Murray Luckas MD MRCOG

• Consultant Obstetrician and Gynaecologist, Leighton Hospital,
• Crewe

If they are pulled taut by the laryngeal muscles icd-9-cm code for erectile dysfunction extra super cialis 100 mg with amex, they vibrate more rapidly and a higher pitch results erectile dysfunction acupuncture cheap extra super cialis 100mg line. Decreasing the muscular tension on the vocal folds causes them to vibrate more slowly and produce lower-pitch sounds benadryl causes erectile dysfunction buy extra super cialis 100 mg overnight delivery. Due to the influence of male sex hormones erectile dysfunction keywords generic extra super cialis 100mg otc, vocal folds are usually thicker and longer in males than in females erectile dysfunction and diabetes treatment order online extra super cialis, and therefore they vibrate more slowly impotence definition inability buy 100 mg extra super cialis otc. Sound originates from the vibration of the vocal folds, but other structures are necessary for converting the sound in to recognizable speech. The pharynx, mouth, nasal cavity, and paranasal sinuses all act as resonating chambers that give the voice its human and individual quality. We produce the vowel sounds by constricting and relaxing the muscles in the wall of the pharynx. Whispering is accomplished by closing all but the posterior portion of the glottis. Because the vocal folds do not vibrate during whispering, there is no pitch to this form of speech. However, we can still produce intelligible speech while whispering by changing the shape of the oral cavity as we enunciate. As the size of the oral cavity changes, its resonance qualities change, which imparts a vowel-like pitch to the air as it rushes toward the lips. The rings of cartilage that support the trachea may be accidentally crushed, the mucous membrane may become inflamed and swell so much that it closes off the passageway, excess mucus secreted by inflamed membranes may clog the lower respiratory passages, a large object may be aspirated (breathed in), or a cancerous tumor may protrude in to the airway. In this procedure, also called a tracheostomy, a skin incision is followed by a short longitudinal incision in to the trachea below the cricoid cartilage. The firm wall of the tube pushes aside any flexible obstruction, and the lumen of the tube provides a passageway for air; any mucus clogging the trachea can be suctioned out through the tube. The wall of the trachea is lined with mucous membrane composed of pseudostratified columnar epithelium; its cilia and mucus-secreting goblet cells provide the same protection against dust as the membranes lining the nasal cavity and larynx. The C-shaped cartilage rings provide a semirigid support so that the tracheal wall does not collapse inward (especially during inhalation) and obstruct the air passageway. As a result, an aspirated object is more likely to enter and lodge in the right primary bronchus than the left. The mucous membrane of the carina is one of the most sensitive areas of the entire larynx and trachea for triggering a cough reflex. On entering the lungs, the primary bronchi divide to form smaller bronchi-the secondary (lobar) bronchi, one for each lobe of the lung. Because this extensive branching from the trachea through the terminal bronchioles resembles an upsidedown tree, it is commonly referred to as the bronchial tree. Recall that mucus produced by goblet cells traps inhaled particles, and cilia move the mucus and trapped particles toward the pharynx for removal. In regions where nonciliated simple cuboidal epithelium is present, inhaled particles are removed by macrophages. However, because there is no supporting cartilage, muscle spasms can close off the airways. This is what happens during an asthma attack, which can be a life-threatening situation. They are separated from each other by the heart and other structures in the mediastinum, which divides the thoracic cavity in to two anatomically distinct chambers. As a result, if trauma causes one lung to collapse, the other may remain expanded. Between the visceral and parietal pleurae is a narrow space, the pleural cavity, which contains a lubricating fluid secreted by the membranes. This pleural fluid reduces friction between the membranes, allowing them to slide easily over one another during breathing. Pleural fluid also causes the two membranes to adhere to one another just as a film of water causes two glass microscope slides to stick together, a phenomenon called surface tension. The broad inferior portion of the lung, the base, is concave and fits over the convex area of the diaphragm. The left lung also contains a medial indentation, the cardiac notch, in which the heart lies. Due to the space occupied by the heart, the left lung is about 10 percent smaller than the right lung. It is performed by applying a quick upward thrust between the navel and costal margin that causes sudden elevation of the diaphragm and forceful, rapid expulsion of air in the lungs; this action forces air out the trachea to eject the obstructing object. The abdominal thrust maneuver is also used to expel water from the lungs of near-drowning victims before resuscitation is begun. Although the right lung is thicker and broader, it is also somewhat shorter than the left lung because the diaphragm is higher on the right side, accommodating the liver that lies inferior to it. The oblique and horizontal fissures divide the right lung in to superior, middle, and inferior lobes. Thus, the right primary bronchus gives rise to three secondary (lobar) bronchi called the superior, middle, and inferior secondary (lobar) bronchi, and the left primary bronchus gives rise to superior and inferior secondary (lobar) bronchi. As noted above, within the lung, the secondary bronchi give rise to the tertiary (segmental) bronchi. Because alveoli participate in gas exchange, respiratory bronchioles are considered the first part of the respiratory zone of the respiratory system. The more numerous type I alveolar cells are simple squamous epithelial cells that form a nearly continuous lining of the alveolar wall. Surfactant lowers the surface tension of alveolar fluid, which reduces the tendency of alveoli to collapse (described later). Also present are alveolar macrophages (dust cells), wandering phagocytes that remove fine dust particles and other debris from the alveolar spaces. It has been estimated that the lungs contain 300 million alveoli, providing an immense surface area of 70 m2 (750 ft2)-about the size of a racquetball court-for gas exchange. If the piston is pushed down, the gas molecules are squeezed in to a smaller volume; now with less wall area, each segment of the exposed wall is struck more often by the gas molecules, creating greater gas pressure. The gauge shows that the pressure doubles as the gas is compressed to half its original volume. In other words, the same number of molecules in half the volume produces twice the pressure. Conversely, if the piston is raised to increase the volume, the gas molecules spread farther apart and the pressure decreases. Differences in pressure caused by changes in lung volume force air in to our lungs when we inhale and out when we exhale. For inhalation to occur, the lungs must expand, which increases lung volume and thus decreases the pressure in the lungs to below