Notes on Human Nervous System

Human Nervous System

This section deals with the composition and functionality of the human nervous system, which is categorized into different types based on structure and function.

Types of Nervous Systems

The human nervous system is primarily divided into two main components:

1. Central Nervous System (CNS)

  • Brain: The central processing unit of the nervous system that integrates sensory information and coordinates response.

  • Spinal Cord: A vital pathway that conveys information between the brain and the peripheral nervous system.

2. Peripheral Nervous System (PNS)

The peripheral nervous system connects the CNS to limbs and organs. It is subdivided into:

  • Somatic Nervous System: Controls voluntary movements and transmits sensory information to the CNS.

  • Autonomic Nervous System: Regulates involuntary bodily functions, including heart rate and digestion.

Functionality of the Nervous System

  • Neurons: The fundamental units of the nervous system that detect changes in the environment and allow the body to respond accordingly.

Types of Neurons

Neurons are specialized cells that transmit impulses throughout the nervous system. They can be categorized into three major types:

1. Sensory Neurons

  • Function: These neurons carry impulses from sensory receptors towards the central nervous system.

2. Motor Neurons

  • Function: These neurons transmit impulses away from the central nervous system to effectors, such as muscles and glands.

3. Connector Neurons (Interneurons)

  • Function: Found within the central nervous system, connector neurons carry impulses between sensory and motor neurons, facilitating communication within the CNS.

Nerve Impulse

A nerve impulse is defined as an electrical signal that is conveyed by neurons, enabling rapid communication across the nervous system. The structural components of a neuron involved in transmitting these impulses are:

  • Dendrites: These are branch-like structures that receive signals from other neurons and transmit impulses to the cell body.

  • Cell Body (Soma): Contains the nucleus of the neuron and processes all signals received from the dendrites. The integration of these signals determines whether to transmit an impulse further.

  • Nucleus: The control center of the cell, housing genetic information that regulates cell activities.

  • Myelin Sheath: This insulating layer surrounds the axon, which enhances the speed of impulse transmission along the nerve.

  • Axon: A long, slender projection that carries impulses away from the cell body to other neurons or effectors.

Differences Between Sensory and Motor Neurons

  • Cell body Placement: In sensory neurons, the cell body is positioned in the middle of the axon, whereas in motor neurons, the cell body is located at one end of the neuron.

Synapse

  • Definition: A synapse is the microscopic gap that exists between neurons.

  • Function: Neurotransmitters are chemical messengers that bridge this gap, transmitting signals between neurons, thus facilitating communication in the nervous system.