Question

A and B are the two systems of control and coordination in the human body. The messages in system A are transmitted in the form of chemical substances C which travel comparatively slowly through the blood stream. The substances C are made in tissues D present in the head and trunk of human body. The messages in system B are transmitted very quickly in the form of electrical impulses through fibres E. The effect of messages transmitted by system B usually lasts for a much shorter time as compared to those transmitted by system A.
(a) Name the system A. What does system A consist of?
(b) Name the chemical substance C.
(c) What is tissue D? Name any five such tissues in the human body.
(d) Name the system B. What does system B consist of?
(e) Name the fibres E.
(f) State whether system A controls the working of system B or system B controls the working of system A.

Answer 1

(a) A represents the endocrine system. The endocrine system is composed of glands.
(b) C represents hormones. Hormones are the chemical messengers of the body and they travel slowly through the bloodstream.
(c) D represents endocrine glands that are made up of tissues. Hypothalamus, thyroid, thymus, pancreas and adrenal glands are some of the endocrine glands present in the human body.
(d) B represents the nervous system. It comprises the brain, spinal cord and nerves.
(e) E represents nerve fibres. They transmit messages very quickly in the form of electrical impulses.
(f) The nervous system (B) controls the working of the endocrine system (A).