By N. Ballock. Duke University. 2018.
By contrast 80mg super cialis with amex erectile dysfunction natural remedies diabetes, the superficial fascia under the skin of the back of the hand, elbow, and facial region is thin. The Deep fascia surrounds adjacent muscles, compartmentalizing and more movable bony attachment of the muscle, known as the in- binding them into functional groups. Subserous fascia extends be- sertion, is pulled toward its less movable attachment, the origin. Nerves and vessels In muscles associated with the girdles and appendages, the origin traverse subserous fascia to serve serous membranes. The fleshy, thickened portion of a muscle is referred to as The tenderness of meat is due in part to the amount of con- nective tissue present in a particular cut. An example is the galea aponeurotica, which is found and may present a social problem in trying to extract it discreetly on the top and sides of the skull (see fig. Attached to muscles generally do not contract separately but work as func- articulating bones, retinacula anchor groups of tendons and keep tional groups. Muscles that contract together in accomplishing a them from bowing during muscle contraction. Muscular System © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Chapter 9 Muscular System 237 FIGURE 9. Muscular System © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 238 Unit 4 Support and Movement TABLE 9. Antagonistic muscles perform opposite functions and pendage are shortened. For exam- Seldom does the action of a single muscle cause a move- ple, the two heads of the biceps brachii muscle, together with the ment at a joint. Utilization of several synergistic muscles brachialis muscle, contract to flex the elbow joint. The triceps rather than one massive muscle allows for a division of labor. One brachii muscle, the antagonist to the biceps brachii and muscle may be an important postural muscle, for example, whereas brachialis muscles, extends the elbow as it is contracted. Antagonistic muscles are necessary because the fibers in a contracted muscle are shortened and must be elongated be- fore they can once again cause movement through another Muscle Architecture contraction. Gravity may also act as the antagonist for certain Skeletal muscles may be classified on the basis of fiber arrange- muscles. When an elevated upper appendage is relaxed, for ex- ment as parallel, convergent, sphincteral (circular), or pennate ample, gravity brings it down to the side of the body, and the (table 9. Each type of fiber arrangement provides the muscle with distinct capabilities. Muscle fiber architecture can be observed on a cadaver or other dissection specimen. If you have the opportunity to learn the muscles of the body from a cadaver, observe the fiber ar- synergistic: Gk. Muscular System © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Chapter 9 Muscular System 239 Origins TABLE 9. When one antagonistic group contracts, and (c) multipennate the other one must relax; otherwise, movement does not occur. Muscle fibers will atrophy if they are not periodically stim- require extensive vascularity to receive nutrients and oxygen ulated to contract. Smaller muscles generally have a single artery supplying blood and perhaps two veins returning For years it was believed that muscle soreness was simply caused by a buildup of lactic acid within the muscle fibers blood (fig. The microscopic capillary exchange between arteries and factor related to soreness, recent research has shown that there is veins occurs throughout the endomysium that surrounds indi- also damage to the contractile proteins within the muscle. This means that there must be exten- microscopic damage causes an inflammatory response that re- sive innervation (served with neurons) to a muscle to ensure the sults in swelling and pain. If enough proteins are torn, use of the entire muscle may be compromised.
