Human Nervous System - Structure, Function, and Types

The Human Nervous System is a network of specialized cells and tissues that includes the brain, spinal cord, and a complex network of peripheral nerves. The types of nervous systems and their functions are discussed in this article. The human nervous system is responsible for receiving, transmitting, and processing information within the body. The nervous system functions to enable communication between different parts of the body and allows organisms to interact with their environment. In this article, we will study types of nervous systems and their functions in detail.

What is the Nervous System?

The nervous system, also known as the neural system, consists of a complex network of neurons specialized for message transmission. The complexity of the nervous system increases as we ascend the evolutionary hierarchy. In simpler organisms like flatworms, there are basic nerve networks distributed throughout their bodies.

As we move top of the hierarchy, like crustaceans, they possess a more complex nervous network consisting of two nerve centers known as the dorsal ganglion and ventral ganglion. A developed brain is present in higher organisms like vertebrates.

The basic unit of the nervous system is a neuron, which is responsible for transmitting information throughout the body. It helps in communication between different parts of the body, including the brain, spinal cord, and other organs. Neurons consist of a cell body, dendrites, and an axon. They are defined as follows:

• Cell Body: The cell body, is the central part of a neuron that contains the nucleus and other cellular components, act as control center for the neuron's activities.
• Dendrites: Dendrites are the branched extensions of a neuron that receive signals from other neurons or sensory receptors, facilitating the transmission of information to the cell body.
• Axon: The axon is a long, slender projection of a neuron that carries electrical signals away from the cell body, enabling communication with other neurons or target cell.

Human Nervous System Diagram

The labelled diagram of human nervous system is shown below:

The electrical signals, are carried among the brain, spinal cord, and various parts of the body, enabling communication through the nerves. There are three primary types of nerves based on their function:

• Sensory Nerves: These nerves carry sensory information from the body to the central nervous system. They help us perceive sensations such as touch, temperature, pain, and other sensory experiences.
• Motor Nerves: Motor nerves transmit signals from the central nervous system to muscles and glands, enabling voluntary and involuntary muscle movements and controlling glandular secretions.
• Mixed Nerves: These nerves contain both sensory and motor fibers, allowing for two-way communication. Most nerves in the body fall into this category, enabling the coordination of sensory input and motor output.

Types of Nervous System and Their Functions

Nervous system is consists of two parts:

1. Central Nervous System - consists of the brain and spinal cord
2. Peripheral Nervous System - comprising of all the nerves

Human Nervous System Flow Chart

The flow chart of nervous system is given below:

Central Nervous System

The central nervous system (CNS) forms an important part of the human nervous system, consisting of the brain and spinal cord. It act as the command center, processing information from the body and coordinating various functions, including thought, sensation, memory, and emotion. It maintains homeostasis and enables communication between different parts of the body.

Brain

The brain is enclosed within the cranium (or skull) for protection, and act as the control center of the body. It is responsible for various functions such as memory, emotion, sensory processing, and the coordination of voluntary and involuntary actions. The human brain is composed of three major parts:

1. Forebrain: The forebrain is the anterior and largest part of the brain, which is responsible for advanced cognitive functions and sensory processing. The forebrain consists of the cerebrum, thalamus and hypothalamus.

• Cerebrum - It is divided into two halves: right and left cerebral hemisphere. They are covered by layers of cells called cerebral cortex which are responsible for major functions like memory and communication.
• Thalamus - Coordinates sensory and motor signaling, memory and consciousness
• Hypothalamus - Maintains homeostasis of the body. It also secretes hypothalamic hormones that regulates various body processes.

2. Midbrain: The midbrain is a central part of the brainstem located between the forebrain and the hindbrain. It relays sensory and motor signals, regulating arousal and attention, and coordinating visual and auditory reflexes.

3. Hindbrain: The hindbrain is the posterior part of the brain, located near the base of the skull. It is responsible for various functions like balance, coordination, breathing, and regulating essential bodily processes.

Spinal Cord

The spinal cord is a long, cylindrical bundle of nerve tissue that runs down the vertebral column (spine) and transfers sensory information to the brain and carries motor signals from the brain to the body. It plays an important role in reflexes and basic motor functions, and it serves as a key link between the peripheral nervous system and the central nervous system.

Types of Peripheral Nervous System and their Functions

The peripheral nervous system (PNS) consists of network of nerves and ganglia. The PNS connects the CNS to the rest of the body, enabling communication between the central nervous system and sensory organs, muscles, glands, and other tissues. It has two main divisions:

• Sensory (Afferent) fibres It carries sensory information from the body and external environment to the CNS. It receives stimuli such as touch, temperature, pain, and sensory input from organs.
• Motor (Efferent) fibres: It transmits motor commands from the CNS to muscles, glands, and other effector organs. It controls voluntary movements (somatic nervous system) and involuntary processes (autonomic nervous system), such as heart rate, digestion, and glandular secretions.

The peripheral nervous system (PNS) can be classified into two major divisions:

• Somatic Nervous System (SNS): It is responsible for voluntary movements and sensory perception. It receives sensory information from the body's sensory receptors (skin, joints, muscles) and transmit it to the central nervous system (CNS).
• Autonomic Nervous System (ANS): The ANS is responsible for involuntary functions that help regulate the internal environment of the body to maintain homeostasis.

What are the Functions of the Nervous System?

Functions of Nervous System are as follows:

• Nervous system helps in reflex action
• It helps in memory and learning
• Voluntary control
• Maintains involuntary functions like heartbeat
• Nervous system also helps in maintaining homeostasis.

Conclusion: Human Nervous System - Structure, Function, and Types

In conclusion, the human nervous system serves vital functions including sensation, movement, cognition, and regulation of bodily processes. Through intricate pathways the nervous system functions to ensure efficient communication within the body. Understanding the types of nervous system and their function is important to learn how our body performs processes, and coordinates movement. As a complex network of specialized cells and tissues, the nervous system is responsible for the human adaptability and interaction with the environment which is essential for survival and well-being.