Chapter 12: Coordination and Control (Class 10)
The chapter “Coordination and Control” in 10th grade biology explores how organisms maintain a stable internal environment and respond to external stimuli. This process, known as homeostasis, is crucial for survival and involves the coordination and control of various systems in the body. Here’s a summary of the key topics covered in this chapter:
1. Nervous System
The nervous system is the body’s primary control system. It consists of the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS includes the brain and spinal cord, while the PNS comprises all the nerves outside the CNS. The nervous system functions by receiving sensory information, processing it, and sending out responses.
- Neurons: These are the functional units of the nervous system, responsible for transmitting signals. Neurons have three main parts: the cell body, dendrites, and axon.
- Synapse: The junction between two neurons where neurotransmitters are released to transmit impulses.
- Reflex Action: A rapid, automatic response to a stimulus, involving a simple pathway called the reflex arc.
2. Endocrine System
The endocrine system controls body functions through hormones, which are chemical messengers secreted by glands. Unlike the nervous system, which provides quick responses, the endocrine system works more slowly but has long-lasting effects.
- Glands: The main endocrine glands include the pituitary, thyroid, adrenal, pancreas, and gonads. Each gland releases specific hormones that regulate various bodily functions.
- Hormones: These are chemical substances that travel through the bloodstream and affect specific target cells.
3. Coordination between Nervous and Endocrine Systems
Both systems work together to maintain homeostasis. For example, the hypothalamus in the brain controls the pituitary gland, which in turn regulates other endocrine glands. This integration ensures that the body’s internal environment remains stable despite changes in the external environment.
4. Plant Hormones and Responses
Plants also have a system of coordination and control, primarily through plant hormones such as auxins, gibberellins, cytokinins, abscisic acid, and ethylene. These hormones regulate growth, development, and responses to environmental stimuli.
- Tropisms: These are directional movements in response to external stimuli. For example, phototropism is the growth of a plant towards light, and geotropism is growth in response to gravity.
5. Disorders of the Nervous and Endocrine Systems
The chapter also touches on common disorders related to these systems, such as diabetes (a disorder of the endocrine system due to insulin deficiency) and Parkinson’s disease (a nervous system disorder affecting movement).
This chapter provides a comprehensive overview of how organisms maintain balance and respond to their environment through intricate systems of coordination and control.