By N. Brontobb. Spertus College.
The increase in Expiration lung volume during full inspiration is shown by comparison with the lung volume in full expiration (dashed lines) 100 mg viagra jelly free shipping. For the most part best 100mg viagra jelly, expiration is a passive process that occurs as the muscles of inspiration are relaxed and the rib cage returns to its original position. The lungs recoil during expiration as elastic fibers within the lung tissue shorten and the pulmonary alveoli draw to- gether. Lowering of the surface tension in the pulmonary alveoli, Van De Graaff: Human VI. Respiratory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 620 Unit 6 Maintenance of the Body FIGURE 17. The principal muscles of inspiration are shown on the right side of the trunk and the principal mus- cles of forced expiration are shown on the left side. A deficiency in surfac- tant in premature infants can cause respiratory distress syndrome Respiratory Volumes and Capacities (RDS) or, as it is commonly called, hyaline membrane disease. The respiratory system is somewhat inefficient because the air Even under normal conditions, the first breath of life is a diffi- enters and exits at the same place, through either the nose or the cult one because the newborn must overcome large surface mouth. Consequently, there is an incomplete exchange of gas tension forces in order to inflate its partially collapsed pulmonary during each ventilatory cycle, and approximately five-sixths of alveoli. The transpulmonary pressure required for the first breath is 15 to 20 times that required for subsequent breaths, and an infant the air present in the lungs still remains when the next inspira- with respiratory distress syndrome must duplicate this effort with tion begins. Fortunately, many babies with this condition can be The amount of air breathed in a given time and the de- saved by mechanical ventilators that keep them alive long enough for gree of difficulty in breathing are important indicators of a per- their lungs to mature and manufacture sufficient surfactant. The amount of air exchanged during During forced expiration, such as coughing or sneezing, pulmonary ventilation varies from person to person according contraction of the interosseous portion of the internal intercostal to age, gender, activity level, general health, and individual dif- muscles causes the rib cage to be depressed. Respiratory volumes are measured with a spirometer cles may also aid expiration because, when contracted, they force (fig. Any ventilatory abnormalities can then be com- abdominal organs up against the diaphragm and further decrease pared to what is accepted as normal. Thus, intrapulmonary pressure can rise tory volumes and capacities are presented in table 17. Respiratory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 Chapter 17 Respiratory System 621 TABLE 17. Intercostal nerves Contraction of the external intercostal muscles and the interchondral portion of the internal intercostal muscles elevates the ribs, thus increasing the capacity of the thoracic cavity. With the exception of the residual Accessory, cervical, Forced inspiration is accomplished through volume, which is measured using special techniques, this instrument and thoracic nerves contraction of the scalenes and sternocleido- can determine respiratory air volumes. Pulmonary ventilation during forced inspiration usually occurs through the mouth TABLE 17. Expiration Tidal volume (TV) 500 cc Volume moved in or out of the lungs during quiet breathing Nerve stimuli to the inspiratory muscles cease and the muscles relax. Inspiratory reserve 3,000 cc Volume that can be inhaled during volume (IRV) forced breathing in addition to The rib cage and lungs recoil as air is forced out tidal volume of the lungs because of the increased pressure. Intercostal and lower Forced expiration occurs when the interosseus Expiratory reserve 1,000 cc Volume that can be exhaled during spinal nerves portion of the internal intercostal and volume (ERV) forced breathing in addition to abdominal muscles are contracted. Dyspnea may occur even when ventilation is normal, however, and may not occur even during exercise, when the total volume of air movement is very high. Some of the terms used to describe ventila- tion are defined in table 17. Nonrespiratory Air Movements Knowledge Check Air movements through the respiratory system that are not asso- 14. Describe the actions of the diaphragm and intercostal mus- ciated with pulmonary ventilation are termed nonrespiratory cles during relaxed inspiration. Describe how forced inspiration and forced expiration are