chief cell

Examples of chief cell in the following topics:

• Gastric Phase

  • Histamine is a paracrine secretion from the enteroendocrine cells in the gastric glands.
  • Gastrin is a hormone produced by enteroendocrine G cells in the pyloric glands.
  • All three of these stimulate parietal cells to secrete hydrochloric acid and intrinsic factor.
  • The chief cells secrete pepsinogen in response to gastrin and especially Ach, and ACh also stimulates mucus secretion.
  • Below pH of two, stomach acid inhibits the parietal cells and G cells: a negative feedback loop that winds down the gastric phase as the need for pepsin and HCl declines.

• Digestive Properties of the Stomach

  • The hormone gastrin causes an increase in the secretion of HCl from the parietal cells and pepsinogen from the chief cells in the stomach.
  • Gastrin is released by G-cells in the stomach, via the base cells of the pyloric, cardiac, and fundic glands, in response to distension of the antrum, and digestive products (especially large quantities of incompletely digested proteins).
  • Parietal cells secrete hydrochloric acid and intrinsic factor

• Histology of the Large Intestine

  • The crypts and intestinal villi are covered by epithelium that contains two types of cells: goblet cells that secrete mucus and enterocytes that secrete water and electrolytes.
  • This is in contrast to the stomach, where the chief cells secrete pepsinogen.
  • In the intestine, the digestive enzymes are not secreted by the cells of the intestine.
  • During each mitosis, one of the two daughter cells remains in the crypt as a stem cell, while the other differentiates and migrates up the side of the crypt and eventually into the villus.
  • Goblet cells are among the cells produced in this fashion.

• Microscopic Anatomy of the Stomach

  • Different types of cells are at different locations down the pits.
  • The cells at the base of these pits are chief cells that are responsible for the production of pepsinogen, an inactive precursor of pepsin, which degrades proteins.
  • The secretion of pepsinogen prevents self-digestion of the stomach cells.
  • Further up the pits, parietal cells produce gastric acid and a vital substance, intrinsic factor.
  • Near the top of the pits, closest to the contents of the stomach, there are mucus-producing cells called goblet cells that help protect the stomach from self-digestion.

• Bone Tissue and the Effects of Aging

  • The osteoclasts are multi-nucleated cells that contain numerous mitochondria and lysosomes.
  • These cells are responsible for the resorption of bone and are generally present on the outer layer of bone, just beneath the periosteum.
  • The osteoclast then induces an infolding of its cell membrane and secretes collagenase and other enzymes important in the resorption process.
  • Low levels of calcium stimulate the release of parathyroid hormone (PTH) from chief cells of the parathyroid gland.

• Gross Anatomy of the Stomach

  • The stomach is divided into four sections, each of which has different cells and functions.
  • A mucous membrane lines the stomach that contains the glands (with chief cells) that secrete gastric juices.
  • The stomach is divided into four sections, each of which has different cells and functions .

• Postganglionic Neurons

  • The two exceptions mentioned above are the postganglionic neurons of sweat glands and the chromaffin cells of the adrenal medulla.
  • Within this endocrine gland, the pre-ganglionic neurons create synapses with chromaffin cells and stimulate the chromaffin cells to release norepinephrine and epinephrine directly into the blood.
  • The postsynaptic cell then goes on to innervate the targeted end effector (i.e., gland, smooth muscle, etc.).
  • The pelvic splanchnic efferent preganglionic nerve cell bodies reside in the lateral gray horn of the spinal cord at the S2–S4 spinal levels.
  • The parasympathetic nervous system uses acetylcholine (ACh) as its chief neurotransmitter, although peptides (such as cholecystokinin) may act on the PSNS as a neurotransmitter.

• Specific T-Cell Roles

  • T helper cells assist the maturation of B cells and memory B cells while activating cytotoxic T cells and macrophages.
  • Differentiation into helper T cell subtypes occurs during clonal selection following T cell activation of naive T cells.
  • Cytotoxic T cells (TC cells, or CTLs) destroy virus-infected cells and tumor cells, and cause much of the damage in in transplant rejection and autoimmune diseases.
  • Memory T cells comprise two subtypes: central memory T cells (TCM cells) and effector memory T cells (TEM cells), which have different properties and release different cytokines.
  • Regulatory T cells (Treg cells), also known as suppressor T cells, are crucial for the maintenance of immunological tolerance.

• Physiology of Lactation

  • The chief function of lactation is to provide nutrition and immune protection to the young after birth.
  • The release of prolactin triggers the cells in the alveoli to make milk.
  • It contains higher amounts of white blood cells and antibodies than mature milk, and is especially high in immunoglobulin A (IgA), which coats the lining of the baby's immature intestines, and helps to prevent pathogens from invading the baby's system.

• Natural Killer Cells

  • The role of NK cells is similar to that of cytotoxic T cells in the adaptive immune response.
  • NK cells provide rapid responses to virus-infected cells and respond to tumor formation by destroying abnormal and infected cells.
  • NK cells use wo cytolytic granule-mediated apoptosis to destroy abnormal and infected cells.
  • Virus-infected cells destroyed by cell lysis release their replicated virus particles into the body, which infects other cells.
  • Cells that are osponized with antibodies are easier for NK cells to detect and destroy.