atmospheric pressure. The most important muscle of inhalation is the diaphragm, the dome-shaped skeletal muscle that forms the floor of the thoracic cavity. It is innervated by the phrenic nerves, which emerge from the cervical region of the spinal cord. As the diaphragm contracts, it becomes flatter and descends, which increases the vertical diameter of the thoracic cavity. Contraction of the diaphragm is responsible for about 75 percent of the air the process of gas exchange in the body, called respiration, has three basic steps: 1. Pulmonary ventilation (pulmon- lung), or breathing, is the inhalation (inflow) and exhalation (outflow) of air and involves the exchange of air between the atmosphere and the alveoli of the lungs. External respiration is the pulmonary exchange of gases across the respiratory membrane between the alveoli of the lungs and the blood in pulmonary capillaries. Internal respiration is the tissue exchange of gases between blood in systemic capillaries and tissue cells. In pulmonary ventilation, air flows between the atmosphere and the alveoli of the lungs because of alternating pressure differences created by contraction and relaxation of respiratory muscles. The rate of airflow and the amount of effort needed for breathing are also influenced by alveolar surface tension, compliance of the lungs, and airway resistance (each described shortly). Pressure Changes during Pulmonary Ventilation Air moves in to the lungs when the air pressure inside the lungs is less than the air pressure in the atmosphere surrounding the body. Air moves out of the lungs when the air pressure inside the lungs is greater than the air pressure in the atmosphere. Piston Pressure gauge 1 1 Inhalation Breathing in is called inhalation (inspiration). Just before each inhalation, the air pressure inside the lungs is equal to the pressure of the atmosphere, which at sea level is about 760 millimeters of mercury (mmHg), or 1 atmosphere (atm). For air to flow in to the lungs, the pressure inside the alveoli must become lower than the atmospheric pressure. The pressure of a gas in a closed container is inversely proportional to the volume of the container. During quiet exhalation, the diaphragm relaxes and the lungs recoil inward, forcing air out of the lungs. Advanced pregnancy, excessive obesity, or confining abdominal clothing can prevent complete descent of the diaphragm and may cause shortness of breath. As a result, there is an increase in the anteroposterior and lateral diameters of the thoracic cavity. Contraction of the external intercostals is responsible for about 25 percent of the air that enters the lungs during normal quiet breathing. During quiet inhalations, the pressure in the pleural cavity between the visceral and parietal pleurae, called intrapleural pressure, is lower than the atmospheric pressure. Just before inhalation, it is about 4 mmHg less than the atmospheric pressure, or about 756 mmHg at an atmospheric pressure of 760 mmHg. As the diaphragm and external intercostals contract and the overall size of the thoracic cavity increases, the volume of the pleural cavity also increases, which causes intrapleural pressure to decrease from 756 to about 754 mmHg. During expansion of the thorax, the parietal and visceral pleurae normally adhere tightly because of the subatmospheric pressure between them and because of the surface tension created by their moist adjoining surfaces. As the thoracic cavity expands, the parietal pleura lining the cavity is pulled outward in all directions, and the visceral pleura and lungs are pulled along with it. Maintenance of a subatmospheric pressure in the pleural cavity is vital to the functioning of the lungs because it helps keep the alveoli slightly inflated. Alveoli are so elastic that at the end of an exhalation they recoil inward and tend to collapse on themselves like the walls of a deflated balloon. The "suction" created by the slightly lower pressure in the pleural cavities helps prevent lung collapse. As the volume of the lungs increases, the pressure inside the lungs, called the alveolar pressure, drops from 760 to 758 mmHg. Because air always flows to a region of lower pressure, inhalation takes place as air flows from the atmosphere (higher pressure) in to the lungs (lower pressure). The accessory muscles are so named because they make little, if any, contribution during normal quiet inhalation, but during forced ventilation, such as occurs during exercise, they may contract vigorously. Atmospheric pressure = 760 mmHg Atmospheric pressure = 760 mmHg Alveolar pressure = 760 mmHg Intrapleural pressure = 756 mmHg Alveolar pressure = 758 mmHg Intrapleural pressure = 754 mmHg 1. During inhalation (diaphragm contracting) Atmospheric pressure = 760 mmHg Alveolar pressure = 762 mmHg Intrapleural pressure = 756 mmHg 3. During exhalation (diaphr agm relaxing) Air moves in to the lungs when alveolar pressure is less than atmospheric pressure, and out of the lungs when alveolar pressure is greater than atmospheric pressure. Because both normal quiet inhalation and inhalation during forced ventilation involve muscular contraction, the process of inhalation is said to be an active process. Exhalation becomes active only during forceful breathing, as occurs while playing a wind instrument or during exercise. Contraction of the abdominal muscles moves the inferior ribs downward and compresses the abdominal viscera, thereby forcing the diaphragm superiorly. Exhalation Breathing out, called exhalation (expiration), is also due to a pressure gradient, but in this case the gradient is in the opposite direction: the pressure in the lungs is greater than the pressure of the atmosphere. Normal exhalation during quiet breathing, unlike inhalation, is a passive process because no muscular contractions are involved. Instead, exhalation results from elastic recoil of the thoracic wall and lungs, both of which have a natural tendency to spring back after they have been stretched. Two inwardly directed forces contribute to elastic recoil: (1) the recoil of elastic fibers that were stretched during inhalation and (2) the inward pull of surface tension due to the film of alveolar fluid. These movements decrease the vertical, lateral, and Other Factors Affecting Pulmonary Ventilation As you have just learned, air pressure differences drive airflow during inhalation and exhalation. However, three other factors affect the rate of airflow and pulmonary ventilation: surface tension of the alveolar fluid, compliance of the lungs, and airway resistance. During labored inhalation, sternocleidomastoid, scalenes, and pectoralis minor also contract. Alveolar pressure increases to 762 mmHg Atmospheric pressure is about 760 mmHg at sea level Thoracic cavity increases in size and volume of lungs expands Alveolar pressure decreases to 758 mmHg (a) Inhalation During normal quiet exhalation, diaphragm and external intercostals relax. Thoracic cavity decreases in size and volume, and lungs recoil (b) Exhalation Inhalation and exhalation are caused by changes in alveolar pressure. Recall that surfactant reduces surface tension and is necessary to prevent the collapse of alveoli during exhalation. The condition is also more common in infants whose mothers have diabetes and in male infants, and occurs more often in European Americans than African Americans.

