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By P. Vandorn. University of Wisconsin-Milwaukee.

Hyperopia (farsightedness) is a condition in which the eyeball is too short 5 mg buspar free shipping, which causes light rays to be brought to a focal point behind the retina purchase 5mg buspar amex. Although visual accommodation aids a hyperopic person, it generally does not help enough for the person to clearly see very close or distant Hyperopia Convex lens corrects (farsightedness) farsightedness objects. In order to read print on a page, a person with presbyopia must hold the page farther from the eyes than the normal reading distance. Astigmatism is a condition in which an irregular curvature of the cornea or lens of the eye distorts the refraction of light rays. If a person with astigmatism views a circle, the image will not appear clear in all 360 degrees; the part of the circle that appears blurred Astigmatism Uneven lens corrects can be used to map the astigmatism. Rays do not focus astigmatism (d) Various glass or plastic lenses are generally prescribed for people with the visual impairments just described. Myopia may be corrected with a biconcave lens; hyperopia with a biconvex FIGURE 15. Correction for astigmatism If the eye is too long, as in myopia (b), the focus is in front of the retina. If the eye is too requires a careful assessment of the irregularities and a prescrip- short, as in hyperopia (c), the focus is behind the retina. In astigmatism (d), light refraction is uneven As an alternative to a concave lens, a surgical procedure because of an abnormal shape of the cornea or lens. In this technique, 8 to 16 microscopic slashes, like the spokes of a wheel, are made in the cornea from Cataracts the center to the edge. The ocular pressure inside the eyeball A cataract is a clouding of the lens that leads to a gradual blur- bulges the weakened cornea and flattens its center, changing the ring of vision and the eventual loss of sight. It is caused by injury, poisons, infections, tened by vaporizing microscopic slivers from its surface. Recent evidence indicates that even exces- sive UV light may cause cataracts. Sensory Organs © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 532 Unit 5 Integration and Coordination a tiny intraocular lens that either clips to the iris or is secured into A normal, healthy person who has overindulged in alcoholic the vacant lens capsule. Special contact lenses or thick lenses for beverages may experience diplopia. Infections and Diseases of the Eye Retinal Damage Retinal detachment is a separation of the nervous or visual layer Infections of the retina from the underlying pigment epithelium.

Although somewhat rare buy buspar 5 mg with amex, there are documented cases of inherited diseases in which a point mutation in- Proglucagon volving an amino acid residue at the cleavage site results in an inability to convert the prohormone into active hor- N-peptide Glucagon IP-1 GLP-1 IP-2 GLP-2 mone buy buspar 5mg visa, resulting in a state of hormone deficiency. Partially Pancreatic Gastrointestinal alpha cells tract ACTH Glicentin γ-MSH α-MSH CLIP γ-LPH β-Endorphin Proopiomelanocortin N-peptide N-peptide Glucagon IP-1 (POMC) Glucagon GLP-1 AVP Neurophysin IP-2 Propressophysin IP-1 GLP-1 IP-2 GLP-2 GLP-2 FIGURE 31. In alpha cells of the pancreas (left), the major bioactive product formed from proglucagon is glucagon it- FIGURE 31. It is not currently known whether the other peptides are tive sizes of individual peptides are only ap- processed to produce biologically active molecules. MSH melanocyte-stimulating hormone; CLIP cells (right), proglucagon is cleaved to produce the four peptides corticotropin-like intermediate lobe peptide; LPH shown. Glicentin is the major glucagon-containing peptide in the lipotropin; AVP arginine vasopressin; TRH thyrotropin- intestine. IP-1, intervening peptide 1; IP-2, intervening peptide 2; releasing hormone. The product of the insulin gene is a peptide known beta cell insulin secretory capacity. As with other secretory peptides, the who are receiving exogenous insulin injections, the meas- prepeptide or signal peptide is cleaved off early in the urement of circulating insulin levels would not provide any biosynthetic process, yielding proinsulin. Proinsulin is an useful information about their own pancreatic function be- 86-amino acid protein that is subsequently cleaved at two cause it would primarily be the injected insulin that would sites to yield insulin and a 31-amino acid peptide known as be measured. Insulin and C-peptide are, therefore, localized in such patients would provide an indirect measure of how within the same secretory vesicle and are co-secreted into well the beta cells were functioning with regard to insulin the bloodstream. In most processing in the Golgi apparatus, peptide hormones are cases, 90% or more of steroid and thyroid hormones in the stored in membrane-enclosed secretory vesicles. Some of the plasma pro- of the peptide hormone occurs by exocytosis; the secretory teins that bind hormones are specialized, in that they have a vesicle is translocated to the cell surface, its membrane considerably higher affinity for one hormone over another, fuses with the plasma membrane, and its contents are re- whereas others, such as serum albumin, bind a variety of hy- leased into the extracellular fluid. The extent to which a hormone is pro- tory vesicle and membrane fusion are triggered by an in- tein-bound and the extent to which it binds to specific ver- crease in cytosolic calcium stemming from an influx of sus nonspecific transport proteins vary from one hormone to calcium into the cytoplasm from internal organelles or the another. The principal binding proteins involved in specific extracellular fluid. In some cells, an increase in cAMP and and nonspecific transport of steroid and thyroid hormones the subsequent activation of protein kinases is also involved are listed in Table 31.

