Organs Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Organs and links to relevant pages within the course.
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|Specimens Containing a Lumen|
Any specimen that is a transverse section of a hollow structure or a specimen containing a lumen will almost always be placed in the block face to show the lumen or other opening in cross-section on the final slide. For any organs with very large lumen's in which the tube has been transected, you will embed on the cut surface to demonstrate the lining and layers present. Of special concern are specimens with very tiny lumen openings, such as temporal arteries or vas deferens. Since the lumen opening is so tiny, it is sometimes difficult to see. Some laboratories may lightly dip the end of the tiny tube opening in black ink. This indicates the "end" that should be placed down in the block face. Some laboratories may submit such tiny tubes whole and ask that they be cut into cross-section at embedding. This allows the histologist to clearly see the opening during dissection. Other means to flag these specimens can be by using an abbreviation on the cassette such as "vas" for vas deferens, alerting the histologist that the specimen contained will need to be embedded on end to show the lumen in cross-section.
The mesothelium is the name given to the membrane that lines most body cavities and surrounds the internal organs. Cells that shed from these membranes are commonly found in pleural, peritoneal and pericardial fluids. Mesothelial cells are large cells that may be found as single cells or in clusters and clumps. They tend to have a large round centrally placed nucleus with a generous amount of basophilic cytoplasm which can appear frayed at the edges. They will have one ore two small, well-defined, deeply staining nucleoli. While they may have small pinpoint vacuoles, they will not have the larger "foamy" vacuoles seen in macrophages or histocytes.There are two mesothelial cells in the image below (see arrows). While they are different in size, they are definitely larger than the background lymphocytes and plasmacytoid lymphocytes. Notice the irregular frayed edge to the cytoplasmic membrane.
|Clinical Significance of Blood in Urine|
Blood is normally not present in the urine of healthy individuals, apart from blood during menses that may be detected in urine samples from females, Hematuria is associated with renal or genital disorders in which the bleeding is the result of irritation to the involved organs or some type of trauma. Examples include:Renal calculiPyelonephritisGlomerulonephritisTumorsTraumaExposure to toxic chemicals or drugsStrenuous exerciseHemoglobinuria may be due to the lysis of red blood cells within the urinary tract. This can be caused by intravascular hemolysis, as the hemoglobin is filtered through the glomeruli. In a healthy, normal individual, the hemoglobin molecule attaches to haptoglobin and bypasses the kidney filtration system. When the hemoglobin/haptoglobin system is overwhelmed, hemoglobin passes into the urine. Hemoglobinuria may be associated with:Hemolytic anemiaSevere burnsTransfusion reactionInfection Strenuous exercise
|Vaso-occlusive Crisis, Continued|
This painful event of vaso-occlusive crisis often results in tissue necrosis. Organs affected include the bone marrow, brain, lungs, kidneys, liver, and spleen. Disorders that may result include bone and joint pathology, stroke, acute chest syndrome, nephropathies, and infections. Triggering mechanisms for this crisis include infection, fever, acidosis, dehydration, cold temperatures, anxiety, stress, and depression. Adults may experience acute chest syndrome due to pulmonary infarcts caused by sickling in the pulmonary microvasculature, whereas children with sickle cell disease can experience acute chest syndrome due to infections.
Sequestration crisis occurs in sickle cell disorders when large numbers of RBCs are suddenly pooled in the spleen and liver. These organs can enlarge rapidly causing pain, hypoxemia, and hypovolemic shock. Treatment of sequestration crisis may include chronic transfusion, exchange transfusion, and/or splenectomy, depending on the patient's age and the severity of the sequestration (as determined by the hemoglobin level and degree of drop in hemoglobin).
|Symptoms and Laboratory Findings in Severe HDFN Due to Anti-D|
Anti-D causes the most severe HDFN. Symptoms and laboratory findings in HDFN due to anti-D typically include:1. Anemia: Cord Hb can be less than 10 g/dL (100 g/L) and as low as 3–5 g/dL (30–50 g/L).2. Jaundice (icterus gravis): Jaundice occurs after delivery, as fetal bilirubin is cleared by the mother during pregnancy. Extravascular fetal red cell destruction by maternal antibody produces high bilirubin levels. The newborn, who is unable to produce adequate amounts of the liver enzyme glucuronyl transferase, is unable to conjugate the bilirubin into its water-soluble, excretable form.3. Kernicterus: If indirect bilirubin levels reach approximately 20 mg/dL (340 mmol/L) the fat soluble unconjugated bilirubin deposits in the fat-rich brain cells causing brain cell damage. Cerebral palsy, deafness, mental retardation, and other serious disorders can result.4. Hydrops fetalis: Gross edema occurs in severely affected infants, and often results in stillbirth or death soon after birth. Liver failure and hypoproteinemia also play a role in this syndrome.5. Enlarged organs, e.g., liver, spleen and heart6. Laboratory findings include a positive direct antiglobulin test (DAT), low hemoglobin (as above), increased reticulocyte count, and increased nucleated red cells.
|What is Connective Tissue?|
Connective tissue offers structural and metabolic support structure for organs and tissue. It is the most abundant tissue type in the body and can be found throughout. Cells and extracellular material called connective tissue matrix make up connective tissue. Fibroblasts, mast cells, macrophages, adipose cells, blood leukocytes, and plasma cells can all be found to some degree in connective tissue. In addition to cells, the matrix has 3 different fibers present:Reticular fibers - Support soft organs and the network around nerve fibers, fats cells, lymph nodes, and muscle fibers.Collagenous fibers - Found in ligaments, tendons, cartilage, and bone.Elastic fibers - Allow tissue to expand and are typically located in skin and blood vessel walls.
