Question

Give a scientific reason -
Endocrine glands are highly vascular.

Answer 1

Hormone is known as the intercellular messengers which do not contain any nutrients and are produced by the endocrine glands in a very small amount and hit the organ where it is necessary like thyroid hormone, growth hormone, etc.

Complete answer:
Endocrine glands are also known as ductless glands since their products directly release into the bloodstream without the presence of any ducts, that is why these glands are highly vascularised with many small capillaries present between them.

Additional Information: The products of endocrine glands are called hormones. Hormones are non-nutrient chemicals that act as intracellular messengers and are produced in very small amounts. In humans, the endocrine glands along with specialized cells producing hormones in different parts of the body together constitute the endocrine system in humans. The human endocrine glands include the Pituitary, pineal thyroid, adrenal, pancreas, parathyroid thymus, and gonads. The hormones produce their effect on target tissues only due to the presence of specialized proteins present on target organs, called hormone receptors. Receptors are highly hormone specific. When the hormones bind with the receptors present on the cell membrane, a hormone-receptor complex is formed.
On the basis of chemical nature, hormones are of the following type
->Peptide, polypeptide, protein hormones - insulin, glycogen, pituitary hormones, hypothalamic hormones.
->Steroids - cortisol, testosterone, estradiol, progesterone
->Iodothyronines - thyroid hormones
->Amino acid derivatives - epinephrine

Note: ->Protein hormones and steroid hormones function with different mechanisms.
->Neural system and endocrine system jointly coordinate and regulate the physiological functions in the body.
->Gastro-intestinal tract, liver-kidney, and heart are endocrine organs that produce hormones as well.