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While the nervous system and endocrine system have their own features, they have a common method of communication. Both the systems release chemicals to communicate between cells. Together these two systems carry out a very complex process of maintaining a homeostatic (balanced) internal environment of an organism.
- With increasing complexity, the organisms have had to develop means of control and coordination between the different parts of the body.
- Coordination is necessary for acting as one unit and also maintain the homeostasis or steady state within the body.
- The growth of the plants, their development and their responses to the environment are controlled or coordinated with the help of chemicals called the growth regulators. They are different from the hormones as they either promote or inhibit the growth of the plants.
- Auxins are phytohormones and are mainly concerned with cell enlargement.
- The chief functions of auxins are shoot and root development, apical dominance and delay in abscission.
- Commercially, one of the major roles of auxins is in parthenocarpy, that involves production of seedless fruits.
- Gibberellins are concerned with cell elongation and cause bolting in rossette plants like cabbage.
- GA-3 (gibberellic acid), a gibberellin that has been most studied, is used in the brewing industry for malting.
- Cytokinins are phytohormones that enable cell divisions even in mature tissues.
- Commercially, cytokinins are mainly used in tissue culture to induce cell division and to keep the cut flowers fresh.
- Ethylene is a gaseous growth regulator that speeds up the ripening process. It is commercially used for artificial ripening of fruits.
- It is a growth inhibitor that results in dormancy and abscission.
- It conserves energy during drought by suppressing growth and conserves water by closing the stomata.
- Control and coordination in animals is done with the help of nerves and chemicals called the hormones.
- The nervous system has three parts - central nervous system (CNS), peripheral nervous system (PNS) and autonomic nervous system (ANS).
- The CNS is made up of brain and spinal cord. Brain has different areas that are responsible for specific functions. The areas are divided into:
- sensory nerves that receives messages from the body
- motor nerves that sends messages to the body and association areas that relate the message to previous experiences.
- Spinal cord is protected by the vertebral column and gives out nerves.
- The nervous system is composed of three types of nerve cells or neurons - sensory neurons that receive messages and carry it to the CNS, the motor neuron that carries messages from the CNS to the muscle or gland and the interneuron that runs between sensory and motor neurons.
- A bunch of neurons together make up a nerve.
- Based on the types of neurons present, the nerve is called sensory, motor and mixed.
- The messages are transmitted along the nerves in the form of electrical impulses. These are maintained by the changing concentrations of potassium and sodium ions across the cell membrane of the neurons.
- When the body instantly responds to an external stimulus, it is called reflex action.
- Reflex may be natural or conditioned. Natural reflex does not involve the brain whereas conditioned reflex involves the brain. The path along which the impulses travel in a reflex are called the reflex arc.
- Chemical coordination and control is done with the help of hormones. Hormones are secreted by endocrine glands.
- Human body has eight types of endocrine glands that pour their secretions into the blood. In addition, it also has the gastrointestinal glands.
- The endocrine glands are pituitary, pineal, thyroid, parathyroid, thymus, pancreas, adrenal and the gonads (ovaries and testes).
- Some of the important hormones are growth hormone, thyroxine and insulin.
- Though both nervous and endocrine systems are different, they both basically function by the release of chemicals. Together they bring about a balance or homeostatic state in the body.
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