juxtaglomerular cells

(noun)

The juxtaglomerular cells (JG cells, or granular cells) are cells in the kidney that synthesize, store, and secrete the enzyme renin.

Related Terms

Examples of juxtaglomerular cells in the following topics:

  • Long-Term Renal Regulation

    • When blood volume is low, juxtaglomerular cells in the kidneys secrete renin directly into circulation.

  • Adrenal Cortex

    • Aldosterone exerts its effects on the distal convoluted tubule and collecting duct of the kidney where it causes increased reabsorption of sodium and increased excretion of both potassium (by principal cells) and hydrogen ions (by intercalated cells of the collecting duct).
    • Angiotensin is stimulated by the juxtaglomerular cells when renal blood pressure drops below 90 mmHg.
    • It increases blood glucose levels in response to stress, by inhibiting glucose uptake into muscle and fat cells
    • Testosterone : a hormone with a wide variety of effects, ranging from enhancing muscle mass and stimulation of cell growth to the development of the secondary sex characteristics.

  • Adrenergic Neurons and Receptors

    • Many cells possess these receptors, and the binding of an agonist will generally cause a sympathetic (or sympathomimetic) response (e.g., the fight-or-flight response).
    • The former interacts with calcium channels of the endoplasmic and sarcoplasmic reticulum, thus changing the calcium content in a cell.

  • Nephron, Parts, and Histology

    • A group of specialized cells known as juxtaglomerular apparatus (JGA) are located around the afferent arteriole where it enters the renal corpuscle.
    • It is composed of visceral (simple squamous epithelial cells; inner) and parietal (simple squamous epithelial cells; outer) layers.
    • Red blood cells and large proteins, such as serum albumins cannot pass through the glomerulus under normal circumstances.
    • Juxtaglomerular apparatus.

  • Regulation of Water Intake

    • When the osmolarity of blood changes (i.e. it is more or less dilute), water diffusion into and out of the osmoreceptor cells changes.
    • The macula densa cells in the walls of the ascending loop of henle of the nephron is another type of osmoreceptor, however it stimulates the juxtaglomerular apparatus (JGA) instead of the hypothalamus.

  • Regulation of Water Output

    • To review the renin-angiotensin system, low blood volume activates the juxtaglomerular apparatus in a variety of ways, which secretes renin.
    • It acts on mineralcorticoid receptors in the epithelial cells of the distal convoluted tubule and collecting duct, which increases their expression of Na+/K+ ATPase pumps and activates those pumps.

  • 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 virally infected cells and tumor cells, and are also 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.

  • 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.

  • Lymphoid Cells

    • The three major types of lymphocyte are T cells, B cells, and natural killer cells.
    • If cancer cells evade NK cell detection for long enough, however, they can grow into tumors that are more resistant to NK cell activity.
    • T cells are involved in cell-mediated immunity whereas B cells are primarily responsible for humoral immunity.
    • There are two types of T cells involved in adaptive, cell-mediated immunity.
    • Following activation, B cells and T cells leave a lasting legacy of the antigens they have encountered in the form of memory cells.

  • Maturation of T Cells

    • T cells belong to a group of white blood cells known as lymphocytes and play a central role in the cell-mediated branch of the adaptive immune system.
    • They are distinguished from other lymphocytes, such as B cells and natural killer cells (NK cells), by the presence of a T cell receptor (TCR) on the cell surface.
    • T cells can be either helper T cells or cytoxic T cells based on whether they express CD4 (helper) or CD8 (cytotoxic) glycoprotein.
    • A T cell is then signaled by the thymus to become a CD4+ cell by reducing expression of its CD8 cell surface receptors.
    • The remaining cells exit the thymus as mature naive T cells.