Final answer:
The absorptive process in the small intestine that requires a carrier and energy is known as active transport. It is employed for absorbing amino acids from proteins and monosaccharides from carbohydrates, using carrier proteins and ATP to move substances against their concentration gradient.
Step-by-step explanation:
Absorptive Process in the Small Intestine
Among the absorptive processes in the small intestine, the one requiring a carrier and energy to transport nutrients into absorptive epithelial cells is called active transport. In the context of protein absorption, active transport mechanisms are predominantly located in the duodenum and jejunum, where they absorb proteins in the form of amino acids. The process utilizes carrier proteins that are often linked to the active transport of sodium. The energy needed for this transport is derived from adenosine triphosphate (ATP).
Short chain peptides, such as dipeptides and tripeptides, also use this active transport process to enter absorptive epithelial cells. Once inside, they are further broken down into amino acids before diffusing into the capillary blood. Similarly, carbohydrate absorption involves the transport of monosaccharides such as glucose and galactose into epithelial cells via a mechanism known as secondary active transport, which also operates in conjunction with sodium.
It is important to note that active transport is distinct from other forms of transport like passive diffusion, facilitated diffusion, co-transport, and endocytosis, as it specifically moves substances against their concentration gradient, necessitating the use of cellular energy.