control and coordination

📖 Control and Coordination: Complete Class 10 Notes

1. Fundamental Concepts

  • Stimulus: Any change in the internal or external environment to which an organism responds (e.g., light, heat, cold, touch, pressure, sound)12.

  • Response: The reaction of an organism’s body to a stimulus (e.g., withdrawing a hand when touching a hot object)12.

  • Coordination: The systematic working together of various organs in a body to produce an appropriate response to a stimulus2.

  • Control Systems in Animals: Organisms utilize two integrated systems for control and coordination:

    1. Nervous System: Uses electrical impulses for rapid, localized, and short-term responses13.

    2. Endocrine System: Uses chemical messengers (hormones) for widespread, slower, and longer-lasting responses13.

2. Animal Nervous System

A. The Neuron (Nerve Cell)

The neuron is the structural and functional unit of the nervous system45. It consists of three primary parts4more_horiz:

  • Dendrites: Branching, tree-like projections that receive electrical/chemical impulses from sensory receptors or other neurons4more_horiz.

  • Cyton (Soma / Cell Body): Contains the cell nucleus and cytoplasm; processes the incoming impulse from dendrites4more_horiz.

  • Axon: A long, slender projection that transmits electrical impulses away from the cell body toward another neuron, muscle, or gland4more_horiz.

    • Myelination: Axons may be myelinated (covered with a myelin sheath) or non-myelinated. Impulse transmission is significantly faster in myelinated neurons4more_horiz.

B. Synapse & Signal Transmission

  • Synapse: The specialized microscopic gap/junction between the axon terminal of one neuron and the dendrite of the next neuron (or an effector cell like a muscle/gland)9more_horiz.

  • Impulse Route: Receptors detect environmental signals →\rightarrow Electrical impulse is generated in dendrites →\rightarrow Cyton →\rightarrow Axon →\rightarrow Axon terminals →\rightarrow Chemical signal released across Synapse →\rightarrow Dendrite of next neuron4more_horiz.

C. Reflex Action and Reflex Arc

  • Reflex Action: A sudden, rapid, and involuntary response of the body to a stimulus, operating without conscious thought to protect the body from harm (e.g., knee jerk, pulling hand away from a sharp or hot object)11more_horiz.

  • Reflex Arc: The shortest pathway taken by electrical impulses during a reflex action1315.

  • Components of a Reflex Arc: Receptor (Sense Organ)→Sensory NeuronSpinal Cord (Interneuron/Relay Neuron)→Motor NeuronEffector (Muscle/Gland)\text{Receptor (Sense Organ)} \xrightarrow{\text{Sensory Neuron}} \text{Spinal Cord (Interneuron/Relay Neuron)} \xrightarrow{\text{Motor Neuron}} \text{Effector (Muscle/Gland)}

    1. Receptor: Detects the stimulus1617.

    2. Sensory (Afferent) Neuron: Carries signals from the receptor to the central command center (spinal cord)15more_horiz.

    3. Relay Neuron (Interneuron): Located in the spinal cord; processes the input signal and instantly links it to a motor output17more_horiz.

    4. Motor (Efferent) Neuron: Transmits the command impulse from the spinal cord to the target organ15more_horiz.

    5. Effector: The muscle or gland that carries out the physical action15more_horiz.

[Stimulus] ➔ Receptors ➔ Sensory Neuron ➔ Spinal Cord (Relay Neuron) ➔ Motor Neuron ➔ Effector Muscle ➔ [Response]

D. Divisions of the Human Nervous System

1. Central Nervous System (CNS)

Comprises the Brain and the Spinal Cord2021.

  • Protection of CNS:

    • Brain: Enclosed inside a bony skull called the cranium1522. It is surrounded by three protective membrane layers called meninges (Dura mater, Arachnoid, and Pia mater) and cushioned by Cerebrospinal Fluid (CSF), which absorbs mechanical shocks15more_horiz.

    • Spinal Cord: Protected inside the hollow canal of the vertebral column (backbone)20more_horiz.

2. Structural & Functional Regions of the Human Brain

The human brain is divided into three main regions21more_horiz:

Brain Region

Sub-structure

Primary Functions

Forebrain

Cerebrum

Main thinking part of the brain; controls reasoning, logic, memory, speech, intelligence, voluntary actions, and processing visual, auditory, and taste stimuli20more_horiz.


Hypothalamus

Control center for body temperature, hunger, thirst, sleep-wake cycles, and controls the pituitary gland28more_horiz.

Midbrain

Midbrain

Relays motor and sensory signals between the forebrain and hindbrain; coordinates visual and auditory reflexes (head/eye movements)20more_horiz.

Hindbrain

Cerebellum

Maintains body posture, physical balance, and precision of voluntary movements (e.g., walking a straight line, riding a bicycle)20more_horiz.


Pons

Relays signals across the brain; regulates rate and pattern of breathing20more_horiz.


Medulla Oblongata

Controls vital involuntary actions such as blood pressure, heart rate, salivation, swallowing, vomiting, and sneezing20more_horiz. Continues downward into the spinal cord20more_horiz.

3. Peripheral Nervous System (PNS)

Nerves originating from the CNS that connect it to the rest of the body22more_horiz. It includes 12 pairs of cranial nerves (from the brain) and 31 pairs of spinal nerves (from the spinal cord)22more_horiz.

  • Somatic Nervous System: Controls voluntary bodily movements via skeletal muscles22more_horiz.

