You will also learn that the human lungs are so efficiently designed that gas exchange can increase over 20-fold to remove carbon dioxide and to supply oxygen to tissues in order to meet the body’s energy demands purchase vardenafil 20mg otc impotence blog. For example purchase vardenafil 10mg without a prescription impotence 18 year old, a marathon runner who staggers across the 26-mile finish line in <3 hours or someone who swims the English Channel in record time is rarely limited by the amount of oxygen taken up or carbon dioxide removed by the lungs order vardenafil 20mg on line erectile dysfunction treatment for diabetes. These examples of human activity not only underscore the functional capacity of the lungs but also illustrate the important role respiration plays in body’s extraordinary adaptability to the external environment. Finally, you will learn that respiratory physiology plays a critical role in medicine, because of the impact that many of the respiratory diseases (e. Gas exchange involves the transfer of oxygen and carbon dioxide between the atmosphere and the lungs. The first involves the exchange of oxygen and carbon dioxide from the cells of the body. The second step is intracellular and involves a series of complex metabolic reactions that burns fuel, releasing carbon dioxide and energy. Recall that oxygen is required in the final step of cellular respiration to serve as an electron acceptor in the process by which cells obtain energy. The respiratory system can be divided into the following components: ventilation and the mechanics of breathing, gas transfer and transport, pulmonary circulation, and the control of breathing. This chapter discusses ventilation, the mechanics of breathing, and the work of breathing. Chapter 20 discusses the pulmonary circulation and the matching of airflow with blood flow in the lungs. Chapter 21 deals with basic breathing rhythms, breathing reflexes, integrated control of breathing, and the control of breathing in unusual environments. The lungs alone cannot bring air in and out of the lungs or exchange oxygen and carbon dioxide from the blood. For example, without respiratory muscles and an airtight chest wall to create a negative pressure within the chest, the lungs would become nonfunctional in gas exchange. Moreover, without blood flow going to the lungs and the matching of airflow with blood flow, there would be essentially no gas exchange. The human gas exchange organ consists of two lungs, each divided into several lobes. The lungs comprise two tree-like structures, the vascular tree and the airway tree, which are embedded in highly elastic connective tissue. The vascular tree consists of arteries and veins connected by capillaries (see Chapter 20). The airway tree consists of a series of hollow branching tubes that decrease in diameter at each branching (Fig. Each bronchus enters a lung and branches many times into progressively smaller bronchi, which, in turn, form bronchioles. The airway tree consists of a series of highly branched hollow tubes that become narrower, shorter, and more numerous as they penetrate the deeper parts of the lung. The airways are divided into two functional zones with the first 16 generations of branches comprising the conducting zone and functioning to conduct air to the deeper parts of the lungs. The last seven generations participate in gas exchange and comprise the respiratory zone. The trachea and the first 16 generations of airway branches make up the conducting zone. The trachea, bronchi, and bronchioles of the conducting zone have three important functions to (1) warm and humidify inspired air, (2) distribute air evenly to all regions of the lungs, and (3) serve as part of the body’s defense system (removal of dust, bacteria, and noxious gases from the lungs). The first four generations of the conducting zone are subjected to changes in negative and positive pressures and contain a considerable amount of cartilage to prevent airway collapse. Further down, in the lobar and segmental bronchi, the cartilaginous rings give way to small plates of cartilage. Bronchioles are suspended by elastic tissue in the lung parenchyma, and the elasticity of the lung tissue helps keep these airways open. The conducting zone has its own separate circulation, the bronchial circulation, which originates from the descending aorta and drains into the pulmonary veins. The last seven generations of airways make up the respiratory zone and is the site of gas exchange. The exchange of gases is accomplished in the mosaic of millions of specialized cells that form thin- walled air sacs called alveoli. Like the conducting zone, the respiratory zone has its own separate and distinct circulation, the pulmonary circulation. The pulmonary circulation receives all of the cardiac output, and therefore, blood flow is high. The formation of outpockets from the small airways to form alveoli accomplishes an increase in internal surface area (see Fig. As mentioned above, a network of capillaries surrounds each alveolus and brings blood into close proximity with air inside the alveolus. Adult lungs contain 300 to 500 million alveoli, with