Chapter 5 the skeletal system

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Chapter 5 the skeletal system

References Role of zinc in human metabolic processes Zinc is present in all body tissues and fluids. The total body zinc content has been estimated to be 30 mmol 2 g. Skeletal muscle accounts for approximately 60 percent of the total body content and bone mass, with a zinc concentration of 1.

Zinc concentration of lean body mass is approximately 0. Plasma zinc has a rapid turnover rate and it represents only about 0. This level appears to be under close homeostatic control.

High concentrations of zinc are found in the choroid of the eye 4. Zinc stabilises the molecular structure of cellular components and membranes and contributes in this way to the maintenance of cell and organ integrity. Furthermore, zinc has an essential role in polynucleotide transcription and thus in the process of genetic expression.

Its involvement in such fundamental activities probably accounts for the essentiality of zinc for all life forms. Zinc plays a central role in the immune system, affecting a number of aspects of cellular and Humoral immunity 2. The role of zinc in immunity was reviewed extensively by Shanglar et al.

The clinical features of severe zinc deficiency in humans are growth retardation, delayed sexual and bone maturation, skin lesions, diarrhoea, alopecia, impaired appetite, increased susceptibility to infections mediated via defects in the immune system, and the appearance of behavioural changes 1.

The effects of marginal or mild zinc deficiency are less clear. A reduced growth rate and impairments of immune defence are so far the only clearly demonstrated signs of mild zinc deficiency in humans.

Other effects, such as impaired taste and wound healing, which have been claimed to result from a low zinc intake, are less consistently observed. Zinc metabolism and homeostasis Zinc absorption is concentration dependent and occurs throughout the small intestine.

Under normal physiologic conditions, transport processes of uptake are not saturated. Zinc administered in aqueous solutions to fasting subjects is absorbed efficiently percentwhereas absorption from solid diets is less efficient and varies depending on zinc content and diet composition 3.

Chapter 5 the skeletal system

Zinc is lost from the body through the kidneys, skin, and intestine. Starvation and muscle catabolism increase zinc losses in urine. Strenuous exercise and elevated ambient temperatures could lead to losses by perspiration. The body has no zinc stores in the conventional sense.

In conditions of bone resorption and tissue catabolism, zinc is released and may be re-utilised to some extent. Human experimental studies with low-zinc diets 2.

Controlled depletion-repletion studies in humans have shown that changes in the endogenous excretion of zinc through the kidneys, intestine, and skin and changes in absorptive efficiency are how body zinc content is maintained The underlying mechanisms are poorly understood.

Sensitive indexes for assessing zinc status are unknown at present. Static indexes, such as zinc concentration in plasma, blood cells, and hair, and urinary zinc excretion are decreased in severe zinc deficiency.

A number of conditions that are unrelated to zinc status can affect all these indexes, especially zinc plasma levels. Infection, stress situations such as fever, food intake, and pregnancy lower plasma zinc concentrations whereas, for example, long-term fasting increases it However, on a population basis, reduced plasma zinc concentrations seem to be a marker for zinc-responsive growth reductions 12, Experimental zinc depletion studies suggest that changes in immune response occur before reductions in plasma zinc concentrations are apparent So far, it has not been possible to identify zinc-dependent enzymes which could serve as early markers for zinc status.

A number of functional indexes of zinc status have been suggested, for example, wound healing, taste acuity, and dark adaptation Changes in these functions are, however, not specific to zinc and these indexes have so far not been proven useful for identifying marginal zinc deficiency in humans.Learn all about the nutritional importance of proteins, fats and carbohydrates in our diet, and explore how our bodies use these macronutrients.

Chapter 5 The Skeletal System AXIAL SKELETON Skull 9. Using the key choices, identify the bones indicated by the following descrip- 77 tions. Enter the appropriate. Chapter 5 The Skeletal System (made of bones & articulations).

Chapter The brain, cranial nerves and meninges Nervous system. The nervous system in general is described in chapter 3.

The divisions of the brain are summarized here in table This chapter is limited to a brief description of the gross structure of the brain, an account of the ventricles, and some general remarks on the cranial nerves, the meninges, and the blood supply.

Name: Period: Dr. Kelly Skeletal System Study Guide (Chapter 5 in the textbook) 1. Bone names, locations, and numbers [pg] a. Label a diagram like that shown in Figure with the bone names and numbers.

The muscular system is the biological system of humans that produces movement. The muscular system, in vertebrates, is controlled through the nervous system, although some muscles, like cardiac muscle, can be completely autonomous.

Chapter 5: The Skeletal System.

Chapter 5 the skeletal system

Although the word skeleton comes from the Greek word meaning "dried-up body," our internal framework is so beautifully designed and engineered that it puts any modern skyscraper to shame. Strong, yet light, it is perfectly adapted for its functions of body protection and motion.

Indeed, our skeleton is a tower .

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