  • Autonomic Nervous System (ANS): Controls involuntary visceral body functions (e.g., heart rate, digestion)9more_horiz. Divided into:

    • Sympathetic Division: Prepares the body for emergency "fight-or-flight" situations912.

    • Parasympathetic Division: Calms the body, slows high-energy processes, and promotes relaxation ("rest and digest")1214.

3. Coordination in Plants

Plants lack a nervous system and muscles; they coordinate responses entirely using chemical signals (plant hormones) and cellular water movements35more_horiz.

A. Types of Plant Movements

1. Tropic Movements (Tropisms)

Growth movements that are directional (dependent on the direction of the stimulus). Growth toward a stimulus is positive, while growth away is negative38more_horiz.

  • Phototropism: Growth response to light. Stems show positive phototropism (bend toward light), whereas roots show negative phototropism39more_horiz.

  • Geotropism (Gravitropism): Growth response to gravity. Roots grow downward (positive geotropism), while stems grow upward (negative geotropism)39more_horiz.

  • Hydrotropism: Directional movement/growth of roots toward water or moisture39more_horiz.

  • Chemotropism: Growth response to chemical substances (e.g., growth of a pollen tube down the style toward the ovule)39more_horiz.

  • Thigmotropism: Growth response to touch/contact (e.g., tendrils coiling around a support)39more_horiz.

2. Nastic Movements

Non-directional movements that occur independently of the direction of the stimulus (growth-independent responses)3841.

  • Example: Thigmonasty in Mimosa pudica ("touch-me-not" plant). Leaves fold and droop rapidly when touched due to quick changes in cellular water pressure (turgor pressure)3841.

B. Plant Hormones (Phytohormones)

Phytohormone

Action / Function

Key Application / Mechanism

Auxin

Promotes cell elongation and apical shoot growth40more_horiz.

Accumulates on the shaded side of a stem tip, causing those cells to elongate faster and bend the stem toward light47.

Gibberellin

Stimulates stem elongation, seed germination, and flowering40more_horiz.

Helps break seed/bud dormancy in spring4047.

Cytokinin

Promotes active cell division and delays cell aging (senescence)45more_horiz.

Found in high concentrations in areas of rapid cell division (fruits, seeds, growing tips)4648.

Abscisic Acid (ABA)

Growth inhibitor; promotes leaf wilting and seed dormancy40more_horiz.

"Stress hormone" that closes stomata during drought conditions to conserve water4849.

Ethylene

Gaseous hormone that promotes fruit ripening45.

Controls leaf drop and fruit maturation45.

4. Human Endocrine System (Chemical Coordination)

The endocrine system uses endocrine glands—ductless glands that secrete chemical messengers (hormones) directly into the bloodstream to reach target organs40more_horiz.

Endocrine Gland ➔ Secretes Hormone directly into Bloodstream ➔ Carried to Target Organ ➔ Specific Physiological Response

Major Human Endocrine Glands & Hormones

Gland

Location

Primary Hormone(s)

Main Functions & Key Clinical Notes

Pituitary Gland

Base of the brain

Growth Hormone (GH), TSH, FSH, LH, Vasopressin51more_horiz.

Known as the "Master Gland" because it regulates other endocrine glands29more_horiz. GH controls overall growth and tissue development5152. <br>• Hyposecretion: Causes Dwarfism5152. <br>• Hypersecretion: Causes Gigantism5152.

Thyroid Gland

Throat / Neck region

Thyroxine49more_horiz.

Regulates carbohydrate, fat, and protein metabolism49more_horiz. Iodine is strictly required to synthesize thyroxine51more_horiz. <br>• Iodine Deficiency: Causes Goitre (characterized by a swollen neck)51more_horiz.

Pancreas

Below the stomach

Insulin and Glucagon49more_horiz.

Dual function (both exocrine and endocrine)5657. Insulin lowers and regulates blood glucose levels49more_horiz. <br>• Insulin Deficiency: Causes Diabetes Mellitus (treated with diet, medication, or insulin injections)55more_horiz.

Adrenal Glands

One above each kidney

Adrenaline (and Noradrenaline)49more_horiz.

Called the "fight-or-flight" / emergency hormone54more_horiz. Prepares the body for stress by increasing heart rate, breathing rate, blood pressure, and blood flow to muscles49more_horiz.

Testes (Male Gonads)

Scrotum (outside abdomen)

Testosterone49more_horiz.

Regulates male gamete (sperm) production and secondary sexual characteristics during puberty (deep voice, facial hair, penis growth)58more_horiz.

Ovaries (Female Gonads)

Lower abdomen

Estrogen and Progesterone49more_horiz.

Estrogen: Controls female puberty changes and egg production53more_horiz. <br>Progesterone: Regulates changes in the uterine lining during the menstrual cycle and maintains pregnancy53more_horiz.

Feedback Mechanism of Hormones

The timing and quantity of hormone release are regulated by internal feedback mechanisms to maintain homeostasis35more_horiz.

  • Example (Blood Sugar Control):

    1. High blood glucose levels are detected by the β\beta-cells of the pancreas35more_horiz.

    2. The pancreas responds by secreting insulin into the bloodstream35more_horiz.

    3. Insulin stimulates cells to absorb glucose, lowering the blood sugar level back to normal49more_horiz.

    4. As blood glucose falls, the signal to secrete insulin is reduced (negative feedback)35more_horiz.📖 Control and Coordination: Complete Class 10 Notes

      1. Fundamental Concepts

      • Stimulus: Any change in the internal or external environment to which an organism responds (e.g., light, heat, cold, touch, pressure, sound)12.

