Help with Kidney (1 Viewer)

[ssovon]

I dont understand the idea around the kidney and its functions, any help would be apreciated. sveno35@hotmail.com msg me if u have any answers or notes that you can send to me.

Thanks.

 

[jagshemesh]

I dont understand the idea around the kidney and its functions, any help would be apreciated. sveno35@hotmail.com msg me if u have any answers or notes that you can send to me.

Thanks.

The kidney basically cleans up fluids and gets rid of waste for example such as wastes within the blood or other parts of the body such as urea which is a toxin to the body. If built up too much and kept in the body, the urea may become harmful and affect your body.

 

[ari89]

I dont understand the idea around the kidney and its functions, any help would be apreciated. sveno35@hotmail.com msg me if u have any answers or notes that you can send to me.

Thanks.

Basically:

The functions of mammalian kidneys are to regulate the internal salt and water concentrations of the body and excrete the nitrogenous waste, urea. Three main processes achieve this:

• Filtration
• Reabsorption
• [FONT=&quot]Secretion [/FONT]

[FONT=&quot]More Detail:
The basic functional unit of the kidney is the nephron. Nephrons regulate water and soluble matter in the body by first filtering the blood, then reabsorbing some necessary fluid and molecules while secreting other, unneeded molecules. Reabsorption and secretion are accomplished with both cotransport and countertransport mechanisms. The final solution is then excreted as urine.

[/FONT][FONT=&quot]Blood enters the kidney from the body through the renal artery. The artery then separates into a series of much smaller vessels. When these reach the Bowman’s capsule they then form a network of capillaries called the glomerulus. Due to the high blood pressure in the capillaries some of the blood is forced through the permeable walls into the Bowman’s capsule. Also, small molecules pass through the walls passive filtration. The blood is then separated into two parts: the part remaining in the capillaries consisting of the blood cells and the part in the Bowman’s capsule consisting of mostly blood plasma called the glomerular filtrate. The plasma entering the Bowman’s capsule consists mostly of water, nitrogenous waste, glucose, amino acids, other ions and hormones. The glomerular filtrate is then forced along the proximal tube of the nephron tubule where the concentration of the glomerular filtrate is adjusted so that unwanted substances are only present to form the waste called urine.

[/FONT][FONT=&quot]Reabsorption is the movement of re-usable materials from the nephron tubule back to the blood stream via the capillary network surrounding the tubule Since this is an active process energy is required. This reabsorption of substances, including glucose, amino acids, water and some vitamins, mostly occurs in the proximal and distal parts of the nephron tubule and also in the loop of Henle.

[/FONT][FONT=&quot]Unlike filtration, secretion is a selective process and like reabsorption it is an active process requiring energy. Secretion refers to the active transport of substances from the blood into the nephron occurring in the proximal and distal parts of the nephron tubule.

[/FONT] The nephron is a regulatory unit and, by the constant reabsorption and secretion of substances back and forth between the blood and nephron, the composition of the blood and interstitial fluid can be maintained.

The kidney regulates the pH, mineral ion concentration, and water composition of the blood. By exchanging hydronium ions and hydroxyl ions, the blood plasma is maintained by the kidney at pH 7.4. Urine, on the other hand, becomes either acidic at pH 5 or alkaline at pH 8.

[FONT=&quot]The regulation of salt also occurs in the kidneys through the active movement of sodium ions back into the blood. This movement of the positive sodium ions causes a passive follow on by the negative chloride ions. As the salt moves out the concentration is changed and by osmotic pressure water follows the movement of the ions.

[/FONT][FONT=&quot]The concentration of salt and water is also regulated by the loop of Henle. This works because the dropping part of the loop of Henle is permeable to water but not salt therefore water, by osmosis, passes. In the rising part the opposite occurs and the walls are permeable to salt but not to water. The salt passively passes across a thin wall and then actively (costing energy) throught the thick wall. The passing out of the salt results with highly concentrated interstitial fluid in the medulla are of the kidney. This makes it darker in colour to the cortex.[/FONT]