By Q. Bernado. Lutheran Bible Institute. 2018.
The results of this research increase our understanding of life and lay the foundation for advances in the diagnosis cheap depakote 500mg otc, treatment and prevention of disease generic 250 mg depakote visa. Produced by the Ofﬁce of Communications and Public Liaison National Institute of General Medical Sciences National Institutes of Health U depakote 500mg with amex. But how did we and our very distant rela writer inventing a story set on a distant tives come to look so different and develop so many different ways of getting along in the planet could hardly imagine three more dif world? Now, researchers know, and what they are still learning, researchers can examine all of the genes in a liv about the role of genes in health and disease. They are Finally, in Chapter 5,“21stCentury doing this for organisms on every branch of the Genetics,” see a preview of things to come. Learn tree of life and ﬁnding that the genomes of mice, how medicine and science are changing in big frogs, ﬁsh and a slew of other creatures have ways, and how these changes inﬂuence society. From metabolism to medicines to agriculture, So why doesn’t your brother look like your the science of genetics affects us every day. In Chapter 3,“Life’s Genetic Tree,” ﬁnd out how evolution works and how it relates to genetics and medical research. C H A P T E R 1 How Genes Work eople have known for many years that Proteins do many other things, too. When a cell needs Firming up the details took quite some time, more proteins, it uses the manufacturing instruc though. Genetics in the Garden In 1900, three European scientists inde The monk Gregor Mendel ﬁrst described pendently discovered an obscure research how traits are inherited paper that had been published nearly 35 from one generation to years before. Mendel had studied how pea plants When he crossbred purpleﬂowered pea plants inherited the two variant forms of easytosee with whiteﬂowered ones, the next generation had traits. Over Rosalind Franklin, a physical chemist work time, mutations supply the raw material from ing with Maurice Wilkins at King’s College in which new life forms evolve (see Chapter 3, London, was among the ﬁrst to use this method “Life’s Genetic Tree”). Her experiments plants were bred to each other, some of their off factors, whatever they were, must be physical spring had white ﬂowers. What’s more, the material because they passed from parent to secondgeneration plants displayed the colors in a offspring in a mathematically orderly way. On average, 75 percent of the until many years later, when the other scientists secondgeneration plants had purple ﬂowers and unearthed Mendel’s report, that the factors were 25 percent of the plants had white ﬂowers. Mendel’s mathematical rules of inheritance applied Trying to solve the mystery of the missing color not just to peas, but also to all plants, animals and blooms, Mendel imagined that the reproductive people. The discovery of a quantitative rule for cells of his pea plants might contain discrete inheritance was momentous. It revealed that a “factors,” each of which speciﬁed a particular trait, common, general principle governed the growth such as white ﬂowers. Although Franklin did not earn a you know the sequence of nucleotide building share of the prize due to her untimely death at age blocks on one strand, you know the sequence of 38, she is widely recognized as having played a nucleotide building blocks on the other strand: signiﬁcant role in the discovery. A always matches up with T and C always links The spiral staircaseshaped double to G (see drawing, page 7). But what and groups of genes are packaged tightly into is so beautiful about the structures called chromosomes. Every cell in your discovery of the twisting body except for eggs, sperm and red blood cells ladder structure isn’t just contains a full set of chromosomes in its nucleus. It taught were connected in this way, it would stretch them that the two connected approximately 67 billion miles! P Nucleotide S C 8 National Institute of General Medical Sciences Copycat It’s astounding to think that your body consists of trillions of cells. Each strand becomes cellular spellchecker catches and corrects nearly a pattern, or template, for making a new strand, all of these errors. The trouble is that most of these G C T A drugs do affect normal cells that grow and T A divide frequently, such as cells of the immune system and hair cells. A T G C Most of your cells are called diploid G C A T (“di” means two, and “ploid” refers to sets of A T chromosomes) because they have two sets of chromosomes (23 pairs). Each G C C G G C haploid cell has only one set of 23 chromosomes C G so that at fertilization the math will work out: A T A T A haploid egg cell will combine with a haploid sperm cell to form a diploid cell with the right A T number of chromosomes: 46. Matching chromosomes pair up This creates a mix of new genetic Chromosomes swap material in the offspring’s cells.