They may per- on the nature of the condition discount super cialis 80 mg visa impotence with diabetes, procre- ceive chronic illness or disability as a ation may be difﬁcult or impossible, or, if violation of their own well-being, and the individual already has young children, they may choose to leave the relationship. In some cases the family’s Ideally, older adults have adapted to the overprotectiveness may prevent them triumphs and disappointments of life and from having experiences appropriate to have accepted their own life and immi- their own age group. Although physical limitations associated with normal aging are variable, Chronic Illness or Disability in older adults often experience diminished Middle Age physical strength and stamina, as well as losses of visual and hearing acuity. Illness Individuals in middle age are generally or disability during older adulthood can established in their career, have a commit- pose physical or cognitive limitations in ted relationship, and are often providing addition to those due to aging. The spouse guidance to their own children as they or signiﬁcant others of the same age group leave the family to establish their own may also have decreased physical stami- careers and families. At the same time, na, making physical care of individuals middle-aged individuals may be assuming with chronic illness or disability more dif- greater responsibility for their own elder- ﬁcult. When older adults with chronic ill- ly parents, who may be becoming increas- ness or disability are unable to attend to ingly fragile and dependent. During their own needs or when care in the home middle age, individuals may begin to is unmanageable, they may ﬁnd it neces- reassess their goals and relationships as sary to surrender their own lifestyle and they begin to recognize their own mortal- move to another environment for care and ity and limited remaining time. Many individuals in the older Illness or disability during middle age age group live on a ﬁxed retirement in- can interfere with further occupational come, and the additional expenses associ- development and may even result in ear- ated with chronic illness or disability place ly retirement. Such changes can have a signiﬁcant strain on an already tight bud- signiﬁcant impact on the economic well- get. Not all older individuals, of course, have 12 CHAPTER 1 PSYCHOSOCIAL AND FUNCTIONAL ASPECTS OF CHRONIC ILLNESS AND DISABILITY retirement beneﬁts, savings, or other re- which is also determined by social and sources to draw on in time of ﬁnancial need. OTHER ISSUES IN CHRONIC Chronic illness or disability forces an ILLNESS AND DISABILITY individual to alter his or her self-image to accommodate associated changes. Factors Self-Concept and Self-Esteem inﬂuencing the degree of alteration include: • the visibility of change Self-concept is tied to self-esteem and per- • the functional signiﬁcance of the sonal identity. It can be deﬁned as individ- change uals’ perceptions and beliefs about their • the speed with which change occurred own strengths and weaknesses, as well as • the importance of physical change or others’ perceptions of them. Self-esteem associated functional limitations to can be deﬁned as “the evaluative compo- the individual reactions of others nent of an individual’s self concept” (Moore et al. It is often thought of as the assessment of one’s own self- The degree to which an altered self- worth with regard to attained qualities image is perceived by the individual in a and performance (Gledhill et al. A negative and success or failure in the workplace self-concept can produce negative re- (Cusack, 2000). Consequently, self-concept has a ment is not always proportional to the signiﬁcant impact on interactions with reaction it provokes. Change considered others and on the psychological well- minimal by one individual may be con- being of the individual. Changes do not have to be visible in or- Body Image der to alter body image. Burn scars on parts of the body normally covered by Body image, an important part of self- clothing or the introduction of an artiﬁ- concept, involves individuals’ mental view cial opening or stoma such as with colo- of their body with regard to appearance stomy may cause signiﬁcant alteration in and ability to perform various physical body image even though physical changes tasks. It is inﬂuenced by bodily sensations, are not readily apparent to others. Body image also changes is not only the way individuals perceive over time as one’s appearance, capabilities, themselves, but also the way they perceive and functional status change over the life others as seeing them. It is inﬂuenced by each individual’s one’s body can be a barrier to psycholog- personal conception of attractiveness, ical well-being, social interactions, func- The Impact of Uncertainty 13 tional capacity, and workplace adjust- als from reaching their full potential. Consequently, the ultimate goal is an effort to avoid stigma, individuals may to help individuals adapt to changes deny, minimize, or ignore their condition brought about by chronic illness or disabil- and/or treatment recommendations, even ity, integrating those changes into a restruc- though it is detrimental to their welfare. It is possible to reduce the negative impact of societal stigma by Stigma is a signiﬁcant factor in many helping individuals establish a sense of chronic illnesses and disabilities. Despite their own intrinsic worth, despite the efforts to create a heightened awareness of characteristics of their medical condition. Individuals who deviate from bility of the progression of the disease, or societal expectations of what is acceptable ambiguous symptoms.