as laughing, sighing, crying, or yawning, or they may function to produced. Indicate the respiratory volumes being used during a sneeze, a deep inspiration prior to jumping into a swim- ming pool, maximum ventilation while running, and quiet breathing while sleeping. Respiratory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 622 Unit 6 Maintenance of the Body FIGURE 17. Stimulus may be foreign material expiration that results abruptly opens the glottis, sending a blast irritating the larynx or trachea. Sneezing Similar to a cough, except that the forceful expired air is directed primarily Reflexive response to irritating stimulus of the nasal mucosa. Sighing Deep, prolonged inspiration followed by a rapid, forceful expiration. The inspired air Usually reflexive in response to drowsiness, fatigue, or is usually held for a short period before sudden expiration. Crying Similar to laughing, but the glottis remains open during entire Somewhat reflexive but under voluntary control. Hiccuping Spasmodic contraction of the diaphragm while the glottis is closed, Reflexive; serves no known function. Respiratory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 Chapter 17 Respiratory System 623 REGULATION OF BREATHING The rhythm of breathing is controlled by centers in the brain stem. These centers are influenced by higher brain function and regu- lated by sensory input that makes breathing responsive to the changing respiratory needs of the body. Objective 15 Describe the functions of the pneumotaxic, apneustic, and rhythmicity centers in the brain stem.
LH binds to specific membrane receptors on two-cell buy discount viagra jelly 100mg on line, two-gonadotropin hypothesis requires recogni- theca cells buy discount viagra jelly 100mg on-line, activates adenylyl cyclase through a G protein, tion that the actions of FSH are restricted to granulosa cells and increases the production of cAMP. LH LDL receptor mRNA, the uptake of LDL cholesterol, and actions, on the other hand, are exerted on theca, granulosa, cholesterol ester synthesis. The port of cholesterol from the outer to the inner mitochondr- expression of LH receptors is time-dependent because ial membrane, the site of pregnenolone synthesis, using a theca cells acquire LH receptors at a relatively early stage, unique protein called steroidogenic acute regulatory pro- whereas LH receptors on granulosa cells are induced by tein (StAR). Pregnenolone, a 21-carbon steroid of the FSH in the later stages of the maturing follicle. Aromatase is expressed only in granulosa Two steroidogenic pathways may be used for subse- cells, and its activation and induction are regulated by quent steroidogenesis (see Fig. Granulosa cells are deficient in 17 -hydroxylase delta 5 pathway is predominant; in granulosa cells and the and cannot proceed beyond the C-21 progestins to gen- corpus luteum, the delta 4 pathway is predominant. Conse- nenolone gets converted to either progesterone by 3 -hy- quently, estrogen production by granulosa cells depends droxysteroid dehydrogenase in the delta 4 pathway or to on an adequate supply of exogenous aromatizable andro- 17 -hydroxypregnenolone by 17 -hydroxylase in the gens, provided by theca cells. In the delta 4 pathway, progesterone gets cells produce androgenic substrates, primarily an- converted to 17 -hydroxyprogesterone (by 17 -hydroxy- drostenedione and testosterone, which reach the granu- lase), which is subsequently converted to androstenedione losa cells by diffusion. The androgens are then converted and testosterone by 17,20-lyase and 17 -hydroxysteroid to estrogens by aromatization. In In follicles, theca and granulosa cells are exposed to dif- the delta 5 pathway, 17 -hydroxypregnenolone gets con- ferent microenvironments. Vascularization is restricted to verted to dehydroepiandrosterone (by 17,20-lyase), which the theca layer because blood vessels do not penetrate the Theca cell Granulosa cell Cholesterol Cholesterol cAMP LH FIGURE 38. The follicular theca cells, un- Progesterone der control of LH, produce 17OH pregnenolone androgens that diffuse to the follicular granulosa cells, Androstenedione where they are converted to Dehydroepiandrosterone cAMP estrogens via an FSH-sup- Testosterone ported aromatization reac- tion. The dashed line indi- Androstenedione ATP FSH cates that granulosa cells cAMP cannot convert progesterone Estradiol Estrone to androstenedione because Testosterone of the lack of the enzyme 17 -hydroxylase. Theca cells, therefore, have better ac- hypertrophy and may remain in the ovary for extended pe- cess to circulating cholesterol, which enters the cells via riods of