      • Response: The reaction of an organism’s body to a stimulus (e.g., withdrawing a hand when touching a hot object)12.

      • Coordination: The systematic working together of various organs in a body to produce an appropriate response to a stimulus2.

      • Control Systems in Animals: Organisms utilize two integrated systems for control and coordination:

        1. Nervous System: Uses electrical impulses for rapid, localized, and short-term responses13.

        2. Endocrine System: Uses chemical messengers (hormones) for widespread, slower, and longer-lasting responses13.

      2. Animal Nervous System

      A. The Neuron (Nerve Cell)

      The neuron is the structural and functional unit of the nervous system45. It consists of three primary parts4more_horiz:

      • Dendrites: Branching, tree-like projections that receive electrical/chemical impulses from sensory receptors or other neurons4more_horiz.

      • Cyton (Soma / Cell Body): Contains the cell nucleus and cytoplasm; processes the incoming impulse from dendrites4more_horiz.

      • Axon: A long, slender projection that transmits electrical impulses away from the cell body toward another neuron, muscle, or gland4more_horiz.

        • Myelination: Axons may be myelinated (covered with a myelin sheath) or non-myelinated. Impulse transmission is significantly faster in myelinated neurons4more_horiz.

      B. Synapse & Signal Transmission

      • Synapse: The specialized microscopic gap/junction between the axon terminal of one neuron and the dendrite of the next neuron (or an effector cell like a muscle/gland)9more_horiz.

      • Impulse Route: Receptors detect environmental signals →\rightarrow Electrical impulse is generated in dendrites →\rightarrow Cyton →\rightarrow Axon →\rightarrow Axon terminals →\rightarrow Chemical signal released across Synapse →\rightarrow Dendrite of next neuron4more_horiz.

      C. Reflex Action and Reflex Arc

      • Reflex Action: A sudden, rapid, and involuntary response of the body to a stimulus, operating without conscious thought to protect the body from harm (e.g., knee jerk, pulling hand away from a sharp or hot object)11more_horiz.

      • Reflex Arc: The shortest pathway taken by electrical impulses during a reflex action1315.

      • Components of a Reflex Arc: Receptor (Sense Organ)→Sensory NeuronSpinal Cord (Interneuron/Relay Neuron)→Motor NeuronEffector (Muscle/Gland)\text{Receptor (Sense Organ)} \xrightarrow{\text{Sensory Neuron}} \text{Spinal Cord (Interneuron/Relay Neuron)} \xrightarrow{\text{Motor Neuron}} \text{Effector (Muscle/Gland)}

        1. Receptor: Detects the stimulus1617.

        2. Sensory (Afferent) Neuron: Carries signals from the receptor to the central command center (spinal cord)15more_horiz.

        3. Relay Neuron (Interneuron): Located in the spinal cord; processes the input signal and instantly links it to a motor output17more_horiz.

        4. Motor (Efferent) Neuron: Transmits the command impulse from the spinal cord to the target organ15more_horiz.

        5. Effector: The muscle or gland that carries out the physical action15more_horiz.

      [Stimulus] ➔ Receptors ➔ Sensory Neuron ➔ Spinal Cord (Relay Neuron) ➔ Motor Neuron ➔ Effector Muscle ➔ [Response]

      D. Divisions of the Human Nervous System

      1. Central Nervous System (CNS)

      Comprises the Brain and the Spinal Cord2021.

      • Protection of CNS:

        • Brain: Enclosed inside a bony skull called the cranium1522. It is surrounded by three protective membrane layers called meninges (Dura mater, Arachnoid, and Pia mater) and cushioned by Cerebrospinal Fluid (CSF), which absorbs mechanical shocks15more_horiz.

        • Spinal Cord: Protected inside the hollow canal of the vertebral column (backbone)20more_horiz.

      2. Structural & Functional Regions of the Human Brain

      The human brain is divided into three main regions21more_horiz:

      Brain Region

      Sub-structure

      Primary Functions

      Forebrain

      Cerebrum

      Main thinking part of the brain; controls reasoning, logic, memory, speech, intelligence, voluntary actions, and processing visual, auditory, and taste stimuli20more_horiz.


      Hypothalamus

      Control center for body temperature, hunger, thirst, sleep-wake cycles, and controls the pituitary gland28more_horiz.

      Midbrain

      Midbrain

      Relays motor and sensory signals between the forebrain and hindbrain; coordinates visual and auditory reflexes (head/eye movements)20more_horiz.

      Hindbrain

      Cerebellum

      Maintains body posture, physical balance, and precision of voluntary movements (e.g., walking a straight line, riding a bicycle)20more_horiz.


      Pons

      Relays signals across the brain; regulates rate and pattern of breathing20more_horiz.


      Medulla Oblongata

      Controls vital involuntary actions such as blood pressure, heart rate, salivation, swallowing, vomiting, and sneezing20more_horiz. Continues downward into the spinal cord20more_horiz.

      3. Peripheral Nervous System (PNS)

      Nerves originating from the CNS that connect it to the rest of the body22more_horiz. It includes 12 pairs of cranial nerves (from the brain) and 31 pairs of spinal nerves (from the spinal cord)22more_horiz.

      • Somatic Nervous System: Controls voluntary bodily movements via skeletal muscles22more_horiz.

      • Autonomic Nervous System (ANS): Controls involuntary visceral body functions (e.g., heart rate, digestion)9more_horiz. Divided into:

        • Sympathetic Division: Prepares the body for emergency "fight-or-flight" situations912.

