Control and Coordination Class 10 Notes

Control and coordination are essential functions in living organisms that help them respond to stimuli and maintain homeostasis. In animals, the nervous system and endocrine system work together to regulate bodily functions, whereas in plants, hormonal and environmental responses control growth and movements.

Control and Coordination in Animals

1. Nervous System

The nervous system in animals is responsible for detecting changes in the environment and coordinating appropriate responses. It consists of:

a) Neurons (Nerve Cells)

Neurons are the fundamental units of the nervous system. They transmit electrical and chemical signals through the body. A neuron consists of three main parts:

• Cell body (Cyton): Contains the nucleus and cytoplasm.
• Dendrites: Receive signals from other neurons or sensory receptors.
• Axon: Transmits electrical impulses away from the cell body.

b) Types of Neurons

• Sensory Neurons: Carry impulses from sensory organs to the brain/spinal cord.
• Motor Neurons: Transmit commands from the brain/spinal cord to muscles or glands.
• Interneurons: Connect sensory and motor neurons.

2. Central Nervous System (CNS)

The CNS consists of the brain and spinal cord, which process information and coordinate responses.

a) Brain

The brain is the control center of the body and is divided into three main parts:

• Forebrain: Includes the cerebrum, which controls thinking, memory, sensory perception, and voluntary movements.
• Midbrain: Acts as a relay center for sensory and motor information.
• Hindbrain: Includes the cerebellum (balance and coordination) and medulla oblongata (controls involuntary actions like heartbeat and breathing).

b) Spinal Cord

The spinal cord transmits signals between the brain and the rest of the body and is responsible for reflex actions.

3. Peripheral Nervous System (PNS)

The PNS consists of:

• Somatic Nervous System: Controls voluntary actions (e.g., moving arms and legs).
• Autonomic Nervous System: Regulates involuntary functions (e.g., heartbeat, digestion). It is further divided into:
  • Sympathetic Nervous System: Prepares the body for stress responses (fight or flight).
  • Parasympathetic Nervous System: Controls relaxation and normal bodily functions.

4. Reflex Action and Reflex Arc

A reflex action is an automatic, rapid response to a stimulus (e.g., pulling your hand away from a hot object). The reflex arc is the neural pathway that controls reflexes, involving sensory neurons, interneurons, and motor neurons.

Hormonal Coordination in Animals

The endocrine system works alongside the nervous system to regulate body functions using chemical messengers called hormones.

1. Endocrine Glands and Their Functions

• Pituitary Gland: “Master gland” that controls other endocrine glands; secretes growth hormone.
• Thyroid Gland: Produces thyroxine, which regulates metabolism.
• Adrenal Glands: Secrete adrenaline (fight or flight hormone).
• Pancreas: Produces insulin and glucagon to regulate blood sugar levels.
• Ovaries (Females): Secrete estrogen and progesterone, regulating the menstrual cycle and pregnancy.
• Testes (Males): Produce testosterone, responsible for male characteristics.

Control and Coordination in Plants

Unlike animals, plants do not have a nervous system but rely on chemical control for coordination.

1. Plant Hormones (Phytohormones)

• Auxins: Promote cell elongation and are involved in phototropism (growth towards light).
• Gibberellins: Stimulate stem elongation, seed germination, and fruit development.
• Cytokinins: Promote cell division and delay aging in leaves.
• Abscisic Acid (ABA): Inhibits growth and induces dormancy.
• Ethylene: Stimulates fruit ripening and leaf shedding.

2. Tropic Movements in Plants

Plants show directional growth responses to external stimuli, called tropisms:

• Phototropism: Growth in response to light (e.g., shoots growing towards sunlight).
• Geotropism: Growth in response to gravity (e.g., roots growing downward).
• Hydrotropism: Growth in response to water (e.g., roots growing towards moisture).
• Thigmotropism: Growth in response to touch (e.g., tendrils coiling around objects).

3. Nastic Movements in Plants

Nastic movements are non-directional responses to stimuli, such as:

• Seismonasty: Response to mechanical stimuli (e.g., touch-sensitive Mimosa pudica folding leaves).
• Photonasty: Response to light intensity (e.g., night-blooming flowers closing in daylight).

Life Processes Class 10 Notes Science

Differences Between Nervous and Endocrine Coordination

Conclusion

Control and coordination are vital for survival in both animals and plants. While the nervous and endocrine systems regulate bodily functions in animals, plants rely on hormones and external stimuli to coordinate growth and responses.