time. Granulosa cells, on the other hand, prima- rily produce cholesterol from acetate, a less efficient process than uptake. In addition, granulosa cells are bathed Meiosis Resumes During the Periovulatory Period in follicular fluid and exposed to autocrine, paracrine, and All healthy oocytes in the ovary remain arrested in prophase juxtacrine control by locally produced peptides and growth of the first meiosis. This maturation is accomplished FSH acts on granulosa cells by a cAMP-dependent by two successive cell divisions in which the number of chro- mechanism and produces a broad range of activities, in- mosomes is reduced, producing haploid gametes. At fertil- cluding increased mitosis and cell proliferation, the stimu- ization, the diploid state is restored. As the follicle first meiosis) have duplicated their centrioles and DNA matures, the number of receptors for both gonadotropins (4n DNA) so that each chromosome has two identical increases. Crossing over and chromatid exchange occur tors and induces the appearance of LH receptors. The re- bined activity of the two gonadotropins greatly amplifies sumption of meiosis, ending the first meiotic prophase estrogen production. At low concentrations, andro- breakdown), and alignment of the chromosomes on the gens enhance aromatase activity, promoting estrogen pro- equator of the spindle. At high concentrations, androgens are converted ogous chromosomes move in opposite directions under by 5 -reductase to a more potent androgen, such as dihy- the influence of the retracting meiotic spindle at the cel- drotestosterone (DHT). At meiotic telophase 1, an unequal divi- by androgens, the intrafollicular androgenic environment sion of the cell cytoplasm yields a large secondary oocyte antagonizes granulosa cell proliferation and leads to apop- (2n DNA) and a small, nonfunctional cell, the first polar tosis of the granulosa cells and subsequent follicular atresia. Each cell contains half the original 4n number of chromosomes (only one member of each ho- Follicular Atresia Probably Results From a mologous pair is present, but each chromosome consists Lack of Gonadotropin Support of two unique chromatids). The secondary oocyte is formed several hours after the Follicular atresia, the degeneration of follicles in the ovary, initiation of the LH surge but before ovulation. It rapidly is characterized by the destruction of the oocyte and gran- begins the second meiotic division and proceeds through a ulosa cells. Atresia is a continuous process and can occur at short prophase to become arrested in metaphase. During a woman’s life- stage, the secondary oocyte is expelled from the graafian time approximately 400 to 500 follicles will ovulate; those follicle. In re- are the only follicles that escape atresia, and they represent sponse to penetration by a spermatozoon during fertiliza- a small percentage of the 1 to 2 million follicles present at tion, meiosis 2 resumes and is rapidly completed. The cause of follicular atresia is likely due to lack of unequal cell division soon follows, producing a small sec- gonadotropin support of the growing follicle. For example, ond polar body (1n DNA) and a large fertilized egg, the at the beginning of the menstrual cycle, several follicles are zygote (2n DNA, 1n from the mother and 1n from the fa- selected for growth but only one follicle, the dominant fol- ther). The first and second polar bodies either degenerate licle, will go on to ovulate. Because the dominant follicle or divide, yielding small nonfunctional cells. If fertilization has a preferential blood supply, it gets the most FSH (and does not occur, the secondary oocyte begins to degenerate LH). Other reasons for the lack of gonadotropin support of within 24 to 48 hours. FOLLICLE SELECTION AND OVULATION During atresia, granulosa cell nuclei become pyknotic (referring to an apoptotic process characterized by DNA The number of ovulating eggs is species-specific and is in- laddering), and/or the oocyte undergoes pseudomatura- fluenced by genetic, nutritional, and environmental factors. During the early stages of In humans, normally only one follicle will ovulate, but mul- oocyte death, the nuclear membrane disintegrates, the tiple ovulations in a single cycle (superovulation) can be chromatin condenses, and the chromosomes form a induced by the timed administration of gonadotropins or metaphase plate with a spindle; the term pseudomaturation is antiestrogens. The mechanism by which one follicle is se- appropriate because these oocytes are not capable of suc- lected from a cohort of growing follicles is poorly under- cessful fertilization.
