*Destroyer Error Thread*

[Emmie]

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Anyone want to explain Bio #291?
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Bio #68

I thought the ans is a bit weird...

it said that ascending loop of Henle are impermeable to water. As the urine descends the loop, it becomes more and more concentrated (I'm totally cool up to this point) and becomes less concentrated in the ascending branch

Why is it become less concentrated in the ascending branch if it's impermeable to water? confused!

SOLVED, Thanks UCB05
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Just found one...

Bio #172
c) The greatest resistance to blood flow is in the arterioles

The greatest resistance should be in the capillary because the diameter of a capillary is smaller than an arteriole

SOLVED, thanks guys
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ok guys,

I found another one worth mention...

Bio #80

d) The medulla is involved in control of breathing

I thought the question is not clear. I'm pretty sure he is referring to medulla oblongata but there is another structure called adrenal medulla which is not involved with control of breathing. 🙂

 

[Extirpator]

Sorry, destroyer is correct.

Resistence is very low in the capillaries because they are arranged into beds.

 

[Emmie]

yea, you're right.

 

[nze82]

Just found one...

Bio #172
c) The greatest resistance to blood flow is in the arterioles

The greatest resistance should be in the capillary because the diameter of a capillary is smaller than an arteriole

If capillaries aren't included in answer choices, then arterioles would be the next correct answer. Sorry! But nice try...
Don't have the book, so I don't know if capillary is included as an answer choice or not.

 

[Extirpator]

yea, you're right.

Actually... I was thinking of pressure lol... you may be right, sorry...

Through the capillary bed resistance would definately be lower, but I'm not sure if that is included when referring to a single capillary or not...

 

[RetiredEngineer]

I didn't feel like typing just read this

Snapshots of hemodynamics page 22

http://books.google.com/books?id=KZ...yNyRBg&sa=X&oi=book_result&ct=result&resnum=4

 

[Emmie]

Bio #80, see 1st post

 

[joonkimdds]

adrenal medulla and medulla oblangata are not the only medulla in our body. There are other kinds too. But the main difference is that medulla can refer to as the diff parts or it can be 'actual name'.

 

[dentene ice]

Infact the aterioles experience the greatest resistance in all of the circulatory system due to the great drop in pressure.

 

[Sublimation]

Ok guys this kinda got under my skin when i got it "wrong" although i hope the DAT does not have any misleading answer choices like this. Correct me if im wrong. Surface tension is the force that helps hold molecules of a liquid together at the surface, not allowing it to break through. (for example when u place a paper clip on water, it will float and not break through the water) i do kno surface tension is characterized by the attractive force of a compound to itself. Now cohesive forces are characterized by the formation of droplets due to this property ( that is of like compound to attrack themselves to each other). I have always seen my professors and teachers for as long as i can remember connecting the term "surface tension" to something walking on water or floating on it without breaking through it. And cohesive force the force that allows water to form into droplets. Am i totally wrong on this. Or is there something that im missing here?

 

[Emmie]

JoonKim: General speaking, those are the ones that worth mention.

Sublimation: Is it the hydrogen bondings btwn water molecules contribute to the surface tension? Need to double check that.

 

[joonkimdds]

JoonKim: General speaking, those are the ones that worth mention.

Kidney has cortex and medulla and i think it's also important. They can ask you something like where can you find renal corpuscle from kidney, collecting duct from kidney...etc.

Thymus has cortex and medulla, too. DAT might ask where can you find T lymphocyte/blood vessel/hassal's corpuscle in thymus 🙂




By the way, I think the reason capillary has less resistance is because it can exchange gas with alveoli.
it's true that capillary is smaller than arterioles but it got holes 😀

 

[TooQuickSlick]

Just found one...

Bio #172
c) The greatest resistance to blood flow is in the arterioles

The greatest resistance should be in the capillary because the diameter of a capillary is smaller than an arteriole
------------------------

ok guys,

I found another one worth mention...

Bio #80

d) The medulla is involved in control of breathing

I thought the question is not clear. I'm pretty sure he is referring to medulla oblongata but there is another structure called adrenal medulla which is not involved with control of breathing. 🙂

Number 172 is correct the greatest resistance to blood flow is in the arterioles due to the vast difference in size from arteries.

Number 80, when they say medulla its usually medulla oblongata. The definition of medulla just mean the inside of something relative to the cortex.

 

[nze82]

Seriously, I think you guys would be better off spending all this time studying instead of trying to find typos in destroyer! But that's just me!

 

[Emmie]

Seriously, I think you guys would be better off spending all this time studying instead of trying to find typos in destroyer! But that's just me!

It's more like confusion than typos

 

[Emmie]

Kidney has cortex and medulla and i think it's also important. They can ask you something like where can you find renal corpuscle from kidney, collecting duct from kidney...etc.

Thymus has cortex and medulla, too. DAT might ask where can you find T lymphocyte/blood vessel/hassal's corpuscle in thymus 🙂




By the way, I think the reason capillary has less resistance is because it can exchange gas with alveoli.
it's true that capillary is smaller than arterioles but it got holes 😀

People hardly refers "medulla" to the medulla in the lymph node or in the thymus!

 

[whawha]

Destroyer 2008 Bio #291

Can someone please explain this for me? Or is there anything missing?

 

[Emmie]

Bio #68, see the first post

 

[whawha]

#68? What do you mean?

Bio #68, see the first post

 

[TooQuickSlick]

#68? What do you mean?

It means the person edited the first post.

 

[UCB05]

There are two ways to change concentration - varying solvent or solute. The descending loop is permeable to water but impermeable to ions, so water flows out and urine becomes more concentrated. The ascending loop is impermeable to water but permeable to ions. Ions flow out and the urine becomes less concentrated.

Remember arterioles are muscular and have muscular sphincters at the borders of capillary beds. Technically using physics, you can say one capillary tube will exert greater resistance than one arteriole tube due to radius size, but physiologically, the arterioles as a system are what control the pressure and resistance to blood flow into the capillary beds, which offer very little overall resistance due to mass pressure drop.

 

[joonkimdds]

Destroyer 2008 Bio #291

Can someone please explain this for me? Or is there anything missing?

RNA polymerase has to bind to a promotor site to start transcription 🙂



By the way, if decending makes urine more concentrated and ascending makes it less concentrated, what's the final result? it's not concentrated nor dilute?

Because I remember reading one of the destroyer question saying that bird has long loop of henle and thus have concentrated urine. I don't understand this.

 

[UCB05]

RNA polymerase has to bind to a promotor site to start transcription 🙂



By the way, if decending makes urine more concentrated and ascending makes it less concentrated, what's the final result? it's not concentrated nor dilute?

Because I remember reading one of the destroyer question saying that bird has long loop of henle and thus have concentrated urine. I don't understand this.

The "filtrate" becomes more concentrated down the loop as water leaves. It becomes less concentrated as certain ions are transported out in the ascending loop, and again more concentrated again as it travels through the collecting duct. The final result, depending on the organism and the goal (concentrated urine or diuresis) is urine that is concentrated in waste products such as urea, but dilute in needed ions like NaCl or Ca. The importance of the ascending loop, and the reason why this area involves active transport of ions is to maintain the concentration gradient in the interstitium of the medulla for the passive processes in the other parts of the nephron

 

[whawha]

In the solution, is the first one really chiral? Isn't this wrong according to what is said here
http://forums.studentdoctor.net/showthread.php?t=596268
??

Both carbons have a methyl group, how can it be a chiral molecule? Or is it that just two atoms have to be different on each carbon?

Thank you!