Lymphoid stem cells start differentiating in to lymphocytes in red bone marrow blood pressure drugs erectile dysfunction buy discount extra super cialis, and then complete development in lymphatic tissues impotence world association order extra super cialis online pills. A hemoglobin molecule consists of the protein globin composed of four polypeptide chains; bound to each chain is a ringlike popular erectile dysfunction drugs order extra super cialis 100mg on line, nonprotein pigment called heme erectile dysfunction humor buy extra super cialis without a prescription. About 23 percent of the carbon dioxide transported by the blood combines with globin wellbutrin erectile dysfunction treatment generic extra super cialis 100 mg fast delivery. The non-iron portion of heme is eventually converted to bilirubin and secreted in to bile that passes in to the intestines erectile dysfunction treatment non prescription cheap extra super cialis 100mg line. The production of red blood cells, termed erythropoiesis, begins in the red bone marrow. Reticulocytes enter the bloodstream where, within 1 to 2 days, they become mature erythrocytes. Erythropoiesis is stimulated by hypoxia, which results in the release of erythropoietin by the kidneys. Animation-Erythropoietin Clinical Connection-Anemia Clinical Connection-Blood Doping Concept 18. Plasma typically contains anti-A antibodies or anti-B antibodies, called agglutinins, directed against A or B antigens, respectively. The transfer of whole blood or blood components in to the bloodstream is called a transfusion. Eosinophils have large, uniform granules stained red-orange and a nucleus with two or three lobes. Basophils have variable-sized granules stained blue-purple that obscure the two-lobed nucleus. Lymphocytes have a sky blue cytoplasm with a dark, round, slightly indented nucleus. Monocytes have a blue-gray cytoplasm with a foamy appearance and a kidney-shaped nucleus. Chemotaxis occurs when pathogens and inflamed tissues release chemicals that attract phagocytic neutrophils and macrophages. Eosinophils stop the effects of histamine and other mediators of inflammation in allergic reactions. Basophils release heparin, histamine, and serotonin, which intensify the inflammatory reaction. T cells combat viruses, fungi, transplanted cells, cancer cells, and some bacteria. Resources Concepts and Connections- Blood Clinical Connection-Leukemia Concept 18. The hormone thrombopoietin stimulates myeloid stem cells to develop in to megakaryocytes. Platelets stop blood loss in damaged vessels by forming a platelet plug in the vessel wall. Anatomy Overview-Platelets Concepts and Connections- Blood Clinical Connection-Stem Cell Transplants from Bone Marrow and Cord Blood Concept 18. Hemostasis is a sequence of responses to stop blood loss from a damaged blood vessel. Three mechanisms are involved: vascular spasm, platelet plug formation, and blood clotting. Vascular spasms of the smooth muscle in the wall of a damaged vessel help reduce blood loss. Platelets that come in to contact with damaged blood vessels aggregate in to a platelet plug to stop bleeding. A clot is a network of insoluble protein fibers (fibrin) in which formed elements of blood are trapped. Clotting is a cascade of reactions involving clotting factors that activate one another. Stages of clotting include the following: formation of prothrombinase, conversion of prothrombin in to thrombin, and conversion by thrombin of soluble fibrinogen in to insoluble fibrin. Clotting is initiated by the interplay of the extrinsic and intrinsic pathways of blood clotting. Because the next two stages of clotting are the same for both pathways, they are collectively called the common pathway. The clot plugs the damaged area of the blood vessel and undergoes clot retraction, which pulls the blood vessel edges closer together. Clotting in an unbroken blood vessel is called thrombosis; the clot is called a thrombus. A dislodged thrombus can be swept away in the blood and is then called an embolus. Concepts and Connections-Blood Clinical Connection- Hemophilia Clinical Connection-Aspirin and Thrombolytic Agents 6. How does the volume of blood in your body compare to the volume of fluid in a two-liter bottle of soda How is the development of lymphocytes unique when compared with the development of the other formed elements How are red blood cells able to squeeze through capillaries that are smaller in diameter than they are What would happen if a person with type B blood were given a transfusion of type O blood During an anatomy and physiology exam you are asked to view white blood cells in prepared slides of standard human blood smears. Why would the level of leukocytes be higher in an individual who has been infected with a parasitic disease In regions where malaria is endemic, some people build up immune resistance to the malaria pathogen. He arrives at the ticket counter to face a long, slow-moving line, time he gets in the boarding line, he is gasping for air, and thinks to himself, "I am really out of shape. I should have been able to run from security to the gate without getting this short of breath. He leans his head against the window, watching the last of the luggage being loaded in to the belly of the plane. His breathing is a little easier, but his chest feels tight and he is experiencing a burning sensation. He decides to take one of the pills that his doctor prescribed to help him relax while flying, but it will have to wait until the flight attendant offers him something to drink. In the meantime, he closes his eyes and tries to focus on the meditation techniques he has learned to ease himself in to a more relaxed state. He has no personal history of health problems, but his grandfather died of a sudden heart attack at the age of 70 and his father died of the same condition at the age of 60. You will learn the answers to these questions and others in this chapter on the circulatory system, which emphasizes the crucial role of the heart in maintaining the supply of oxygen to the body. The clerk tells him to hurry: he only has thirty minutes to make it through security and to his gate for boarding. Without his luggage Hiroshi is able to move more quickly, but the security line, as usual, is long. He walks through the metal detector, collects his computer, and runs down the concourse to make his flight. The heart beats about 100,000 times every day, which adds up to about 35 million beats in a year and approximately 2. The right side of the heart pumps blood through the lungs, so that it can pick up oxygen and unload carbon dioxide. Even while you are sleeping, your heart pumps 