# Human Nervous & Glandular Systems - Grade 10 (SEE) Science
## Complete Chapter Notes with All Exercises - NEB Curriculum
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## 🎯 Chapter Overview
**Think of your body's coordination like a high-tech command center.** The **Nervous System** is the super-fast internet, sending electrical signals in milliseconds, while the **Glandular (Endocrine) System** is the reliable postal service, sending chemical messages (hormones) through the bloodstream. Together, they control everything you think, feel, and do.
**This chapter is a fascinating journey into the body's control systems and is crucial for the SEE exam.** We'll explore the structure of the brain, spinal cord, and neurons, understand lightning-fast reflex actions, and learn about the powerful hormones that regulate our growth, mood, and metabolism. Every exercise from your textbook is solved here with clear, detailed explanations.
**Weightage:** 7-9 marks in SEE examination
**Time Required:** 15-20 periods
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## 📚 Learning Objectives
After studying this chapter, you will be able to:
- Differentiate between the nervous and glandular systems.
- Draw a labeled diagram of a neuron and describe its structure.
- Describe the structure and functions of the main parts of the human brain.
- Explain the mechanism of reflex action with a reflex arc.
- Differentiate between endocrine and exocrine glands.
- State the location, hormones, and functions of major endocrine glands.
- Understand the causes and effects of hormonal imbalances.
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## 🧠 Part A: The Nervous System (The High-Speed Network)
The nervous system is the body's primary control and communication network. It receives information from the environment (**stimulus**) and generates a suitable response (**reaction**).
-   **Stimulus:** Any change in the internal or external environment that causes a response in an organism. (e.g., touching a hot object).
-   **Reaction (Response):** The action performed by the organism due to a stimulus. (e.g., pulling your hand away).

### 1. The Neuron: The Basic Unit
A **neuron** (or nerve cell) is the structural and functional unit of the nervous system. Its job is to transmit nerve impulses (electrical signals).

**Structure of a Neuron:**
1.  **Cell Body (Cyton):** The main part containing the nucleus.
2.  **Dendrites:** Short, branched fibers that **receive** nerve impulses from other neurons and carry them **towards** the cell body.
3.  **Axon:** A single, long fiber that carries nerve impulses **away** from the cell body to other neurons or muscles.



[Image of the structure of a neuron]


### 2. Central Nervous System (CNS): The Central Processor
The CNS is the main control center, consisting of the brain and the spinal cord.

#### A. The Brain
The brain is the command center of the body, protected within the **cranial cavity** of the skull. It is covered by three protective membranes called **meninges** (Dura mater, Arachnoid mater, and Pia mater).

| Part | Location | Key Functions |
|---|---|---|
| **Cerebrum** | Largest, uppermost part of the brain. | • Center of intelligence, memory, emotion, logic, and consciousness.<br>• Controls all voluntary actions (walking, talking, etc.). |
| **Cerebellum** | Below the cerebrum, at the back of the head. | • Controls body balance and posture.<br>• Coordinates and smooths out voluntary movements. |
| **Medulla Oblongata** | Lowest part of the brain, connecting to the spinal cord. | • Controls vital involuntary actions like heartbeat, breathing rate, and blood pressure.<br>• **Injury here causes instant death.** |

#### B. The Spinal Cord
The spinal cord is a long, cylindrical bundle of nerve tissue that extends from the medulla oblongata down the back, protected by the vertebral column.
-   **Functions:**
    1.  Acts as a pathway for nerve signals between the brain and the rest of the body.
    2.  It is the control center for **reflex actions**.

### 3. Reflex Action and Reflex Arc
-   **Reflex Action:** A sudden, rapid, and involuntary response to a stimulus, controlled by the spinal cord. It is a protective mechanism.
    -   **Example:** Immediately withdrawing your hand when you touch a pin. You pull your hand back before your brain even registers the pain.
-   **Reflex Arc:** The neural pathway that a nerve impulse follows during a reflex action.
    **Path:** Receptor (skin) $\rightarrow$ Sensory Neuron $\rightarrow$ Spinal Cord $\rightarrow$ Motor Neuron $\rightarrow$ Effector (muscle).



[Image of a reflex arc diagram]


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## 🧪 Part B: The Glandular System (The Chemical Mail)
The glandular or endocrine system consists of glands that produce chemical messengers called **hormones**. Hormones travel through the bloodstream to target cells and regulate various bodily functions like growth, metabolism, and mood.

### 1. Types of Glands

| Feature | Endocrine Glands | Exocrine Glands |
|---|---|---|
| **Ducts** | **Ductless**; they release hormones directly into the bloodstream. | **Have ducts** (tubes) to carry their secretions to a specific location. |
| **Secretion** | Hormones (e.g., Insulin, Thyroxine). | Enzymes, sweat, saliva, tears, mucus. |
| **Example** | Pituitary gland, Thyroid gland, Adrenal gland. | Salivary glands, Sweat glands, Liver. |

### 2. Major Endocrine Glands and Their Hormones

| Gland | Location | Hormone(s) | Key Function(s) | Effects of Imbalance |
|---|---|---|---|---|
| **Pituitary Gland** | Base of the brain. | Growth Hormone (GH), TSH | **Master Gland**: Controls other glands; regulates body growth. | **Hypo**secretion: **Dwarfism**. **Hyper**secretion: **Gigantism**. |
| **Thyroid Gland** | Neck (in front of trachea). | Thyroxine | Controls the body's metabolic rate. Requires **iodine** to function. | **Hypo**secretion (due to Iodine deficiency): **Goitre**. |
| **Adrenal Gland**| On top of kidneys. | Adrenaline | **Emergency Hormone**: Prepares the body for "Fight or Flight" response. | |
| **Pancreas** | Behind the stomach. | Insulin & Glucagon | Regulates blood glucose (sugar) level. | **Hypo**secretion of Insulin: **Diabetes Mellitus**. |
| **Gonads (Testes/Ovaries)** | Pelvic region. | Testosterone (males), Estrogen (females) | Control development of secondary sexual characteristics. | |

### 3. Heterocrine (Mixed) Gland: The Pancreas
The pancreas is called a **mixed or heterocrine gland** because it has both endocrine and exocrine functions.
-   **Endocrine function:** Produces hormones (insulin and glucagon) and releases them into the blood.
-   **Exocrine function:** Produces pancreatic juice (digestive enzymes) and releases it into the small intestine through a duct.

