Kidney Osmolarity and Female Reproduction

[crazy person]

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Hi all ! I was wondering if someone could please help me out with some questions that I'm not quite understanding.

1) Why is the urine with a much higher osmolarity than plasma? I thought that the collecting duct reabsorbs all water under the influence of ADH, thus makes the filtrate more concentrated with less urine. When TPR is mentioning plasma, are they referring to the IF? I'm confused because I thought the IF and the collecting duct end up balancing the osmolarity gradient since the IF is reabsorbing all the water and sodium. Since sodium is being reabsorbed, shouldn't the osmolarity be less than the IF (plasma)

2) What would happen if the estrogen and progesterone levels in a woman's blood were kept high for the entire month?
The answer is the woman would not be able to ovulate. But why? What's the reasoning behind it? I thought if pregnancy does not occur, then secretion of estrogen and progesterone decline and menstruation happens.

 

[sazerac]

1) plasma = blood = what comes in on the renal artery. When the urine goes through the collecting duct, if there is a lot of ADH then the water gets absorbed and the osmolarity of the remaining urine can go as high as 1200.

 

[phattestlewt]

2) What would happen if the estrogen and progesterone levels in a woman's blood were kept high for the entire month?
The answer is the woman would not be able to ovulate. But why? What's the reasoning behind it? I thought if pregnancy does not occur, then secretion of estrogen and progesterone decline and menstruation happens.

If estrogen and progesterone levels were kept high, then the body is being tricked into preparing for pregnancy because both hormones (mostly progesterone) are responsible for the maintenance of the endometrial lining.
In a normal cylce, where fertilization does not happen, estrogen and progesterone levels would decline and the cycle would start back up with increasing estrogen, FSH, and LH levels to cause ovulation.

That's how birth control pills work. Birth control pills are estrogen and progesterone hormoens.

 

[shinsoochoo]

The lining must be maintained to allow the embryo to grow, so as mentioned above, progesterone levels need to remain high. These high levels inhibit LH from being produced by the pituitary via negative feedback. The lack of LH is also the reason for ovulation to not occur because ovulation occurs with the increase in LH.

Also, as a result of the lining remaining in place, menstruation does not occur either. Decrease in the two hormones is needed for that to occur. This is why females take birth control for pain during periods.

 

[Blueprint MCAT Tutor]

1) plasma = blood = what comes in on the renal artery.

Sorry, just one hyper-picky comment here.

The plasma is the fluid part of the blood. So its:

Blood - Cells = Plasma