Condet

Connie Watkins Bales, PhD

• Professor in Medicine
• Senior Fellow in the Center for the Study of Aging and Human Development

https://medicine.duke.edu/faculty/connie-watkins-bales-phd

Covalent bonds between atoms are among the strongest chemical bonds in nature; they are so strong that they rarely break apart pulse pressure graph order exforge 80mg mastercard. In structural formulas blood pressure form buy exforge 80mg without prescription, a covalent bond is depicted as a line drawn between two atoms blood pressure medication hydroxyzine cheap exforge 80 mg. Hydrogen gas offers an example of how a covalent (electron-sharing) bond fills the outermost shells of two atoms 000 heart attack generic exforge 80 mg on-line. Each of the two hydrogen atoms has just one electron in the first shell, which can accommodate two electrons. When joined together by a covalent bond (forming H2, a gas), each atom has, in effect, a "full" first shell of two electrons. As a result, H2 gas is more stable than the same two hydrogen atoms by themselves. An oxygen atom has eight electrons: Two of these fill the first electron shell, and the remaining six occupy the second electron shell (which can accommodate eight). Two oxygen atoms may join to form a molecule of oxygen gas by sharing two pairs of electrons, thus completing the outer shells of both atoms. Appendix B Chemistry Review B-5 Written formula Structural representation Structural formula with covalent bond Hydrogen (H2) H H H H Single covalent bond Oxygen (O2) O O O O Double covalent bond Water (H2O) O H O H H H Two single covalent bonds Figure B. A molecule of water forms from one oxygen and two hydrogen atoms because this combination completely fills the outermost shells of both hydrogen and oxygen. The prevalence of water on earth follows from the simple rule described earlier: Matter is most stable when it contains the least potential energy. That is, both hydrogen and oxygen are more stable when together (as H2O) than when they are independent atoms. Ionic Bonds Occur Between Oppositely Charged Ions A second way that atoms can fill their outer shell of electrons is to give up electrons completely (if they have only one or two electrons in their outermost shell) or to take electrons from other atoms (if they need one or two to fill their outermost shell). Such a loss (or gain) of electrons gives the atom a net charge, because now there are fewer (or more) negatively charged electrons than positively charged protons in the nucleus. The net charge is positive () for each electron lost and negative () for each electron gained. Note that ions can have a shortage or surplus of more than one electron (for example, Ca2 has lost two electrons). A positively charged ion is called a cation; a negatively charged ion is called an anion. It should come as no surprise that oppositely charged ions are attracted to each other. In aqueous (watery) solutions, where ionic bonds are not as strong as covalent bonds, ions tend to dissociate (break away) from each other relatively easily. In the human body, for example, almost all of the sodium is in the form of Na, and most of the chlorine is in its ionized form, called chloride (Cl). When positive and negative ions are united by ionic bonds, they are called ionic compounds. The physical and chemical properties of an ionic compound such as NaCl are very different from those of the original elements. For example, the original elements of NaCl are sodium, a soft, shiny metal, and chlorine, a yellow-green poisonous gas. Yet, as positive and negative ions, they form table salt, a white, crystalline substance that is common in our diet. In a crystal of NaCl, which has a cubic shape, the larger Cl ions are packed close together in a lattice structure. Ions in aqueous solutions are sometimes called electrolytes because solutions of water containing ions are good conductors of electricity. Cells can control the movement of certain ions, creating electrical forces essential to the functioning of nerves, muscles, and other living tissues.

