By O. Mason. University of California, Hastings College of Law.
This remarkable work basis for the classification of living organisms explains the process of genetic replication and Darwin buy cheap zithromax 250mg line, Charles 250mg zithromax sale. Its The ideas set forth in this classic took many anatomical value is in comparative anatomy effective 500mg zithromax, years to be understood and accepted cheap 500 mg zithromax free shipping. Kinesiology of the human where the anatomy of different species is importance to anatomy is that it provided an body under normal and pathological conditions. Versuche über basic physiological concepts are presented in pflanzenhybriden (Experiments with plant this book, including a summary of what was hybrids). Through observation and then known of the functioning of the nervous experimentation, Mendel demonstrated the system. History of Anatomy © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Chapter 1 History of Anatomy 7 FIGURE 1. The people of ancient Mesopotamia regarded the liver as the seat of human emotions. Many early investigations of the body represented an at- tempt to describe basic life forces. For example, people wondered which organ it was that constituted the soul. Certain diseases, injuries, deformities, and occasionally causes was extensively studied in sacrificial animals (fig. Even today, several European cul- tures associate the liver with various emotions. The Egyptian techniques of embalming could have con- The warm blood and arrangement of blood vessels are obvi- tributed greatly to the science of anatomy had they been recorded. In fact, em- Therefore, some concluded, blood must contain a vital, life-giving balmers were frequently persecuted and even stoned. The scholars of Mesopotamia were influenced by this idea, as was Aristotle, the Greek scientist who lived centuries later. Aristotle was a mystic art related more to religion than to science, and be- believed that the seat of the soul was the heart and that the brain cause it required a certain amount of mutilation of the dead body, functioned in cooling the blood that flowed from the heart. Consequently, embalming techniques ciation of the heart, in song and poetry, with the emotions of love and that could have provided embalmed cadavers as dissection speci- caring has its basis in Aristotelian thought. The ancient Egyptian culture neighbored Mesopotamia to the Several written works concerning anatomy have been dis- west. Here, the sophisticated science of embalming the dead in covered from ancient Egypt, but none of these influenced succeed- the form of mummies was perfected (fig. Menes, a king-physician during the first Egyptian tempts were made to perform anatomical or pathological studies dynasty of about 3400 B. It was reserved for royalty and the wealthy to prepare writings (2300–1250 B. History of Anatomy © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 8 Unit 1 Historical Perspective Like the people of Mesopotamia and Greece, the ancient monks from Japan were trained in China where they were ex- Egyptians were concerned with a controlling spirit of the posed to Chinese philosophy, and so Chinese beliefs concern- body. In fact, they even had a name for this life force—the Ba spirit— and they believed that it was associated with the bowels and the ing the body became prevalent in Japan as well. Food was placed in the tomb of a mummy to feed the Ba spirit eighteenth century, Western influences, especially the Dutch, during the journey to Osiris, Egyptian god of the underworld. In 1774, a five-volume work called Kaitai Shinsho (A New Book of Anatomy), published China and Japan by a Japanese physician, Genpaku Sugita, totally adopted the Dutch conceptualization of the body. This book marked the be- China ginning of a modern era in anatomy and medicine for the Japanese people. In ancient China, interest in the human body was primarily philosophical. Ideas about anatomy were based on reasoning For several hundred years, Western nations were welcome in rather than dissection or direct observation. In 1603, however, the Japanese government banned revered the body and abhorred its mutilation. An apparent ex- all contact with the Western world because they feared the influences of Christianity on their society. Although this ban was strictly enforced ception was the practice of binding the feet of young girls and and Japan became isolated, Japanese scholars continued to circu- women in an attempt to enhance their beauty.
