Question

• • Released in response to ________________ ________________ monitored by juxtaglomerular apparatus
• ______________ _________________: Increases permeability to water of collecting ducts, resulting in more water moving from filtrate to blood
• ________________ _________________ _________________: Released from the right atrium of the heart in response to increased blood volume and pressure
• Kidneys have two homeostatic functions unrelated to the urinary system
  • Release ____________________: Hormone that stimulates the production of red blood cells in red bone marrow
  • Transform _________________ into its active form
• ______________ ________________ _________________: Caused by presence of microorganisms in organs of the urinary system
• ___________ _______________: Decrease or complete cessation of glomerular filtration
  • What are some of the causes?

• _______________: Using artificial devices (e.g., artificial kidney machine) to cleanse the blood

Answer 1

1. Released in response to drop in blood pressure in the renal arteriole monitored by juxtaglomerular apparatus.

• The juxtaglomerular apparatus (JGA) is a group of modified cells found in the distal convoluted tubule of nephron.
• When the blood pressure in the arteriole reduces, the JGA produces renin, which acts upon angiotensinogen and converts it into angiotensin-l and further into angiotensin-ll.
• The angiotensin-ll stimulates secretion of aldosterone hormone, which in turn causes reabsorption of sodium ions and water. This increases the blood pressure.

2. Aldosterone and vasopressin Increases permeability to water of collecting ducts, resulting in more water moving from filtrate to blood.

• Aldosterone, as explained above, is secreted due to stimulation by angiotensin-ll. It causes reabsorption of sodium ions and water.
• Vasopressin, also called as anti-diuretic hormone (ADH), is secreted by hypothalamus. It causes reabsorption of water and increases blood pressure.

3.Atrial Natriuretic hormone: Released from the right atrium of the heart in response to increased blood volume and pressure.

• When blood pressure increases, the atrial natriuretic hormone is released by the heart.
• It inhibits the secretion of renin, thereby it reduces reabsorption of sodium ions and water in the renal tubule. This reduces the blood pressure.

4. Kidneys have two homeostatic functions unrelated to the urinary system.

• Release erythropoietin: Hormone that stimulates the production of red blood cells in red bone marrow.
  • Erythropoietin is a glycoprotein that stimulates the bone marrow to produce red blood cells.
  • It is produced by kidney and small amounts of it is produced by liver.
  • It is produced in response to low concentration of oxygen in the blood.
• Transform vitamin-D into its active form.
  • Activated form of vitamin-D helps in effective absorption of calcium and phosphorus contents into the body.

5.Urinary tract infections: Caused by presence of microorganisms in organs of the urinary system.

It is caused by pathogens like E. coli, Mycoplasma etc. When these microbes enter the urine, they travel to the urethra, urinary bladder and kidney and cause infections. This may result in painful urination and renal failure.

6.Renal failure: Decrease or complete cessation of glomerular filtration.

7.Causes of renal failure may be infections, injury to the nephron, formation of calculi or side effects of certain medicines.

Injuries such as inflammation of glomerulus (glomerulonephritis), presence of kidney stone resulting in blockage etc will prevent the flow of blood into the kidney. This reduces blood filtration.

In case of acute renal failure, kidney transplant can be done.

8.Hemodialysis: Using artificial devices (e.g., artificial kidney machine) to cleanse the blood.

• When kidneys fail to filter blood, hemodialysis can be used to remove the wastes from the blood.
• In this method, blood is pumped out of the body of patient into the dialyzer, consisting of a series of tubes made up of semipermeable membrane.
• These tubes are surrounded by a dialysing fluid having composition same as that of blood, except for the nitrogenous wastes.
• The nitrogenous wastes of the blood diffuses out into the dialysing fluid.The purified blood is returned to the patient.