By P. Vandorn. University of Wisconsin-Milwaukee.

Hyperopia (farsightedness) is a condition in which the eyeball is too short 5 mg buspar free shipping, which causes light rays to be brought to a focal point behind the retina purchase 5mg buspar amex. Although visual accommodation aids a hyperopic person, it generally does not help enough for the person to clearly see very close or distant Hyperopia Convex lens corrects (farsightedness) farsightedness objects. In order to read print on a page, a person with presbyopia must hold the page farther from the eyes than the normal reading distance. Astigmatism is a condition in which an irregular curvature of the cornea or lens of the eye distorts the refraction of light rays. If a person with astigmatism views a circle, the image will not appear clear in all 360 degrees; the part of the circle that appears blurred Astigmatism Uneven lens corrects can be used to map the astigmatism. Rays do not focus astigmatism (d) Various glass or plastic lenses are generally prescribed for people with the visual impairments just described. Myopia may be corrected with a biconcave lens; hyperopia with a biconvex FIGURE 15. Correction for astigmatism If the eye is too long, as in myopia (b), the focus is in front of the retina. If the eye is too requires a careful assessment of the irregularities and a prescrip- short, as in hyperopia (c), the focus is behind the retina. In astigmatism (d), light refraction is uneven As an alternative to a concave lens, a surgical procedure because of an abnormal shape of the cornea or lens. In this technique, 8 to 16 microscopic slashes, like the spokes of a wheel, are made in the cornea from Cataracts the center to the edge. The ocular pressure inside the eyeball A cataract is a clouding of the lens that leads to a gradual blur- bulges the weakened cornea and flattens its center, changing the ring of vision and the eventual loss of sight. It is caused by injury, poisons, infections, tened by vaporizing microscopic slivers from its surface. Recent evidence indicates that even exces- sive UV light may cause cataracts. Sensory Organs © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 532 Unit 5 Integration and Coordination a tiny intraocular lens that either clips to the iris or is secured into A normal, healthy person who has overindulged in alcoholic the vacant lens capsule. Special contact lenses or thick lenses for beverages may experience diplopia. Infections and Diseases of the Eye Retinal Damage Retinal detachment is a separation of the nervous or visual layer Infections of the retina from the underlying pigment epithelium.

Although somewhat rare buy buspar 5 mg with amex, there are documented cases of inherited diseases in which a point mutation in- Proglucagon volving an amino acid residue at the cleavage site results in an inability to convert the prohormone into active hor- N-peptide Glucagon IP-1 GLP-1 IP-2 GLP-2 mone buy buspar 5mg visa, resulting in a state of hormone deficiency. Partially Pancreatic Gastrointestinal alpha cells tract ACTH Glicentin γ-MSH α-MSH CLIP γ-LPH β-Endorphin Proopiomelanocortin N-peptide N-peptide Glucagon IP-1 (POMC) Glucagon GLP-1 AVP Neurophysin IP-2 Propressophysin IP-1 GLP-1 IP-2 GLP-2 GLP-2 FIGURE 31. In alpha cells of the pancreas (left), the major bioactive product formed from proglucagon is glucagon it- FIGURE 31. It is not currently known whether the other peptides are tive sizes of individual peptides are only ap- processed to produce biologically active molecules. MSH melanocyte-stimulating hormone; CLIP cells (right), proglucagon is cleaved to produce the four peptides corticotropin-like intermediate lobe peptide; LPH shown. Glicentin is the major glucagon-containing peptide in the lipotropin; AVP arginine vasopressin; TRH thyrotropin- intestine. IP-1, intervening peptide 1; IP-2, intervening peptide 2; releasing hormone. The product of the insulin gene is a peptide known beta cell insulin secretory capacity. As with other secretory peptides, the who are receiving exogenous insulin injections, the meas- prepeptide or signal peptide is cleaved off early in the urement of circulating insulin levels would not provide any biosynthetic process, yielding proinsulin. Proinsulin is an useful information about their own pancreatic function be- 86-amino acid protein that is subsequently cleaved at two cause it would primarily be the injected insulin that would sites to yield insulin and a 31-amino acid peptide known as be measured. Insulin and C-peptide are, therefore, localized in such patients would provide an indirect measure of how within the same secretory vesicle and are co-secreted into well the beta cells were functioning with regard to insulin the bloodstream. In most processing in the Golgi apparatus, peptide hormones are cases, 90% or more of steroid and thyroid hormones in the stored in membrane-enclosed secretory vesicles. Some of the plasma pro- of the peptide hormone occurs by exocytosis; the secretory teins that bind hormones are specialized, in that they have a vesicle is translocated to the cell surface, its membrane considerably higher affinity for one hormone over another, fuses with the plasma membrane, and its contents are re- whereas others, such as serum albumin, bind a variety of hy- leased into the extracellular fluid. The extent to which a hormone is pro- tory vesicle and membrane fusion are triggered by an in- tein-bound and the extent to which it binds to specific ver- crease in cytosolic calcium stemming from an influx of sus nonspecific transport proteins vary from one hormone to calcium into the cytoplasm from internal organelles or the another. The principal binding proteins involved in specific extracellular fluid. In some cells, an increase in cAMP and and nonspecific transport of steroid and thyroid hormones the subsequent activation of protein kinases is also involved are listed in Table 31.