Environment: The Human Nervous System

The Basic Structure and Functions of the Human Nervous System

The nervous system is a complex network of nerves and cells, or neurones, that carry messages to and from the brain and spinal cord to various parts of the body.
The central nervous system (CNS) consists of the brain and spinal cord. It is responsible for processing information and controlling the majority of functions of the body and mind.
The peripheral nervous system (PNS) consists of all the nerves outside the CNS. It connects the CNS to the limbs and organs.
The PNS is further divided into the somatic nervous system, which controls voluntary muscle movements and the autonomic nervous system, which controls involuntary actions like breathing and digestion.

Components of the Nervous System

Neurones are the basic unit of the nervous system. They are specialised cells designed to transmit electrical signals or nerve impulses.
Each neurone is composed of a cell body, a dendrites - extensions that receive signals from other neurones, and an axon - a long nerve fibre that conducts the impulse away from the cell body.
Synapses are junctions where two neurones meet. They allow for the transmission of nerve impulses through the release of neurotransmitters.

Response to Stimuli

The sequence of events following a stimulus is known as a reflex arc. This includes the following stages: reception by sensory neurones, transmission to the CNS, transmission to the effector organs through motor neurones, and the response by effector organs.
Reflex actions are rapid, involuntary responses to stimuli. They are important for survival, as they can help to prevent injury by allowing quick reaction to potentially harmful situations.
Coordination occurs as a result of two systems in our body – the nervous system and the Endocrine system. The nervous system provides quick responses while the endocrine system generally provides slower, long term responses.

Key Parts of the Brain

The cerebrum is the largest part of the brain. It controls intelligence, creativity, emotion, and sensory processing.
The cerebellum is responsible for coordinating voluntary movements, maintaining posture and balance.
The medulla oblongata controls vital life-sustaining functions such as heartbeat, breathing, and digestion.
The hypothalamus regulates body temperature, hunger, thirst, and some aspects of behaviour.

In revising the human nervous system, make sure to understand these components, their functions and how they work together to react to changes in the environment. This coordination and response to changes is crucial for survival and overall well-being.