renal threshold of glucose

Examples of renal threshold of glucose in the following topics:

• Glucosuria

  • Glycosuria or glucosuria is the excretion of glucose into the urine .
  • The proximal tubule can only reabsorb a limited amount of glucose.
  • This point is called the renal threshold of glucose (RTG).
  • With normal kidney (renal) function, glucose is excreted in the urine only when there are abnormally elevated levels of glucose in the blood.
  • However, in those with renal glycosuria, glucose is abnormally elevated in the urine due to improper functioning of the renal tubules, which are the primary components of the nephrons that act as the filtering units of the kidneys.

• Location and External Anatomy of the Kidneys

  • The kidneys are the primary functional organ of the renal system.
  • They are also responsible for the reabsorption of water, glucose, and amino acids, and will maintain the balance of these molecules in the body.
  • They are covered by the renal capsule, which is a tough capsule of fibrous connective tissue.
  • Resting on top of each kidney is an adrenal gland (adrenal meaning on top of renal), which are involved in some renal system processes despite being a primarily endocrine organ.
  • The renal artery branches off from the lower part of the aorta and provides the blood supply to the kidneys.

• Kidney Transplant

  • Kidney transplantation is the organ transplant of a kidney into a patient with end-stage renal disease.
  • Kidney transplantation, or renal transplantation, is the organ transplant of a kidney into a patient with end-stage renal disease.
  • The indication for kidney transplantation is end-stage renal disease (ESRD), regardless of the primary cause.
  • Prednisolone suppresses the immune system, but its long-term use at high doses causes a multitude of side effects, including glucose intolerance and diabetes, weight gain, osteoporosis, muscle weakness, hypercholesterolemia, and cataract formation.
  • Prednisolone alone is usually inadequate to prevent rejection of a transplanted kidney.

• Glomerular Filtration

  • Glomerular filtration is the renal process whereby fluid in the blood is filtered across the capillaries of the glomerulus.
  • It describes the process of blood filtration in the kidney, in which fluid, ions, glucose, and waste products are removed from the glomerular capillaries.
  • Many of these materials are reabsorbed by the body as the fluid travels through the various parts of the nephron, but those that are not reabsorbed leave the body in the form of urine.
  • The process by which glomerular filtration occurs is called renal ultrafiltration.
  • The force of hydrostatic pressure in the glomerulus (the force of pressure exerted from the pressure of the blood vessel itself) is the driving force that pushes filtrate out of the capillaries and into the slits in the nephron.

• Facilitated transport

  • An example of this occurs in the kidney, where both forms of channels are found in different parts of the renal tubules.
  • Glucose, water, salts, ions, and amino acids needed by the body are filtered in one part of the kidney.
  • This filtrate, which includes glucose, is then reabsorbed in another part of the kidney.
  • Because there are only a finite number of carrier proteins for glucose, if more glucose is present than the proteins can handle, the excess is not transported; it is excreted from the body in the urine.
  • A different group of carrier proteins called glucose transport proteins, or GLUTs, are involved in transporting glucose and other hexose sugars through plasma membranes within the body.

• 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 stimulates gluconeogenesis, the production of glucose from newly-released amino acids and lipids
  • 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.

• Nephron, Parts, and Histology

  • The glomerulus is a capillary tuft that receives its blood supply from an afferent arteriole of the renal circulation.
  • A group of specialized cells known as juxtaglomerular apparatus (JGA) are located around the afferent arteriole where it enters the renal corpuscle.
  • The visceral layer lies just beneath the thickened glomerular basement membrane and only allows fluid and small molecules like glucose and ions like sodium to pass through into the nephron.
  • Water and glucose follow sodium through the basolateral membrane via an osmotic gradient, in a process called co-transport.
  • Approximately 2/3rds of water in the nephron and 100% of the glucose in the nephron are reabsorbed by cotransport in the proximal convoluted tubule.

• Tubular Reabsorption

  • Reabsorption in the nephron may be either a passive or active process, and the specific permeability of the each part of the nephron varies considerably in terms of the amount and type of substance reabsorbed.
  • Water can follow other molecules that are actively transported, particularly glucose and sodium ions in the nephron.
  • Some substances can also pass through tiny spaces in between the renal epithelial cells, called tight junctions.
  • In the proximal convoluted tubules, all the glucose in the filtrate is reabsorbed, along with an equal concentration of ions and water (through cotransport), so that the filtrate is still 300 mOsm/L as it leaves the tubule.
  • A diagram of the nephron that shows the mechanisms of reabsorption.

• Physical Characteristics and Volume

  • Blood appears red because of the high amount of hemoglobin, a molecule found on RBCs.
  • Deoxygenated blood is a darker shade of red.
  • Most tissues can survive without perfusion for a short amount of time, but the brain needs a continuous supply of oxygen and glucose to stay alive.
  • Many mechanisms exist to regulate blood volume and tissue perfusion, including renal water excretion in the kidney, the pumping activity of the heart, and the abilities of the arteries to constrict or dilate.
  • Two tubes of EDTA-anticoagulated blood.

• Proteins: Sources, Uses in the Body, and Dietary Requirements

  • Proteins are composed of 20 different amino acids, about half of which are essential, meaning they must be obtained from the diet.
  • Some ingested amino acids are used for protein biosynthesis, while others are converted to glucose through gluconeogenesis, or fed into the citric acid cycle.
  • Relatively little evidence has been gathered regarding the effect of long-term high intake of protein on the development of chronic diseases.
  • Increased load on the kidney is a result of an increase in reabsorption of NaCl.
  • When added to any additional renal disease, this may cause permanent glomerular damage.