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.

  • Other Hormonal Controls for Osmoregulation

    • Renin is secreted by a part of the juxtaglomerular complex and produced by the granular cells of the afferent and efferent arterioles.
    • It is released by cells in the atrium of the heart in response to high blood pressure and in patients with sleep apnea.

  • Hormonal Regulation of the Excretory System

    • The anterior pituitary is composed of glandular cells that secrete protein hormones.
    • In contrast to ADH, which promotes the reabsorption of water to maintain proper water balance, aldosterone maintains proper water balance by enhancing Na+ reabsorption and K+ secretion from extracellular fluid of the cells in kidney tubules.
    • Cells in the juxtaglomerular apparatus, which regulates the functions of the nephrons of the kidney, detect this and release renin.

  • 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.

  • Cellular Differentiation

    • Three basic categories of cells make up the mammalian body: germ cells, somatic cells, and stem cells.
    • Pluripotent stem cells undergo further specialization into multipotent progenitor cells that then give rise to functional cells.
    • Hematopoietic stem cells (adult stem cells) from the bone marrow that give rise to red blood cells, white blood cells, and platelets
    • Mesenchymal stem cells (adult stem cells) from the bone marrow that give rise to stromal cells, fat cells, and types of bone cells;
    • Epithelial stem cells (progenitor cells) that give rise to the various types of skin cells

  • Gene Expression in Stem Cells

    • In mammals, there are two broad types of stem cells: embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and adult stem cells, which are found in various tissues.
    • Stem cells can now be artificially grown and differentiated into specialized cell types with characteristics consistent with muscle or nerve cells through cell culture.
    • In one, the daughter cells are initially equivalent but a difference is induced by signaling between the cells, from surrounding cells, or from the precursor cell.
    • Stem cells are indicated by (A), progenitor cells by (B), and differentiated cells by (C).
    • Pluripotent, embryonic stem cells originate as inner cell mass (ICM) cells within a blastocyst.