Accordingly purchase zithromax 250 mg free shipping, umbilical cord gases should be obtained in all depressed or resuscitation-requiring newborns 500mg zithromax mastercard. Hypoxic-ischemic encephalopathy (HIE) injury pattern in the new- born must be placed in perspective with all the known pertinent clini- cal information order zithromax 250 mg overnight delivery. After dealing with the emergent situation purchase 100mg zithromax mastercard, all actions taken or not taken should be clearly documented in the medical record along with explanations provided to the parents. Communication with the baby’s physician is very important not only to clarify the timing of the baby’s neurological injury but also to facilitate the obstetrician’s trans- lation of the baby’s status to the mother and family. The associations with maternal factors are weak except for an expulsive resolution to the second stage of labor and fetal macrosomia often seen in cases of maternal diabetes. Even making the diagnosis of macrosomia is difficult, and late pregnancy sonography is no better than clinical guesstimate. Elective induction of labor or elective C-section delivery for women suspected of carrying a macrosomic fetus is generally not recommended. On the other hand, the case has been made for elective C-section when the estimated fetal weight exceeds 4500 g in women with diabetes. It is essential to review the nurses’ notes to ascertain their concor- dance with your own notes on clinical events. For example, it is not uncommon for the nurse’s notes to reflect the use of fundal pressure rather than suprapubic pressure. Although there are no data to support the use of one maneuver over another, the McRobert’s patient posi- tioning is simple and resolves about 50% of the cases of anterior shoul- der impaction. Fundal pressure prior to the diagnosis of shoulder dystocia is not a standard-of-care issue. Cervical plexus injury has been reported without documented shoulder dystocia at the time of vaginal birth (9) as well as at the time of planned C-section (10). There is no scientific basis that all or even most brachial plexus injuries result from inappropriate maneuvers at deliv- ery (11). Newborn seizure activity is so rare following delivery with shoul- der dystocia that intracerebral hemorrhage must be ruled out. HIE with mental retardation and/or cerebral palsy is also rare (<1%), unless the time from diagnosis of dystocia at delivery of the head to resuscitation exceeds 10 minutes. Video recording during periods of obstetric emer- gencies should not be allowed. Although the severity of the dystocia cannot be defined as mild, moderate, or severe, a videotape is often very revealing as to the twists and turns exerted on the baby’s neck. Documentation of the sequence and timing of the maneuvers is critical as are APGAR scores, need for resuscitation, and evident plexus in- jury. Obstetric hemorrhage is the most common cause of maternal death when associated complications are included. Death secondary to hem- orrhage would be most unusual in a modern obstetric service in the United States. Accepted risk factors include delays in identification of the site of the bleeding and in volume resuscitation with appropriate blood products. This often follows a failure to appreciate the quantity of blood the obstetric patient can lose before exhibiting shock fol- lowed rapidly by cardiovascular collapse and the morbidity of associ- ated organ injury. Furthermore, tachycardia ( 110 bpm) and systolic hypotension ( 90 mmHg) tend to be late signs in the obstetric patient occurring typically after a volume loss of approx 40%. Orthostatic systolic blood pressure checking is a more reliable indicator of signifi- cant hypovolemia—a 10 mmHg decrease equating in pregnancy to a deficit of 1 L or more. The medical management of obstetric hemorrhage, particularly with uterine atony, includes oxytocic agents such as oxytocin, methyler- gonovine, Hemabate™ intrauterine, and misoprostal per rectum. Fibrinogen replace- ment is almost always required because the more common antecedents to the hemorrhage are defibrination associated with placental abruption, dead fetus syndrome, or amniotic fluid embolism. Ligation of the internal hypogastric arteries does not improve survival (13). On the other hand, ligation of the ovarian and uterine pedicles without vessel transection may significantly decrease blood loss (12).
