Hormones – Class 11 | Chapter – 22 | Biology Short Notes Series PDF

Hormones are chemical substances that act like messenger molecules that stream through the bloodstream. Hormone carry chemical messages from the glands where they are produced to cells in different parts of the human body. These chemical messages help to turn on or turn off cellular processes that control stress, appetite, growth, sleep cycles, blood sugar, sex drive, and sexual function.

Hormone are various chemicals released within the human body that regulate and control the activities of multiple organs. The introduction of hormone to the blood takes place via endocrine glands.

Our body contains two different kinds of glands.

  1. Endocrine Glands: These glands, such as the pituitary and adrenal glands, do not have ducts and deliver their secretions through the blood straight to the site of action.

  2. Exocrine Glands: These glands have ducts by which their secretions are transported. Example: sweat and liver,

Types of Hormones

To regulate various functions, different types of hormones are produced in the body. They are classified as follows:

  • Peptide Hormone
  • Steroid Hormone

Peptide Hormone

Peptide hormone are composed of amino acids and are soluble in water. Peptide hormones are unable to pass through the cell membrane as it contains a phospholipid bilayer that stops any fat-insoluble molecules from diffusing into the cell. Insulin is an important peptide hormone produced by the pancreas.

Steroid Hormone

Unlike peptide hormone, steroid hormones are fat-soluble and are able to pass through a cell membrane. Sex hormones such as testosterone, estrogen and progesterone are examples of steroid hormone.

Function of Hormones

Hormone act as a messenger which is released into the blood. Blood transmits them to various organs and tissues of the human body. After reaching a target site, hormones bind to the receptors. Once this process is complete, hormone then transmit the message which causes an organ or tissue to perform a specific action.

The following are some important functions of hormone:

  • Regulating mood and cognitive functions

  • Growth and development

  • Food metabolism

  • Maintaining body temperature

  • Controlling thirst and hunger

  • Initiating and maintaining sexual development and reproduction

List of Important Hormones

  1. Cortisol – It has been named as the “stress hormone” as it helps the body in responding to stress. This is done by increasing the heart rate, elevating blood sugar levels etc.
  2. Estrogen-This is the main sex hormone present in women which bring about puberty, prepares the uterus and body for pregnancy and even regulates the menstrual cycle. Estrogen level changes during menopause because of which women experience many uncomfortable symptoms.
  3. Melatonin – It primarily controls the circadian rhythm or sleep cycles.
  4. Progesterone – It is a female sex hormone also responsible for menstrual cycle, pregnancy and embryogenesis.
  5. Testosterone – This is the most important sex hormone synthesized in men, which cause puberty, muscle mass growth, and strengthen the bones and muscles, increase bone density and controls facial hair growth

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By Team Learning Mantras