BIO 4.3 NEPHRON

The main waste produced by animals are?

carbon dioxide and nitrogenous wastes

carbon dioxide is produce when

carbohydrates or lipids are broken down during cellular respiration to release energy, carbon dioxide and water are produced

nitrogenous wastes are produced when

proteins are broken down, the nirogenous parts are split off and the remainder of the molecule is converted into carbohydrates or lipids which can be used for energy

why do mammals go to the troule of excerting nitrogenous wastes in the form of urea rather than ammonia when it takes so much energy to do so?

urea is less toxic than ammonia

why is it useful for birds and reptiles to excrete their nitrogenous wastes as uric acid rather than urea?

insoluble

the role of the lungs as an excretory organ

excrete gaseous waste such as carbon dioxide which is a waste product of in cellular respiration in cells throught the body

the role of the liver as an excretory organ

responsible for breaking down amino acid to release ammonia which it then covernts into urea

the role of the skin as an excretory organ

through the production of sweat, elimanating excess water and salts as well as a small amount of urea

the role of the kidney as an excretory organ

filter nitrogenous waste products from the blood stream and collecting them in urine

The mammalian kidney

the formation of urine involves passive filtration, selective reabsorption and secretion and the passive removaal of water (outer cortex and inner medulla)

Glomerulus

mass of thin-walled capillaries

Bowman’s capsule

double-walled, cup-shaped structure

Proximal convoluted tubule

descending tubule to the Loop of Henle

Loop of Henle

- long loop extending into the medulla
- removes water from the filtrate by osmosis

Distal convoluted tubule

ascending tubule connecting Loop of Henle to the collecting duct

Collecting duct

last section leading back to the renal pelvis and then into the ureter. 

Filtration in the nephron

The high pressure of blood in the glomerular blood vessels forces fluid containing water, glucose, salts and amino acids through the walls of glomerular capillaries and into the Bowman’s capsule.

Only small molecules and water can pass through the wall membranes; blood cells and large blood proteins remain behind in the glomerular capillaries.

role of antidiuretic hormone (ADH) in water reabsorption

from the pituitary gland increases the permeability of the collecting tublue to water, increasing reabsorption of water and causing urine to become concentrated.

where in the nephron and by what process are amino acids and glucose reabsorbed

proximal tubule

• by active transport against a concentration gradient

where in the nephron and by what process is water reabsorbed

water is reabsorbed from the descending (loop henle) passivrly along an osmotic gradient