Question

The organ system that consists of ductless glands that secrete hormones and the molecular receptors on target cells that respond to the hormones is known as the

• A. Digestive system
• B. Respiratory system
• C. Circulatory system
• D. Endocrine system
• E. Nervous system

Answer 1

The correct option is D Endocrine system

The digestive system includes alimentary canal and associated glands to carry out the digestion of food and release the energy stored in these food substances. The nutrients from digested food are then absorbed in the small intestine of the alimentary canal and carried to different organs via the circulatory system. The primary function of the respiratory system is to allow atmospheric oxygen from the air to enter the blood and carbon dioxide from the blood to exit into the air. The endocrine system includes endocrine glands which are ductless glands that secrete hormones and release them directly into the blood. Hormones secreted by various endocrine glands maintain the normal functioning of target tissues/organs and thereby help to maintain homeostasis. Nervous system serves in the reception of sensory input followed by their integration in the brain and spinal cord and generation of motor output to produce a response. Thus, the correct answer is option D.