Adrenaline, secreted into the blood, accelerates the heart rate, increasing oxygen supply to muscles. It also causes the contraction of muscles around small arteries in the digestive system and skin, redirecting blood flow to skeletal muscles.

In various animals, including humans, adrenaline is secreted from the adrenal glands, serving as a hormonal signal that triggers wide-ranging changes in different tissues, preparing the body for activities such as fighting or fleeing in response to a threatening situation.

Hormones like adrenaline provide a wider range of tissue responses by reaching all cells in the body, allowing for coordinated and energy-efficient preparations for activities like fighting or fleeing, which would be limited with only electrical impulses via nerve cells.

Insulin, a hormone from the pancreas, regulates blood sugar levels. When blood sugar rises, the pancreas produces more insulin, and as sugar levels fall, insulin secretion is reduced.

Puberty-related changes in appearance are influenced by the secretion of testosterone in males and oestrogen in females.

Growth hormone, secreted by the pituitary, regulates the growth and development of the body. A deficiency of this hormone in childhood leads to dwarfism, affecting the overall growth and stature of an individual.

Iodised salt is crucial as iodine is necessary for the synthesis of thyroxin hormone in the thyroid gland. Thyroxin regulates carbohydrate, protein, and fat metabolism, ensuring a balanced environment for growth.

Animal growth is carefully controlled in specific places, ensuring body design maintenance. Unlike plants that can grow leaves in various locations, animals exhibit controlled growth, such as not growing fingers on the face, maintaining a specific body design even during ...

Aerobic respiration, occurring in the presence of oxygen, releases a significantly greater amount of energy compared to anaerobic respiration. It involves the breakdown of pyruvate in the mitochondria, producing carbon dioxide and water.