Three patients have these blood levels. Cortisol and ACTH are given as compared with the normal…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Three patients have these blood levels. Cortisol and ACTH are given as compared with the normal level.
Patient P: weak, loses weight, low blood pressure, low sodium in the blood. Cortisol low, ACTH high.
Patient Q: round face, fat on the trunk, high blood pressure, high blood glucose. Cortisol high, ACTH low. A scan shows a tumour in the adrenal cortex.
Patient R: has taken steroid tablets for months because of a swelling disease. Cortisol in the blood is high, ACTH is low.
- Name the disorder of P and explain why ACTH is high.
- Name the disorder of Q.
- Explain why ACTH is low in R, and what happens to the gland of R.
Need a reminder? The key ideaShow
The adrenal medulla makes adrenaline and noradrenaline, the hormones of fight or flight, under the control of nerves. The cortex makes glucocorticoids (cortisol), mineralocorticoids (aldosterone) and small amounts of androgens, and ACTH controls the cortex. Addison's disease is a lack of the cortical hormones. Cushing's syndrome is too much cortisol.
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) P has Addison's disease. Cortisol is low, so the feedback on the hypothalamus and the pituitary is weak, and the pituitary releases more ACTH. The sodium is low because aldosterone is short too.
Step 2. (b) Q has Cushing's syndrome, from a tumour that makes too much cortisol. The high cortisol switches ACTH down. (This disorder is not in the NEET syllabus text.)
Step 3. (c) The tablets add cortisol from outside. The high cortisol switches ACTH down. With little ACTH, the adrenal cortex makes less of its own cortisol and becomes smaller. This is why steroid tablets must not be stopped suddenly.
Answer: (a) Addison's disease, ACTH high by weak feedback; (b) Cushing's syndrome; (c) the cortisol from the tablets lowers ACTH, and the gland makes less.
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