30 times its own weight each minute, which amounts to about 5 liters (5. At this rate, the heart pumps more than 14,000 liters (3600 gal) of blood in a day or 10 million liters (2. This chapter explores the structure of the heart and the unique properties that permit it to pump for a lifetime without a moment of rest. The base of the heart, the broad superior portion opposite the apex, is formed by the atria (upper chambers of the heart). Location of the Heart For all its might, the heart is relatively small, roughly the same size as your closed fist-about 12 cm (5 in. Recall that the midline is an imaginary vertical line that divides the body in to unequal left and right sides. The pointed apex is formed by the tip of the left ventricle (a lower chamber of the heart) and rests on the diaphragm. It confines the heart to its position in the mediastinum, while allowing sufficient freedom of movement for vigorous and rapid contraction. In this and subsequent illustrations, blood vessels that carry oxygenated blood (which looks bright red) are colored red, and those that carry deoxygenated blood (which looks dark red) are colored blue. The superficial fibrous pericardium is composed of tough, dense irregular connective tissue. It prevents overstretching of the heart, provides protection, and anchors the heart in the mediastinum. Between the parietal and visceral layers of the serous pericardium is a pericardial cavity containing pericardial fluid, a slippery, lubricating secretion of the pericardial membranes that reduces friction between the serous pericardial membranes as the heart moves. As noted earlier, the epicardium is also called the visceral layer of serous pericardium. This thin, transparent outer layer of the heart wall is composed of mesothelium and connective tissue that imparts a smooth, slippery texture to the outermost surface of the heart. The epicardium contains blood vessels and lymphatic vessels that supply the myocardium. It is composed of cardiac muscle tissue and is responsible for its pumping action. Although cardiac muscle fibers are striated like skeletal muscle fibers, they are involuntary like smooth muscle fibers (see Concept 4. The smooth endothelial lining minimizes the surface friction as blood passes through the heart. The endocardium is continuous with the endothelial lining of the large blood vessels attached to the heart. This is good news because it is easier for an emergency dispatcher to give instructions limited to chest compressions to frightened, nonmedical bystanders. From most superficial to deepest, what are the layers of the pericardium and heart wall The coronary sulcus (coron- resembling a crown) encircles most of the heart and marks the external boundary between the superior atria and inferior ventricles. This sulcus continues around to the posterior surface of the heart as the posterior interventricular sulcus, which marks the external boundary between the ventricles on the posterior aspect of the heart. The two upper receiving chambers are the atria (entry halls or chambers), and the two lower pumping chambers are the ventricles (little bellies). The paired atria receive blood from veins, blood vessels returning blood to the heart, while the ventricles eject the blood from the heart in to blood vessels called arteries. Each auricle slightly increases the capacity of an atrium so that it can hold a greater volume of blood. Between the right atrium and left atrium is a thin partition called the interatrial septum (inter- between; -septum a dividing wall or partition). A prominent feature of this septum is an oval depression called the fossa ovalis, the remnant of the foramen ovale, an opening in the interatrial septum of the fetal heart that normally closes soon after birth. The right ventricle is separated from the left ventricle by a partition called the interventricular septum. Blood passes from the right ventricle through the pulmonary valve in to a large artery, the pulmonary trunk, which carries blood to the lungs for oxygenation. Because the ridged pectinate muscles are confined to the auricle of the left atrium, the anterior wall of the left atrium is smooth. Myocardial Thickness and Function the thickness of the myocardium of the four chambers varies according to the amount of work each chamber has to perform. Although the right and left ventricles act as two separate pumps that simultaneously eject equal volumes of blood, the right ventricle has a much smaller workload. The left ventricle pumps blood great distances to all other parts of the body (systemic circulation). Blood passes from the left ventricle through the aortic valve in to the largest artery of the body, the ascending aorta (aorte to suspend, because the aorta once was believed to lift up the heart). Some of the blood in the aorta flows in to the coronary arteries, which branch from the ascending aorta and carry blood to the heart wall; the remainder of the blood passes in to the arch of the aorta and descending aorta. Branches of the arch of the aorta and descending aorta carry blood throughout the body. During fetal life, a temporary blood vessel, called the ductus arteriosus, shunts blood from the pulmonary trunk in to the aorta to bypass the nonfunctioning fetal lungs. At the same time, the papillary muscles contract, which pulls on and tightens the chordae tendineae. This prevents the valve cusps from pushing up in to the atria in response to the high ventricular pressure. As each chamber of the heart contracts, it pushes a volume of blood in to a ventricle or out of the heart in to an artery. Blood flows through the heart from areas of higher blood pressure to areas of lower blood pressure. As the walls of each chamber contract and relax, resulting pressure differences across the heart valves force valves to open and close. Each of the four valves helps to ensure the one-way flow of blood by opening to let blood through and then closing to prevent its backflow. The semilunar valves allow ejection of blood from the heart in to arteries but prevent arterial blood from flowing back in to the ventricles. Surprisingly perhaps, there are no valves between the venae cavae and the right atrium or between the pulmonary veins and the left atrium. As the atria contract, a small amount of blood does flow backward in to these vessels. However, backflow is minimized because contracting atria compress and nearly collapse the openings from these veins. Mitral valve prolapse is one of the most common valvular disorders, affecting as much as 30 percent of the population. It is more prevalent in women than in men, and does not always pose a serious threat.

