renal cortex

Examples of renal cortex in the following topics:

• Nephron: The Functional Unit of the Kidney

  • Each kidney is composed of over one million nephrons that dot the renal cortex, giving it a granular appearance when sectioned sagittally (from front to rear).
  • Eighty-five percent of nephrons are cortical nephrons, deep in the renal cortex; the remaining 15 percent are juxtamedullary nephrons, which lie in the renal cortex close to the renal medulla.
  • The renal corpuscle, located in the renal cortex, is composed of a network of capillaries known as the glomerulus, as well as a cup-shaped chamber that surrounds it: the glomerular or Bowman's capsule.
  • The third part of the renal tubule is called the distal convoluted tubule (DCT); this part is also restricted to the renal cortex.
  • Urine leaves the medullary collecting ducts through the renal papillae, emptying into the renal calyces, the renal pelvis, and finally into the bladder via the ureter.

• Internal Anatomy of the Kidneys

  • The renal cortex is a space between the medulla and the outer capsule.
  • The kidneys are surrounded by a renal cortex, a layer of tissue that is also covered by renal fascia (connective tissue) and the renal capsule.
  • The renal cortex is granular tissue due to the presence of nephrons—the functional unit of the kidney—that are located deeper within the kidney, within the renal pyramids of the medulla.
  • Erythropotein, a hormone necessary for the synthesis of new red blood cells, is also produced in the renal cortex.
  • The kidney is made up of three main areas: the outer cortex, a medulla in the middle, and the renal pelvis.

• Supply of Blood and Nerves to the Kidneys

  • The renal veins drain the kidney and the renal arteries supply blood to the kidney.
  • Due to the position of the aorta, the inferior vena cava, and the kidneys in the body, the right renal artery is normally longer than the left renal artery.
  • The renal arteries carry a large portion of the total blood flow to the kidneys—up to a third of the total cardiac output can pass through the renal arteries to be filtered by the kidneys.
  • Renal blood supply starts with the branching of the aorta into the renal arteries (which are each named based on the region of the kidney they pass through) and ends with the exiting of the renal veins to join the inferior vena cava.
  • The renal plexus are the source of nervous tissue innervation within the kidney, which surround and primarily alter the size of the arterioles within the renal cortex.

• Kidney Structure

  • The third and innermost layer is the renal capsule.
  • Internally, the kidney has three regions: an outer cortex, a medulla in the middle, and the renal pelvis in the region called the hilum of the kidney.
  • Each segmental artery splits further into several interlobar arteries that enter the renal columns, which supply the renal lobes.
  • The interlobar arteries split at the junction of the renal cortex and medulla to form the arcuate arteries.
  • Externally, the kidney is surrounded by the renal fascia, the perirenal fat capsule, and the renal capsule.

• Nephroptosis (Floating Kidney)

  • Nephroptosis, also called floating kidney or renal ptosis, is an abnormal condition in which the kidney drops down into the pelvis when the patient stands up.
  • The renal fascia is a layer of connective tissue encapsulating the kidneys and the suprarenal glands.
  • The deeper layers below the renal fascia are, in order, the adipose capsule of the kidney (or perirenal fat), the renal capsule and finally the parenchyma of the renal cortex.
  • Anterior attachment: Passes anterior to the kidney, renal vessels, abdominal aorta and inferior vena cava and fuses with the anterior layer of the renal fascia of the opposite kidney.
  • The attack of colic pain is called Dittel's crisis or renal paroxysm.

• Other Hormonal Controls for Osmoregulation

  • The renin-angiotensin-aldosterone system (RAAS) stabilizes blood pressure and volume via the kidneys, liver, and adrenal cortex.
  • This, in turn, stimulates the renal tubules to reabsorb more sodium.
  • Mineralocorticoids are hormones synthesized by the adrenal cortex that affect osmotic balance.
  • Almost all of the sodium in the blood is reclaimed by the renal tubules under the influence of aldosterone.
  • Patients who have Addison's disease have a failing adrenal cortex and cannot produce aldosterone.

• Adrenal Cortex

  • The adrenal cortex is devoted to the synthesis of corticosteroid and androgen hormones.
  • Angiotensin is stimulated by the juxtaglomerular cells when renal blood pressure drops below 90 mmHg.
  • Androstenedione (Andro): an androgenic steroid produced by the testes, adrenal cortex, and ovaries.
  • The layers of the adrenal cortex are shown in this figure.
  • Differentiate among the zones (and hormones produced) of the adrenal cortex

• Overview of the Adrenal Glands

  • In humans, the adrenal glands are found at the level of the 12th thoracic vertebra sitting above and slightly medial to the kidneys, lying within the renal fascia, and separated from the kidneys by a thin layer of connective tissue.
  • Each adrenal gland has two distinct structures, the outer adrenal cortex and the inner medulla—both produce hormones.
  • The cortex mainly produces mineralcorticoids, glucocorticoids, and androgens, while the medulla chiefly produces adrenaline and nor-adrenaline.

• Long-Term Renal Regulation

  • Angiotensin II also stimulates the secretion of the hormone aldosterone from the adrenal cortex.

• Polycystic Kidney Disease

  • Studies show that 10% of end-stage renal disease (ESRD) patients treated with hemodialysis in Europe and the U.S. were initially diagnosed and treated for ADPKD.
  • As the cysts accumulate fluid, they enlarge, separate entirely from the nephron, compress the neighboring renal parenchyma, and progressively compromise renal function.
  • Under the function of gene defect, epithelial cells of renal tubule turn into epithelial cells of cyst wall after phenotype change and begin to have the function of secreting cyst fluid, which leads to continuous cysts enlargement.
  • In ARPKD, kidneys retain their shape, but are larger than the normal anatomical range with dilated collecting ducts from the medulla to the cortex.