Endocrine System

Hormones are not enzymes (but may cause enzymes to be formed).

The hypothalamus is below the thalamus, more or less on the “floor” of the brain, but above the pituitary gland.

Peptide hormones are not soluble in lipid so cannot diffuse through the plasma membrane; hence, their receptors are necessarily on its outside. Similarly, catecholamines are not soluble in lipid; hence, their receptors are on the outside the plasma membrane.

The hypothalamus controls the secretion of the anterior pituitary by the use of “releasing hormones” and “inhibitory hormones”.

The hypothalamus secretes releasing and inhibitory hormones that stimulate the anterior pituitary gland to secrete hormones which in turn control the activities of endocrine cells in the thyroid, cortex of adrenal glands and reproductive organs. The hypothalamus produces ADH and oxytocin which are stored and released into blood from post.pit. The hypothalamus exerts neural control over the adrenal medullae.

The thalamus is not involved in the chain of events that causes release of oxytocin from the posterior pituitary.

Hormones are circulating messengers that are transported in blood. A particular hormone does not necessarily affect every cell in the body. Some (but not all) hormones are released by neurones, for example, in the hypothalamus.

It is Ca ions (not a hormone) that bind to troponin to initiate a muscle cell contraction. The other three choices are true.

The “-cort-” part of the word refers to the adrenal cortex, while the “gluco-” part refers to the role carbohydrate (glucose) metabolism.

Endocrine hormones are also known as circulating (in blood) hormones.