medical

Folate deficiency anemia -  Folic acid is present in all food staffs but readily destroyed by 10-15 minutes of cooking. Thus fresh fruits and vegetables are good source of folates. Food folates are mostly in polyglutamate form and must be split into monoglutamate for absorption. Acidic foods and beans and other legumes block the intestinal absorption by inhibiting the enzyme that catalase the polyglutamate into monoglutamate. Pheytoin also inhibit folate absorption. -  The absorption of the folate occurs in the upper third of the intestine. thus malabsorption affecting this site produces folate deficiency. -  The folate is transported in the blood as monoglutamate form and within the cells it is mainly reduced into tetrahydrofolate by an enzyme, a reductase. This reductase is sensitive to inhibition by folate analogues such as methotrexate. The action of this enzyme deprives the cells of folates and hence the capacity to rapidly divide, a property that is the basis for th...

Cor Pulmonale Cor pulmonale is right ventricular hypertrophy and dilation associ ated with pulmonary hypertension. Increased resistance to flow into the pulmonary arteries or arterioles results in pressure over load on the right ventricle with subsequent compensatory hyper trophy. In addition to increased resistance within the pulmonary vessels, hypoxia, acidosis, and hypercapnia contribute to pulmo nary vasoconstriction. Cor pulmonale may occur in the setting of lung parenchymal disease, pulmonary vascular disease, congenital heart disease, or impaired mobility of the thorax (Table 11-8). Cor pulmonale may be acute or chronic. Acute cor pulmonale is the sudden occurrence of pulmonary hypertension, which most often occurs in the setting of massive pulmonary emboli. Chronic cor pulmonale, in contrast, is much more common and is often associated with chronic obstructive pulmonary disease and pulmo nary fibrosis. Grossly, the right ventricle is hypertrophic with a wall thick ness o...

Classification of Congenital Heart Disease Initial left-to-right shunt Ventricular septal defect Atrial septal defect Patent ductus arteriosus Persistent truncus arteriosus Anomalous pulmonary venous drainage Hypoplastic left heart syndrome Right-to-left shunt Tetralogy of Fallot Tricuspid atresia No shunt Complete transposition of the great vessels Coarctation of the aorta Pulmonary stenosis Aortic stenosis Coronary artery origin from pulmonary artery Ebstein malformation Complete heart block Endocardial fibroelastosis

Acute Inflammation:  def.  lasts minutes to days and characterized by exudation of fluid and plasma proteins and emigration of leukocytes, predominantly neutrophils. 1.  Alterations in vascular caliber that lead to increased blood flow: vasodilation 2.  Microvascular structural changes that allow exudation of plasma protens and leukocytes: increased permeability mediated by histamine, bradykinin, leukotrienes, substance P, endothelial retraction exudate (s.g. > 1.012) vs. transudate (s.g. < 1.012) 3.  Emigration of leukocytes: margination, rolling, adhesion, diapedesis, migration neutrophils predominate (6-24 hours) and replaced by monocytes (24-48 hours) E-selectin (endothelium) - rolling, adhesion [induced by IL-1 and TNF] P-selectin (endothelium, platelets) - rolling [present in Weibel-Palade bodies] L-selectin (leukocytes) - homing ICAM (interacts with integrins LFA-1 on leukocytes) - adhesion, arrest, transmigration VCAM (interacts wit...

Frank-Starling Law of the Heart Two physiologists, Otto Frank and Ernest Starling, demonstrated that the strength of ventricular contraction varies directly with the end-diastolic volume (fig. 14.2). Even in experiments where the heart is removed from the body (and is thus not subject to neural or hormonal regulation) and where the still-beating heart is filled with blood flowing from a reservoir, an increase in EDV within the physiological range results in increased contraction strength and, therefore, in increased stroke volume. This rela- tionship between EDV, contraction strength, and stroke volume is thus a built-in, or intrinsic, property of heart muscle, and is known as the Frank-Starling law of the heart.

Regulation of Stroke Volume The stroke volume is regulated by three variables: the end-diastolic volume (EDV), which is the volume of blood in the ventricles at the end of diastole; the total peripheral resistance, which is the frictional resistance, or impedance to blood flow, in the arteries; and the contractility, or strength, of ventricular contraction. The end-diastolic volume is the amount of blood in the ven- tricles immediately before they begin to contract. This is a work- load imposed on the ventricles prior to contraction, and thus is sometimes called a preload. The stroke volume is directly proportional to the preload; an increase in EDV results in an increase in stroke volume. (This relationship is known as the Frank-Starling law of the heart, discussed shortly.) The stroke volume is also directly proportional to contractility; when the ventricles contract more forcefully,...

Effect of pH and Temperature on Oxygen Transport In addition to changes in P O 2 , the loading and unloading reac- tions are influenced by changes in the affinity (bond strength) of hemoglobin for oxygen. Such changes ensure that active skeletal muscles will receive more oxygen from the blood than they do at rest. This occurs as a result of the lowered pH and increased temperature in exercising muscles. The affinity is decreased when the pH is lowered and increased when the pH is raised; this is called the Bohr effect. When the affinity of hemoglobin for oxygen is reduced, there is slightly less loading of the blood with oxygen in the lungs but greater unloading of oxygen in the tissues. The net effect is that the tissues receive more oxygen when the blood pH is lowered (table 16.8). Since the pH can be decreased by carbon dioxide (through the formation of carbonic acid), the Bohr effect helps to provide more oxygen to the tissue...