Answer questions 5 through 10 by choosing responses from the following: a. ammonium ions b. bicarbonate c. calcium d. chloride e. hydrogen ions f. magnesium g. phosphate h. potassium i. sodium j. water Part of an important chemical buffer system in plasma.

Video transcript

Welcome back if you want. Here's our next problem. Answer the question by choosing appropriate responses from the following. And we have eight statements followed by the question which of the above options correctly matches the ions with their descriptions. And then there's four different answer choices A through D each with different combinations of numbers of statements. So we'll pick out which of our statements are correct and that will lead us to our answer choice. So let's start with statement number one, sodium, it is reabsorbed from the proximal convoluted tubule in exchange for potassium. Well, this is correct. These are both positively charged ions and in the proximal convoluted tubule, sodium can be reabsorbed and then potassium moves into the filtrate to keep the electrical gradient the same. Now, let's move on to statement number two. Number two says potassium present outside the cell in a times higher concentration than inside. Well, this one is not correct. Potassium is present at higher concentrations inside the cell that's as opposed to sodium, which is generally present in higher concentrations outside the cell. So sentence number two or statement number two cannot be one of our correct answers Now, let's move on to number three, it says calcium, it has the least concentration in the sarcoplasm reticulum. Well, the sarcoplasm reticulum is that specialized area in a muscle cell that stores and releases calcium ions. So that definitely is going to have the lowest calcium concentration. You'll have a pretty high calcium concentration in that part of a muscle cell. So statement number three, not correct. Let's move on to number four, hydrogen ions. They are secreted in the re renal tubules to reabsorb potassium ions. Well, hydrogen ions are indeed secreted in the renal tubules but not with the end result of reabsorbing potassium ions. It's actually to be able to reabsorb bicarbonate ions. HCO three minus and that helps to maintain the ph balance as well as getting rid of hydrogen ions which are generated by various metabolic processes in the body and need to be dumped to preserve the body. So, Satan four, not correct. Number five says phosphate, it helps regulate ph in intracellular, an intracellular fluid and urine. And this is correct bicarbonate is the better known buffer, but there is a phosphate buffer system that serves as a backup. So this is correct that involves uh the molecules of di hydrogen phosphate and mono hydrogen phosphate able to lose and gain a hydrogen ion. Now, let's move on to statement number six ammonium ions, they help in the formation of urea in the DC T or distal convoluted tubule. Well, this one is not correct. Ammonium ions are not what helps in the formation of urea that's formed in the urea cycle, which takes care of toxic ammonia, not ammonium ions. So statement six, not correct. Now on to number seven, by carbonate ion HCO three minus, it maintains normal blood ph by acting as a chemical buffer. And this is a correct statement by carbonate ion is a very important buffer in the body. It can gain a hydrogen ion to become carbonic acid and then lose it again. So it can, it can act both ways thereby by nature being a buffer. Now, number eight is a statement not actually about an ion. The molecule we're asking about is Albin, which is a protein, but our statement says it contains amino acid residues that can act as both weak acids and weak base by donating and accepting H plus ions and acting as a buffer. And this is a correct statement. Albin as a protein has some acidic bases and some basic bases and can therefore accept and donate H plus ions. So it's yet another buffer and helps protect against abrupt changes in concentrations of ions in the body. So choice A is a correct statement. So we see that we have 157 and eight being correctly matching descriptions. And that would be answer choice C which has those statements listed. 157 and eight is our answer. See you in the next video.