Introduction to Natural Selection (notes based on video from AP Biology Youtube (March 25) AP Biology Introduction to Natural Selection Blood High Na+ Low glucose Epithelial Layer Low Na+ High glucose Intestinal Lumen High Na+ Medium glucose Glucose GLUT 2 Transporter Na+/K+ Pump K+ Na+ Glucose Na+ Glucose Na+ Na+/Glucose Symporter Figure 1: A single cell from the epithelial layer lining the intestine, illustrating movement of glucose and Na+ from the intestinal lumen to the blood. Glucose and sodium move from the lumen of the small intestine into the blood via transport proteins in the epithelial cells lining the small intestines (Figure 1). Based on Figure 1, describe the direct source of energy used to move glucose into the epithelial cell from the intestinal lumen. Explain how this system maximizes glucose absorption from the intestinal lumen into the epithelial cells and from the epithelial cells into the blood. Describe
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Step 1: The direct source of energy for moving glucose from the intestinal lumen into the epithelial cell is the Na+ electrochemical gradient — energy released as Na+ moves down its gradient through the apical Na+/glucose symporter. Show more…
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Intestinal epithelial cells use multiple types of transporters to transfer glucose from the gut lumen to the rest of the body. Identify all types of transport that take place during the transfer of glucose from the gut lumen into the blood. Passive transport - symport of glucose and Na+ from the intestinal cell into the blood. Secondary active transport - symport of glucose and Na+ into the intestinal cell from the intestine. Primary active transport - ATP driven antiport of Na+ out of the cell and K+ into the cell. Primary active transport - symport of Na+ and K+ from the intestinal cell into the blood. Passive transport - uniport of glucose into the intestinal cell from the intestine. Secondary active transport - ATP driven antiport of Na+ out of the cell and K+ into the cell. Passive transport - uniport of glucose from the intestinal cell into the blood
Madhur L.
Glucose (from ingested food) moves from the lumen of the small intestine through an epithelial cell and into the bloodstream, as shown in the diagram. Which statement about this movement is CORRECT? The glucose moves from the epithelial cell to the blood vessel against its concentration gradient. The movement of glucose from the lumen into the epithelial cell requires a facilitated transport protein. The movement of glucose from the lumen into the epithelial cell requires an active transport protein and an energy source. The movement of glucose from the epithelial cell into the blood vessel requires an active transport protein and an energy source. The movement of glucose from the epithelial cell into the blood vessel does not require a transport protein.
Dennis H.
Epithelial Transport of Glucose - What is Epithelial Structure and Function? Epithelial cells are a type of cell that line the surfaces of organs and tissues in the body. They play a crucial role in the transport of substances, such as glucose, across these surfaces. The structure of epithelial cells includes tight junctions, which are specialized protein structures that form a barrier between cells, preventing the movement of substances between them. This barrier is important for maintaining the integrity and function of the epithelial layer. In terms of transport, there are two main pathways that epithelial cells can use: transcellular and paracellular transport. Transcellular transport involves the movement of substances through the cytoplasm of the epithelial cells, while paracellular transport involves the movement of substances between the cells, through the tight junctions. When it comes to glucose absorption, the intestine and kidney are two important organs. In the intestine, glucose is absorbed through the epithelial cells lining the small intestine. This process involves the active transport of glucose from the lumen of the intestine into the cytoplasm of the epithelial cells, followed by the passive diffusion of glucose from the cytoplasm into the bloodstream. This transport is mediated by specific glucose transporters, such as SGLT1 and GLUT2. In the kidney, glucose is reabsorbed from the filtrate in the renal tubules back into the bloodstream. This process occurs in the proximal tubules of the nephron. Glucose is actively transported from the filtrate into the cytoplasm of the epithelial cells lining the tubules, using the SGLT2 transporter. From the cytoplasm, glucose is then transported into the bloodstream through the GLUT2 transporter. Overall, the transport of glucose across epithelial cells involves a combination of active and passive transport mechanisms, mediated by specific transporters. This allows for the absorption or secretion of glucose, depending on the needs of the body.
Adi S.
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