Parathyroid hormoneParathyroid hormone (PTH), also called parathormone or parathyrin, is a peptide hormone secreted by the parathyroid glands that regulates the serum calcium concentration through its effects on bone, kidney, and intestine. PTH influences bone remodeling, which is an ongoing process in which bone tissue is alternately resorbed and rebuilt over time. PTH is secreted in response to low blood serum calcium (Ca2+) levels. PTH indirectly stimulates osteoclast activity within the bone matrix (osteon), in an effort to release more ionic calcium (Ca2+) into the blood to elevate a low serum calcium level.
Calcium in biologyCalcium ions (Ca2+) contribute to the physiology and biochemistry of organisms' cells. They play an important role in signal transduction pathways, where they act as a second messenger, in neurotransmitter release from neurons, in contraction of all muscle cell types, and in fertilization. Many enzymes require calcium ions as a cofactor, including several of the coagulation factors. Extracellular calcium is also important for maintaining the potential difference across excitable cell membranes, as well as proper bone formation.
Smoking and pregnancyTobacco smoking during pregnancy causes many detrimental effects on health and reproduction, in addition to the general health effects of tobacco. A number of studies have shown that tobacco use is a significant factor in miscarriages among pregnant smokers, and that it contributes to a number of other threats to the health of the foetus. Because of the associated risks, people are advised not to smoke before, during or after pregnancy. If this is not possible, however, reducing the daily number of cigarettes smoked can minimize the risks for both the mother and child.
Focal lung pneumatosisA focal lung pneumatosis, is an enclosed pocket of air or gas in the lung and includes blebs, bullae, pulmonary cysts, and lung cavities. Blebs and bullae can be classified by their wall thickness. A bleb has a wall thickness of less than 1 mm. By radiology definition, it is up to 1 cm in total size. By pathology definition, it originates in the pleurae (rather than in the lung parenchyma). A bulla has a wall thickness of less than 1 mm. By radiology definition, it has a total size of greater than 1 cm.
Passive smokingPassive smoking is the inhalation of tobacco smoke, commonly called secondhand smoke (SHS) or environmental tobacco smoke (ETS), by persons other than the active smoker. It occurs when tobacco smoke diffuses into the surrounding atmosphere as an aerosol pollutant, which leads to its inhalation by nearby bystanders within the same environment. Exposure to secondhand tobacco smoke causes many of the same diseases caused by active tobacco smoking, although to a lower prevalence due to the reduced concentration of smoke that enters the airway.
Chest tubeA chest tube (also chest drain, thoracic catheter, tube thoracostomy or intercostal drain) is a surgical drain that is inserted through the chest wall and into the pleural space or the mediastinum in order to remove clinically undesired substances such as air (pneumothorax), excess fluid (pleural effusion or hydrothorax), blood (hemothorax), chyle (chylothorax) or pus (empyema) from the intrathoracic space.
PneumothoraxA pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and shortness of breath. In a minority of cases, a one-way valve is formed by an area of damaged tissue, and the amount of air in the space between chest wall and lungs increases; this is called a tension pneumothorax. This can cause a steadily worsening oxygen shortage and low blood pressure.
Parathyroid glandParathyroid glands are small endocrine glands in the neck of humans and other tetrapods. Humans usually have four parathyroid glands, located on the back of the thyroid gland in variable locations. The parathyroid gland produces and secretes parathyroid hormone in response to a low blood calcium, which plays a key role in regulating the amount of calcium in the blood and within the bones. Parathyroid glands share a similar blood supply, venous drainage, and lymphatic drainage to the thyroid glands.
Fine-needle aspirationFine-needle aspiration (FNA) is a diagnostic procedure used to investigate lumps or masses. In this technique, a thin (23–25 gauge (0.52 to 0.64 mm outer diameter)), hollow needle is inserted into the mass for sampling of cells that, after being stained, are examined under a microscope (biopsy). The sampling and biopsy considered together are called fine-needle aspiration biopsy (FNAB) or fine-needle aspiration cytology (FNAC) (the latter to emphasize that any aspiration biopsy involves cytopathology, not histopathology).
CalcitriolCalcitriol is the active form of vitamin D, normally made in the kidney. It is also known as 1,25-dihydroxycholecalciferol. It is a hormone which binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the expression of many genes. Calcitriol increases blood calcium (Ca2+) mainly by increasing the uptake of calcium from the intestines.