Exposure of the Descending Tlloradc Aorta the most common site ofblunt injury to the thoracic aorta is just distal to the origin of the left subclavian artery erectile dysfunction testosterone generic extra super cialis 100 mg visa, with the tear beginning at the ligamentum arteriosum impotence pills for men generic 100 mg extra super cialis overnight delivery. The right ann is placed on an armboard perpendicular to the patient how to treat erectile dysfunction australian doctor order 100 mg extra super cialis overnight delivery, and the left arm is supported with pillows or on a Mayo stand erectile dysfunction protocol program order extra super cialis 100 mg on-line. The skin incision begins just below the left nipple and extends posteriorly to 1 inch below the tip of the scapula tobacco causes erectile dysfunction cheap 100 mg extra super cialis with mastercard, then cmves upward between the scapula and the spine natural treatment erectile dysfunction exercise generic 100 mg extra super cialis free shipping. The proximal segment of the descending thoracic aorta is best exposed through the fourth interspace, and the distal segment is best exposed through the sixth interspace. The ribs are counted downward from the first the fourth interspace is identified and entered by incising the intercostal muscles along the superior border of the fifth rib. The descending thoracic aorta will be seen anterior to the vertebrae beneath the glistening surface of the mediastinal pleura. The aorta is encircled with heavy tapes, taking care to preserve intercostal arteries. The left vagus nerve and surrounding periaortic tissues are bluntly swept forward until the aorta is sufficiently cleared to be clamped. The left phrenic nerve should be carefully dissected from the aortic arch and gently retracted away from the area of injury. Endovascular grafts for treatment of traumatic injury to the aortic arch and great vessels. Atherosclerotic innominate artery occlusive disease: early and longterm results of surgical reconstruction. Innominate artery occlusive disease: management with central reconstructive techniques. A comparative analysis of open and endovascular repair for ruptured descending thoracic aorta. The vessels exiting the chest and the nerves emerging from the spinal column pass between the scalene muscles above the rim of the superior thomcic aperture. The manubrium of the sternum rises above the plane of the first ribs to articulate with the heads of the clavicles. The mobility of the clavicle is important in determining the amount of space available for passage ofthe subclavian vessels and brachial plexus draped over the first rib. The costoclavicular ligament as well as the sternoclavicular joint attach the clavicle medially. The transverse processes ofthe cervical vertebrae are trough-shaped and contain central apertures. The vertebral arteries normally enterthe sixth transverse fommen and traverse the upper five fimunina to reach the base ofthe skull. The nerves emerge through the intervertebral foramina and lie in the troughs of the transverse processes posterior to the vertebral vessels. The anterior and middle scalene muscles sandwich the roots of the bJ:achial plexus. The middle scalene muscles arise from the posterior tubercles of the lower six cervical transverse processes and attach more broadly to the posterior parts ofthe first nos. The nerves to 1he upper extremity pass between the anterior and middle scalene muscles. At the level of the first rib, the trunb divide in to anterior and posterior divisions which lie posterior to the first part of the axillary artery. The posterior divisions unite to form the posterior cord which continues behind the axillary artery to become the radial nerve. A branch of the medial cord unites with the lateral cord to form the median nerve anterior to the artery. There are three important branches which deviate from the central location of the brachial plexus. Twigs from the roots of the fifth, sixth, and seventh nerves unite to form the long thoracic nerve and pass through the substance of the middle scalene muscle to reach the serratus anterior muscle on the chest wall this relationship is important during the posterior dissection for first rib resection. The intercostobrachial nerve is a b:nmch of the second intercostal nerve which crosses the center of the axillary space and usually joins the medial brachial cutaneous nerve. Some numbness on the inner aspect of the brachium may result from division of this nerve. Elevation of the pectoral girdle widens the passage, while depression and posterior displacement narrow the space. The subclavius muscle forms a bridge from the undersurface of the distal clavicle to the costochondral junction of the first rib. A second bridge is formed by the arching coracoid process and the origin of the pectoralis minor muscle. The clavipectoral fascia extends from the subclavius muscle across the pectoralis minor muscle, which it enfolds, and joins the axillary fascia. The latter spans from the lateral edge of the pectoralis major muscle to the anterior edge of the latissimus dorsi. The insertion of the subclavius muscle forms the medial matgin of the foramen through which the subclavian vein enters the chest. It is an important landmark toward which the needle is directed when cannulating the subclavian vein, and it is the highest point of a complete axillary lymph node dissection. The supreme thoracic and lateral thoracic vessels and thoracoepigastric vein cross the critical portion of the first rib and must be divided for access. The intercostobrachial nerve may be preserved or divided, depending on whether it interferes with exposure. The axons pass from the cord through the ventral nerve root to the ventral rami where they exit via the white rami to the sympathetic trunk. Postganglionic axons from the middle cervical, stellate, and second thoracic ganglia join the roots ofthe brachial plexus or run directly in the adventitia of blood vessels. The majority of upper extremity vascular sympathetic nerves reach their destination through the lower trunk of the brachial plexus and the median and u1nar nerves. The cervical sympathetic chain on each side lies between the carotid sheath and the prevertebral fascia anterior to the transverse processes of the cervical vertebrae. The middle cervical ganglion lies at the level of the C6 transverse process (carotid tubercle) medial to the vertebral artery as it enteu the vertebral foramen. In the chest, the sympathetic trunks and ganglia lie beneath the parietal pleura on the necks of the ribs. The amount of sympathetic innervation left in the upper extremity is not felt to be clinically significant by advocates of this procedure. An older controversy involved the denervation hypersensitivity to circulating catecholamines, which results from interruption of postganglionic sympathetic fibers. Older procedures to selectively divide white rami only have been abandoned, since this syndrome is rarely observed clinically. This area is a common site of subclavian vein compression in patients with effort thrombosis. Roos 11 feels that congenital fibrous bands or