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Control and co-ordination

In the previous section you learnt about body maintenance functions. These functions are being performed constantly without us being aware of it.

What we are aware of is our actions and thoughts.

There are some actions we can control - like choosing to read, write and learn and there are other actions that we cannot control.

The former are called voluntary actions, while the latter are called reflex actions.

The human nervous system is reponsible for all control and coordination in the human body.

You've previously learnt about the building block of the human nervous system- the neuron.

Within a neuron, dendrites acquire information about stimulus around us. This sets off a chemical reaction, which creates a chemical impulse.

The electrical impulse then travels through the axon to the end of the neuron.

At the end of the neuron is another neuron. The information is passed along from one neuron to another.

There are three kinds of neurons -

1. Sensory neurons- which transmit information from the sensors to the CNS (Central Nervous system).

2. Motor neurons which transmit infomation from the CNS to the muscle cells.

3. Interneurons which act as central nodes of neural circuits.

Neurons pass messages between themselves across synapses.

At the synapse the information passes from the transmitting neuron to the receiving neuron with the help of neurotransmitters.

Now that you know more about neurons, you can learn about the human nervous system.

The human nervous system consists of the Central Nervous system and the peripheral nervous system.

The central nervous system consists of the brain and the spinal cord, while the peripheral nervous system consists of nerve cells that carry information and from the central nervous system.

Below is a schematic representation of how our nervous system works for us to repond to stimulus.

In general the three stages of processing information are -> sensory input (through sense organs) -> integration (by the Central Nervous system) and motor output (by the peripheral nervous system).

In a reflex action, the message does not go to the brain, instead the message goes from receptor to neuron to effector.

This is why reflex actions are sometimes called unconscious actions. Your neurons work extremely fast to relay the message without a proper thought process.