Mechanism of urine formation, Biology

MECHANISM OF URINE FORMATION -

Production of urine is uripoisis or diuresis. First of all it was explained by Kushney.

Nephron separates acidic urine from basic blood, so maintain acid base balance i.e. Homeostasis (w. cannon).

Process is completed in three stpes -

1.      ULTRAFILTRATION-

  1. Blood along with waste products come in glomerulus by afferent arteriole.
  2. Concentration of urea is more in afferent arteriole. By efferent arterioles only blood moves out.
  3. Diameter of afferent arteriole is more than efferent one. So blood stops in glomerulus for little time.
  4. Here +70 mm Hg GHP (glomerulur hydrostatic pressure) is exerted.
  5. It is balanced by BCOP & CHP.
  6. B.C.O.P. (Blood colloidal osmotic pressure) is due to blood proteins. It is - 30 mm Hg.
  7. CHP (Capsular hydrostatic pressure) is of -20 mm Hg by nephric filtrate of Bowmann's capsule.
  8. So at +20 mm Hg EFP (Effective filtration pressure) such elements having low molecular weight are filtered in glomerulus.
  9. Nephric filtrate is protein less plasma, it is isotonic. Both kidney form 130 ml filtrate / minute.
  10. According to Ludwig process is due to change in pressure.

2.      SELECTIVE REABSORPTION -

  1. In nephric filtrate some essential chemicals are also present as H O, glucose, minerals, A.A.
  2. 90% of nephric filtrate is reabsorbed. These essential chemicals again reach in blood.
  3. Their reabsorption is based on Threshold value. i.e. needed chemicals.
  4. In PCT 80% H2O is reabsorbed by passive transport. It is obligatory absorption.
  5. Rest water is absorbed in DCT under control of ADH. It is facultative absorption.
  6. In PCT glucose, amino acid, minerals are absorbed by diffusion. In PCT solution remains isotonic.
  7. Positive ions are absorbed by active transport.
  8. Negative ions are absorbed by passive transport.
  9. In descending loop H2O is absorbed so solution becomes hypertonic.
  10. In ascending loop NaCl is given out so solution becomes isotonic.
  11. In DCT again NaCl is absorbed so solution becomes hypotonic. It comes in duct of Bellini.

3.      SECRETION -

  1. Richard proved it by experiment. Renal tubule directly discharges heavy waste products in DCT.
  2. It is active process. These chemicals are mainly creatine, pera amino hippuric acid.
Posted Date: 10/2/2012 4:26:34 AM | Location : United States







Related Discussions:- Mechanism of urine formation, Assignment Help, Ask Question on Mechanism of urine formation, Get Answer, Expert's Help, Mechanism of urine formation Discussions

Write discussion on Mechanism of urine formation
Your posts are moderated
Related Questions
Hydrocolloids are extremely versatile and are used for many other purposes including: (a) Production of pseudoplasticity  (i.e. fluidity under shear) at high temperatures to ea

Considering a pair of homologous chromosomes containing a gene having two different alleles how many different genotypes can the individual present? If a gene of the diploid sp

Which of the following structures in a vertebrate with a four-chambered heart would have blood with the highest oxygen concentration? And why? A. Arteriole end of a capillary B. Ri

Effects of long term malnutrition on adults In adults, once the stored carbohydrates and fats are used up, the body starts using proteins to generate energy. These protei

Q. Is all the cartilage in the body the same? There are 3 types of cartilage in the human body: 1) hyaline cartilage; 2) elastic cartilage and 3) fibrocartilage. Hyaline cartil

The Upper Border of the Heart A:  Mark a point on the lower border of the left second costal cartilage 1.2 cm away from the sternal margin. B:  Mark a point on the upper bord

Arboriculture : It deals with the cultivation of ornamental plants. Arboriculture is the cultivation, management or study of individual shrubs, trees, vines, or other perennial woo

How does brain recognize difference between high and low c and soft and loud sounds?

Explain Rickets Rickets:- A condition in children due to vitamin D deficiency.

State the term Autopsy data - Brain patient Autopsy data are not always entirely usable for validation purposes, in that numerous changes may have taken place in the patient's