Cells of the theca interna persist longer than those of the stratum granulosum but also show degenerative changes heart attack 34 years old proven exforge 80 mg. The theca cells increase in size blood pressure low buy cheap exforge 80 mg on line, lipid droplets appear in the cytoplasm pulse pressure 90 80mg exforge visa, and the cells assume an epithelioid character blood pressure medication new zealand discount 80 mg exforge visa, similar to that of lutein cells. The cells assume a cordlike arrangement, the cords being separated by connective tissue fibers and capillaries. The basal lamina between granulosa cells and the theca interna frequently becomes thicker and forms a hyalinized, corrugated layer, the glassy membrane. This structure is characteristic of growing follicles that have undergone atresia and aids in distinguishing a large atretic follicle from a corpus luteum. Other differences include degenerative changes in the granulosa cells and the presence of fragments of zona pellucida at the center of a follicle without an associated oocyte. Ultimately, the degenerated remains of the follicle are removed and a scar resembling a small corpus albicans is left. In some mammals, especially rodents, clusters of epithelioid cells are scattered in the stroma of the cortex. These interstitial cells contain small lipid droplets and bear a marked resemblance to luteal cells. It is thought that these interstitial cells arise from the theca interna of follicles that are undergoing atresia. In humans, interstitial cells are most abundant during the first year of life, the period during which atretic follicles are most numerous. Their exact role in ovarian physiology is unknown; in humans they elaborate androgens. Other large epithelioid cells, the hilus cells, are found associated with vascular spaces and unmyelinated nerves in the hilus of the ovary. The cells appear similar to the interstitial cells of the testis and contain lipid, lipochrome pigments, and cholesterol esters. Hilus cells are most commonly found during pregnancy and at menopause, but their function is unknown. Maturation of ovarian follicles, their endocrine functions, and the phenomenon of ovulation are regulated by the follicle stimulating and luteinizing hormones. Follicle-stimulating hormone is responsible for the growth of follicles and stimulates the aromatase enzyme complex within granulosa cells to produce estrogens and inhibin. The cyclic nature of follicle formation and ovulation is the result of reciprocal interaction between the hypothalamic-pituitary axis and ovarian hormones. The ovarian steroid hormones have only minor effects on the pituitary directly; their primary action is mediated through neurons in the hypothalamus. Oviducts the oviducts (uterine tubes) are a pair of muscular tubes that extend from the ovary to the uterus along the upper margin of the broad ligament. One end of the tube is closely related to the ovary and, at this end, is open to the peritoneal cavity. The oviduct delivers the ovum, released at ovulation, to the uterine cavity and provides an environment for fertilization and initial segmentation of the fertilized ovum. The ovarian end, the infundibulum, is funnel-shaped, and its margin is drawn out in numerous tapering processes called fimbria. The infundibulum opens into the tortuous, thin-walled ampulla of the tube, which makes up slightly more than half the length of the oviduct. The ampulla is continuous with the isthmus, a narrower, cordlike portion that makes up about the medial one-third. The intramural (interstitial) part is the continuation of the tube where it passes through the uterine wall. As in other hollow viscera, the wall of the oviduct consists of several layers: an external serosa, an intermediate muscularis, and an internal mucosa. In the ampulla the plicae have secondary and even tertiary folds to create a complex labyrinth of epithelial-lined spaces. In the isthmus the plicae are shorter with little branching, while in the intramural part the plicae form only low ridges. Throughout the tube, the plicae consist of a single layer of columnar epithelial cells resting on an incomplete basement membrane and a lamina propria of richly cellular connective tissue that contains a network of reticular fibers and fibroblasts. In women at 42 years of age the ability of the ovary to produce viable ova is reduced to about 50%. The ciliated cells are most numerous on the surface of the fimbria and progressively decrease in number through the ampulla, isthmus, and intramural portions.

Inferior cerebellar hemisphere atrophy in extreme preterm survivors is associated with increased disability blood pressure chart dental treatment buy 80 mg exforge mastercard. Vermis atrophy may follow severe perinatal ischaemic injury-associated cortical heart attack stop pretending discount exforge 80 mg visa, basal ganglia and brainstem lesions should be visible arrhythmia fatigue order exforge 80mg overnight delivery. It is the result of a severe neonatal encephalopathy due to an intrapartum hypoxic event pulse pressure 100 order 80 mg exforge mastercard. It has a poor prognosis if there is bulbar weakness or a tendency to aspiration pneumonia. Increases in limb length, and body and limb weight have adverse biomechanical effects on children with precarious mobility. Gross motor skills are often best late in the first decade and a child who was just walking may cease to: recognizing this prevents unwarranted hunts for neurodegenerative disease. Note that in more severely impaired children (Gross Motor Function Classification System (see Figure 4. Stability and decline in gross motor function among children and youth with cerebral palsy aged 2 to 21 years. Dyslexia, dyspraxia, dysgraphia-like problems may become evident in later years Mild dysarthria Increased emotional and peer problems Mainstream school with support. Extremes of the medical and social models of disability exaggerate, respectively, the importance of intrinsic impairment and environmental context on the disadvantage experienced by disabled people. In situations where we can do little to reduce impairment, devoting energy to improving the environment in which the impaired child lives may have much greater effects on participation. Management of spasticity and contractures Spasticity: excessive and inappropriate involuntary muscle activity, causing a velocity-dependent increase in resistance to passive muscle stretch, i. Realistic treatment goals should be agreed prior to treatment, and are the criteria against which treatment success is assessed. Assessment History Pain, discomfort and ease of care, and the impact of these on the life of child and family. Clinical measures of motor impairment and function Assessment of motor impairment and function should be inter-disciplinary, involving physiotherapists, occupational therapists and orthopaedic surgeons. Numerous structured observational scales and questionnaires exist for measuring motor impairments and functions of daily living. Simple and widely used, but not entirely reliable as speed of movement is not specified. Five-point ordinal scale, scored for the following body parts: eyes, mouth, neck, trunk, and each limb. It is more reliable in children over 2 yrs old, but ignores quality of performance and upper limb functions. Gross motor function measure this is a more involved measure consisting of 66 motor tasks grouped into five dimensions. It can detect change over time, thus it has been used for detecting response to therapy, and defining the prognosis for ambulation. Other measures A wide variety of specialist scales exist to assess specific constructs. The aims of physiotherapy are to retain and improve function, and to preserve muscle length. They could potentially worsen spasticity although others emphasize the importance of maintaining muscle strength. Recent studies suggest training antagonists of shortened muscles may improve function.