Maintaining adequate ﬂuid intake is Some individuals develop leg ulcers also important for individuals with sickle because of the interruption of circulation cell disease discount super cialis 80mg amex erectile dysfunction drugs and nitroglycerin, because adequate hydration during sickle cell crisis. Ulcers may not can minimize the sickling of red blood heal and may become infected, necessi- cells and decrease the blood viscosity. The Conditions Affecting the Blood or Immune System 243 anemia associated with this condition to maintain a “normal” life and minimize sometimes necessitates transfusion thera- their difference from peers (Atkin & py. Adherence to prophylac- hydroxyurea, has recently been tested for tic measures may be especially difﬁcult use in the treatment of sickle cell anemia and require signiﬁcant support (While & and has been found to prevent sickling of Mullen, 2004). Other therapies, of children with sickle cell disease may including the use of antisickling agents experience guilt or fear of the loss of their and bone marrow transplantation, may child. At the same time, the experience sickle cell crisis often require child may learn manipulative behaviors to hospitalization. These maladaptive means ment focuses on restoring ﬂuids if dehy- of coping may persist throughout life, cre- dration has occurred, and relieving the ating a greater barrier than the condition pain associated with the crisis, which itself. Although fection, has precipitated the crisis, some of the factors that provoke a sickle treatment of that condition may also be cell crisis may be identiﬁable, crises are instituted. Organ damage as a result of often unpredictable and beyond individ- sickle cell disease is treated in a similar uals’ control. Not only are the crises pain- fashion to chronic organ disease from oth- ful and debilitating, but there is also the er causes. The lack of control over the tive care, and health maintenance have frequency or severity of sickle cell crises been shown to increase the life expectan- can lead to feelings of hopelessness and cy of individuals with sickle cell disease. Care should be taken to avoid any factors Individuals with sickle cell disease can that precipitate a sickle cell crisis. In most instances, individuals with sickle cell disease do not need to alter Like hemophilia, sickle cell disease usu- activities, unless activities appear to pro- ally manifests itself in childhood, neces- voke a sickle cell crisis. Most activities, if sitating medical attention and, possibly, performed in moderation, can be tolerat- frequent hospitalizations, which can dis- ed. The unpredictability of sickle cell crises rupt social development and educational can alter social functioning for individu- progress. Psychological coping patterns are als with sickle cell disease, who may have relevant both to the experience of pain to cancel or alter plans at the last minute and to broader adjustment issues (Anie, if a crisis should occur. Coping with sick- as a precipitating factor in sickle cell cri- le cell disease may be especially difﬁcult sis must also be considered. Although during adolescence as individuals struggle stress is frequently associated with nega- 244 CHAPTER 8 CONDITIONS OF THE BLOOD AND IMMUNE SYSTEM tive events, stress can also be associated on the individual, the frequency, and the with positive events, such as a graduation seriousness of the crises when they occur. Human Immunodeﬁciency Virus (HIV) Vocational Issues in Sickle Cell Disease Infection Individuals with sickle cell disease must Not all viruses are harmful to humans, consider not only the physical demands but some viruses can cause disease. Because sickle childhood illness to more serious diseases, cell disease is a lifelong condition, most such as poliomyelitis and acquired individuals learn, over the years, which immune deficiency syndrome (AIDS). Despite the organism that cannot grow or reproduce potential relationship of overexertion and outside living cells. In order to survive, a sickle cell crisis, most individuals with virus must enter a living cell and use the sickle cell disease are capable of perform- reproductive capacity of that cell for its ing moderate and, in some instances, even own replication. Normally, the body ﬁc organ or joint damage as a result of re- recognizes viruses as foreign and activates peated sickle cell crises have many of the the immune system to attack and destroy same limitations as those who have simi- the offending agent. In addi- are not destroyed, some remain inactive tion, individuals with sickle cell disease (dormant) for long periods without caus- should avoid extremes in temperature. The direct dam- damp environments can also precipitate age the virus does to the cell itself may a crisis. Consequently, it may be beneﬁcial vary from slight damage to total destruc- for individuals with sickle cell anemia to tion. Some cells are able to reproduce after work in indoor or controlled environ- being damaged, but others, especially ments. It is all individuals react to stress in the same called a retrovirus because it uses a compli- way, nor are perceptions of stress always cated process called reverse transcription. Consequently, the importance This process uses a viral enzyme called of stress must be determined on an indi- reverse transcriptase to integrate its genet- vidual basis. The degree to which absences ic material into the genetic material of due to sickle cell crises become a hin- other cells. In so doing, the HIV essential- drance to work performance is dependent ly takes over other cells and makes them Conditions Affecting the Blood or Immune System 245 produce other infected cells, each of • fetal transmission from a woman which is slightly different. HIV-1 is the There is no evidence that transmission most common and is responsible for most can occur in any way other than through of the cases of HIV infection (Kilby & direct blood-to-blood or sexual contact Eron, 2003).
