Lecture 9: Endocrine System I

Question 1

What are hormones?

Answer 1

Chemical messengers secreted by specific tissue (endocrine gland).

Question 2

What is the difference between exocrine and endocrine glands?

Answer 2

In exocrine glands, secretions exit through a duct.

Endocrine glands are ductless and hormones are secreted into the blood.

Question 3

What are the different types of hormones?

Answer 3

• Peptide hormones – made up of few to many amino acid residues e.g. insulin, glucagon, oxytocin, vasopressin, TRH, FSH, and growth hormone.

• Amine hormones – derivative of the amino acids for example tyrosine. Catecholamines (adrenaline, dopamine) and thyroid hormones are derived from tyrosine.

• Steroid hormones – derivative of cholesterol e.g. cortisol, progesterone, testosterone, and oestrogen.