        • Parasympathetic Division: Calms the body, slows high-energy processes, and promotes relaxation ("rest and digest")1214.

      3. Coordination in Plants

      Plants lack a nervous system and muscles; they coordinate responses entirely using chemical signals (plant hormones) and cellular water movements35more_horiz.

      A. Types of Plant Movements

      1. Tropic Movements (Tropisms)

      Growth movements that are directional (dependent on the direction of the stimulus). Growth toward a stimulus is positive, while growth away is negative38more_horiz.

      • Phototropism: Growth response to light. Stems show positive phototropism (bend toward light), whereas roots show negative phototropism39more_horiz.

      • Geotropism (Gravitropism): Growth response to gravity. Roots grow downward (positive geotropism), while stems grow upward (negative geotropism)39more_horiz.

      • Hydrotropism: Directional movement/growth of roots toward water or moisture39more_horiz.

      • Chemotropism: Growth response to chemical substances (e.g., growth of a pollen tube down the style toward the ovule)39more_horiz.

      • Thigmotropism: Growth response to touch/contact (e.g., tendrils coiling around a support)39more_horiz.

      2. Nastic Movements

      Non-directional movements that occur independently of the direction of the stimulus (growth-independent responses)3841.

      • Example: Thigmonasty in Mimosa pudica ("touch-me-not" plant). Leaves fold and droop rapidly when touched due to quick changes in cellular water pressure (turgor pressure)3841.

      B. Plant Hormones (Phytohormones)

      Phytohormone

      Action / Function

      Key Application / Mechanism

      Auxin

      Promotes cell elongation and apical shoot growth40more_horiz.

      Accumulates on the shaded side of a stem tip, causing those cells to elongate faster and bend the stem toward light47.

      Gibberellin

      Stimulates stem elongation, seed germination, and flowering40more_horiz.

      Helps break seed/bud dormancy in spring4047.

      Cytokinin

      Promotes active cell division and delays cell aging (senescence)45more_horiz.

      Found in high concentrations in areas of rapid cell division (fruits, seeds, growing tips)4648.

      Abscisic Acid (ABA)

      Growth inhibitor; promotes leaf wilting and seed dormancy40more_horiz.

      "Stress hormone" that closes stomata during drought conditions to conserve water4849.

      Ethylene

      Gaseous hormone that promotes fruit ripening45.

      Controls leaf drop and fruit maturation45.

      4. Human Endocrine System (Chemical Coordination)

      The endocrine system uses endocrine glands—ductless glands that secrete chemical messengers (hormones) directly into the bloodstream to reach target organs40more_horiz.

      Endocrine Gland ➔ Secretes Hormone directly into Bloodstream ➔ Carried to Target Organ ➔ Specific Physiological Response

      Major Human Endocrine Glands & Hormones

      Gland

      Location

      Primary Hormone(s)

      Main Functions & Key Clinical Notes

      Pituitary Gland

      Base of the brain

      Growth Hormone (GH), TSH, FSH, LH, Vasopressin51more_horiz.

      Known as the "Master Gland" because it regulates other endocrine glands29more_horiz. GH controls overall growth and tissue development5152. <br>• Hyposecretion: Causes Dwarfism5152. <br>• Hypersecretion: Causes Gigantism5152.

      Thyroid Gland

      Throat / Neck region

      Thyroxine49more_horiz.

      Regulates carbohydrate, fat, and protein metabolism49more_horiz. Iodine is strictly required to synthesize thyroxine51more_horiz. <br>• Iodine Deficiency: Causes Goitre (characterized by a swollen neck)51more_horiz.

      Pancreas

      Below the stomach

      Insulin and Glucagon49more_horiz.

      Dual function (both exocrine and endocrine)5657. Insulin lowers and regulates blood glucose levels49more_horiz. <br>• Insulin Deficiency: Causes Diabetes Mellitus (treated with diet, medication, or insulin injections)55more_horiz.

      Adrenal Glands

      One above each kidney

      Adrenaline (and Noradrenaline)49more_horiz.

      Called the "fight-or-flight" / emergency hormone54more_horiz. Prepares the body for stress by increasing heart rate, breathing rate, blood pressure, and blood flow to muscles49more_horiz.

      Testes (Male Gonads)

      Scrotum (outside abdomen)

      Testosterone49more_horiz.

      Regulates male gamete (sperm) production and secondary sexual characteristics during puberty (deep voice, facial hair, penis growth)58more_horiz.

      Ovaries (Female Gonads)

      Lower abdomen

      Estrogen and Progesterone49more_horiz.

      Estrogen: Controls female puberty changes and egg production53more_horiz. <br>Progesterone: Regulates changes in the uterine lining during the menstrual cycle and maintains pregnancy53more_horiz.

      Feedback Mechanism of Hormones

      The timing and quantity of hormone release are regulated by internal feedback mechanisms to maintain homeostasis35more_horiz.

      • Example (Blood Sugar Control):

        1. High blood glucose levels are detected by the β\beta-cells of the pancreas35more_horiz.

        2. The pancreas responds by secreting insulin into the bloodstream35more_horiz.

        3. Insulin stimulates cells to absorb glucose, lowering the blood sugar level back to normal49more_horiz.

        4. As blood glucose falls, the signal to secrete insulin is reduced (negative feedback)35more_horiz.📖 Control and Coordination: Complete Class 10 Notes

          1. Fundamental Concepts

          • Stimulus: Any change in the internal or external environment to which an organism responds (e.g., light, heat, cold, touch, pressure, sound)12.

          • Response: The reaction of an organism’s body to a stimulus (e.g., withdrawing a hand when touching a hot object)12.

          • Coordination: The systematic working together of various organs in a body to produce an appropriate response to a stimulus2.

          • Control Systems in Animals: Organisms utilize two integrated systems for control and coordination:

            1. Nervous System: Uses electrical impulses for rapid, localized, and short-term responses13.

            2. Endocrine System: Uses chemical messengers (hormones) for widespread, slower, and longer-lasting responses13.

          2. Animal Nervous System

          A. The Neuron (Nerve Cell)

          The neuron is the structural and functional unit of the nervous system45. It consists of three primary parts4more_horiz:

          • Dendrites: Branching, tree-like projections that receive electrical/chemical impulses from sensory receptors or other neurons4more_horiz.

          • Cyton (Soma / Cell Body): Contains the cell nucleus and cytoplasm; processes the incoming impulse from dendrites4more_horiz.

          • Axon: A long, slender projection that transmits electrical impulses away from the cell body toward another neuron, muscle, or gland4more_horiz.

            • Myelination: Axons may be myelinated (covered with a myelin sheath) or non-myelinated. Impulse transmission is significantly faster in myelinated neurons4more_horiz.

          B. Synapse & Signal Transmission

          • Synapse: The specialized microscopic gap/junction between the axon terminal of one neuron and the dendrite of the next neuron (or an effector cell like a muscle/gland)9more_horiz.

          • Impulse Route: Receptors detect environmental signals →\rightarrow Electrical impulse is generated in dendrites →\rightarrow Cyton →\rightarrow Axon →\rightarrow Axon terminals →\rightarrow Chemical signal released across Synapse →\rightarrow Dendrite of next neuron4more_horiz.

          C. Reflex Action and Reflex Arc

          • Reflex Action: A sudden, rapid, and involuntary response of the body to a stimulus, operating without conscious thought to protect the body from harm (e.g., knee jerk, pulling hand away from a sharp or hot object)11more_horiz.

          • Reflex Arc: The shortest pathway taken by electrical impulses during a reflex action1315.

          • Components of a Reflex Arc: Receptor (Sense Organ)→Sensory NeuronSpinal Cord (Interneuron/Relay Neuron)→Motor NeuronEffector (Muscle/Gland)\text{Receptor (Sense Organ)} \xrightarrow{\text{Sensory Neuron}} \text{Spinal Cord (Interneuron/Relay Neuron)} \xrightarrow{\text{Motor Neuron}} \text{Effector (Muscle/Gland)}

            1. Receptor: Detects the stimulus1617.

            2. Sensory (Afferent) Neuron: Carries signals from the receptor to the central command center (spinal cord)15more_horiz.

            3. Relay Neuron (Interneuron): Located in the spinal cord; processes the input signal and instantly links it to a motor output17more_horiz.

            4. Motor (Efferent) Neuron: Transmits the command impulse from the spinal cord to the target organ15more_horiz.

            5. Effector: The muscle or gland that carries out the physical action15more_horiz.

          [Stimulus] ➔ Receptors ➔ Sensory Neuron ➔ Spinal Cord (Relay Neuron) ➔ Motor Neuron ➔ Effector Muscle ➔ [Response]

          D. Divisions of the Human Nervous System

          1. Central Nervous System (CNS)

          Comprises the Brain and the Spinal Cord2021.

          • Protection of CNS:

            • Brain: Enclosed inside a bony skull called the cranium1522. It is surrounded by three protective membrane layers called meninges (Dura mater, Arachnoid, and Pia mater) and cushioned by Cerebrospinal Fluid (CSF), which absorbs mechanical shocks15more_horiz.

            • Spinal Cord: Protected inside the hollow canal of the vertebral column (backbone)20more_horiz.

          2. Structural & Functional Regions of the Human Brain

          The human brain is divided into three main regions21more_horiz:

          Brain Region

          Sub-structure

          Primary Functions

          Forebrain

          Cerebrum

          Main thinking part of the brain; controls reasoning, logic, memory, speech, intelligence, voluntary actions, and processing visual, auditory, and taste stimuli20more_horiz.


          Hypothalamus

          Control center for body temperature, hunger, thirst, sleep-wake cycles, and controls the pituitary gland28more_horiz.

          Midbrain

          Midbrain

          Relays motor and sensory signals between the forebrain and hindbrain; coordinates visual and auditory reflexes (head/eye movements)20more_horiz.

          Hindbrain

          Cerebellum

          Maintains body posture, physical balance, and precision of voluntary movements (e.g., walking a straight line, riding a bicycle)20more_horiz.


          Pons

          Relays signals across the brain; regulates rate and pattern of breathing20more_horiz.


          Medulla Oblongata

          Controls vital involuntary actions such as blood pressure, heart rate, salivation, swallowing, vomiting, and sneezing20more_horiz. Continues downward into the spinal cord20more_horiz.

          3. Peripheral Nervous System (PNS)

          Nerves originating from the CNS that connect it to the rest of the body22more_horiz. It includes 12 pairs of cranial nerves (from the brain) and 31 pairs of spinal nerves (from the spinal cord)22more_horiz.

          • Somatic Nervous System: Controls voluntary bodily movements via skeletal muscles22more_horiz.

          • Autonomic Nervous System (ANS): Controls involuntary visceral body functions (e.g., heart rate, digestion)9more_horiz. Divided into:

            • Sympathetic Division: Prepares the body for emergency "fight-or-flight" situations912.

            • Parasympathetic Division: Calms the body, slows high-energy processes, and promotes relaxation ("rest and digest")1214.

          3. Coordination in Plants

          Plants lack a nervous system and muscles; they coordinate responses entirely using chemical signals (plant hormones) and cellular water movements35more_horiz.

          A. Types of Plant Movements

          1. Tropic Movements (Tropisms)

          Growth movements that are directional (dependent on the direction of the stimulus). Growth toward a stimulus is positive, while growth away is negative38more_horiz.

          • Phototropism: Growth response to light. Stems show positive phototropism (bend toward light), whereas roots show negative phototropism39more_horiz.

          • Geotropism (Gravitropism): Growth response to gravity. Roots grow downward (positive geotropism), while stems grow upward (negative geotropism)39more_horiz.

          • Hydrotropism: Directional movement/growth of roots toward water or moisture39more_horiz.

          • Chemotropism: Growth response to chemical substances (e.g., growth of a pollen tube down the style toward the ovule)39more_horiz.

          • Thigmotropism: Growth response to touch/contact (e.g., tendrils coiling around a support)39more_horiz.

          2. Nastic Movements

          Non-directional movements that occur independently of the direction of the stimulus (growth-independent responses)3841.

          • Example: Thigmonasty in Mimosa pudica ("touch-me-not" plant). Leaves fold and droop rapidly when touched due to quick changes in cellular water pressure (turgor pressure)3841.

          B. Plant Hormones (Phytohormones)

          Phytohormone

          Action / Function

          Key Application / Mechanism

          Auxin

          Promotes cell elongation and apical shoot growth40more_horiz.

          Accumulates on the shaded side of a stem tip, causing those cells to elongate faster and bend the stem toward light47.

          Gibberellin

          Stimulates stem elongation, seed germination, and flowering40more_horiz.

          Helps break seed/bud dormancy in spring4047.

          Cytokinin

          Promotes active cell division and delays cell aging (senescence)45more_horiz.

          Found in high concentrations in areas of rapid cell division (fruits, seeds, growing tips)4648.

          Abscisic Acid (ABA)

          Growth inhibitor; promotes leaf wilting and seed dormancy40more_horiz.

          "Stress hormone" that closes stomata during drought conditions to conserve water4849.

          Ethylene

          Gaseous hormone that promotes fruit ripening45.

          Controls leaf drop and fruit maturation45.

          4. Human Endocrine System (Chemical Coordination)

          The endocrine system uses endocrine glands—ductless glands that secrete chemical messengers (hormones) directly into the bloodstream to reach target organs40more_horiz.

          Endocrine Gland ➔ Secretes Hormone directly into Bloodstream ➔ Carried to Target Organ ➔ Specific Physiological Response

          Major Human Endocrine Glands & Hormones

          Gland

          Location

          Primary Hormone(s)

          Main Functions & Key Clinical Notes

          Pituitary Gland

          Base of the brain

          Growth Hormone (GH), TSH, FSH, LH, Vasopressin51more_horiz.

          Known as the "Master Gland" because it regulates other endocrine glands29more_horiz. GH controls overall growth and tissue development5152. <br>• Hyposecretion: Causes Dwarfism5152. <br>• Hypersecretion: Causes Gigantism5152.

          Thyroid Gland

          Throat / Neck region

          Thyroxine49more_horiz.

          Regulates carbohydrate, fat, and protein metabolism49more_horiz. Iodine is strictly required to synthesize thyroxine51more_horiz. <br>• Iodine Deficiency: Causes Goitre (characterized by a swollen neck)51more_horiz.

          Pancreas

          Below the stomach

          Insulin and Glucagon49more_horiz.

          Dual function (both exocrine and endocrine)5657. Insulin lowers and regulates blood glucose levels49more_horiz. <br>• Insulin Deficiency: Causes Diabetes Mellitus (treated with diet, medication, or insulin injections)55more_horiz.

          Adrenal Glands

          One above each kidney

          Adrenaline (and Noradrenaline)49more_horiz.

          Called the "fight-or-flight" / emergency hormone54more_horiz. Prepares the body for stress by increasing heart rate, breathing rate, blood pressure, and blood flow to muscles49more_horiz.

          Testes (Male Gonads)

          Scrotum (outside abdomen)

          Testosterone49more_horiz.

          Regulates male gamete (sperm) production and secondary sexual characteristics during puberty (deep voice, facial hair, penis growth)58more_horiz.

          Ovaries (Female Gonads)

          Lower abdomen

          Estrogen and Progesterone49more_horiz.

          Estrogen: Controls female puberty changes and egg production53more_horiz. <br>Progesterone: Regulates changes in the uterine lining during the menstrual cycle and maintains pregnancy53more_horiz.

          Feedback Mechanism of Hormones

          The timing and quantity of hormone release are regulated by internal feedback mechanisms to maintain homeostasis35more_horiz.

          • Example (Blood Sugar Control):

            1. High blood glucose levels are detected by the β\beta-cells of the pancreas35more_horiz.

            2. The pancreas responds by secreting insulin into the bloodstream35more_horiz.

            3. Insulin stimulates cells to absorb glucose, lowering the blood sugar level back to normal49more_horiz.

            4. As blood glucose falls, the signal to secrete insulin is reduced (negative feedback)35more_horiz.📖 Control and Coordination: Complete Class 10 Notes

              1. Fundamental Concepts

              • Stimulus: Any change in the internal or external environment to which an organism responds (e.g., light, heat, cold, touch, pressure, sound)12.

              • Response: The reaction of an organism’s body to a stimulus (e.g., withdrawing a hand when touching a hot object)12.

              • Coordination: The systematic working together of various organs in a body to produce an appropriate response to a stimulus2.

              • Control Systems in Animals: Organisms utilize two integrated systems for control and coordination:

                1. Nervous System: Uses electrical impulses for rapid, localized, and short-term responses13.

                2. Endocrine System: Uses chemical messengers (hormones) for widespread, slower, and longer-lasting responses13.

              2. Animal Nervous System

              A. The Neuron (Nerve Cell)

              The neuron is the structural and functional unit of the nervous system45. It consists of three primary parts4more_horiz:

              • Dendrites: Branching, tree-like projections that receive electrical/chemical impulses from sensory receptors or other neurons4more_horiz.

              • Cyton (Soma / Cell Body): Contains the cell nucleus and cytoplasm; processes the incoming impulse from dendrites4more_horiz.

              • Axon: A long, slender projection that transmits electrical impulses away from the cell body toward another neuron, muscle, or gland4more_horiz.

                • Myelination: Axons may be myelinated (covered with a myelin sheath) or non-myelinated. Impulse transmission is significantly faster in myelinated neurons4more_horiz.

              B. Synapse & Signal Transmission

              • Synapse: The specialized microscopic gap/junction between the axon terminal of one neuron and the dendrite of the next neuron (or an effector cell like a muscle/gland)9more_horiz.

              • Impulse Route: Receptors detect environmental signals →\rightarrow Electrical impulse is generated in dendrites →\rightarrow Cyton →\rightarrow Axon →\rightarrow Axon terminals →\rightarrow Chemical signal released across Synapse →\rightarrow Dendrite of next neuron4more_horiz.

              C. Reflex Action and Reflex Arc

              • Reflex Action: A sudden, rapid, and involuntary response of the body to a stimulus, operating without conscious thought to protect the body from harm (e.g., knee jerk, pulling hand away from a sharp or hot object)11more_horiz.

              • Reflex Arc: The shortest pathway taken by electrical impulses during a reflex action1315.

              • Components of a Reflex Arc: Receptor (Sense Organ)→Sensory NeuronSpinal Cord (Interneuron/Relay Neuron)→Motor NeuronEffector (Muscle/Gland)\text{Receptor (Sense Organ)} \xrightarrow{\text{Sensory Neuron}} \text{Spinal Cord (Interneuron/Relay Neuron)} \xrightarrow{\text{Motor Neuron}} \text{Effector (Muscle/Gland)}

                1. Receptor: Detects the stimulus1617.

                2. Sensory (Afferent) Neuron: Carries signals from the receptor to the central command center (spinal cord)15more_horiz.

                3. Relay Neuron (Interneuron): Located in the spinal cord; processes the input signal and instantly links it to a motor output17more_horiz.

                4. Motor (Efferent) Neuron: Transmits the command impulse from the spinal cord to the target organ15more_horiz.

                5. Effector: The muscle or gland that carries out the physical action15more_horiz.

              [Stimulus] ➔ Receptors ➔ Sensory Neuron ➔ Spinal Cord (Relay Neuron) ➔ Motor Neuron ➔ Effector Muscle ➔ [Response]

              D. Divisions of the Human Nervous System

              1. Central Nervous System (CNS)

              Comprises the Brain and the Spinal Cord2021.

              • Protection of CNS:

                • Brain: Enclosed inside a bony skull called the cranium1522. It is surrounded by three protective membrane layers called meninges (Dura mater, Arachnoid, and Pia mater) and cushioned by Cerebrospinal Fluid (CSF), which absorbs mechanical shocks15more_horiz.

                • Spinal Cord: Protected inside the hollow canal of the vertebral column (backbone)20more_horiz.

              2. Structural & Functional Regions of the Human Brain

              The human brain is divided into three main regions21more_horiz:

              Brain Region

              Sub-structure

              Primary Functions

              Forebrain

              Cerebrum

              Main thinking part of the brain; controls reasoning, logic, memory, speech, intelligence, voluntary actions, and processing visual, auditory, and taste stimuli20more_horiz.


              Hypothalamus

              Control center for body temperature, hunger, thirst, sleep-wake cycles, and controls the pituitary gland28more_horiz.

              Midbrain

              Midbrain

              Relays motor and sensory signals between the forebrain and hindbrain; coordinates visual and auditory reflexes (head/eye movements)20more_horiz.

              Hindbrain

              Cerebellum

              Maintains body posture, physical balance, and precision of voluntary movements (e.g., walking a straight line, riding a bicycle)20more_horiz.


              Pons

              Relays signals across the brain; regulates rate and pattern of breathing20more_horiz.


              Medulla Oblongata

              Controls vital involuntary actions such as blood pressure, heart rate, salivation, swallowing, vomiting, and sneezing20more_horiz. Continues downward into the spinal cord20more_horiz.

              3. Peripheral Nervous System (PNS)

              Nerves originating from the CNS that connect it to the rest of the body22more_horiz. It includes 12 pairs of cranial nerves (from the brain) and 31 pairs of spinal nerves (from the spinal cord)22more_horiz.

              • Somatic Nervous System: Controls voluntary bodily movements via skeletal muscles22more_horiz.