abnormal muscle insertions are the most common causes of this disorder. Neural compression is by far the most common type, accounting for nearly 97% of thoracic outlet compression symptoms. Most modem surgeons have adopted this view and remove the frrst rib through one of two approaches, transaxillary and supraclavicular. The anterior supraclavicular approach has undergone rejuvenation and is currently favored by some. The anterior infiaclavicular approach21 offers only limited first nb resection, and the view of the neurovascular structures is o~ structed by the clavicle. It is most useful to ensure sternal disarticulation of the first rib and complete resection of the subclavius muscle in patients with venous thoracic outlet compression (see below). Because of the high reported risk of postoperative shoulder pain, claviculectomy is not recommended for thoracic outlet decompression in most cases. It can also be combined easily with other incisions to comet arterial pathology at the time of outlet decompression. The ideal exposures shown in the following illustrations for clarity are seldom achieved in reality due to the funnel-like depth ofthe operative field. An incision is made 1 to 2 em above and parallel to the clavicle, beginning at the clavicular head and extending approximately 8 em laterally. Just deep to the divided sternocleidomastoid fibers is the internal jugular vein, which should be dissected on its lateral border and carefully retracted medially. The underlying scalene fat pad is mobilized along its medial, superior, and inferior borders and then reflected on a pedicle in the lateral wound. Coursing on the anterior surface ofthis muscle, usually near the medial border, is the phrenic nerve. The nerve should be freed from the adjacent fascia of the anterior scalene muscle and carefully protected during the ensuing dissection. The nerve should not be forcibly retracted because even minimal compression can result in a temporary diaphragmatic palsy. The muscle can then be divided as close to its transverse process origins as possible to complete the resection. Although most compressing bands will be removed with resection of the anterior and middle scalene muscles, the operative field should be palpated to detect the presence of any other fibrous constrictions. Likewise, certain muscle anomalies, such as split middle scalene insertions and posterior scalene hypertrophy, 1 should be recognized. Cervical ribs are usually embedded within the fibers of the middle scalene muscle and are easily resected at the time of middle scalenectomy. Extraperiosteal resection is preferred over the subperiosteal approach because the former is simpler, and removal of the periosteum may prevent reossification of the periosteal bed and associated recurrent symptoms. The posterior rib remnant is removed as close to the transverse process as possible with a rongeur. In addition, the transaxillary approach affords incomplete exposure of the elements comprising the scalene triangle: most of the congenital fibromuscular bands are medial to the first no and thus hidden by the neurovascular trunks in this approach. Ann rettaction should be released on an intermittent basis during the operation to prevent ann ischemia and brachial plexus injury. As an alternative, IlliglO has recently described a method of passive arm elevation using a shoulder suspension kit in which the arm is elevated by a weighted nylon cord suspended over a "shower curtain" assembly. The incision is deepened through subcutaneous tissue and the axillary fascia to reach the fascia of the senatus anterior at the level of the third rib. A tissue plane is begun deep to the axillary fascia and developed superiorly in the loose areolar tissue on the surface of the serratus anterior. The supreme thoracic artery and vein cross the first rib in the anterior wound and will also require division. Gentle elevation of the shoulder by the second assistant and retraction of the pectoralis major will greatly enhance exposure of the structures at the thoracic outlet. From anterior to posterior, one should identify the axillary vein, anterior scalene muscle, axillary artery, brachial plexus, and middle scalene muscle. This provides increased exposure for rib resection and prevents subclavian vein compression by the subclavius muscle. If the vein is adherent to the subclavius muscle, muscle resection should be abandoned to avoid tearing the thin-walled vessel. A right-angled hemostat can be used to retract the anterior scalene away from its surrounding vessels, and its division is best performed a few fibers at a time. In cases involving arterial compression, the artery may be adherent to the rib, and its wall may be thinned from poststenotic dilatation. Cervical ribs are separated from the surrounding middle scalene muscle and resected with rongeurs as close to the spine as possible. If recognized during the acute phase, this so-called effort thrombosis (Paget-Schroetter syndrome) can be treated using catheter-directed clot lysis followed by selective relief of thoracic outlet compression. A transverse skin incision is made 2 em below the clavicle, extending approximately 5 em from the lateral border of the sternum. The incision is deepened through the pectoral fascia, and the pectoralis major muscle is split in the direction of its fibers to expose the junction between the first rib and the stemum. This ligament should be divided because its medial fibers may impinge on the subclavian vein along with the subclavius. Complete division will also simplify removal of the frrst rib at the sternoclavicular junction. The pleura is carefully displaced from the inner border of the rib using blunt dissection, starting in the lateral wound and proceeding medially. Downward traction on the anterior end of the divided rib will help expose the anterior scalene muscle insertion. The phrenic nerve should be identified and carefully protected during this maneuver. The middle scalene muscle can be visualized by retracting the vein and artery together in to the superior wound. Molina36 has recommended that the rib be divided at least 1 em behind the subclavian artery afttlr the middle scalene has been transected. First, recent experience suggests that the procedure is best performed with endoscopic technology. To ensure a complete and permanent sympathetic denervation, some authors believe that the sympathetic chain should be resected from the inferior cervical ganglion to the third dorsal ganglion. To prevent this, most experienced surgeons prefer to spare at least the upper half of the B-4 stellate ganglion. Although modem endoscopic technology may have diminished the value of these exposures to little more than historical interest, they are included in this chapter for the sake of completeness. Despite this limitation, the procedure is considered simple and effective, with operative results similar to other techniques. The supraclavicular incision and deep dissection proceed as described in detail above. The fat pad is dissected away from underlying structures, and the sternocleidomastoid muscle and carotid sheath are mobilized and retracted medially.

