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Reaching the Age of Adolescence - Role of Endocrine Glands and Hormones

Grade 8CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Adolescence is the period of life between the ages of 1111 and 1919 years when the body undergoes changes leading to reproductive maturity.

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Hormones are chemical substances secreted by endocrine glands (ductless glands) that act as messengers in the body.

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The Pituitary gland is known as the 'Master Gland' because it controls the secretions of other endocrine glands and secretes Growth Hormone (GHGH).

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The Thyroid gland produces the hormone ThyroxineThyroxine. Production of ThyroxineThyroxine requires the presence of Iodine (II) in the diet.

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The Pancreas secretes InsulinInsulin, which regulates the level of glucose (C6H12O6C_{6}H_{12}O_{6}) in the blood. Deficiency of InsulinInsulin leads to Diabetes mellitus.

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Adrenal glands secrete AdrenalineAdrenaline, which helps the body to adjust to stress, fear, or anger (the 'fight or flight' response).

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Testosterone is the male sex hormone produced by the testes, and Estrogen is the female sex hormone produced by the ovaries.

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In insects and frogs, metamorphosis is controlled by hormones. In frogs, ThyroxineThyroxine (which requires II in water) initiates the change from tadpole to adult.

📐Formulae

Iodine+Tyrosine (Amino Acid)→ThyroidThyroxine\text{Iodine} + \text{Tyrosine (Amino Acid)} \xrightarrow{\text{Thyroid}} \text{Thyroxine}

High Blood Glucose→InsulinLower Blood Glucose\text{High Blood Glucose} \xrightarrow{\text{Insulin}} \text{Lower Blood Glucose}

Pituitary Gland→TSHThyroid Gland→Thyroxine\text{Pituitary Gland} \xrightarrow{\text{TSH}} \text{Thyroid Gland} \rightarrow \text{Thyroxine}

💡Examples

Problem 1:

A person has a swollen neck and the doctor diagnoses it as Goitre. Which hormone is deficient in this person?

Solution:

The hormone deficient is ThyroxineThyroxine.

Explanation:

Goitre is caused by the enlargement of the thyroid gland due to a lack of iodine (II) in the diet, which is essential for the synthesis of ThyroxineThyroxine.

Problem 2:

Why can tadpoles not mature into adult frogs if they are kept in water that is deficient in iodine?

Solution:

Metamorphosis will not occur without ThyroxineThyroxine.

Explanation:

The thyroid gland of the tadpole produces ThyroxineThyroxine to initiate metamorphosis. Since iodine (II) is necessary for the production of ThyroxineThyroxine, its absence in water prevents the tadpoles from becoming adults.

Problem 3:

Identify the gland responsible for maintaining the correct salt balance in the blood.

Solution:

The Adrenal glands.

Explanation:

Apart from AdrenalineAdrenaline, adrenal glands secrete hormones that maintain the correct salt balance in the blood, such as aldosterone.

Role of Endocrine Glands and Hormones Revision - Class 8 Science CBSE