joonkimdds

Senior Member
10+ Year Member
7+ Year Member
Jun 30, 2005
2,780
2
Status
Pre-Dental
Stomach cell
chief cell = makes pepsinogen
parietal cell = makes HCl
mucous cell = makes mucous

my question comes from G cell
one of the sources I have says G cell makes gastrin that stimulates parietal cells to make HCL.
But the other source I have says ECL cells make histamin that stimulates parietal cells to make HCL.
This 2nd source is saying that G cell makes gastrin that stimulates gastric secretion.

so which one is correct? Which one between ECL and G cell stimulates Pareital cell?


=====================================
My 2nd question is about kidney- Loop of Henle.
1) The combination of passive diffusion and active transport in the Loop of Henle of solutes helps in the conservation of water.
2) Birds have a long loop of henle, thus have concentrated urine.
Both of them are supposed to be true statement.
But I don't understand how.

According to my class lecture slide, it says
Loop of Henle- more soluete is reabsorbed than water.
This means urine is supposed to be more dilute.
But those two statements from DAT destroyer is saying as if the urine is supposed to be more concentrated.

which one is right?
 
Last edited:

Panther85

10+ Year Member
Aug 20, 2007
99
1
Status
Podiatry Student
q1: http://upload.wikimedia.org/wikipedia/commons/2/22/Control-of-stomach-acid-sec.png

q2: i would be more concerned about the type of waste that birds secrete and how they secrete it.

birds: supraorbital glands produce uric acid crystals (remember that humans must convert their nitrogenous waste to urea or else it accumulates, leading to gout)

birds are also osmoregulators (as opposed to sharks which are osmoconformers) therefore they must have a hypertonic urine. an organism that has a hypotonic urine would be a fresh water fish
 

jrobi

10+ Year Member
Dec 12, 2008
2
0
Status
Pre-Dental
Q1: ACh, Gastrin, and Histamine all stimulate HCl secretion from parietal cells (somatostatin inhibits all these)

Q2: If there's ADH present in the collecting duct the urine will be concentrated. I think the question is assuming ADH will be present? If you have a longer the loop of henle, more Na is being reabsorbed so the bird is able to produce a more hypoosmotic fluid in the ascending limb; so when it reaches the collecting duct all that water in the very hypoosmotic fluid is reabsorbed (given there's ADH) so the bird produces a more concentrated urine.

hope this helps!
 
About the Ads