Can you explain to me everything you know about kidneys?

Question

Please describe in full and understandable details =)

I'd like to know:

- Its functions

- How it carries out those functions

- The excretion process (through the kidneys)

- Problems with the kidneys

- The causes, symptoms, treatments, and preventions of those problems

- Etc.

I don't have a book to look it up from and Wikipedia's too confusing. I'll appreciate your help :)

Answer 1

Every vertebrate has a pair of kidneys.

Their functional units are called nephrons. The kidney contains more than a million nephrons, which collect fluid from filtered blood. The renal arteries and renal veins carry blood to and from the kidney. The collected waste material leaves the kidney via the ureter and is stored in the urinary bladder; it is then expelled from the body through the urethra. The kidney filters 1600 liters of blood per day, producing 1 liter of urine.

  

Let's follow the process of urine formation in a nephron.



The nephron's cup shaped Bowmans Capsule surrounds a knot of blood capillaries called the glomerulus. Much of the bloods fluid filters into the glomerulus due to pressure from the circulatory system. Left behind are large proteins and whole cells, which are too large to fit through. This filtrate is then passed through the nephron tubule, which has 4 main parts ( proximal convoluted tubule, loop of Henle, distal convoluted tubule, and the collecting duct).

In the proximal convoluted tubule, a considerable amount of resorbtion occurs. Small proteins, glucose, and ions are returned to the blood by active transport. Negatively charged ions follow passively, followed by the osmosis of water. About 75% of the filtrate is returned in this section of the nephron.

The loop of Henle, lie in the medulla of the kidney, the other parts of the nephron lie outside of the medulla in the cortex. Salt is actively transported out of the filtrate, and since this area impermeable to water, water cannot follow the ions out here.

The distal convoluted tubule, urine is then passed through here to the collecting duct where it is concentrated due to its permeability to water. It leaves the collecting duct into the pelvis of the kidney, which leads to the ureter and the bladder where it is stored.



Regulation of Kidney function



Urine composition and the rate of urine formation are largely regulated by hormones vasopressin, aldosterone, and angiotensin, and the enzyme rennin.



Vasopressin (ADH) is produced by the posterior pituitary gland and increases the bodies ability to resorbtion of water. it increase the permeability of the collecting ducts.

Diabetes insipidus is caused due to a lack of this hormone. It is characterized by thirst, and the production of large amounts of dilute urine.



Angiotensis and Aldosterone are hormones that regulate the amount of sodium that is resorbed from the filtrate in the nephrons. Aldosterone is produced by the adrenal gland. it promotes the resorbtion of sodium by the distal tube. Its action is directed by the bloods salt content. The kidney secretes an enzyme rennin, which changes a plasma protein angiotensinogen into angiotensin, which helps to increase the production of aldosterone and the blood pressure of the kidney.