What are hormones?
Hormones are an organic substance or can said to be a chemical messenger, secreted in plants and animals including humans. These organic substances are basically signaling molecules that are carried by our circulatory system to different tissues and organs. These chemicals reach their destination and trigger a particular response or function in body as a result.Read More
How does hormone signals work? Types of Hormones: Lipid derived hormones: Amino acid derived hormones: Peptides hormones: Hormone Regulation: Effects of hormones:
There are varied kind of glands in human bodies which secrete hormones. These hormone secreting glands constitute a system, which is called Endocrine System. Those glands are also referred as endocrine glands and hormones released from them are called endocrine hormones. Some of the major hormone releasing endocrine glands in the body are given below:
• Adrenal glands
• Pineal gland
• Pituitary gland
Testes in males and ovaries in females also release hormones.
There are number of procedures and functions which take place inside body in the process of hormones signaling. Those steps are given in an order below:
I. Generation of hormone
II. Secretion of hormone
III. Transport of hormone to target organs and tissues
IV. Recognition of hormone by an associated cell membrane or intracellular receptor
V. Reaction of target cells, organs and tissues
VI. Subsequent breakdown of that hormones
There are multiple kinds of hormones which are produced in the body. These hormones can be categorized into 3 types based on their chemical structure and composition. Those 3 classes of hormone types are given as:
• Lipid derived hormones
• Amino acid derived hormones
Lipid hormones are derived from cholesterol as the name itself refers and have similar structure to cholesterol. Steroid hormones – include estrogen, androgen, aldosterone, cortisol are examples of lipid derived hormones. Since these lipid derived hormones are insoluble in water, they stay in circulation for longer period compared to other classes of hormones.
The amino acid-derived hormones are derived from the amino acid tyrosine and tryptophan. Examples of amino acid derived hormones include epinephrine, norepinephrine and thyroxine.
Peptide hormones or protein hormones are hormones whose molecules are peptides or proteins, respectively. These hormones have longer amino acid chain lengths. Examples of such hormones include amylin, angiotensin, atrial natriuretic peptide (ANP), calcitonin, gastrin etc.
The synthesis and regulation of hormone is often regulated by homeostatic negative feedback system. When amount of hormone reaches certain level, stimulation of glands is stopped or decreased to secrete more hormones. In simpler words, negative feedback system prevents the excess secretion of hormone. For example, the amount of glucose in the blood controls the secretion of insulin and glucagon via negative feedback system. This method of inhibiting a hormone’s release is called feedback inhibition. Some other hormones which are regulated by negative feedback inhibition include estrogen, testosterone, progesterone and cortisol.
This feedback system can be positive as well. For example, during pregnancy, more amount of oxytocin hormone is generated in women due to positive feedback system.
The endocrine glands secrete hormones in very microscopic amount. Even little amount of hormones can trigger various physiological functions and brings mood changes.
Some of effects of hormone can involve following functions and procedures of body:
• Sleep cycles
• Activation or inhibition of immune system
• Stimulation or inhibition of growth
• Regulation of metabolism
• Changing phase of life such as hitting puberty, being parent etc
• Mood swings
• Hunger cravings
How does hormone signals work?
Types of Hormones:
Lipid derived hormones:
Amino acid derived hormones:
Effects of hormones: