Urinalysis and Body Fluids 6th Edition by Majorie DiLorenzo, Susan Strasinger

Exercise 25

For active transport to occur, a chemical:

A. Must combine with a carrier protein to create electrochemical energy

B. Must be filtered through the proximal convoluted tubule

C. Must be in higher concentration in the filtrate than in the blood

D. Must be in higher concentration in the blood than in the filtrate

Step 1 of 3

Tubular reabsorption:

• The glomerulus of the nephron filters average of 120 mL of water which contains low molecular weight substances every minute.

• 120 mL of water cannot be lost every minute from the body. So, this ultra-filtrate containing essential substances is reabsorbed in the tubules of the nephron.

The tubular reabsorption has two phases:

• Active transport

• Passive transport

Active transport:

• It is the progress of molecule from the lower to higher concentration.

• The substance which should be reabsorbed has to be joined with carrier protein.

Carrier protein:

• It helps in the dispersal of different molecules

• The carrier proteins are present in the tubular epithelial cells of kidney.

• When the substance or chemical (to be reabsorbed) and the carrier protein are combined an electro chemical energy is produced, which helps in movement of the substances to be reabsorbed in to the blood stream