Animal Biology: Hormones

Hormones are chemical substances that are produced in special glands in the body and then transported in the bloodstream to specific organs or cells where they exert their effect.
The primary role of hormones is to coordinate the functions of different parts of an organism and to regulate internal processes. They control a variety of physiological features such as growth, metabolism, mood, sleep, and reproduction among others.
There are different types of hormones including steroids, peptides, and amines. Each type is designed to communicate with specific cells or tissues.
An understanding of endocrine glands is essential in animal biology. These glands produce hormones and they include the pituitary gland, thyroid gland, adrenal glands, pancreas, and the gonads (ovaries and testes).
The pituitary gland, also known as the master gland, produces hormones that control other endocrine glands. For instance, it produces the growth hormone (GH) which stimulates growth, reproduction and regeneration of cells.
Hormones initiate responses more slowly than nervous responses but the effects of hormones are often long lasting.
The thyroid gland, located in the neck, produces thyroxine. This hormone plays a crucial role in regulating metabolism, heart and digestive function, muscle control, brain development and bone maintenance.
The pancreas plays a major role in hormone production by producing insulin and glucagon. These hormones are key in regulating blood sugar levels, thereby controlling the rate of metabolism.
In terms of reproduction, the ovaries and testes are significant. Ovaries in females produce oestrogen and progesterone, which are vital for the menstrual cycle. The testes in males generate testosterone, which is responsible for male secondary sexual characteristics.
Negative feedback is a major concept in hormonal control. It is a mechanism that reverses a change in conditions to return to the optimum state. For instance, when blood sugar levels rise, insulin is released to decrease these levels.
Imbalances in hormone production can lead to various medical conditions. For example, an overproduction or underproduction of thyroid hormones leads to Graves’ disease and hypothyroidism respectively.
In some cases, synthetic hormones are used to regulate bodily functions or to treat hormone-related conditions. This includes the use of insulin to manage diabetes or hormonal birth control to prevent pregnancy.