For each substance, say whether it is filtered, and whether it is reabsorbed or secreted…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
For each substance, say whether it is filtered, and whether it is reabsorbed or secreted.
- Plasma protein.
- Glucose in a healthy person.
- Amino acids.
- H ions that must be removed from the blood.
- Ammonia and K ions.
Need a reminder? The key ideaShow
Urine forms by filtration, reabsorption and secretion. The glomerular filtration rate (GFR) is about mL/min, which is L a day. About of the filtrate is reabsorbed, and about L of urine is passed. The PCT takes back all the essential nutrients and to of the electrolytes and water. The kidneys receive to mL of blood a minute. The tubule secretes H, K and ammonia.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Plasma protein is not filtered. It stays in the blood.
Step 2. (b) Glucose is filtered, and it is reabsorbed actively in the PCT. A healthy person has none in the urine.
Step 3. (c) Amino acids are filtered and then reabsorbed actively.
Step 4. (d) H ions are secreted by the tubular cells into the filtrate. This helps the acid-base balance.
Step 5. (e) Ammonia and K are secreted into the filtrate.
Answer: (a) not filtered; (b) filtered, reabsorbed; (c) filtered, reabsorbed; (d) secreted; (e) secreted.
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