Studies have shown that the most effective exercise programs include weight-bearing exercises such as jogging heart attack vol 1 pt 15 cheap exforge 80mg otc, stair climbing prehypertension bp generic exforge 80 mg with mastercard, and resistance training arteria in english purchase exforge 80 mg fast delivery. For example prehypertension and stress 80mg exforge mastercard, bisphosphonates are associated with several gastrointestinal side effects, including abdominal pain, constipation, diarrhea, heartburn, irritation of the esophagus, and difficulty swallowing. Chapter 11 Nutrients Involved in Bone Health 437 effective treatment and prevention option for osteoporosis. RecaP Osteoporosis is a major disease of concern for elderly men and women in the United States. Osteoporosis increases the risk for fractures and premature death from subsequent illness. Factors that increase the risk for osteoporosis include genetics, being female, being of the Caucasian or Asian race, low levels of estrogen, cigarette smoking, alcohol abuse, sedentary lifestyle, and diets low in calcium and vitamin D. A healthy diet and regular physical activity can reduce your risk of osteoporosis. See for Yourself Calculate Your Risk for Osteoporosis One in three women and one in eight men will develop osteoporosis in their lifetimes. If you answered yes to any of these questions, it does not mean you have osteoporosis. Discuss your results with your doctor, who can advise you on whether a bone density test is recommended. Do you suffer frequently from diarrhea (caused by problems such as celiac disease or Crohn disease)? Have your periods stopped for 12 months or more (other than because of pregnancy)? Have you ever suffered from impotence, lack of libido, or other symptoms related to low testosterone levels? People at risk for low calcium intakes include elderly people, people who do not consume enough minerals in their diets, and people who do not consume enough food to maintain a healthful weight. Osteoporosis is more common among elderly women, but elderly men are also at increased risk for osteoporosis. Young women who suffer from an eating disorder and menstrual cycle irregularity, referred to as the female athlete triad, may also have osteoporosis. When exposed to sunlight, our bodies can convert a cholesterol compound in our skin to vitamin D. There are many good sources of calcium besides dairy foods, including calciumfortified juices and soy/rice beverages and green leafy vegetables such as kale, broccoli, and collard greens. Recent studies indicate that overweight and obese people are more likely to have poor vitamin D status than people of normal weight. Bone size is determined during growth, bone shape is determined during modeling and remodeling, and bone remodeling also affects the density of bone. Calcium levels are maintained in the blood at all times; calcium is also necessary for normal nerve transmission, muscle contraction, healthy blood pressure, and blood clotting. Consuming excess calcium leads to mineral imbalance, and consuming inadequate calcium causes osteoporosis. Vitamin D regulates blood calcium levels, regulates absorption of calcium and phosphorus from the intestines, and helps maintain bone health. Hypercalcemia results from consuming too much vitamin D, causing weakness, loss of appetite, diarrhea, vomiting, and formation of calcium deposits in soft tissues. Vitamin D deficiency leads to loss of bone mass, causing rickets in children or osteomalacia and osteoporosis in adults. Vitamin K is a fat-soluble vitamin that is obtained in the diet and is also produced in the large intestine by normal bacteria. Magnesium is a major mineral that is part of the structure of bone, influences the formation of hydroxyapatite crystals and bone health through its regulation of calcium balance and the actions of vitamin D and parathyroid hormone, and is a cofactor for more than 300 enzyme systems. Fluoride is a trace mineral that strengthens teeth and bones and reduces the risk for dental caries. Osteoporosis is a major bone disease in the United States, affecting more than 10 million Americans.

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