Aldosterone increases reabsorption of Na from the urine in to the blood erectile dysfunction kuala lumpur buy extra super cialis 100mg without a prescription, and it stimulates excretion of K in to the urine cialis erectile dysfunction wiki order extra super cialis 100 mg. Decreased blood pressure stimulates the kidneys to secrete the enzyme renin in to the blood erectile dysfunction education discount extra super cialis 100mg mastercard. The resulting vasoconstriction of the arterioles helps raise blood pressure to normal erectile dysfunction premature ejaculation treatment 100 mg extra super cialis visa. Blood containing an increased level of aldosterone circulates to the kidneys where it promotes the movement of Na and water from urine to the blood erectile dysfunction medicine name in india discount 100 mg extra super cialis visa. Aldosterone also stimulates the kidneys to increase excretion of K in to the urine erectile dysfunction doctor type order extra super cialis 100mg with visa. As blood volume increases and arterioles constrict, blood pressure increases to normal. Glucocorticoids increase the rate of protein breakdown, mainly in muscle fibers, and thus increase amino acid concentrations in the blood. Glucocorticoids inhibit white blood cells that participate in inflammatory responses. Unfortunately, glucocorticoids also retard tissue repair, which slows wound healing. Although high doses can cause severe mental disturbances, synthetic glucocorticoids are very useful in the treatment of chronic inflammatory disorders such as rheumatoid arthritis. For this reason, glucocorticoids are prescribed for organ transplant recipients to retard tissue rejection by the immune system. After puberty in males, the androgen testosterone is also released in much greater quantity by the testes. Thus, the relative amount of androgens secreted by the adrenal gland in males is usually so low that their effects are insignificant. They contribute to libido (sex drive) and are converted in to estrogens (feminizing sex steroids) by other body tissues. Adrenal androgens also stimulate growth of axillary and pubic hair in boys and girls and contribute to growth spurts before puberty. Adrenal Medulla the inner region of the adrenal gland, the adrenal medulla, is a modified sympathetic ganglion of the autonomic nervous system. It develops from the same embryonic tissue as all other sympathetic ganglia, but its neurons, which lack axons, form clusters around large blood vessels. Rather than releasing a neurotransmitter, the neurons of the adrenal medulla secrete hormones. Because the autonomic nervous system exerts direct control over the adrenal medulla through sympathetic innervation, hormone release can occur very quickly. The hormones of the adrenal medulla intensify sympathetic responses that occur in other parts of the body. In stressful situations and during exercise, sympathetic impulses initiated by the hypothalamus stimulate the adrenal medulla to secrete epinephrine and norepinephrine. These two hormones greatly augment the fight-or-flight response that was described in Concept 14. By increasing heart rate and force of contraction, epinephrine and norepinephrine increase the pumping output of the heart, which increases blood pressure. They also increase blood flow to the heart, liver, skeletal muscles, and adipose tissue; dilate airways to the lungs; and increase blood levels of glucose and fatty acids. Thus, precursor molecules accumulate, and some of these are weak androgens that can undergo conversion to testosterone. In a female, virile characteristics include growth of a beard, development of a much deeper voice and a masculine distribution of body hair, growth of the clitoris so it may resemble a penis, atrophy of the breasts, and increased muscularity that produces a masculine physique. In prepubertal males, the syndrome causes the same characteristics as in females, plus rapid development of the male sexual organs and emergence of male sexual desires. How do the hypothalamus and anterior pituitary influence glucocorticoid secretion Which chemical does the adrenal medulla and the autonomic nervous system both produce Complete removal of the adrenal glands would eliminate the release of which hormones The acini produce digestive enzymes, which flow in to the gastrointestinal tract through a network of ducts. Abundant capillaries serve both the exocrine and endocrine portions of the pancreas. We discuss its endocrine functions in this chapter and its exocrine functions in the digestive system in Concept 23. The principal action of glucagon is to increase blood glucose level when it falls below normal. The level of blood glucose controls secretion of glucagon and insulin via negative feedback. Glucagon acts on liver cells to accelerate the breakdown of glycogen in to glucose and formation of glucose from lactic acid and certain amino acids. As a result, the liver releases glucose in to the blood more rapidly, and blood glucose level rises. If blood glucose continues to rise, high blood glucose level (hyperglycemia) inhibits release of glucagon by alpha cells (negative feedback). At the same time, high blood glucose (hyperglycemia) stimulates secretion of insulin by beta cells of the pancreatic islets. Insulin acts on body cells to increase uptake of glucose, accelerate synthesis of glycogen from glucose, increase uptake of amino acids by cells and increase protein synthesis, and increase fatty acid synthesis. If blood glucose level drops below normal, low blood glucose inhibits release of insulin by beta cells (negative feedback) and stimulates release of glucagon. Human growth hormone and adrenocorticotropic hormone indirectly stimulate insulin secretion because they elevate blood glucose level. Digestion and absorption of food containing both carbohydrates and proteins stimulates insulin release. In contrast, the high blood levels of amino acids following meals containing mainly proteins stimulates glucagon secretion. You are reading through a medical journal and encounter an article entitled "Clinical Implications of Beta-Cell Tumor Hypersecretion. Which division of the autonomic nervous system interacts with the pancreas to regulate glucose level after the meal Which division of the autonomic nervous system interacts with the pancreas to regulate glucose level while you swim However, it would also stimulate an increase in the production of a group of hormones called androgens. These would produce a condition called hirsutism, which can present as excess body hair. The hormone imbalance could also interfere with the onset of her menstrual periods. Your adrenal glands are not making enough glucocorticoids or mineralocorticoids, which could explain the fatigue and dizziness. Without enough aldosterone, one of the mineralocorticoids, you can easily become dehydrated and that could explain your constant thirst. As these hormones begin to send correct messages to the hypothalamus and anterior pituitary, that should help balance your sex hormone levels and stabilize the menstrual irregularities. They also promote enlargement of the breasts and widening of the hips at puberty, and help maintain these female secondary sex characteristics. During pregnancy, the ovaries and placenta produce a hormone called relaxin, which increases