Endocrine and Immune Systems - NCLEX-PN

Calcitonin is produced by the thyroid gland. The hormone plays an important role in lowering blood calcium levels. It is also synthesized as a drug and used in the treatment of hypercalcemia. The other three hormones are indeed secreted by the islets of Langerhans in the pancreas. Insulin, secreted by the beta cells lowers blood sugar, glucagon, secreted by the alpha cells, increases blood sugar, and somatostatin, secreted by the gamma cells regulates digestive and metabolic processes. Lipase is not a hormone, but an enzyme that facilitates the breakdown of lipids. The pancreas does indeed secrete lipase.

Endocrine glands secrete hormones into the blood. The endocrine glands include the ovaries, testes, hypothalamus, thyroid, pituitary, adrenal glands, pancreas, the pineal gland, and others. Salivary glands are considered exocrine glands. Exocrine glands secrete substances through ducts to the body surface or into body cavities, such as the mouth in the case of salivary glands.

Oxytocin is produced by the hypothalamus, and is released by the posterior pituitary. Women experience an increased level of oxytocin during labor, after birth, and while breastfeeding. It helps to increase uterine contractility, aiding in the delivery process and preventing hemorrhage after birth. Progesterone and estrogen are hormones released from the ovary. Estrogen is has many effects on the body, one of which is the development of sex characteristics in females. Progesterone is important in regulation of the uterine lining. Prolactin is made by the anterior pituitary gland and functions in the production on breast milk.

Epinephrine is the only hormone of those listed that is produced by the adrenal medulla. The adrenal medulla is the center of the adrenal gland. Antidiuretic hormone is produced by the posterior pituitary. Calcitonin is produced by the thyroid. Thyroid-stimulating hormone is secreted from the anterior pituitary, as is follicle-stimulating hormone.

All of these are correct effects of parathyroid hormone. The kidneys resorb calcium and as a result, less is released into the urine. The intestines absorb additional calcium from food and calcium is released from the bone through the work of osteoclasts.

Catecholamines are hormones produced by the adrenal medulla. Adrenal glands are located above each kidney. Catecholamines may also function as neurotransmitters, important chemical messengers. They regulate the sympathetic nervous system's response to stress.

Thyroid-stimulating hormone (TSH) is produced by the anterior pituitary. TSH causes the thyroid to release thyroid hormones (T3 and T4). A TSH blood test is often ordered to diagnose hypoactive thyroid.

The thyroid gland is located (in front) anterior to the trachea. The parathyroid glands are located on the backside on the thyroid. The thyroid is stimulated in response to TSH produced by the anterior pituitary. It will then secrete T3 and T4 although T3 is more potent and produced in a lesser quantity. Calcitonin, a hormone which decreases blood calcium levels, is also produced by the thyroid.

Aldosterone is a hormone secreted by the adrenal glands. Serum aldosterone levels vary throughout the day. Aldosterone presence is highest in the morning. Of the answer choices, 7 AM is the best choice. A physician may have the patient come to the office at a specific time of day for this reason.

IgA, primarily in its secretory form (sIgA), is the most abundant immunoglobulin in the lining of the gastrointestinal tract and in the mucus membranes of the respiratory tract. It is also present in the urogenital tract, in tears, in saliva, and in breast milk. All of the other immunoglobulins may be present in mucus membranes, depending on the presence of active infection or allergy, but none is as abundant in secretions as IgA. IgE is primarily involved in binding allergens and inducing the allergic response via release of histamine. IgM is expressed on the surface of B cells and is the first immunoglobulin to fight pathogens at the site of infection/injury. IgG are the most abundant antibody throughout the body and play the largest role in fighting pathogens. IgG can cross the placenta and thus confer passive immunity to the fetus.

The presence of CMV IgM would suggest an active cytomegalovirus infection, as IgM is the immunoglobulin released during the initial, active infection with a pathogen. The presence of IgG would suggest a past infection, where IgG specific to the virus would be present as part of adaptive immunity (ready to respond to the virus should the host ever be re-exposed). IgE is not formed when an individual contracts CMV, as IgE is produced in response to allergens rather than pathogens (except parasites). The function of IgD is thought to be related to the allergic response by regulating basophils and mast cells.

The only immunoglobulin that has been shown to be able to cross the placenta is IgG. This is important in that it confers short term immunity to the fetus that continues into the first few months of the infant's life. Note that it is common to give Rh-negative anti-Rh IgG injections at about 28 weeks gestation; a booster may also be given at about 34 weeks gestation.

Insulin is produced by beta cells of the pancreatic islets. Insulin's action is to decrease blood glucose, facilitating its uptake into cells. Alpha cells produce glucagon, which has the opposite effect as insulin. Delta cells produce somatostatin, which inhibits many digestive processes. and gamma cells produce pancreatic polypeptide, which regulate pancreatic secretion.

The pituitary is located just below the hypothalamus. The pituitary and the hypothalamus are connected by nerves and maintain an important working relationship with one another. Both are located near the base of the brain.

Lysozymes are a group of defense enzymes found in tears, saliva, mucus, and breast milk. It is considered part of our innate immune systems, as its presence in tears prevents infectious conjunctivitis. Cathelicidin, Defensin-5, and DEFA1 are found in the lysosomes of polymorphonuclear leukocytes (PMN's) and macrophages.

Interleukins (IL) are cytokines that play a role in signaling the immune cells. IL-8 is produced mainly by macrophage and dendritic cells and plays a major role in inflammation as a chemoattractant for neutrophils. IL-1 and IL-6 both induce acute phase proteins. TNF-alpha is involved in the acute phase reaction. It is an endogenous pyrogen (meaning it induces fever) and is also involved in apoptosis and tumor inhibition.

Major histocompatibility complex 1 in a membrane protein that binds to peptide fragments from pathogens such as viruses and bacteria and then displays them on the cell surface in order to alert other immune cells of the presence and nature of infection.

All cells with nuclei express MHC-1. Red blood cells do not have nuclei, and do not express MHC-1 on membranes.

Antibodies are only produced by B cells, specifically by a type of specialized B cell called a plasma cell. B cells belong to a broader category of leukocytes known as lymphocytes, which are agranulocytes.

T lymphocytes are so titled because they mature in the thymus, unlike B lymphocytes, which mature in the bone marrow. The thymus is located in the anterior superior mediastinum, ventral to the heart and dorsal to the sternum. It is most active in the neonatal and pre-adolescent periods, afterwards, it degenerates and is replaced with adipose tissue.

Lymphoid progenitor cells are produced in all of the following tissues: the liver, the bone marrow, spleen, and gut associated lymphoid tissue (mainly found in the liver and intestines). However, note that the vast majority of all blood cells are produced in the red bone marrow of long bones by hematopoietic stem cells.