Control And Coordination Complete Chapter Class 10

Control And Coordination Complete Chapter

Control and coordination are essential processes in living organisms that ensure the body functions efficiently and responds effectively to changes in the environment. These processes help maintain homeostasis, adapt to external stimuli, and execute both voluntary and involuntary actions.

Control and Coordination in Animals :

In humans, control and coordination are primarily carried out by two major systems :

i) What is the Nervous system?

The nervous system consists of nerve fibres and nerve cells which transmit impulses of the nerve between different parts of the body.It is a system found in animals that synchronizes its functions by passing signals to and from different parts of the body.

This system uses electrical signals to transmit information rapidly between different parts of the body. It involves the brain, spinal cord, and a network of nerves. The nervous system is responsible for quick responses, such as reflex actions and conscious decision-making.

ii)What is Endocrine System?

It involves glands that secrete hormones directly into the bloodstream. Hormones regulate various bodily functions, including growth, metabolism, and reproduction.

• Major Glands: Include the pituitary, thyroid, adrenal, and pancreas.
• Hormones: Chemical messengers like insulin, adrenaline, and thyroxine.

The two systems work together to ensure smooth and efficient functioning of the body. Additionally, the five sense organs—eyes, ears, nose, tongue, and skin—play a critical role in gathering information from the surroundings. They act as receptors that detect stimuli, such as light, sound, smell, taste, and touch, and send signals to the brain for processing.

Role of the Nervous System(Control And Coordination Complete Chapter)

The nervous system consists of the brain, spinal cord, and nerves. It processes and transmits information received from the environment through electrical impulses. The five sense organs—eyes, ears, nose, tongue, and skin—are key components of this system. They act as receptors by detecting specific stimuli such as light, sound, smell, taste, and touch.

• Eyes detect light and enable vision.
• Ears sense sound waves and help in hearing and balance.
• Nose detects odors and helps in the sense of smell.
• Tongue perceives taste through taste buds.
• Skin senses touch, pressure, temperature, and pain.

Role of the Endocrine System

The endocrine system complements the nervous system by producing and secreting hormones. These chemical messengers travel through the bloodstream to target specific organs, regulating functions like growth, metabolism, reproduction, and mood.

Parts of neuron:

A neuron is the basic structural and functional unit of the nervous system responsible for transmitting signals within the body. It consists of three main parts, each with a specific function:

• Cell Body (Soma): This is the central part of the neuron that contains the nucleus and most of the cell’s organelles. It’s responsible for maintaining the life of the cell and integrating information.
• Dendrites: These are branching projections that receive electrical signals from other neurons and convey this information to the cell body.
• Axon: A long, singular projection that transmits electrical impulses away from the cell body to other neurons, muscles, or glands. The axon can be quite long, reaching up to a meter in humans!
• Myelin Sheath: This is a fatty layer that wraps around the axon in segments, acting as insulation. It helps increase the speed of electrical transmission along the axon.
• Nodes of Ranvier: These are gaps in the myelin sheath where the axon membrane is exposed. These gaps facilitate the rapid conduction of nerve impulses.
• Axon Terminals (Synaptic Boutons): These are the ending points of the axon where the neuron communicates with other neurons or effectors through synapses.
• Synapse: This is the junction between two neurons, consisting of the presynaptic terminal, the synaptic cleft, and the postsynaptic membrane. Neurotransmitters are released from the axon terminals and cross the synaptic cleft to transmit signals to the next neuron.

