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Dmitrij [34]
2 years ago
10

Why the red blood cell In the embryo produced mainly in the liver, instead of the bone marrow ...?​

Health
1 answer:
Katyanochek1 [597]2 years ago
6 0
In the human embryo, the first site of blood formation is the yolk sac. Later in embryonic life, the liver becomes the most important red blood cell-forming organ, but it is soon succeeded by the bone marrow, which in adult life is the only source of both red blood cells and the granulocytes. Their job is to transport oxygen to the body's tissues in exchange for carbon dioxide, which is carried to and eliminated by the lungs. Red blood cells are formed in the red bone marrow of bones. Stem cells in the red bone marrow called hemocytoblasts give rise to all of the formed elements in blood. Erythroid (red blood) cells are the first cell type to be specified in the postimplantation mammalian embryo and serve highly specialized, essential functions throughout gestation and postnatal life. The existence of 2 developmentally and morphologically distinct erythroid lineages, primitive (embryonic) and definitive (adult), was described for the mammalian embryo more than a century ago. Cells of the primitive erythroid lineage support the transition from rapidly growing embryo to fetus, whereas definitive erythrocytes function during the transition from fetal life to birth and continue to be crucial for a variety of normal physiologic processes. Over the past few years, it has become apparent that the ontogeny and maturation of these lineages are more complex than previously appreciated. In this review, we highlight some common and distinguishing features of the red blood cell lineages and summarize advances in our understanding of how these cells develop and differentiate throughout mammalian ontogeny.
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3 years ago
Why were the principles in the North American Model of Wildlife Conservation developed? to manage and conserve wildlife resource
WITCHER [35]

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to manage and conserve wildlife resources.

to deregulate the sale of dead game animals

Explanation:

The main reason for the development of North American Model of Wildlife Conservation is to provide protection to the wildlife resources and to also protect them from extinction. This model of Wildlife Conservation also used to eliminates trafficking and prevents the sale of dead game animals in the market which helps in the protection of wildlife animals.

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Read 2 more answers
Explain the role of health education to reduce the prevalence of malnutntion,
snow_lady [41]

Answer:

The paradigmatic shift in the past decade in our understanding of the role of health and nutrition in school-age children has fundamental implications for the design of effective programs. Improving the health and nutrition of schoolchildren through school-based programs is not a new concept. School health programs are ubiquitous in high-income countries and most middle-income countries. In low-income countries, these programs were a common feature of early, particularly colonial, education systems, where they could be characterized as heavily focused on clinical diagnosis and treatment and on elite schools in urban centers. This situation is changing as new policies and partnerships are being formulated to help ensure that programs focus on promoting health and improving the educational outcomes of children, as well as being socially progressive and specifically targeting the poor, girls, and other disadvantaged children. This evolution reflects five key changes in our understanding of the role of these programs in child development.

First, ensuring good health at school age requires a life cycle approach to intervention, starting in utero and continuing throughout child development. In programmatic terms this requirement implies a sequence of programs to promote maternal and reproductive health, management of childhood illness, and early childhood care and development. Promoting good health and nutrition before and during school age is essential to effective growth and development.

Second, operations research shows that the preexisting infrastructure of the educational system can often offer a more cost-effective route for delivery of simple health interventions and health promotion than can the health system. Low-income countries typically have more teachers than nurses and more schools than clinics, often by an order of magnitude.

Third, empirical evidence shows that good health and nutrition are prerequisites for effective learning. This finding is not simply the utopian aspiration for children to have healthy bodies and healthy minds, but also the demonstration of a systemic link between specific physical insults and specific cognitive and learning deficits, grounded in a new multisectoral approach to research involving public health and epidemiology, as well as cognitive and educational psychology.

Fourth, the provision of quality schools, textbooks, and teachers can result in effective education only if the child is present, ready, and able to learn. This perception has additional political momentum as countries and agencies seek to achieve Education for All (EFA) by 2015 and address the Millennium Development Goals of universal basic education and gender equality in education access. If every girl and boy is to be able to complete a basic education of good quality, then ensuring that the poorest children, who suffer the most malnutrition and ill health, are able to attend and stay in school and to learn while there is essential.

Finally, education, including education that promotes positive health behaviors, contributes to the prevention of HIV/AIDS—the greatest challenge for generations to come. School health and nutrition programs that help children complete their education and develop knowledge, practices, and behaviors that protect them from HIV infection as they mature have been described as a "social vaccine" against the disease.

Because of the success of child survival programs, the number of children reaching school age (defined as 5 to 14 years of age) is increasing and is estimated to be 1.2 billion children, with 88 percent living in less developed countries (U.S. Census Bureau 2002). As figure 58.1 illustrates, the pattern of disease is age specific. A large body of evidence shows that these conditions affect cognition, learning, and educational achievement (see Jukes, Drake, and Bundy forthcoming; Pollitt 1990 for reviews of this extensive literature).

Explanation:

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