The Law Posted September 3, 2008 Report Share Posted September 3, 2008 Thought this should be here too. Anybody have any good videos/animations on fetal circulation? Link to comment Share on other sites More sharing options...
The Law Posted September 5, 2008 Author Report Share Posted September 5, 2008 Can someone please clarify two points: -Does ADH improve the collecting duct or the distal convuluted tubule's water permeability or both? -Is the distal convluted tubule normally permeable to water (even without ADH)? Link to comment Share on other sites More sharing options...
cling Posted September 5, 2008 Report Share Posted September 5, 2008 Can someone please clarify two points: -Does ADH improve the collecting duct or the distal convuluted tubule's water permeability or both? -Is the distal convluted tubule normally permeable to water (even without ADH)? 1) Both, according to wiki. 2) Yes it is permeable to water. ADH increases aquaporin density. Link to comment Share on other sites More sharing options...
The Law Posted September 5, 2008 Author Report Share Posted September 5, 2008 Thanks for the clarifications. I recall reading that the collecting duct is normally impermeable to water, unless ADH is present - is that right? I'd think that ADH just makes it more permeable, but maybe I'm wrong. Link to comment Share on other sites More sharing options...
cling Posted September 5, 2008 Report Share Posted September 5, 2008 Well I think it is one of those where ADH increases permeability manyfold, so it is as though without ADH it is not permeable at all. It is essentially relative terms. Link to comment Share on other sites More sharing options...
avenir001 Posted September 5, 2008 Report Share Posted September 5, 2008 be patient with law guys, it's quite challenging for him to grasp these things. Link to comment Share on other sites More sharing options...
The Law Posted September 5, 2008 Author Report Share Posted September 5, 2008 Thanks cling for clarifying. be patient with law guys, it's quite challenging for him to grasp these things. I can only hope to one day amass copious amounts of knowledge like you have ma dear. 'Till that day though, I only ask you be patient with me. Link to comment Share on other sites More sharing options...
avenir001 Posted September 5, 2008 Report Share Posted September 5, 2008 Thanks cling for clarifying. I can only hope to one day amass copious amounts of knowledge like you have ma dear. 'Till that day though, I only ask you be patient with me. indeed i look forward to the day u become an info-absorbing sponge ma dear. Link to comment Share on other sites More sharing options...
The Law Posted September 7, 2008 Author Report Share Posted September 7, 2008 So, EK says Parasympathetic uses ACh, while Sympathetic uses epinephrine. TPR has a picture that shows Preganglionic neurons of Autonomic Nervous System release ACh, while the post ganglionic releases ACh OR Epinephrine. Does this mean that both Para and Symp use Ach as the preganglionic neurotransmitter, but then post ganglionic, para uses only ACh while symp uses Epinephrine. Clarification much apprecaited! Link to comment Share on other sites More sharing options...
avenir001 Posted September 7, 2008 Report Share Posted September 7, 2008 ^^ oui oui. Link to comment Share on other sites More sharing options...
The Law Posted September 8, 2008 Author Report Share Posted September 8, 2008 So potassium leak channels send potassium outside of the cell (via facilitated diffusion). I think. What's the purpose of this though? It seems kind of contrary to the function of the Na+/K+ atpase... Link to comment Share on other sites More sharing options...
The Law Posted September 8, 2008 Author Report Share Posted September 8, 2008 Could someone please clarify: 1) Does the duodenum also release disaccharide degesting enzymes, or is this only at the "brush border" of the intestine? 2) Where along the intestine does most fat//sugar//protein get absorbed? Link to comment Share on other sites More sharing options...
The Law Posted September 8, 2008 Author Report Share Posted September 8, 2008 My innundation of questions continues... Decreased sodium flow through which nephron segment is most likely to stimulate the macula densa to signal to the juxtaglomerular cells to release Renin? A) The Renal Pelvis The proximal convoluted tubule C) the collecting duct D) the renal calyx I am a tiny bit confused here, I realize that renin is secreted when the blood concentration of sodium is low. However, when blood concentration of sodium is low, wouldn't there generally be more of it still in the nephron, waiting for aldosterone to get the pump going? Link to comment Share on other sites More sharing options...
always_panicked Posted September 8, 2008 Report Share Posted September 8, 2008 So potassium leak channels send potassium outside of the cell (via facilitated diffusion). I think. What's the purpose of this though? It seems kind of contrary to the function of the Na+/K+ atpase... The purpose of the leak channel is that it operates after the sodium channels close so that the charge can once again become negative (i.e. positive charge out to make the inside of the cell negative compared to the outside, as it was before the onset of the action potential). Link to comment Share on other sites More sharing options...