At the onset of the swallow super cialis 80 mg fast delivery ramipril erectile dysfunction treatment, the lower Motor Behavior of the Antral Pump Is Swallow Initiated by a Dominant Pacemaker Gastric action potentials determine the duration and strength of the phasic contractions of the antral pump and are initiated by a dominant pacemaker located in the cor- Anatomic regions Functional motor regions Fundus Lower Reservoir esophageal Pylorus (tonic contractions) Corpus sphincter 100 mm Hg (body) 5 sec Antrum FIGURE 26. The propulsive segment of the peristaltic behavioral complex produces a positive FIGURE 26. The musculature in the region of the sphincter shortly after the onset of the swallow, and the sphincter antral pump exhibits phasic contractions that function in the mix- remains relaxed until the propulsive complex has transported the ing and trituration of the gastric contents. CHAPTER 26 Neurogastroenterology and Gastrointestinal Motility 469 pus distal to the midregion. A leading contraction, with a relatively constant am- site, the action potentials propagate rapidly around the gas- plitude, is associated with the rising phase of the action po- tric circumference and trigger a ring-like contraction. The tential, and a trailing contraction, of variable amplitude, is action potentials and associated ring-like contraction then associated with the plateau phase (Fig. The gastric action potential lasts about 5 seconds and has a The leading contractions produced by the rising phase rising phase (depolarization), a plateau phase, and a falling of the gastric action potential have negligible amplitude as phase (repolarization) (see Fig. As the rising phase reaches the terminal antrum and spreads into the pylorus, contrac- tion of the pyloric muscle closes the orifice between the The Gastric Action Potential Triggers stomach and duodenum. The trailing contraction follows Two Kinds of Contractions the leading contraction by a few seconds. As the trailing The gastric action potential is responsible for two compo- contraction approaches the closed pylorus, the gastric con- nents of the propulsive contractile behavior in the antral tents are forced into an antral compartment of ever-de- creasing volume and progressively increasing pressure. This results in jet-like retropulsion through the orifice formed by the trailing contraction (Fig. Trituration and reduction in particle size occur as the material is Gastric action potential forcibly retropelled through the advancing orifice and back Trailing and contractile cycle Gastric contraction start in midcorpus into the gastric reservoir to await the next propulsive cycle. Plateau phase Gastric Rapid action Enteric Neurons Determine the Minute-to-Minute upstroke potential Strength of the Trailing Antral Contraction The action potentials of the distal stomach are myogenic Gastric action potential (i. The myogenic characteristics of the action poten- tial are modulated by motor neurons in the gastric ENS. Neurotransmitters primarily affect the amplitude of the plateau phase of the action potential and, thereby, control the strength of the contractile event triggered by the plateau phase. Neurotransmitters, such as ACh from exci- tatory motor neurons, increase the amplitude of the plateau Gastric action potential and contractile cycle arrive at pylorus; pylorus is closed by Onset of terminal Complete terminal leading contraction; antral contraction antral contraction second cycle starts in midcorpus Pylorus Pylorus closing closed FIGURE 26. The rising phase of the gastric action potential ac- counts for the leading contraction that propagates toward the py- lorus during one contractile cycle. Physiology of the Gastroin- is increased pressure in the terminal antrum as the trailing antral testinal Tract. In- hibitory neurotransmitters, such as NE and VIP, decrease the amplitude of the plateau and the strength of the associ- ated contraction. The magnitude of the effects of neurotransmitters in- creases with increasing concentration of the transmitter Tonic Reservoir substance at the gastric musculature. Higher frequencies contraction of action potential discharged by motor neurons release Decrease Relaxation greater amounts of neurotransmitter. In this way, motor in volume Increase neurons determine, through the actions of their neuro- Antral in volume transmitters on the plateau phase, whether the trailing pump contraction of the propulsive complex of the distal stom- ach occurs. With sufficient release of transmitter, the plateau exceeds the threshold for contraction. The action potentials in the terminal antrum and pylorus Neural mechanisms of feedback control determine intramural differ somewhat in configuration from those in the more contractile tone in the reservoir. The principal difference is the occur- rence of spike potentials on the plateau phase (see Fig. These may contribute to the sphincteric func- Gastric Reservoir tion of the pylorus in preventing a reflux of duodenal con- Neurally mediated decreases in tonic contracture of the tents back into the stomach. Receptive relaxation is initiated by the act Neural Control of Muscular Tone Determines of swallowing. It is a reflex triggered by stimulation of Minute-to-Minute Volume and Pressure in the mechanoreceptors in the pharynx followed by transmission Gastric Reservoir over afferents to the dorsal vagal complex and activation of The gastric reservoir has two primary functions. One is to efferent vagal fibers to inhibitory motor neurons in the gas- accommodate the arrival of a meal, without a significant in- tric ENS. Adaptive relaxation is triggered by distension of crease in intragastric pressure and distension of the gastric the gastric reservoir. Failure of this mechanism can lead to the uncomfort- stretch receptors in the gastric wall, transmission over vagal able sensations of bloating, epigastric pain, and nausea.
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