a 2 combined internal surface area of ~75 m, which is approximately the size of a tennis court. During growth, alveolar surface area increases in two ways: in alveolar number and in diameter, as seen in Table 18. However, after adolescence, alveoli only increase in size and, if damaged, have limited ability to repair themselves. Cigarette smoke, for example, can destroy alveoli and lead to concomitant decrease in alveolar surface area for gas exchange. In the respiratory zone, a group of alveolar ducts and their alveoli merge with pulmonary capillaries to form a terminal respiratory unit; there are ~60,000 of these units in both lungs. The alveolar–capillary membrane of these units forms a blood–gas interface, sometimes referred to as blood–gas barrier that separates the blood in the pulmonary capillaries from the gas in the alveoli (Fig. It consists of an alveolar membrane separated by a capillary membrane by interstitial fluid and is essentially a fluid barrier. The architectural design provides a large surface area for the diffusion of oxygen and carbon dioxide. Air is brought to one side of the interface by ventilation-the movement of air to and from the alveoli. As the blood perfuses the alveolar capillaries, oxygen is taken up and carbon dioxide crosses the blood–gas interface by diffusion. The respiratory muscles include the diaphragm, intercostal muscles, scalene muscles of the neck, and the sternocleidomastoids, which are inserted into the top of the sternum. The lungs are housed in an airtight thoracic cavity and are separated from the abdomen by the large dome-shaped skeletal muscle, the diaphragm (Fig. The thoracic cavity is made up of 12 pairs of ribs, the sternum, and internal and external intercostal muscles, which lie between the ribs. The rib cage is hinged to the vertebral column, allowing it to be raised and lowered during breathing. The space between the lungs and chest wall is the pleural space, which contains a thin layer of fluid (~10 μm thick), that functions, in part, as a lubricant so the lungs can slide against the chest wall.
A physical examination and psychiatric medications include antidepressants purchase generic vardenafil online erectile dysfunction doctors in st louis mo, laboratory testing rule out an underlying medical mood stabilizers order discount vardenafil erectile dysfunction blood pressure, anti-anxiety medications discount 10 mg vardenafil mastercard erectile dysfunction treatment alprostadil, stim- condition as the etiological agent of the signs and ulants, and antipsychotics. Laboratory testing may include blood contact with reality that usually includes delu- tests, imaging tests, urinalysis, hormone testing, sions (false beliefs about what is taking place or and electroencephalogram to measure and record who one is) and hallucinations (seeing or hearing the electrical activity of the brain. The inter- recommended when patients can’t care for them- view will cover a wide range of topics. Additional assessment may include nia or excessive sleep; change in appetite; personality, reasoning, aptitude, and intelligence difficulty concentrating, thinking, or making quotient testing. Psychotherapy helps physical examination, laboratory testing, and patients understand the behaviors, emotions, comprehensive psychiatric evaluation. Treat- and ideas that contribute to their mental disor- ment may include antidepressant medications, der. The knowledge and insights gained during psychotherapy, electroconvulsive therapy, and psychotherapy help patients manage the signs other brain stimulation therapies. Behavior Observed: Mannerisms, expression, eye contact Attitude Observed: Pleasant, cooperative, agitated, hostile, open, secretive, evasive, suspicious, apathetic, easily distracted, focused, defensive Level of consciousness Observed: Is the patient conscious? Speech and language Observed: Are speech and language normal in tone, volume, and quantity? Thought process Observed/inquired: Are the patient’s responses to general questioning logical, relevant, and organized? Are there thoughts or images you have a really difficult time getting out of your head? Does it ever seem like people are stealing your thoughts or perhaps inserting thoughts into your head? Suicidality and homicidality Inquired: Do you ever feel that life isn’t worth living? Do you think about hurting others or getting even with people who have wronged you? If you found a stamped, addressed envelope on the street, what would you do with it? Attention span Observed/inquired: I will recite a series of numbers to you, and then I will ask you to repeat them to me, first forward and then backward. Starting with 100, subtract 7 from 100, and then keep subtracting 7 from that number as far as you can go. I am going to ask you to remember three words and I will ask you to repeat them to me in 5 minutes. Intellectual functioning Observed/inquired: Name the current president and vice president. It is a myth that depres- estimated prevalence of paranoid personality sion is part of the aging process. Many senior citizens • Schizoid personality disorder-They are think that depression is a character flaw. They