Hormones

[Carly291287]

I am having trouble finding the answers to the following:

1) Explain how the presence of only a very small amount of steroid hormone in the intercellular fluid can result in a large change in the activity of the cell.
2) Adrenaline has an effect on its target cells within seconds of its release from the adrenal glands, and its effects last only for a short time. Steroid hormones take much longer to act on their target cells, and their effects last longer. Explain why this is so.
3) How does an underactive pituitary affect blood glucose and insulin levels?

Any help would be very appreciated.

[mith]

Have you tried wikipedia?

[Carly291287]

I've searched through the text books I have, and done numerous Google searches, looking at websites including Wikipedia.

[clarence]

1) Explain how the presence of only a very small amount of steroid hormone in the intercellular fluid can result in a large change in the activity of the cell.

Lipid soluble hormones, including steroid hormones, bind to receptors via diffusion within target cells. Such hormones alter gene expression, forming mRNA for synthesizing specific proteins on ribosomes, and thus result in a large scale change in cell activity.

2) Adrenaline has an effect on its target cells within seconds of its release from the adrenal glands, and its effects last only for a short time. Steroid hormones take much longer to act on their target cells, and their effects last longer. Explain why this is so.

Epinephrine and norepinephrine (also called adrenaline and noradrenaline) only enhance the activity of the sympathetic division of the autonomic nervous sytem in the fight-or-flight response or stress situations. They produce effects similar to sympathetic responses but are not the main players in it. Also, the ANS controls the chromaffin cells directly, the hormone-producing cells of the adrenal medulla, and thus hormone release can occur very quickly.

3) How does an underactive pituitary affect blood glucose and insulin levels?

An underactive pituitary produces low amounts of hGH and in turn IGFs, which slows down breakdown of glycogen to glucose in the liver, producing hypoglycemia. Hypoglycemia in turn inhibits release of insulin and instead stimulates release of glucagon to raise bloood glucose.

Hope this helps.

Clarence

[Carly291287]

Thank you very much.