Explain selective reabsorption in the process of excretion
Answers
Answer:
Explanation:
Selective reabsorption is the second of the three processes by which blood is filtered and urine is formed
It involves the reuptake of useful substances from the filtrate and occurs in the convoluted tubules (proximal and distal)
The majority of selective reabsorption occurs in the proximal convoluted tubule, which extends from the Bowman’s capsule
The proximal convoluted tubule has a microvilli cell lining to increase the surface area for material absorption from the filtrate
The tubule is a single cell thick and connected by tight junctions, which function to create a thin tubular surface with no gaps
There are also a large number of mitochondria within these tubule cells, as reabsorption involves active transport
Substances are actively transported across the apical membrane (membrane of tubule cells facing the tubular lumen)
Substances then passively diffuse across the basolateral membrane (membrane of tubule cells facing the blood)
The tubules reabsorb all glucose, amino acids, vitamins and hormones, along with most of the mineral ions (~80%) and water
Mineral ions and vitamins are actively transported by protein pumps and carrier proteins respectively
Glucose and amino acids are co-transported across the apical membrane with sodium (symport)
Water follows the movement of the mineral ions passively via osmosis.
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Answer:in the process of excretion many usefull components also get filtered so they are again absorbed in the tubule , this process is called selective reabsorption
Explanation: