↪ The primary active transport of Na - K pump develops a large concentration gradient of Na+ ion by acquiring its high concentration outside and low concentration inside the cell membrane.
↪ This gradient is also known as electrochemical gradient and it is a store house of energy it tends the excess Na+ ions present outside to diffuse inside the cell membrane.
↪ The diffusion sodium then pulls the other substance such as glucose molecule along with Na+ through the cell membrane into the ICF.
↪ This phenomenon is secondary active transport that involves in Na - glucose pump.
Functioning of the Pump
The mechanism of secondary active transport is studied in detail in sodium-glucose pump.
It is also known as co-transport of glucose along with sodium ions or sodium glucose link transport (SGLT).
Here the transport carrier protein present being penetrated through the cell membrane and the protein on its external side has two binding sites, one for Nation and one for glucose molecule.
Carrier protein uses the energy of concentration gradient of sodium to drive the transport of glucose molecule.
The energy so stored is called the diffusion energy of sodium and it brings about the conformational change in transport protein and allow Nation to move inside of the cell membrane along with glucose molecule.
Importance of the pump
↪ Glucose is the important substance to provide energy at every part of our body. Na - glucose pump is important for transporting glucose from extra cellular fluid to cytoplasm (intra-cellular fluid) of all the cells where glucose by splitting with special protein enzymes releases requisite amount of energy for the functioning of the body.
↪ Active transport is important in the functioning of kidney. Substances that the body need from the waste can be reabsorbed into the blood. Those are glucose, amino acids etc.
Here, secondary active transport and primary active transport play important role for reabsorption and also to excrete excess electrolytes being diluted water from the urine.