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## 📋 4. COMPLETE EXERCISE SOLUTIONS

### **1. Differentiate Between:**
**a. Cerebrum and Cerebellum**
| Cerebrum | Cerebellum |
|---|---|
| The largest part of the brain. | Smaller than the cerebrum, located at the back. |
| It is the center of intelligence, memory, and voluntary actions. | It maintains body balance, posture, and coordinates movements. |
| Part of the forebrain. | Part of the hindbrain. |

**b. Sensory Nerves and Motor Nerves**
| Sensory Nerves (Afferent) | Motor Nerves (Efferent) |
|---|---|
| Carry nerve impulses from sense organs **to** the CNS (brain/spinal cord). | Carry nerve impulses **from** the CNS to muscles or glands (effectors). |
| They inform the CNS about stimuli. | They carry out the commands from the CNS. |

**c. Sympathetic and Parasympathetic ANS**
| Sympathetic ANS | Parasympathetic ANS |
|---|---|
| Prepares the body for a **"fight or flight"** response in emergencies. | Brings the body back to a calm **"rest and digest"** state. |
| Increases heart rate, breathing rate, blood pressure. | Decreases heart rate, breathing rate, blood pressure. |

### **2. Give Reasons:**
**a. The pituitary gland is called the master gland.**
**Answer:** Because the pituitary gland produces several hormones (like TSH, ACTH) that control and regulate the functioning of many other endocrine glands, such as the thyroid and adrenal glands.

**b. The adrenal gland is also called an emergency gland.**
**Answer:** Because it secretes the hormone **adrenaline** during conditions of stress, fear, or excitement. Adrenaline prepares the body for a "fight or flight" response by increasing heart rate, blood pressure, and glucose levels, providing a burst of energy to face the emergency.

**c. A person dies instantly when the medulla oblongata is injured.**
**Answer:** The medulla oblongata controls vital, involuntary life functions such as **heartbeat, breathing, and blood pressure**. Any severe injury to it, like in the case of hanging, disrupts these functions, leading to immediate cessation of breathing and heartbeat, causing instant death.

**d. The pancreas is a mixed gland.**
**Answer:** Because it performs both endocrine and exocrine functions. As an endocrine gland, it secretes hormones (insulin, glucagon) directly into the blood. As an exocrine gland, it secretes pancreatic juice into the duodenum through a duct.

**e. Hormones are called chemical messengers.**
**Answer:** Hormones are chemical substances produced by endocrine glands that are transported by the blood to target organs or cells elsewhere in the body, where they deliver a "message" to regulate a specific function, like growth or metabolism.

### **3. Answer the following questions:**
**a. Why do animals respond more quickly than plants?**
**Answer:** Animals respond more quickly because they possess a well-developed nervous system for rapid electrical signal transmission and an endocrine system for hormonal control. Plants lack these specialized systems and respond much more slowly through chemical changes.

**b. In the given diagram of the endocrine system, identify glands B, D, and F and write one function of each.**


[Image of the human endocrine system]

**Ans:**
- **B (Thyroid Gland):** Its function is to secrete thyroxine, which controls the body's overall metabolic rate.
- **D (Pancreas):** Its function is to secrete insulin and glucagon to regulate blood sugar levels.
- **F (Testes - in males):** Its function is to produce testosterone, which is responsible for male secondary sexual characteristics.

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## ✅ 5. CHAPTER CHECKLIST & EXAM TIPS
**Exam Hotspots 🔥:**
-   **Diagrams:** The diagram of a neuron is very frequently asked. The diagram of the brain is also important.
-   **Brain Functions:** Be able to state at least two functions for the cerebrum, cerebellum, and medulla oblongata.
-   **Reflex Arc:** Understand and be able to describe the path of a reflex arc.
-   **Glands & Hormones:** The location, hormone, and function of the Pituitary, Thyroid, and Pancreas are high-priority topics.
-   **Give Reasons:** The reasons why the pituitary is the 'master gland', the adrenal is the 'emergency gland', and the pancreas is a 'mixed gland' are classic exam questions.

**Your Pre-Exam Checklist:**
- [ ] I can draw and label a neuron.
- [ ] I can state the main functions of the cerebrum, cerebellum, and medulla oblongata.
- [ ] I can explain what a reflex action is and trace the path of a reflex arc.
- [ ] I can differentiate between endocrine and exocrine glands.
- [ ] I can name the hormone responsible for goitre and diabetes.
- [ ] I can explain why the pituitary is called the "Master Gland".
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## 🎊 CONCLUSION
The nervous and glandular systems are the master coordinators of our body, working in perfect harmony to keep us alive, responsive, and balanced. Understanding how they operate is key to appreciating the complexity and wonder of the human body.
**Key to Success:** Master the Diagrams + Learn the Functions by Heart + Understand the "Why" Questions = A Top Score!