When special receptors in the muscles and joints are stimulated buy discount depakote 500mg line, you sense the position of the different parts of the body and know whether they are moving and in which direction they are moving without even looking at them purchase 250 mg depakote amex. Perhaps you have never realized that you have this sense of position and movement a sense called proprioception or kinaesthesia order 250 mg depakote fast delivery. Lippincot Company) 199 Human Anatomy and Physiology Disruption of general sense organs can occur by a variety of mechanisms. For example, third degree burns can completely destroy general sense receptors throughout the affected area. This commonly occurs when you put your legs in a position that presses your legs in a way that reduces blood flow. When you try to stand up, you cannot feel you legs because the general sense organs are temporarily impaired. What are the functions of the sympathetic part of the autonomic nervous system, and how do these compare with those of the parasympathetic nervous system? For example, the nervous system acts by means of electric impulses and chemical stimuli; where as the endocrine system has more widespread, slower, and longer lasting effects. The endocrine system also has more generalized effects on such activities as growth, metabolism, and reproduction. The blood reaches all cells of the body, but only certain cells respond to specific hormones; these responding cells are unique in that they have receptors to which the hormones attach. Only cells that have receptors for a given hormone will respond to that hormone; these cells make up what is called the target tissue. These glands are also called the ductless glands because they secrete directly into the blood stream, in contrast to the endocrine glands, which secrete into body cavities. The organs believed to have the very richest blood supply of any in the body are the tiny adrenal, or suprarenal, glands, which are located near the upper part of the kidneys. Some of the glands included in this system, such as the pancreas and the sex glands, have other nonendocrine functions as well, but hormone secretion is is one of their main functions. In addition, some body organs, such as the stomach, small intestine, and kidney, produce hormones, but since their main function is not hormone production, they are not discussed in this unit. Many of the hormones secreted by the pituitary gland are critical to the activity of target glands, including the thyroid, adrenal and gonads. Anatomy The pituitary gland (hypophysis cerebri) is located at the base of the brain, resting with in the sella turcica of the sphenoid bone. The pituitary gland maintains elaborate neural and vascular connections with the hypothalamus of the brain, which plays a central role in the integration of neuroendocrine activity (Figure 8-1). The pituitary gland has two major divisions: The anterior lobe (adenohypophysis) and the posterior lobe (neuro- hypophysis). Adenohypophysis The adenohypophysis is served by an elaborate vascular system, including the hypothalamohypophyseal portal system, 207 Human Anatomy and Physiology which transports hypothalamic regulating hormones (hypophyseotropic hormones) to the glandular cells of the adenohypophysis. The classification of cells in the adenohypophysis is based on specific immunohistochemical techniques. In addition to growth hormone, the thyroid hormones, insulin, androgens, and estrogens play important roles in normal human growth and development at various times of the life cycle. However, in cartilage, bone, and other body tissues, the protein anabolic and growth-promoting actions are mediated by insulinlike growth factors (somatomedins). The elevation of plasma levels of free fatty acids resulting from the hydrolysis of triglycerides (stored neutral fats) is potentially ketogenic. Prolactin facilitates the secretion of dopamine in the hypothalamus, thereby regulating its own secretion by a negative feedback mechanism. Actions Prolactin initiates and maintains milk secretion from breasts primed for lactation by other hormones such as estrogens, progesterone, and insulin. It also appears to inhibit the effects of the gonadotropins and may prevent ovulation in lactating women. Actions Follicle-stimulating hormone directly stimulates the sertoli cells in testicular seminiferous tubles, there by promoting spermatogenesis in the male. Actions Thyroid-stimulating hormone maintains the structural integrity of the thyroid gland and promotes the synthesis and release of thyroid hormones thyroxine (T4) and triiodothyronine (T3). The enhanced reabsorption of water from the renal tubules results in the production a concentrated urine that is reduced in volume. The early observations that posterior pitutary extracts produce a marked elevation of arterial blood pressure led to the initial naming of this hormone as vasopressin. Oxytocin Control of Secretion and Actions The two major physiologic actions of oxytocin are exerted on the female breast and uterus. Oxytocin binds to a G-protein coupled receptor that ultimately brings about elevated intracellular calcium levels.
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