|Functions of Connective Tissue|
The primary functions of connective tissues include:Transportation of nutrients and metabolites through direct diffusion between organs and connective tissue properImmunological defense (fights invading cells via inflammation)Structural supportTissue repair (after injury) Additional functions found in certain body sites include:Energy storage (fat)Heat generation (brown fat)Haematopoiesis/haemopoiesis (blood formation)
|Where are reticular fibers found?||View Page|
|Gordon and Sweet's Silver Staining - Diagnostic Applications|
Reticular fibers support body organs like the liver, spleen, and kidney. The Gordon and Sweet's silver staining method is used to demonstrate abnormal reticular fiber patterns that may indicate cirrhosis or necrosis of the liver. This is why reticular stains are often requested on liver biopsies. Abnormal reticular fiber patterns may also indicate the presence of certain tumor types in the liver, spleen, or kidney.
|Role of Adipokines|
Over twenty adipokines have been identified. Some adipokines are secreted solely by adipocytes; several are secreted by adipocytes and other body cells. Their role is very widespread as they integrate with various body organs and tissues: skeletal muscle, adrenal cortex, brain and sympathetic nervous system. Adipokines function in: Energy balance Immune reactions Insulin sensitivity Angiogenesis Blood pressure maintenance Lipid metabolism Hemostasis
|Glossary of Terms N through Z.|
N:C Ratio - Nuclear: cytoplasmic Ratio - The ratio of nuclear volume to cytoplasmic volume within any one cell.Neoplasm - Any new and abnormal growth, such as a tumor.Neutrophilic Granules - Specific granules present in the cytoplasm of neutrophils. These granules resemble pencil stippling and stain a lilac color due to their affinity for both basic and acid dyes.Phagocyte - Any cell that ingests microorganisms or other cells and foreign particles.Phagocytosis - The ingestion and destruction of microorganisms or other foreign particles.Plasma - The fluid portion of blood in which the various blood cells are suspended.PF3 (platelet Factor 3) - A lipoprotein component of the platelet membrane; functions as a surface catalyst during blood coagulation.Pseudopod - A temporary protrusion of the cytoplasm of a cell.Refractile - Capable of refracting or changing the direction of light.Senescence - The process or condition of growing old.Serotonin - A constituent of blood platelets and other cells and organs; induces constriction of the blood vessels.Specific Granules - Granules found in cells of the more mature stages of the granulocytic series. They have distinct staining reactions which differ with each type of granulocyte.T-cell - Thymus derived lymphocyte which mediates cellular immunity.Thrombocyte (Platelet) - A circular or oval disk found in the blood; concerned with hemostasis.Thymus - A ductless gland-like body situated in the anterior mediastinal cavity; reaches its maximum development during the early years of childhood.Vacuole - Any small space or cavity formed in the cytotoplasm of a cell.
VirusMost Likely Means of Dissemination Primary Route of EntryGeneral Signs and SymptomsLaboratory TestingSmallpox: Image courtesy of CDCAs an aerosol Inhalation High fever with extreme lethargySevere headache, backache, and abdominal painRash that starts as red bumps but quickly develops into small, itchy blisters Consult local APHL prior to sample collectionShell vial and DFA Monoclonal IFAMolecular tests Viral Hemorrhagic Fevers (Ebola, Marburg, Lassa, and Argentine): SolidLiquidAerosol AbsorptionInhalationIngestion Vary by type of viral hemorrhagic fever (VHF), but initial signs and symptoms often include: Marked feverFatigueDizzinessMuscle aches, loss of strength, and exhaustionSevere cases of VHF often show signs of bleeding under the skin, within internal organs, or from body orifices like the mouth, eyes, or ears Enzyme-linked immunosorbent assay (ELISA)Polymerase chain reaction (PCR)Viral culture
A unit of red blood cells (RBCs) contained 250 mg of iron as part of the hemoglobin molecule. A long-term complication of red cell transfusion is iron overload, or hemosiderosis. As red cells are destroyed, they release iron. The iron cannot be excreted and is stored as hemosiderin and ferritin. Iron accumulates in the liver, heart, spleen, and endocrine organs. Tissue damage, heart failure, liver failure, diabetes, and hypothyroidism can occur. Patients who are transfused frequently are at the greatest risk for iron overload. Diseases such as sickle cell disease, thalessemia, aplastic anemia, and other chronic anemias usually require frequent transfusions. Signs and symptoms of hemosiderosis include muscle weakness, fatigue, weight loss, mild jaundice, anemia, and cardiac arrhythmias. Ferritin levels and other iron studies should be assessed. Specific stains may be used to detect iron in tissue biopsies. Iron chelation may be used to treat and prevent iron overload. Chelation works by using an agent which binds to iron and helps remove it through the urine or feces.
|Definition and Incidence|
Transfusion-associated graft versus host disease (TA-GVHD) is a rare but highly lethal adverse reaction. The disease has a 90% mortality rate. It is caused by the transfusion of donor lymphocytes to a recipient who is immunocompromised. The donor lymphocytes engraft and escalate an immune response against the host's tissues including organs such as the lungs, skin, intestines, and liver. The recipient is unable to destroy the foreign lymphocytes and the cells proliferate and respond to incompatible antigens in the host. Certain recipients have increased risk for developing TA-GVHD. They are: Neonates less than 4 months of age Fetuses Recipients with a congenital or acquired immunodeficiency Recipients of donor units from a blood relative