Small changes in arteriolar radius can tion 1 shows that if pressure and flow are expressed in units cause large changes in flow to a tissue or organ because flow of mm Hg and mL/min quality zithromax 500mg, respectively zithromax 250 mg online, R is in mm Hg is related to the fourth power of the radius buy zithromax 500mg low price. Poiseuille’s law incorporates all of the factors influencing Conditions in the Cardiovascular System Deviate flow purchase 500 mg zithromax fast delivery, so that From the Assumptions of Poiseuille’s Law 4 Q P r /8 Despite the usefulness of Poiseuille’s law, it is worthwhile to In the body, changes in radius are usually responsible for examine the ways the cardiovascular system does not variations in blood flow. First, CHAPTER 12 An Overview of the Circulation and Hemodynamics 213 the cardiovascular system is composed of tapering, branch- ing, elastic tubes, rather than rigid tubes of constant diam- eter. These conditions, however, cause only small devia- tions from Poiseuille’s law. Application of Poiseuille’s law requires that flow be steady rather than pulsatile, yet the contractions of the heart cause cyclical alterations in both pressure and flow. Despite this, Poiseuille’s law gives a good estimate of the re- lationship between pressure and flow averaged over time. Another criterion for applying Poiseuille’s law is that flow be streamlined. Streamline (laminar) flow describes the movement of fluid through a tube in concentric layers that slip past each other. The layers at the center have the fastest velocity and those at the edge of the tube have the slowest. This is the most efficient pattern of flow velocities, in that the fluid exerts the least resistance to flow in this configuration. Turbulent flow has crosscurrents and ed- dies, and the fastest velocities are not necessarily in the middle of the stream. Several factors contribute to the ten- dency for turbulence: high flow velocity, large tube diame- ter, high fluid density, and low viscosity. All of these fac- tors can be combined to calculate Reynolds number (NR), Axial streaming and flow velocity. As flow velocity increases, red blood cells NR vd / (4) move toward the center of the blood vessel (axial streaming), where v is the mean velocity, d is the tube diameter, is the where velocity is highest. Axial streaming of red blood cells low- fluid density, and is the fluid viscosity. This value is hardly ever exceeded in a normal cardiovascular system, but high flow velocity is the most common cause of turbulence in pathological states. Once turbulence occurs, a given in- sure gradient along a tube and flow changes at the point crease in pressure gradient causes less increase in flow be- cause the turbulence dissipates energy that would other- wise drive flow. Under normal circumstances, turbulent flow is found only in the aorta (just beyond the aortic valve) and in certain localized areas of the peripheral sys- tem, such as the carotid sinus. Pathological changes in the cardiac valves or a narrowing of arteries that raise flow velocity often induce turbulent flow. Turbulent flow generates vibrations that are transmitted to the surface of Streamline flow Turbulent flow the body; these vibrations, known as murmurs and bruits, can be heard with a stethoscope. Finally, blood is not a strict newtonian fluid, a fluid that exhibits a constant viscosity regardless of flow velocity. When measured in vitro, the viscosity of blood decreases as the flow rate increases. This is because red cells tend to Critical velocity collect in the center of the lumen of a vessel as flow veloc- ity increases, an arrangement known as axial streaming (Fig. Axial streaming reduces the viscosity and, therefore, resistance to flow. Because this is a minor effect in the range of flow velocities in most blood vessels, we usually assume that the viscosity of blood (which is 3 to 4 Pressure gradient times that of water) is independent of velocity. When flow is streamlined, concentric layers of fluid PRESSURES IN THE CARDIOVASCULAR SYSTEM slip past each other with the slowest layers at the interface be- Pressures in several regions of the cardiovascular system are tween blood and vessel wall. When the critical velocity is reached, turbulent readily measured and provide useful information. In the presence of turbulent flow, flow does not in- pressure is too high, it is a risk factor for cardiovascular dis- crease as much for a given rise in pressure because energy is lost eases, including stroke and heart failure. A more compliant structure exhibits a greater change in volume for a given transmural pressure change. The lower The Contractions of the Heart Produce the compliance of a vessel, the greater the pressure that will Hemodynamic Pressure in the Aorta result when a given volume is introduced. For example, The left ventricle imparts energy to the blood it ejects into each time the left ventricle contracts and ejects blood into the aorta, and this energy is responsible for the blood’s cir- the aorta, the aorta expands; in doing so, it exerts an elastic cuit from the aorta back to the right side of the heart.