themselves for their depression and are too ashamed to get are often distant, detached, or indifferent to help. People with this dis- Personality Disorders order usually have cognitive or perceptual distortions as well as eccentricities in their A deeply ingrained, inflexible pattern of relat- everyday behavior. The estimated preva- ing, perceiving, and thinking that is serious lence of schizotypal personality is 5% of enough to cause distress or impaired function- adults in the United States. Personality • Obsessive–compulsive personality dis- disorders occur in approximately 9% of adults order-They have a preoccupation with in the United States. Their inflexibility often makes • Antisocial personality disorder-They them incapable of adapting to change. They repeatedly perform acts that are grounds are never satisfied with their accomplish- for arrest. They lack often making it difficult for them to make remorse for their behavior, and they are decisions or complete tasks. The esti- mated prevalence of obsessive–compulsive mated prevalence of antisocial personality personality disorder is 1% of adults in the disorder is 1% in adults in the United States. They can’t avoid work or social activities that involve make decisions without the advice of oth- socializing or interacting with others. They feel uncomfortable and helpless estimated prevalence is 5% of adults in the when alone. They have are attention-seekers that always need an unstable and fluctuating self-image. The estimated prevalence of bor- may engage in seductive or provocative derline personality disorder is 2% of adults behavior to draw attention to themselves. The estimated prevalence of histrionic Chapter Fifteen Mental Disorders L 345 personality disorder is 2% of adults in the followed by behavior that compensates United States. Signs and symptoms of buli- personality disorder is 1% of adults in the mia nervosa may include damaged teeth United States. An estimated 1% of volatile relationships, social isolation, suspicion the adult population in the United States and mistrust of others, difficulty forming close suffers from bulimia nervosa. The etiology of three times more likely to experience buli- personality disorders is idiopathic; however, mia nervosa than men. Diagnosis may include a complete medical extreme overeating without trying to history, physical examination, laboratory test- compensate for the behavior. People with binge eating ality disorder and may include psychotherapy disorder experience guilt, shame, and and medications to reduce signs and symptoms distress about their binge eating, which (antidepressants, mood stabilizers, anti-anxiety can lead to more binge eating. An estimated 3% of the adult pop- mated that 8 million Americans have an eating ulation in the United States suffers from disorder: 7 million women and 1 million men. Women are 75% main types of eating disorders are anorexia ner- more likely to have binge eating disorder vosa, bulimia nervosa, and binge eating disorder. Eating, however, biological, social, psychological, and food, and weight control become obses- interpersonal factors may contribute to the sions. Diagnosis extreme thinness, an intense fear of gaining may include a complete medical history, physi- weight, extremely restricted eating, and a cal examination, laboratory testing, and com- distorted body image. Treatment the adult population in the United States may include medical care and monitoring, suffers from anorexia nervosa. Women psychotherapy, weight restoration, nutritional are three times more likely to experience counseling, medications (antidepressants, anorexia nervosa than men. In July 2013 the Food and Drug Administra- disturbing thoughts or fears that cause tion approved a brain-wave test to help diagnose them to perform certain rituals or routines. Signs and symptoms may include lant medication that increases the levels of the flashbacks, nightmares, and severe anxiety, neurotransmitters dopamine and norepineph- as well as uncontrolled thoughts about the rine to help control hyperactivity and impulsive event. Behavior modification may be used to • Social anxiety disorder-An excessive and support healthy behavior and decrease problem unreasonable fear of social situations. The esti- enting skills training and family psychotherapy mated prevalence of social anxiety disorder may also be part of treatment. Spe- symptoms of the manic phase of bipolar dis- cific phobia usually begins in childhood; order may include euphoria, increased energy the median age of onset is 7. Signs and symptoms of the depressive alence of generalized anxiety disorder is 3% phase of bipolar disorder may include sadness, of adults in the United States.