Passing Signals Through a Neuron(Control And Coordination Complete Chapter)

1. Resting Potential: Neurons have a resting state where the inside of the neuron is negatively charged compared to the outside. This is due to the distribution of ions, primarily sodium (Na+) and potassium (K+).
2. Action Potential: When a neuron receives a strong enough stimulus, it undergoes a rapid change in membrane potential called an action potential. This is a brief reversal of the membrane potential, making the inside of the neuron positively charged.
   • Depolarization: Sodium channels open, allowing Na+ to enter the neuron, causing depolarization.
   • Repolarization: Potassium channels open, allowing K+ to leave the neuron, restoring the negative charge.
   • Hyperpolarization and Return to Resting Potential: The neuron briefly becomes more negative than the resting potential before stabilizing.
3. Propagation of Action Potential: The action potential travels along the axon in a wave-like manner. In myelinated neurons, the action potential jumps between the nodes of Ranvier in a process called saltatory conduction, which speeds up the transmission.

Signal Transmission Between Neurons (Chemical Signaling at the Synapse)

Neurons communicate with one another at synapses, which are small gaps between the axon terminal of one neuron (presynaptic neuron) and the dendrites or cell body of another neuron (postsynaptic neuron). This involves chemical signaling:

• Arrival of Action Potential: When the action potential reaches the axon terminal of the presynaptic neuron, it triggers the opening of voltage-gated calcium (Ca²⁺) channels.
• Release of Neurotransmitters: Calcium ions enter the axon terminal and stimulate synaptic vesicles to release neurotransmitters into the synaptic cleft.
• Binding to Receptors: The neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic neuron’s membrane.
• Generation of Postsynaptic Potential: The binding of neurotransmitters opens ion channels on the postsynaptic neuron, causing either:
  • Excitatory Postsynaptic Potential (EPSP): If positive ions (e.g., Na⁺) enter, making the neuron more likely to fire an action potential.
  • Inhibitory Postsynaptic Potential (IPSP): If negative ions (e.g., Cl⁻) enter, making the neuron less likely to fire.
• Signal Termination: Neurotransmitters are either broken down by enzymes, reabsorbed by the presynaptic neuron (reuptake), or diffuse away, ensuring the signal is brief.

Types of neuron:

Neurons come in various types based on their structure, function, and location. Here are the main types:

Based on Structure

1. Multipolar Neurons:
   • Description: These have one axon and multiple dendrites.
   • Location: Commonly found in the brain and spinal cord.
   • Function: They are involved in motor and sensory information processing.
2. Bipolar Neurons:
   • Description: These have one axon and one dendrite.
   • Location: Found in the retina of the eye and the olfactory system.
   • Function: They are involved in sensory processing.
3. Unipolar (or Pseudounipolar) Neurons:
   • Description: These have a single process that splits into two branches, one acting as an axon and the other as a dendrite.
   • Location: Commonly found in the sensory ganglia of the peripheral nervous system.
   • Function: They transmit sensory information from the body to the central nervous system.

Based on Function

This classification is based on the role a neuron plays in the nervous system:

a) Sensory Neurons (Afferent Neurons)

• Function: Transmit sensory information from receptors (e.g., in the skin, eyes, or ears) to the central nervous system (CNS).
• Direction: Carry signals toward the CNS.
• Example: Neurons that respond to light, sound, or touch stimuli.

b) Motor Neurons (Efferent Neurons)

• Function: Transmit commands from the CNS to effectors like muscles or glands.
• Direction: Carry signals away from the CNS.
• Example: Neurons that stimulate muscle contraction or glandular secretion.

c) Interneurons (Association Neurons)

• Function: Act as connectors between sensory and motor neurons within the CNS.
• Direction: Confined to the CNS; process information and facilitate communication.
• Example: Neurons in the brain and spinal cord involved in reflexes or complex processing.

Based on Location

1. Cortical Neurons:
   • Location: Found in the cerebral cortex of the brain.
   • Function: Involved in higher cognitive functions like thinking, memory, and decision-making.
2. Peripheral Neurons:
   • Location: Found outside the brain and spinal cord.
   • Function: Transmit information between the central nervous system and the rest of the body.

