Endocrine glands, hormones and their disorders
Endocrine glands release hormones into the blood to control growth, metabolism and growing up. Too much or too little causes disorders such as goitre and diabetes.
What hormones do
As we grow from babies into adults, our height, weight and body shape change. At adolescence the body begins to mature. Endocrine glands guide these changes. They make chemicals called hormones and release them directly into the blood. The blood carries each hormone to its target organ, where it starts a particular activity. The word comes from the Greek hormaein, to set in motion. Very exact amounts are released. If a gland makes too much (hyperactivity) or too little (hypoactivity), disease follows. This control by hormones is chemical coordination.
Endocrine glands, their hormones and jobs
| Gland | Where | Hormone | Job |
|---|---|---|---|
| Pituitary | Base of the brain | Growth hormone (somatotropic hormone, STH) | Controls growth, especially of the long bones |
| Pituitary | Base of the brain | Gonad stimulating hormone | Makes the ovaries and testes work, especially from puberty |
| Thyroid | Front of the neck | Thyroid hormone (thyroxine) | Sets the speed of metabolism; needed for life, growth and development |
| Pancreas | Below the stomach | Insulin and glucagon | Control the metabolism of glucose; insulin lowers blood sugar |
| Ovaries (females) | Lower abdomen | Oestrogen and progesterone | Bring about the secondary sexual characters of girls |
| Testes (males) | Scrotum | Testosterone | Bring about the secondary sexual characters of boys |
Disorders of too much or too little hormone
| Disorder | Cause | What happens |
|---|---|---|
| Dwarfism | Too little growth hormone in childhood | The long bones grow too little, so the person stays very short |
| Gigantism | Too much growth hormone | The long bones grow too much, so the person becomes very tall |
| Cushing's disease | An overactive pituitary gland | Often a rounded face and weight gain on the trunk. Your NIOS lesson also lists extra hair growth; in women, a beard and moustache and being unable to have children; in men, shrinking of the testes |
| Hyperthyroidism and hypothyroidism | The thyroid makes too much or too little hormone | Metabolism runs too fast or too slow |
| Cretinism | An untreated lack of thyroid hormone from birth, or a long lack of iodine | Badly stunted physical and mental growth in children |
| Goitre | Too little iodine in the diet | The thyroid gland enlarges: a swelling in the front of the neck |
| Diabetes mellitus | Too little insulin from the pancreas | Too much glucose stays in the blood |
Activity: find out India's plan against iodine deficiency
A lack of iodine causes goitre and can harm a child's growing brain. India fights it mainly through **iodised salt**. Find out how.
- 1Look at the salt packet in your kitchen. Check that it says iodised, and note the brand and the date of packing.
- 2Ask a health worker, an anganwadi worker or the ration shop what the government advises about salt.
- 3Look in newspapers, on the radio, on TV or on the internet for the National Iodine Deficiency Disorders Control Programme. It began as the National Goitre Control Programme.
- 4Note what you find. For example, the programme asks every household to use iodised salt instead of plain salt.
- 5Keep salt in a closed container, away from heat and damp, so that less iodine is lost.
- 6★Record: write a short note of 5 or 6 lines on what you found, and share it with your family.
★ key step
How to draw the main endocrine glands
- Draw an outline of the human body from the head to the hips.
- At the base of the brain, mark the hypothalamus and the pea-sized pituitary gland just below it.
- In the front of the neck, draw the butterfly-shaped thyroid gland.
- On top of each kidney, draw a small cap: the adrenal gland, which makes adrenaline.
- Below the stomach, draw the leaf-shaped pancreas.
- Draw the two ovaries in the lower abdomen of a female figure, or the two testes in the scrotum of a male figure. Label each gland with its hormone.
Salt packets in Indian kitchens say iodised because iodine lets the thyroid make its hormone and prevents goitre. Many families have someone with diabetes who checks blood sugar regularly, eats carefully and may need insulin.
2 marks: “Why does the government advise everyone to use iodised salt?” The thyroid gland needs iodine to make thyroid hormone, which controls metabolism. A lack of iodine causes goitre, and in children it can cause cretinism.
3 marks: “Growth, the speed of metabolism and the level of blood sugar are each controlled by a hormone. For each, name the hormone and the gland that makes it.” Growth: growth hormone, from the pituitary. Speed of metabolism: thyroid hormone (thyroxine), from the thyroid. Blood sugar: insulin (with glucagon), from the pancreas.
2 marks: “What is a hormone? How does it reach its target organ?” A chemical made by an endocrine gland that starts a specific activity in a target organ. It is released directly into the blood, which carries it to that organ.
Iodine → thyroid → hormone: no iodine, and the neck swells (goitre). Insulin is the sugar police of the pancreas.