Hormones In Animals

Animals are more complex than plants. They have many specialised organs that perform specialised functions for their control and coordination. This coordination in animals occurs due to the nervous coordination (Nervous System) and the chemical coordination (Endocrine System).  Both these systems act in a coordinated manner in animals, so as to regulate the various body activities. Let’s learn more about the hormones in animals.

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Endocrine System

The endocrine system comprises of different endocrine glands and hormones. These endocrine glands in animals help in the chemical coordination. They secrete chemicals called hormones. They are special messengers that control many body functions, including hunger, body temperature, mood, growth and development, metabolism, reproductive processes etc.  The endocrine glands are ductless and hence are also called as ductless glands.

Browse more Topics under Control And Coordination

• Coordination in Plants
• Human Brain
• Nervous System
• Reflex Action

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What are Hormones?

Hormones are chemicals secreted by the endocrine glands directly into the bloodstream. Through the blood, these hormones in animals reach their target organs to stimulate or inhibit specific physiological processes. The site of production of the hormones is different and the site of action is different. Even though there are different hormones in the bloodstream, each will act only on the specific target organ. There are around 20 major hormones in animals that are released by the endocrine glands into the blood, playing a major role in many of the physiological processes happening in the body.

Did you know that the hormone levels in the body can be influenced by several factors? Stress, infection, minerals in the blood etc. influence the hormone levels in animals.

Different Endocrine Glands

• Hypothalamus
• Pituitary gland
• Thyroid gland
• Parathyroid gland
• Pineal gland
• Adrenal gland
• Pancreas
• Testes
• Ovaries

(Source – Wikipedia)

Hypothalamus

This gland forms an important link between the nervous system and the endocrine system, via the pituitary gland.

Some of the important functions are:

• Helps in maintaining the body temperature, controls sleep, hunger, thirst, emotions and moods.
• It also controls the release of 8 major hormones by the pituitary gland.
• Controls the sexual behaviour and reproduction.
• It controls the circadian rhythm of the body.

Pituitary Gland

The pituitary gland is very small in size but is called as the Master Gland, as many endocrine glands are controlled by the hormones secreted by it. It also stimulates other endocrine glands to produce hormones.  Some of the hormones released by this gland are growth hormone, thyroid stimulating hormone, MSH, LH, FSH etc.

Thyroid Gland

It is the largest endocrine gland that is shaped like a butterfly. It produces the thyroxine hormone, which controls the metabolic rate in the body. Apart from that, it also plays a role in the bone growth, development of the brain and nervous system in children. Iodine is important for the synthesis of thyroxine.

Parathyroid Gland

This gland releases parathormone which helps in regulating the calcium and phosphorus levels in the bone.

Pineal gland

This produces melatonin hormone that regulates the sleep patterns.

Adrenal gland

These glands are located on top of the kidneys and produce hormones such as adrenaline, cortisol, and aldosterone etc. These hormones control stress, help control blood sugar, burn protein and fat and also regulate blood pressure.

Pancreas

They secrete two important hormones – insulin and glucagon. Both work together to maintain the glucose levels in the blood.

Testes

These glands are present in males and produce testosterone hormone.

Ovaries

These glands are present in females. The hormones produced by ovaries are oestrogen and progesterone.

Solved Examples For You

1. Why is the use of iodised salt recommended?

Ans. The hormone thyroxine that is produced in the thyroid gland is stimulated by iodine. Hence it is advisable to have sufficient intake of iodine, so that thyroid glands function normally. Deficiency of thyroid hormone leads to goitre.

2. The gland that produces insulin – Pancreas