Hormones, glands and growth
Many secondary growth disorders are caused by issues in the hormonal (endocrine) system. The endocrine system is made up of a number of glands that secrete hormones.
Glands and the hormones they release regulate many processes in the body; from growth, puberty, metabolism and reproduction, hormones play a role in almost everything we do.
Glands involved in growth include:
- Pituitary – connected to the hypothalamus – this is known as a ‘master gland’ and is responsible for releasing and controlling a number of hormones.
- Thyroid – located at the base of the neck. The thyroid releases thyroxine (T4) and triiodothyronine (T3). These hormones regulate the metabolism in the body and support the activity of the growth hormone, which cannot function without thyroxine.
- Adrenal – There are two adrenal glands, one above each kidney. The adrenal glands make several hormones, including cortisol. Cortisol plays a role in metabolism: it promotes the conversion of proteins and fats into glucose. Cortisol also inhibits growth.
- Pineal – Found at the base of the brain, this produces the hormone melatonin, which is involved in sleep regulation.
- Thymus – This gland is found in your chest, just behind the breastbone (sternum) and between your lungs. It secretes hormones that are important during puberty and development of the immune system.
- Testes - These are found in men in the part of the body called the scrotum – the small ‘pouch’ just below the penis. The testes (which are part of the testicles) produce the sex hormone testosterone, which is important for the development of sperm, bone and muscle mass as well as secondary sexual characteristics such as facial and body hair.
- Ovaries – These are found in women and produce not only sex hormones but also eggs. These glands produce both oestrogen and progesterone, which are involved in female breast development, fat distribution in the hips and legs, as well as the development of reproductive organs and overall fertility.
The pituitary: the ‘master gland’
The pituitary is also known as the ‘master gland’. It is located just behind the bridge of the nose and is responsible for producing a number of hormones involved in growth. It also regulates the function of other glands (the adrenal, thyroid, testes and ovaries) some of which are directly or indirectly involved with growth processes. The pituitary gland is largely controlled by the hypothalamus, which is the part of the brain involved with control of the nerves and hormones throughout the body.
Hormones that the pituitary gland produces include:
- Growth hormone: regulates growth processes
- Luteinizing hormone (LH): a type of sex hormone, released during puberty (and beyond). During this time it promotes development of sexual organs. Sex hormones cause a growth spurt during puberty.
- Follicle stimulating hormone (FSH): A type of sex hormone. Released during puberty (and beyond). During this time it encourages the sexual organs to develop. Sex hormones cause a growth spurt during puberty.
- Thyroxine stimulating hormone (TSH): Stimulates the thyroid gland to produce thyroxine.
- Adrenocorticotrophic hormone (ACTH): Stimulates the adrenal glands to produce cortisol.
Conditions affecting the pituitary gland, the hypothalamus and some of the other glands mentioned above can cause growth problems.