An example would be a small direct when diagnosis is difficult and is not entirely reli- inguinal hernia buy vardenafil 20mg low cost impotence risk factors, or an incisional hernia that consists able vardenafil 20 mg visa impotence 23 year old. It is indicated when: of a general bulge of the wound area without a sharp- the patient has groin pain or localized edged defect vardenafil 10 mg low price impotence jelly. In assessing the need for definitive tenderness without a lump treatment the following factors should be considered. A small hernia in a lump, not detected by the surgeon after young patient will enlarge and cause problems repeated examinations whereas a similar hernia in an older patient there is a cough impulse of uncertain significance. The risks of obscure the physical signs and when diagnosis is surgery in a frail elderly diabetic patient may be important if strangulation is a significant possibility. The recurrence rate after repair of an inguinal hernia in a child is virtually zero but the result of surgery for a complex incisional hernia in an elderly adult is uncertain. Modification of life style A physically active patient is more likely to have symptoms from a hernia than, for example, a patient confined to a wheelchair. Treatment is more likely to be the sac is excised, or inverted, and its neck ligated successful if the patient stops smoking. Diet Herniorraphy Herniae often have fatty sacs, contain omentum or consist solely of extraperitoneal fat. Loss of weight Herniorraphy means repairing the abdominal usually makes a hernia smaller. External support However, if the tissues in the area had not failed, a hernia would probably not have External pressure devices to reduce and control developed so it is usually necessary to reinforce herniae have been employed for centuries. There is the local tissues with a natural or synthetic consensus that they do not prevent complications material. This was done There are many varieties of truss for inguinal traditionally with fascia or nylon using a variety herniae. They rarely function properly and it is of complex suturing and darning techniques. A repair Abdominal support belts are useful for patients using a synthetic material is sometimes called a with incisional herniae. The cardinal rule for success in hernia surgery is to keep the repair tension free. If there is tension the Surgery stitches holding the reinforcing materials in place A hernia is a mechanical problem whose cure requires will tear out. Herniae are repaired electively for two reasons: Surgical approach to relieve symptoms to prevent complications, especially intestinal In the traditional open operation the hernia is obstruction and bowel strangulation. Herniotomy is literally the opening of the hernia It is also possible to insert a mesh into the sac so that the contents of the sac can be restored to pre-peritoneal plane from outside using an open whence they came, usually the abdomen, followed approach. This is the basis of the Stoppa repair, Inguinal hernia 361 where a mesh is placed in exactly the same place Infection as it would be if placed laparoscopically. This approach has been superseded by the laparoscopic An elective hernia repair is a clean operation and the repair because it achieves the same objective with- chance of infection, usually from skin organisms, out a large external incision. However, the consequences of infection The choice of approach for each variety of her- when it does occur can be disastrous, as most her- nia is discussed later. The risk to life following an elective hernia repair in a patient under 60 is negligible, but thereafter it Haematoma increases with age to approximately 3 per cent in Repair of a large hernia often requires extensive patients over 80. If the resulting cavity The risk for operations on large abdominal inci- cannot be closed it may fill with blood that may sional herniae is greater. This risk may be reduced by the The mortality following surgery for a strangu- use of closed suction wound drainage. This is because the risk of strangulation rises with age; older patients are more likely to have significant Damage to other structures co-morbidity and the risks include the complica- The testicular vessels and segmental nerves may be tions that follow operations performed in the injured during the repair or damaged later by post- presence of damaged bowel. Thromboembolism Recurrence Most hernia repairs carry a very low risk of deep The operation may fail to cure the hernia. Nevertheless, prophylactic meas- ures against thromboembolism should always be At some time in their lives, 9 per cent of males applied, particularly in the presence of any specific and 1 per cent of females will develop an inguinal thrombosis risk factors. Repair is a routine procedure in developed The risk is higher after the repair of major countries. Places without surgical services sufficient incisional herniae and is similar to that for open to offer elective repair have an increased incidence abdominal surgery. It can be argued that inguinal hernia repair is perhaps the most important operation in general Retention of urine surgery. The commonest type of groin hernia is the male Because of the local pain and discomfort pro- inguinal hernia. This hernia is most frequently seen duced by the swelling and the risk of strangulation in the older age group. Postoperative retention of increasing with time, surgical repair is the treatment urine is therefore quite common as these patients of choice for all reasonably fit patients. Another sig- often have a mild degree of symptomless prostatic nificant factor is the cosmetic appearance – patients hypertrophy. All techniques follow the basic principles of a Tanner slide herniotomy and herniorraphy outlined above. When the hernia is indirect, the peritoneal sac is Nylon Darn At least 10 per cent emptied and then excised. Shouldice repair 1–2 per cent If the hernia is a sliding hernia, in which a viscus Lichtenstein repair 1–2 per cent forms part of the wall of the sac, the herniotomy has to be carried out distal to the viscus and the proximal sac reduced into the abdomen. The gap between the The anatomy of these varieties of inguinal hernia is conjoint tendon and the inguinal ligament is discussed in detail in Symptoms and Signs. Its results The Bassini repair, described in the nineteenth are comparable to the Shouldice repair but the century, was the first reasonably successful operation is technically easier. After the The Lichtenstein repair is now the standard open herniotomy, the conjoint tendon is sutured to procedure for repair of an inguinal hernia. This results in tension be performed as a day case with local or general and increases the chance of recurrence. Tanner slide, an incision in the anterior rectus sheath, is a modification that was introduced to Complications specific to open repair reduce the tension and stress at the suture line. The hernia sac hernia repairs there are two specific complications is dissected out and excised in the usual way, that follow open repair of an inguinal hernia. It relies upon a meticulous swelling followed by testicular atrophy, or it may be dissection and overlapping repair of the insidious. Local anaesthesia is used men have persisting pain in the distribution of routinely in the Shouldice clinic. This was the the iliohypogastric, ilio-inguinal or genitofemoral first method of repair to be subjected to proper nerves after the postoperative pain has resolved. It audit and some degree of long-term follow-up is not known if this is caused by direct trauma at the and the first to produce good evidence of good time of surgery, nerve ischaemia or late incorpora- long-term results (Table 16. The advantages gained from avoiding an abdomi- nal incision are a more rapid recovery and a better cosmetic appearance. Abdominal herniae are clearly seen on lapar- oscopy as the insufflated carbon dioxide expands the abdominal wall and distends the hernial sac, so it was not surprising that attempts were soon made to repair herniae from the inside of the abdomen. The benefit in terms of reduced trauma is not so great as with cholecystectomy as the standard Inguinal open repair of a hernia is not as traumatic as an ligament upper abdominal incision. Laparoscopic repair is Spermatic also technically more difficult than open repair.
Color vision is made possible by photoreceptors Prompt treatment can prevent corneal scarring in the retina called cones discount generic vardenafil canada erectile dysfunction surgical treatment options. Prevention includes wearing pro- to certain wavelengths of light that are associ- tective eyewear when indicated purchase vardenafil 20 mg without prescription webmd erectile dysfunction treatment, as when working ated with different colors purchase vardenafil 20mg otc experimental erectile dysfunction treatment. Contact lenses should be main- in these cones cause various degrees of impaired tained in clean condition and discarded when color vision. Lens cases should be disinfected reg- vision cannot distinguish shades of red and ularly and replaced periodically. The prevalence of this type is about 1 in pes infections should be treated and controlled 12 males of northern European ancestry but so that they cannot spread to the cornea. Some people with impaired color vision cannot distinguish Uveitis Uveitis is inflammation of the uvea, shades of blue and yellow. Complete absence of uncommon, affecting about 38,000 people annu- color vision is called color blindness and is rare, ally in the United States. Color vision The pinna directs sound into the auditory canal, impairments and color blindness are carried on a skin-lined tube that leads to the middle ear. Color blindness can be diagnosed with a substance that keeps the tympanic membrane multicolored, spotted eye chart in which colored soft and flexible. There is no treatment for brane (ear drum), a fibrous tissue that spans the impaired color vision and it cannot be prevented. Sound waves trigger vibrations of the tympanic membrane, which transmits the vibrations to three middle-ear bones, the Ocular Tumors auditory ossicles. The ossicles are the malleus, Retinoblastoma Retinoblastoma is a rare, reces- incus, and stapes. Vibrations moving through mately 40% of retinoblastomas are inherited, the fluid of the cochlea stimulate specialized with carriers of the mutant gene having a structures called hair cells, which transmit infor- 10,000-fold increased risk for the development of mation about the vibrations along the auditory retinoblastoma. Treatment of retinoblastoma is aimed at preserv- ing vision, destroying the tumor, and monitoring Diagnostic Tests and Procedures: for metastasis. Large tumors are treated by removal