He’s actually had chest pain off and on for 3 days 100mg viagra jelly visa, not just for 2 minutes buy 100 mg viagra jelly overnight delivery. If there is any question of altered level of conscious- ness or abnormal behavior, then the observations of the family or friends may be absolutely crucial. Lack of English Is No Excuse—for You The law says it is our fault if a language barrier interferes with communication. All of us, or our ances- tors, came from somewhere else, even Native Americans. Immigrants often do not have insurance and they are disproportionately repre- sented among our patients in the ED. There is not only a language variation but a cultural variation as well. Depending on the background of the physi- cian, we may be misled by these cultural differences. In some cultures, it is deemed disrespectful to let the doctor think you do not understand him or her. Perhaps you have had the experience of asking the patient if he or she understands what you’re saying, and he or she nods yes. You then ask if he or she is totally confused, and he or she nods yes again. Were you to ask if the patient was eaten by a horse, you may receive another nod yes. By this time, it may occur to you that you have a language as well as a cultural problem. However, AT&T provides a 24-hour foreign-language hotline that can be extremely helpful if you do not have an interpreter available. Trained volunteers speak by phone with both the physician and the patient, and I have found this service to be excellent. You might consider installing a phone with two hand- sets so that you can both speak with the interpreter simultaneously. How- ever, be aware of socially sensitive situations, particularly regarding Ob/Gyn issues. In legal proceedings such as depositions and in court, a stenographer records every single word spoken; nowadays, stenographers use tape 104 Bresler recorders and computerized stenographs. Nevertheless, the eternal truth according to plaintiff attorneys is as follows: “If it wasn’t documented, it wasn’t done. It will not be sufficient in front of a jury to say that you did not document pertinent details because they were negative. Be Careful When Using Template Charts Template (check-off) charting is useful for billing documentation. Sometimes it is tempting to check off items that were not actually performed. Finally, always write or dictate a summary note, except in the most routine cases (e. It is very difficult to defend your thought process if it is not apparent from the chart. Check marks and circles do not explain why you sent that chest pain patient home. Read the Nursing Notes Read these notes—even if they are not written for you. This may sometimes be true for inpatient charting, such as noting family visits, bowel movements, and so on. I have seen many legal cases lost and a few won because of the nursing notes. You should read them before enter- ing the examining room, periodically during the course of the patient’s stay, and certainly when you write or dictate your own notes. If you disagree with something in the nursing notes, then mention that in your own notes and the reason that you feel the nursing note is not correct. Nurses and paramedics often function under severe time con- straints and may not complete their charting until much later. Three rules you should follow in reviewing nursing and paramedic notes include the following: (a) Beware of notes written after the patient Chapter 9 / Emergency Medicine 105 leaves the emergency department; (b) beware of notes written after you have completed your chart; and (c) document if the paramedic notes are not available to you. After-Care Instructions Are Crucial Both in Writing and in Reality Ensure that your patient understands what to do. Studies have shown that as many as two-thirds of patients have no idea what the instruc- tions they were given actually say. Review the after-care instructions with the patient yourself, at least verbally. Ideally, have the patient repeat the instructions back to you, preferably in a language you both understand. You can then have the nurse provide written instructions and explain them one more time when the patient is actually discharged. I would strongly urge that family be included in the instruction process. Often, the patient is too distracted by pain, fear, or relief to fully comprehend your instructions. If there is any question of altered level of consciousness, such as head injury, then instructing the family is particularly crucial.
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