Table of Contents
- Nervous System in Animals
- Human Brain and Its Functions
- Endocrine System in Animals
- Coordination in Plants
- Conclusion
Nervous System in Animals
Introduction
In living organisms, various life processes ensure maintenance and survival. One key aspect is the ability to respond to environmental changes, which is controlled and coordinated by specialized systems. This chapter delves into the mechanisms of control and coordination, particularly focusing on the nervous system in animals.
Understanding Movement in Living Organisms
Visible Movements and Life:
- Movement is often associated with life. For example:
- Plants: Seed germination and growth result in visible movements.
- Animals: Activities like a cat running, children playing, or buffaloes chewing cud.
Responses to Environmental Changes:
- Movement is a response to environmental stimuli.
- Example: A cat runs when it sees a mouse.
- Movements help organisms use environmental changes to their advantage:
- Plants grow towards sunlight.
- Buffaloes chew cud to aid digestion.
Nervous System and its Function
The nervous system is crucial for detecting stimuli and coordinating responses. It comprises specialized tissues that conduct electrical impulses, which facilitate communication between different parts of the body.
Structure of Neurons
Neurons are the fundamental units of the nervous system, specialized for transmitting information.
- Dendrites: Receive information from sensory receptors or other neurons.
- Cell Body: Processes the information.
- Axon: Transmits impulses away from the cell body to other neurons or muscles.
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| Neuron (Source: NCERT) |
The synapse, a junction between two neurons, is where the electrical impulse is converted into a chemical signal and transferred to the next neuron.
Reflex Actions
Definition and Examples:
- Reflex actions are sudden responses to environmental changes without conscious thought.
- Example: Pulling hand back from a flame.
Reflex Arc:
- Reflex actions are controlled by a reflex arc.
- Reflex arcs are formed in the spinal cord for quick responses.
- Reflex actions evolved as efficient responses even before complex thinking processes developed.
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| Reflex Arc (Source: NCERT) |
Human Brain and Its Functions
Brain Structure and Function
The human brain, protected by the skull and a fluid-filled cavity, is the control center for voluntary and involuntary actions. It processes sensory information, makes decisions, and coordinates movements.
Major Parts of the Brain
- Cerebrum: Responsible for thinking, learning, and memory.
- Cerebellum: Manages balance and coordination.
- Medulla Oblongata: Controls involuntary actions like heartbeat and breathing.
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| Human Brain (Source: NCERT) |
Protection of Nervous Tissue
Brain Protection:
- Brain is enclosed in a bony box and cushioned by a fluid-filled balloon.
- Spinal cord is protected by the vertebral column (backbone).
Muscle Action and Nervous Tissue
Mechanism of Muscle Movement:
- Nerve impulses cause muscle cells to change shape and shorten.
- Muscle cells have special proteins that respond to electrical impulses.
Types of Muscles:
- Voluntary muscles: Controlled consciously.
- Involuntary muscles: Operate without conscious control.
Endocrine System in Animals
Hormonal Control and Coordination
The endocrine system regulates bodily functions through hormones, which are chemical messengers secreted by glands.
Major Endocrine Glands and Hormones
- Pituitary Gland: Produces growth hormone, which stimulates growth in tissues.
- Thyroid Gland: Secretes thyroxine, regulating metabolism.
- Pancreas: Produces insulin, which regulates blood sugar levels.
- Adrenal Glands: Secrete adrenaline, preparing the body for 'fight or flight' responses.
Feedback Mechanisms
Hormone secretion is regulated by feedback mechanisms to maintain homeostasis. For instance, high blood sugar levels trigger insulin production, which lowers blood sugar, reducing further insulin release.
Coordination in Plants
Plant Hormones and Their Functions
Plants also exhibit control and coordination through hormones, which regulate growth and responses to stimuli.
Major Plant Hormones
- Auxins: Promote cell elongation and are involved in phototropism (growth towards light).
- Gibberellins: Stimulate stem elongation, germination, and flowering.
- Cytokinins: Promote cell division and differentiation.
- Ethylene: Regulates fruit ripening and response to stress.
- Abscisic Acid: Induces dormancy and helps plants withstand stress conditions.
Tropic Movements
Plants respond to environmental stimuli through tropic movements:
- Phototropism: Growth towards light.
- Geotropism: Growth in response to gravity.
- Hydrotropism: Growth towards water.
Conclusion
Control and coordination are vital for the survival and efficient functioning of living organisms. In animals, these functions are managed by the nervous and endocrine systems, while in plants, they are regulated by various hormones. Understanding these processes provides insight into the intricate mechanisms that maintain life.
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