collecting duct

Examples of collecting duct in the following topics:

• Tubular Secretion

  • Hydrogen, creatinine, and drugs are removed from the blood and into the collecting duct through the peritubular capillary network.
  • Urine is the substance leftover in the collecting duct following reabsorption and secretion.
  • Tubular secretion occurs throughout the different parts of the nephron, from the proximal convoluted tubule to the collecting duct at the end of the nephron.

• Nephron, Parts, and Histology

  • The distal convoluted tubule and collecting duct is the final site of reabsorption in the nephron.
  • The collecting duct is similar in function to the distal convoluted tubule and generally responds the same way to the same hormone stimuli.
  • The osmolarity of fluid through the distal tubule and collecting duct is highly variable depending on hormone stimulus.
  • After passage through the collecting duct, the fluid is brought into the ureter, where it leaves the kidney as urine.
  • Collecting duct, 9.

• Overview of Urine Formation

  • The fluid passes through the components of the nephron (the proximal/distal convoluted tubules, loop of Henle, the collecting duct) as water and ions are removed as the fluid osmolarity (ion concentration) changes.
  • In the collecting duct, secretion will occur before the fluid leaves the ureter in the form of urine.
  • During secretion some substances±such as hydrogen ions, creatinine, and drugs—will be removed from the blood through the peritubular capillary network into the collecting duct.
  • The end product of all these processes is urine, which is essentially a collection of substances that has not been reabsorbed during glomerular filtration or tubular reabsorbtion.

• Regulation of Urine Concentration and Volume

  • Antidiuretic hormone (ADH) is produced by the pituitary gland to control the amount of water that is reabsorbed through the collecting ducts.
  • ADH increases the permeability to water of the distal convoluted tubule and collecting duct, which are normally impermeable to water.

• Associated Organs

  • The bile produced in the liver is collected in bile canaliculi, which merge from bile ducts.
  • These eventually drain into the right and left hepatic ducts, which in turn merge to form the common hepatic duct.
  • The cystic duct, from the gallbladder, joins with the common hepatic duct to form the common bile duct.
  • The common bile duct and the pancreatic duct enter the duodenum together.
  • The liver and gallbladder are connected via the cystic duct, the liver and pancreas are connected via the pancreatic duct, and all three enter the duodenum at the common bile duct,

• Mammary Glands

  • The myoepithelial cells can contract under the stimulation of oxytocin, excreting milk secreted from alveolar units into the lobule lumen toward the nipple where it collects in sinuses of the ducts.
  • They exist in both sexes during the embryonic stage, forming only a rudimentary duct tree at birth.
  • A mature duct tree reaching the limit of the fat pad of the mammary gland is formed by bifurcation of duct terminal end buds, secondary branches sprouting from primary ducts and proper duct lumen formation.
  • However, a functional lactiferous duct tree can be reformed when a female is pregnant again.
  • Milk duct 7.

• Distribution of Lymphatic Vessels

  • The efferent lymph vessels in the left and lower side of the body drain into the left subclavian vein through the thoracic duct, while the efferent lymph vessels of the right side of the body drain into the right subclavian vein through the right lymphatic duct.
  • The lymphatic vessels start with the collection of lymph fluid from the interstitial fluid.
  • When the pressure for interstitial fluid in the interstitial space becomes large enough it leaks into lymph capillaries, which are the site for lymph fluid collection.
  • As the lymph vessels become larger, their function changes from collecting fluid from the tissues to propelling fluid forward.
  • Lymph nodes found closer to the heart filter lymph fluid before it is returned to venous circulation through one of the two lymph ducts.

• Lymph Transport

  • Lymphatic capillaries are the site of lymph fluid collection from the tissues.
  • The lymph vessels that receive lymph fluid from many capillaries are called collecting vessels.
  • The collecting vessels typically transport lymph fluid either into lymph nodes or lymph trunks.
  • The lymph trunks then converge into the two lymph ducts, the right lymph duct and the thoracic duct.
  • These ducts take the lymph into the right and left subclavian veins, which flow into the vena cava.

• Testes Ducts

  • Testes ducts, which include the seminiferous tubules and vas deferens, are involved in the creation or transportation of sperm.
  • The efferent ducts connect the rete testis with the initial section of the epididymis.
  • In humans and other large mammals, there are approximately 15-20 efferent ducts which occupy nearly one-third of the head of the epididymis.
  • Two ducts connect the left and right epididymis to the ejaculatory ducts in order to move sperm.
  • The sperm are transferred from the vas deferens into the urethra, collecting secretions from the male accessory sex glands such as the seminal vesicles, prostate gland, and bulbourethral glands, which provide the bulk of semen.

• Pancreatitis

  • Late complications include recurrent pancreatitis and the development of pancreatic pseudocyst, which are collections of pancreatic secretions that have been walled off by scar tissue.
  • These may cause pain, become infected, rupture and bleed, block the bile duct and cause jaundice, or migrate around the abdomen.
  • The pancreas connects to the small intestine via the pancreatic duct.
  • A blockage in this duct can cause pancreatitis.