form homodimers. It has been documented that in case of food deprivation, there is a rapid decrease in leptin gene expression. Leptin acts centrally. It inhibits the synthesis and effect of neuropeptide Y. Such role is the most prominent in the arcuate nucleus of the hypothalamus. There is a lipostatic theory of leptin. Leptin is secreted in the white adipocytes, afterwards secreted into the blood circulation and transported to brain structures. In the brain it inhibits or release the aforementioned factors in order to regulate food intake.
Ghrelin is a fast-acting hormone. It has the role in the meal initiation. It is known that leptin resistant individuals are obese. Ghrelin is a 28-amino acid that stimulates appetite and the release of growth hormone. Nearly 70 percent of ghrelin is secreted by the stomach and small intestine. Ghrelin has a major role in white adipose tissue where it stimulates adipogenesis, fat storage enzymes and increases trygliceride concentration. It decreases lipolysis.