The Law Posted September 8, 2008 Author Report Share Posted September 8, 2008 The purpose of the leak channel is that it operates after the sodium channels close so that the charge can once again become negative (i.e. positive charge out to make the inside of the cell negative compared to the outside, as it was before the onset of the action potential). Hmm, okay, isn't the leak channel always active though? I thought that it was the voltage-gated potassium channels that work after sodium channels close. Is the leak channel an added mechanism to keep the resting potential stable? lol Link to comment Share on other sites More sharing options...
avenir001 Posted September 9, 2008 Report Share Posted September 9, 2008 So potassium leak channels send potassium outside of the cell (via facilitated diffusion). I think. What's the purpose of this though? It seems kind of contrary to the function of the Na+/K+ atpase... it's just the way it is...the Na+/K+ pump not only sets up the Na+ & K+ concentration differences across the membrane, but it also has to keep working to maintain these differences (and so maintain the resting membrane potential) by balancing the leaks. Could someone please clarify: 1) Does the duodenum also release disaccharide degesting enzymes, or is this only at the "brush border" of the intestine? 2) Where along the intestine does most fat//sugar//protein get absorbed? -small intestine doesn't secrete any digestive enzymes into the lumen...the enzymes act at the brush border. -mainly in the jejunum & ileum. My innundation of questions continues... Decreased sodium flow through which nephron segment is most likely to stimulate the macula densa to signal to the juxtaglomerular cells to release Renin? A) The Renal Pelvis The proximal convoluted tubule C) the collecting duct D) the renal calyx I am a tiny bit confused here, I realize that renin is secreted when the blood concentration of sodium is low. However, when blood concentration of sodium is low, wouldn't there generally be more of it still in the nephron, waiting for aldosterone to get the pump going? huh? lol when blood concentration of sodium is low, the extracellular fluid volume & blood pressure are also low..so these are all signals to activate the renin-angiotensin-aldosterone system so u can reabsorb more Na+ from the urine. fall in NaCl ---> renin secretion ---> angiotensinogen to angiotensin I ---> angiotensin I to angiotensin II ---> aldosterone secretion from adrenal cortex ---> fix the problem. Link to comment Share on other sites More sharing options...
The Law Posted September 9, 2008 Author Report Share Posted September 9, 2008 it's just the way it is...the Na+/K+ pump not only sets up the Na+ & K+ concentration differences across the membrane, but it also has to keep working to maintain these differences (and so maintain the resting membrane potential) by balancing the leaks. -small intestine doesn't secrete any digestive enzymes into the lumen...the enzymes act at the brush border. -mainly in the jejunum & ileum. huh? lol when blood concentration of sodium is low, the extracellular fluid volume & blood pressure are also low..so these are all signals to activate the renin-angiotensin-aldosterone system so u can reabsorb more Na+ from the urine. fall in NaCl ---> renin secretion ---> angiotensinogen to angiotensin I ---> angiotensin I to angiotensin II ---> aldosterone secretion from adrenal cortex ---> fix the problem. Thanks avenir, I get everything including what you mentioned at the end... but this question seems to imply that sodium concentration in the nephron also has an effect on the renin-angiotensinogen system. Link to comment Share on other sites More sharing options...
avenir001 Posted September 9, 2008 Report Share Posted September 9, 2008 Thanks avenir, I get everything including what you mentioned at the end... but this question seems to imply that sodium concentration in the nephron also has an effect on the renin-angiotensinogen system. right, it does..the macula densa cells are sensitive to the NaCl moving past them thru the lumen! if there's less Na in the lumen, it means there wasn't enough in the blood to be filtered. Link to comment Share on other sites More sharing options...
The Law Posted September 9, 2008 Author Report Share Posted September 9, 2008 right, it does..the macula densa cells are sensitive to the NaCl moving past them thru the lumen! if there's less Na in the lumen, it means there wasn't enough in the blood to be filtered. ooh gotcha! thanks yo! gonna beat your 14 in bio with a 15 hahaha Link to comment Share on other sites More sharing options...
avenir001 Posted September 9, 2008 Report Share Posted September 9, 2008 ooh gotcha! thanks yo! gonna beat your 14 in bio with a 15 hahaha if u do, i'll never speak to u again! :p Link to comment Share on other sites More sharing options...
eng_dude786 Posted September 9, 2008 Report Share Posted September 9, 2008 avenir....i must say: I'm deeply impressed by your ability to retain copious amounts of heavy detailed biology knowledge. Impressive! Link to comment Share on other sites More sharing options...
avenir001 Posted September 9, 2008 Report Share Posted September 9, 2008 thank u, thank u...it's common knowledge that i'm a genius. Link to comment Share on other sites More sharing options...
leviathan Posted September 9, 2008 Report Share Posted September 9, 2008 So, EK says Parasympathetic uses ACh, while Sympathetic uses epinephrine. TPR has a picture that shows Preganglionic neurons of Autonomic Nervous System release ACh, while the post ganglionic releases ACh OR Epinephrine. Does this mean that both Para and Symp use Ach as the preganglionic neurotransmitter, but then post ganglionic, para uses only ACh while symp uses Epinephrine. Clarification much apprecaited! Just a minor correction that the post-ganglionic sympathetic synapses use NORepinephrine, not epinephrine, for transmission. Everything else is correct. Link to comment Share on other sites More sharing options...
The Law Posted September 9, 2008 Author Report Share Posted September 9, 2008 Just a minor correction that the post-ganglionic sympathetic synapses use NORepinephrine, not epinephrine, for transmission. Everything else is correct. Thanks levi! Didn't catch that while reading. Link to comment Share on other sites More sharing options...
The Law Posted September 9, 2008 Author Report Share Posted September 9, 2008 Can someone please confirm or reject: -Liver synthesizes bile acids and bile -Gall bladder stores bile acids and bile -Liver secretes bile -Gall bladder secretes bile acids (to help with absorption of fats in intestine) Link to comment Share on other sites More sharing options...
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