renal medulla

Examples of renal medulla in the following topics:

• Internal Anatomy of the Kidneys

  • The renal cortex is a space between the medulla and the outer capsule.
  • The renal medulla contains the majority of the length of nephrons, the main functional component of the kidney that filters fluid from blood.
  • 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.
  • The medulla consists of multiple pyramidal tissue masses, called the renal pyramids, which are triangle structures that contain a dense network of nephrons.
  • The kidney is made up of three main areas: the outer cortex, a medulla in the middle, and the renal pelvis.

• Nephron: The Functional Unit of the Kidney

  • 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 second part is called the loop of Henle, or nephritic loop, because it forms a loop (with descending and ascending limbs) that goes through the renal medulla.
  • The collecting ducts amass contents from multiple nephrons, fusing together as they enter the papillae of the renal medulla.
  • 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.
  • The glomerulus and convoluted tubules of the nephron are located in the cortex of the kidney, while the collecting ducts are located in the pyramids of the kidney's medulla.

• Kidney Function and Physiology

  • Second, the renal tubules collect the filtrate.
  • In the loop of Henle, the filtrate continues to exchange solutes and water with the renal medulla and the peritubular capillary network.
  • Additionally, the loop of Henle invades the renal medulla, which is naturally high in salt concentration.
  • The osmotic gradient increases as it moves deeper into the medulla.
  • Water flows from the filtrate to the interstitial fluid, so osmolality inside the limb increases as it descends into the renal medulla.

• 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.

• 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.

• 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.

• 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.

• Adrenal Medulla

  • The adrenal medulla is the core of the adrenal glands, and is surrounded by the adrenal cortex.
  • The adrenal medulla is responsible for the production of catecholamines, derived from the amino acid tyrosine.
  • The adrenal medulla secretes approximately 20% noradrenaline (norepinephrine) and 80% adrenaline (epinephrine).
  • Chromaffin cells are the neuroendocrine cells found in the medulla; they are modified post-synaptic sympathetic neurons that receive sympathetic input.
  • The adrenal medulla sits below the three layers of the adrenal cortex and is innervated by nerve fibers.

• Medulla Oblongata

  • The medulla oblongata controls autonomic functions and connects the higher levels of the brain to the spinal cord.
  • The medulla oblongata is the lower half of the brainstem.
  • An open or superior part where the dorsal surface of the medulla is formed by the fourth ventricle.
  • During development, the medulla oblongata forms from the myelencephalon.
  • Describe the location and function of the medulla oblongata region of the brain stem

• Renal Disease and Failure

  • Renal failure uremia is a syndrome of renal failure characterized by elevated levels of urea and creatinine in the blood.
  • Renal failure (also kidney failure or renal insufficiency) is a medical condition in which the kidneys fail to adequately filter waste products from the blood.
  • Renal failure uremia is a syndrome of renal failure that includes elevated blood urea and creatinine levels.
  • Acute renal failure can be reversed if diagnosed early.
  • It is considered to be chronic renal failure if the decline of renal function is to less than 25%.