Types of nurvous action(Control And Coordination Complete Chapter)

The nervous system coordinates actions in the body through two main types of nervous actions: voluntary actions and involuntary actions. These are differentiated by the level of conscious control involved.

i) Voluntary Actions

• Definition: Actions that are consciously controlled by the brain.
• Control Center: These actions are regulated by the cerebral cortex of the brain.
• Examples: Walking, speaking, writing, playing sports, or any activity that requires conscious effort.
• Pathway:
  1. Stimulus is detected by sensory organs and transmitted to the brain via sensory neurons.
  2. The brain processes the information and sends signals through motor neurons to the appropriate muscles or glands.
• Characteristics:
  • Require conscious thought and decision-making.
  • Can be learned and improved with practice.
  • Typically slower than reflex actions as they involve complex neural processing.

ii) Involuntary Actions: These actions happen without conscious control and are further divided into:

• Reflex Actions: Quick, automatic responses to stimuli, such as pulling your hand back from a hot surface. These actions are controlled by the spinal cord.
• Autonomic Actions: These regulate internal body functions like heart rate, digestion, and respiratory rate. The autonomic nervous system controls these actions, and it operates independently of voluntary control.

Reflex action

Reflex actions are quick, involuntary responses to stimuli that protect our body from harm. They are controlled by the spinal cord rather than the brain, which is why they happen so swiftly. Here’s a closer look:

Types of Reflexes:

• Simple Reflexes: These involve a single synapse between a sensory neuron and a motor neuron. An example is the knee-jerk reflex.
• Complex Reflexes: These involve multiple synapses and interneurons. An example is the withdrawal reflex, like pulling your hand away from a hot object.

Importance of Reflex Actions

1. Protection: Prevents injuries by enabling quick responses to harmful stimuli.
2. Homeostasis: Maintains internal balance (e.g., regulating heart rate or breathing).
3. Efficiency: Allows the body to function effectively without overburdening the brain with routine decisions.

Reflex Arc(Control And Coordination Complete Chapter)

A reflex action is carried out through a reflex arc, which is the neural pathway involved in the response. It bypasses the brain to ensure a faster reaction.

Steps in a Reflex Arc

1. Stimulus: A stimulus, such as heat or pain, is detected by sensory receptors.
2. Sensory Neuron: The receptor sends an impulse to the spinal cord via a sensory neuron.
3. Interneuron: In the spinal cord, the impulse is transmitted to an interneuron (connector neuron), which processes the signal.
4. Motor Neuron: The interneuron relays the impulse to a motor neuron.
5. Effector: The motor neuron carries the signal to an effector (muscle or gland), which performs the response (e.g., muscle contraction to pull away from heat).

Components of a Reflex Arc:

1. Receptor: Detects the stimulus (e.g., pain receptors in the skin).
2. Sensory Neuron: Transmits the signal to the spinal cord.
3. Interneuron: Processes the information and sends it to a motor neuron (present in complex reflexes).
4. Motor Neuron: Carries the signal to the muscle or gland.
5. Effector: The muscle or gland that responds to the signal (e.g., muscle contraction).

The brain is the control center of the body, responsible for coordinating all bodily functions and enabling thought, memory, emotion, and learning. It’s an incredibly complex organ, divided into several main parts, each with distinct functions.

Brain(Control And Coordination Complete Chapter) :

Main Parts of the Brain:

1. Cerebrum:
   • Function: Responsible for higher brain functions such as thought, action, and sensory processing.
   • Structure: Divided into two hemispheres (left and right) and further divided into four lobes (frontal, parietal, temporal, and occipital).
2. Cerebellum:
   • Function: Coordinates voluntary movements, balance, and posture.
   • Location: Situated under the cerebrum at the back of the brain.
3. Brainstem:
   • Function: Controls basic life functions such as breathing, heart rate, and blood pressure.
   • Structure: Includes the midbrain, pons, and medulla oblongata.
4. Limbic System:
   • Function: Involved in emotions, memory, and arousal.
   • Components: Includes structures such as the hippocampus, amygdala, and hypothalamus.

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