of the affected External exam reveals conditions of the exter- eye(s) with as much of the optic nerve as neces- nal ear and auditory canal. About 90% of cases of intraocular tumors visualization of the auditory canal and the con- can be cured. Hearing tests toma tends to spread to the brain and bone mar- utilize head phones or tuning forks to assess row and is associated with a poor prognosis. In children at risk, prevention requires examinations every 2–4 months for 2 years to Diseases and Disorders screen for the development of additional tumors. Genetic counseling can help families understand of the Ear the genetic consequences of retinoblastoma and estimate the risk of disease in family members. Diseases and Disorders of the External Ear Cerumen Impaction As already noted, cerumen keeps the tympanic membrane soft and flex- Anatomy and Physiology Review: ible. It is that is secreted slowly moves to the outer ear composed of three regions: an outer ear, middle and flakes off. Signs that is external to the skull is called the pinna; and symptoms of impaction are ringing in the it is covered by skin and supported by cartilage. Treatment should be done Otitis Externa Otitis externa, or “swimmer’s ear,” by a doctor because the tympanic membrane is is an infection of the auditory canal caused by delicate and can be easily injured while removing bacteria and fungi. It is usually To prevent impaction, the ear should not caused by water remaining in the external ear be cleaned with cotton swabs, which usually after swimming. It can also be caused by abra- push cerumen deeper and against the tympanic sion of the external auditory canal. If buildup is excessive, a doctor may and signs include pain, itching, redness, and recommend occasionally applying baby oil or discharge. If advanced, the infection may cause hydrogen peroxide to soften the cerumen, fol- fever and temporary hearing loss. Diseases and Disorders of the Inner Ear Hearing Loss Presbycusis is age-related hearing Diseases and Disorders loss and is the most common cause of hearing of the Middle Ear loss in adults. Presbycusis occurs in a third of Otitis Media Otitis media is a middle ear infec- adults age 65–75 and half of those over age 75. More than 5 million cases of acute otitis The risk factors include increasing age, family media occur among children in the United States history of presbycusis, repeated exposure to loud each year. Age is the main risk factor for otitis noises, smoking, and certain medical conditions. Children are more susceptible than adults standing conversations, especially in a noisy because their nearly horizontal auditory tubes room. Tinnitus and inability to hear high pitches are Symptoms include pain, swelling, edema, and also signs of presbycusis. Severe swelling may perforate the tympanic diagnosed with routine hearing tests and tuning membrane. Treatment may include hearing aids if the tion of a bulging tympanic membrane and effu- auditory nerve and cochlea remain functional. In healthy children, most The degree of age-related hearing loss can be pre- cases resolve on their own. For a bacterial infec- vented by reducing exposure to loud noises or by tion, antibiotics may be prescribed. Pain can be using ear plugs and ear protection when exposed controlled with analgesics such as acetamino- to loud noises. Aspirin should never be given trauma, high fever, toxins, certain antibiotics, and to children. Genetic causes of hearing impairment require small ear tubes (tympanostomy tubes) or deafness may be noted in newborns. Hearing protectors can help reduce Age-Related Diseases dangerous noise in areas where noise cannot be controlled or eliminated. How can you tell if hearing loss is caused by nerve prob- With age the curvature of the cornea decreases, lems or by problems with middle ear ossicles? With age the lens increases in thickness and decreases in elasticity, making it more difficult to accommodate and focus on objects at a close Meniere’s Disease Meniere’s disease is a condition distance. A thickened lens becomes less trans- of intermittent hearing impairment, tinnitus, parent and admits less light into the eye. Meniere’s disease is not Age-related hearing loss is especially pro- uncommon; it affects more than 600,000 people nounced at high frequencies. Alterations in sound in the United States annually, mainly people age receptors, neurons, and blood supply to the inner 40–60, but it can occur at any age. Fluid accumulation aged with surgical procedures, eyeglasses, and in the inner ear is responsible for its signs and hearing aids. Older adults may not like using symptoms, hearing devices or eyeglasses because of cost The main symptoms of Meniere’s disease and embarrassment about these signs of aging. Diagnosis and coordination contribute to falls among aging requires a physical exam, hearing test, and adults. Treatment is symp- as possible can help prevent injuries from falls tomatic and includes medications for vertigo. What problems are associated with he knew there was nothing intentionally or elevated eye pressure? A condition in which near objects are clear middle ear are signs of___________________.