              • Autonomic Nervous System (ANS): Controls involuntary visceral body functions (e.g., heart rate, digestion)9more_horiz. Divided into:

                • Sympathetic Division: Prepares the body for emergency "fight-or-flight" situations912.

                • Parasympathetic Division: Calms the body, slows high-energy processes, and promotes relaxation ("rest and digest")1214.

              3. Coordination in Plants

              Plants lack a nervous system and muscles; they coordinate responses entirely using chemical signals (plant hormones) and cellular water movements35more_horiz.

              A. Types of Plant Movements

              1. Tropic Movements (Tropisms)

              Growth movements that are directional (dependent on the direction of the stimulus). Growth toward a stimulus is positive, while growth away is negative38more_horiz.

              • Phototropism: Growth response to light. Stems show positive phototropism (bend toward light), whereas roots show negative phototropism39more_horiz.

              • Geotropism (Gravitropism): Growth response to gravity. Roots grow downward (positive geotropism), while stems grow upward (negative geotropism)39more_horiz.

              • Hydrotropism: Directional movement/growth of roots toward water or moisture39more_horiz.

              • Chemotropism: Growth response to chemical substances (e.g., growth of a pollen tube down the style toward the ovule)39more_horiz.

              • Thigmotropism: Growth response to touch/contact (e.g., tendrils coiling around a support)39more_horiz.

              2. Nastic Movements

              Non-directional movements that occur independently of the direction of the stimulus (growth-independent responses)3841.

              • Example: Thigmonasty in Mimosa pudica ("touch-me-not" plant). Leaves fold and droop rapidly when touched due to quick changes in cellular water pressure (turgor pressure)3841.

              B. Plant Hormones (Phytohormones)

              Phytohormone

              Action / Function

              Key Application / Mechanism

              Auxin

              Promotes cell elongation and apical shoot growth40more_horiz.

              Accumulates on the shaded side of a stem tip, causing those cells to elongate faster and bend the stem toward light47.

              Gibberellin

              Stimulates stem elongation, seed germination, and flowering40more_horiz.

              Helps break seed/bud dormancy in spring4047.

              Cytokinin

              Promotes active cell division and delays cell aging (senescence)45more_horiz.

              Found in high concentrations in areas of rapid cell division (fruits, seeds, growing tips)4648.

              Abscisic Acid (ABA)

              Growth inhibitor; promotes leaf wilting and seed dormancy40more_horiz.

              "Stress hormone" that closes stomata during drought conditions to conserve water4849.

              Ethylene

              Gaseous hormone that promotes fruit ripening45.

              Controls leaf drop and fruit maturation45.

              4. Human Endocrine System (Chemical Coordination)

              The endocrine system uses endocrine glands—ductless glands that secrete chemical messengers (hormones) directly into the bloodstream to reach target organs40more_horiz.

              Endocrine Gland ➔ Secretes Hormone directly into Bloodstream ➔ Carried to Target Organ ➔ Specific Physiological Response

              Major Human Endocrine Glands & Hormones

              Gland

              Location

              Primary Hormone(s)

              Main Functions & Key Clinical Notes

              Pituitary Gland

              Base of the brain

              Growth Hormone (GH), TSH, FSH, LH, Vasopressin51more_horiz.

              Known as the "Master Gland" because it regulates other endocrine glands29more_horiz. GH controls overall growth and tissue development5152. <br>• Hyposecretion: Causes Dwarfism5152. <br>• Hypersecretion: Causes Gigantism5152.

              Thyroid Gland

              Throat / Neck region

              Thyroxine49more_horiz.

              Regulates carbohydrate, fat, and protein metabolism49more_horiz. Iodine is strictly required to synthesize thyroxine51more_horiz. <br>• Iodine Deficiency: Causes Goitre (characterized by a swollen neck)51more_horiz.

              Pancreas

              Below the stomach

              Insulin and Glucagon49more_horiz.

              Dual function (both exocrine and endocrine)5657. Insulin lowers and regulates blood glucose levels49more_horiz. <br>• Insulin Deficiency: Causes Diabetes Mellitus (treated with diet, medication, or insulin injections)55more_horiz.

              Adrenal Glands

              One above each kidney

              Adrenaline (and Noradrenaline)49more_horiz.

              Called the "fight-or-flight" / emergency hormone54more_horiz. Prepares the body for stress by increasing heart rate, breathing rate, blood pressure, and blood flow to muscles49more_horiz.

              Testes (Male Gonads)

              Scrotum (outside abdomen)

              Testosterone49more_horiz.

              Regulates male gamete (sperm) production and secondary sexual characteristics during puberty (deep voice, facial hair, penis growth)58more_horiz.

              Ovaries (Female Gonads)

              Lower abdomen

              Estrogen and Progesterone49more_horiz.

              Estrogen: Controls female puberty changes and egg production53more_horiz. <br>Progesterone: Regulates changes in the uterine lining during the menstrual cycle and maintains pregnancy53more_horiz.

              Feedback Mechanism of Hormones

              The timing and quantity of hormone release are regulated by internal feedback mechanisms to maintain homeostasis35more_horiz.

              • Example (Blood Sugar Control):

                1. High blood glucose levels are detected by the β\beta-cells of the pancreas35more_horiz.

                2. The pancreas responds by secreting insulin into the bloodstream35more_horiz.

                3. Insulin stimulates cells to absorb glucose, lowering the blood sugar level back to normal49more_horiz.

                4. As blood glucose falls, the signal to secrete insulin is reduced (negative feedback)35more_horiz.