the flexibility of the pubic symphysis during pregnancy and helps dilate the uterine cervix during labor and delivery. The testes produce and secrete testosterone, the primary androgen or male sex hormone. Testosterone stimulates descent of the testes before birth, regulates production of sperm, and stimulates development and maintenance of masculine secondary sex characteristics such as beard growth and deepening of the voice. A detailed discussion of the ovaries, testes, and the hormones they produce will be presented in Chapter 25. Because of its role in immunity, the details of the structure and functions of the thymus are discussed in Chapter 21. As more melatonin is liberated during darkness than in light, this hormone is thought to promote sleepiness. In response to visual input from the eyes (retina), the hypothalamus stimulates sympathetic neurons, which in turn stimulate the pineal gland to secrete melatonin in a rhythmic pattern, with low levels of melatonin secreted during the day and significantly higher levels secreted at night. During sleep, the level of melatonin in the bloodstream increases tenfold and then declines to a low level again before awakening. Small doses of melatonin given orally can induce sleep and reset daily rhythms, which might benefit workers whose shifts alternate between daylight and nighttime hours. In animals that breed during specific seasons, melatonin inhibits reproductive functions outside the breeding season, but it is unclear whether melatonin influences human reproductive function. The level of melatonin is higher in children and declines with age in to adulthood, but there is no evidence that changes in melatonin secretion correlate with the onset of puberty and sexual maturation. Nevertheless, because melatonin causes atrophy of the gonads in several animal species, the possibility of adverse effects on human reproduction must be studied before its use to reset daily rhythms can be recommended. Hormones from Other Endocrine Tissues and Organs As you learned at the beginning of this chapter, cells in organs other than those usually classified as endocrine glands have an endocrine function and secrete hormones. You learned about several of these in this chapter: the hypothalamus, pancreas, ovaries, testes, and thymus. From arachidonic acid, different enzymatic reactions produce the various prostaglandins or leukotrienes. The prostaglandins alter smooth muscle contraction, glandular secretions, blood flow, reproductive processes, platelet function, respiration, impulse transmission, lipid metabolism, and immune responses. They also have roles in promoting inflammation and fever, and in intensifying pain. Leukotrienes stimulate chemotaxis (attraction to a chemical stimulus) of white blood cells and mediate inflammation. Full-spectrum bright-light therapy-repeated doses of several hours of exposure to artificial light as bright as sunlight-provides relief for some people. Three to six hours of exposure to bright light also appears to speed recovery from jet lag, the fatigue suffered by travelers who quickly cross several time zones. If Lisa had not received hormone treatments before the end of puberty, what could have been the long-term effects of her condition Badeer not suspect the problem to be associated with the ovaries and sex hormones The endocrine system releases hormones to control body activities and help maintain homeostasis. A hormone is a molecule that is released in one part of the body but regulates the activity of cells in other parts of the body. In contrast to the rapid communication and control associated with the nervous system, the endocrine system responses are slower and more sustained. Exocrine gland secretions enter ducts that carry the secretions to body surfaces or in to cavities. Endocrine glands secrete hormones in to interstitial fluid to diffuse in to the blood where they circulate to target tissues. The endocrine system comprises all of the endocrine glands and hormone-secreting cells. Hormones affect only target cells that have specific receptors to bind to a given hormone. The number of hormone receptors may decrease (down-regulation) or increase (up-regulation). Water-soluble hormones circulate in blood plasma unattached to plasma proteins; most lipid-soluble hormones circulate attached to transport proteins. Transport proteins increase blood solubility of lipid-soluble hormones, prevent loss of small hormone molecules to urine, and provide a ready reserve of hormones in the blood. Hormones can stimulate synthesis of molecules, alterations in membrane permeability, stimulation of membrane transport, alterations in metabolic rate, and contraction of smooth and cardiac muscle. Hormone secretion is regulated by nervous system signals, chemical changes in the blood, and other hormones. Anatomy Overview-Lipidsoluble Hormones Anatomy Overview-Watersoluble Hormones Anatomy Overview-Local Hormones Animation-Introduction to Hormonal Regulation, Secretion, and Concentration Animation-Mechanisms of Hormone Action Animation-Introduction to Hormone Feedback Loops Clinical Connection- Administering Hormones Concept 17. The hypothalamus is the major integrating link between the nervous and endocrine systems. Although the pituitary gland secretes several hormones that control other endocrine glands, it is also controlled by the hypothalamus. The pituitary gland sits in the sella turcica of the sphenoid bone and is attached by a stalk, the infundibulum, to the hypothalamus. The pituitary gland is divided in to the anterior pituitary and the posterior pituitary. Secretion of anterior pituitary hormones is stimulated by releasing hormones and suppressed by inhibiting hormones from the hypothalamus. These hypothalamic hormones reach the anterior pituitary through the hypophyseal portal system that links the hypothalamus and the anterior pituitary. Several anterior pituitary hormones are tropic hormones, hormones that influence the secretion of other endocrine glands. Anterior pituitary hormone secretion is regulated by two factors: releasing and inhibiting hormones of the hypothalamus, and negative feedback from rising blood levels of target gland hormones. Thyroid-stimulating hormone stimulates the thyroid gland to secrete triiodothyronine and thyroxine. Although there are melanocyte-stimulating hormone receptors in the brain, its function in humans is unknown. The posterior pituitary stores and releases two hypothalamic hormones, oxytocin and antidiuretic hormone, which are produced by hypothalamic neurosecretory cells. Anatomy Overview-The Hypothalamus Anatomy Overview-Hormones of the Hypothalamus Anatomy Overview- Hypothalamic Reproductive Hormones Animation-Antidiuretic Hormone Clinical Connection-Diabetes Insipidus Concept 17. Internally, the gland consists of thyroid follicles with follicular cells that produce two thyroid hormones: triiodothyronine (T3) and thyroxine (T4), and parafollicular cells that produce calcitonin. The thyroid gland is the only endocrine gland that stores its secretory products in large supply. Thyroid hormones regulate oxygen use and metabolic rate, cellular metabolism, and growth and development.

Discount extra super cialis 100 mg on line. Libido / Impotence / Sexual Symptoms - Diagnostic Methods in Chinese Medicine (The 10 questions).