scilearner

Thanks once again for the reply Mr Skeptic Yes that makes sense I also like to add something. May be because these cells are so specialized you can't directly reproduce them. Like a person with a lot of experience you can't just clone him but get experience from starting from square one. Stem cells can be used to start from square one.

I see Thanks Mr Skeptic and CharonY

Nerve and muscle tissue don't grow back much but epithelial cells in the skin grow very quickly. Why is that some tissues find it difficult to grow back and are replaced by fibrous scar tissue. Can't they do some mitosis and regrow? Thank you

Thanks a lot for your answer You mean 2 strands not molecules here right. I consider one dna molecule to be a double helix. So when the cell is not replicating it has 46 DNA molecules or 92 DNA strands.

Ok this seems like a simple question but when I checked I get so confused. Please use these terms to answer my question. 1 DNA molecule- This means a double helix (2 strands) 1 DNA strand- This means when you break the double helix and one separate strand I thought one chromatid contain 1 DNA strand and 2 chromatids make a chromosome and 1 DNA molecule. So in a diploid cell you have 46 DNA molecules or 92 strands. Is this wrong? EDIT: Oh wait I know why I don't understand this. Chromatid also contains a DNA molecule right. When the cell is replicating each chromosome has 2 dna molecules and when it is not it only has one. So when the cell is not reproducing there are 46 DNA molecules and when it is there are 92 DNA molecules is that right?

Ok density of water is 1000 g/ 1 L I don't know isn't this 1 L composed completely of water. This is confusing me. Do find the concentration you have to find the moles and divide by 1 L. 1000/18=55 M . I thought concentration of pure water you can't find because the solution is complete water. I hope you understand what I mean. Thanks

Does NADH provide energy to move protons out of the membrane or does it send its own proton out of the membrane? When it oxidizes it produces a H+ so does this have any significance. I mean can any reaction that produce energy move the protons out of the membrane. Thanks!!

Hello everyone, So in so many regulatory mechanism veins are constricted or venomotor tone is increased so pooled blood can go to heart and increase venous return. That makes sense but if you keep the vein constricted for some time after that wouldn't this reduce the flow? I mean initially it would increase the flow but how about after that. Thanks!!

Hello everyone, My note says in fatty acid synthesis, one acetyl unit enters the synthesis pathway directly but the remainder must be first converted to malonyl CoA. I can understand the latter but why does one acetyl unit enter directly where did it come from? Thanks

Is it because they are unsaturated and can unfold. I understand how one radical would create another radical but I don't know exactly how radical could spread in a fatty acid chain. Any diagram would be useful. Thank you

Hello guys, This might be a stupid question but artery has an inner endothelium and muscle outside. So if molecules diffuse out from the endothelium do they diffuse out of the muscle cells as well. How is that done, do muscle cells have the same membrane proteins as endothelium? Thanks Merged post follows: Consecutive posts mergedOh right I forgot about capillary which is just one endothelium . Sorry guys!!

Hello guys, In electrophoresis I mean sorry. In electrophoresis is a similar electromotive force applied to all particles or are all particles accelerated at the same rate? What I mean is let's say if every particle gets 10N. F=ma and bigger particle would travel slower. So can't I include this in the answer. If they are only accelerated at the same rate I can understand how different particles would have different resistances? So is the answer F=ma? Thank you!!

Hello guys, when blood vessels going to brain are constricted, there is less blood flow and less 02 and CO2 entering the blood vessels in the brain. How does this create hypercapnea (too much CO2), is all the 02 that comes in extracted and turned to carbon dioxide which causes this. Also this hypercapnea then develops everywhere. Why is that? Thanks a lot

Oh I see. What I was thinking is that elevator provided a force like gravity uniform in all parts to the person in it. I understand now. Thank you guys!! Thanks for everyone who helped. "The blood is going up. If it wasn't, it would be pooling at the bottom of the elevator shaft while your exsanguinated corpse continued inside the rising elevator." Wouldn't the create a great avater? lol

lol Ok thanks both of you for your replies. Now what I'm thinking is that gravity is what makes your blood pool. I don't understand the inertia you are referring to. Is inertia caused by gravity pulling down blood, and you suddenly accelerate up, but blood still wants to go down. Wouldn't this last for only few minutes though!!

If we are moving up in a lift, Normal reaction force is greater than gravity, meaning there is a net force up, but still blood doesn't go up, why is that? Also if you overcome force of gravity and go up with some acceleration is that free fall in the reverse direction?

I have worked out the elevator problem but they say as you move up the elevator blood pooling increases in the legs. For example when I stand for long time there is pooling of blood in the legs. If gravity is balanced by the normal reaction force how can it have any effect in our body? Isn't gravity cancelled by NRF?

Hello everyone, Ok I thought I knew gravity and just realized I absolutely have a very poor understanding about it. Ok let's say a person was moving in a lift 1. The blood would pool around the legs because of gravity, but my question is aren't we overcoming the gravity force to go up, why would it affect us? Ok the explanation is that upward force from the lift is not acting on the body. But if we are moving up how come it doesn't affect us. 2. Ok what about lift moving down, why don't we feel any weight? Ok the explanation is we are moving with gravity, but if the lift is not accelerating at 9.8 ms2 we should feel the gravity right. 3. About basic free fall without a lift? Ok now we are accelerating because of gravity, but why don't we feel the force. Aren't we accelerated down because of that force, why don't we feel it. I basically don't understand the difference between force and acceleration and how one can exist without other 4. Why do we feel weight because of normal reaction force? It is the force of body on the earth. So how come we need a normal reaction force to feel the gravity. I can understand how staying still would make you feel gravity but what does normal reaction force have to do with it. 5. What is gravity? How is there an acceleration without a force. I know this is a big question but just give me a simple explanation, I have a long way to go before I want to really know the answer for this. Thank you so much for anyone who is going to take their time and help me. It would certainly do my physics a world of good. Thanks

Hello As the topic say I have difficult understanding equation for perfusion. How does venous pressure affect perfusion I thought only arterial pressure does. Thanks!!

If a diphosphate is broken down by water into 2 phosphates is the energy released equivalent to an ATP. Does ATP provide more energy?

Why is it that in the glycogen synthesis UDP glucose is added to glucose. Does UDP glucose provide energy? Or is it ATP that provides energy for this polymerisation. I don't understand why you need UDP? Thanks!!

Hello thanks a lot for your response So in the electron transport chain lack of ADP inhibits oxidative phosphorylation and caused NADH to accumulate. Are NADs from electron transport chain used in the citric acid cycle? So now there are less NADS and citric acid cycle is affected. Is that right? Thanks again

My textbook says, I checked the whole citric acid cycle, and only the conversion of succinyl coA requires ADP or GDP. I don't understand how a lack of this would make NADH accumulate. Could anyone explain this. Thanks a lot

Thanks a lot for the help Bob. I have this feeling that fluid particles nicely travel in straight line in narrowed regions and has less collisions with walls? So friction loss mostly occurs in the non narrowed region due to the restriction. Is this wrong?

Thanks for the response Can you elaborate on friction and turbulence in this case. Is the friction created by the higher pressure in the non narrowed region or is it because of the difficulty to move through the walls of the pipe, in a narrowed region.