Communication: Interpretation Of Signals.

Question 1

identify neurones as nerve cells that are the transmitters of signals by electro-chemical changes in their membranes

Answer 1

A neurone is a nerve cell that transmits a signal or impulse from one part of the body to another.
A nerve impulse can be detected as a change in voltage. The impulse is transmitted as a wave of electrical changes that travel along the cell membrane of the neurone.
The electrical changes are caused as sodium ions move into the neurone. Thus the signal is described as an electrochemical impulse.
After the signal has been transmitted, potassium ions move to the outside of the cell to restore the original charge of the neurone.

Question 2

define the term threshold and explain why not all stimuli generate an action potential

Answer 2

When a neurone fires it is known as the ‘all or none’ response or the ‘all or nothing’ response. The reaction either occurs at the maximum or does not fire at all.
The point of excitation that causes the neurone to fire is called the threshold of reaction.
The intensity of the stimulus is recorded by the firing of all neurones not in a greater or lesser action potential of an individual cell.

Question 3

identify those areas of the cerebrum involved in the perception and interpretation of light and sound

Answer 3

The functional areas of the cerebrum have been mapped, and the regions involved in speech, sight and sound perception are shown on the diagram below.

Language 
Speech 
Hearing 
Smell taste
Motor control 
Vision
Reading 
Body awareness
Sensory area

Question 4

explain using specific examples, the importance of correct interpretation of signals by the brain for the coordination of animal behaviour

Answer 4

The environment in which an organism lives is constantly changing. Sense organs such as the ear and the eye detect these changes and send information to the brain. The brain then interprets the information and sends an impulse to an effector organ such as a muscle. It is essential that the brain interpret signals from the sense organs correctly.
The cerebral cortex is the most important association centre of the brain. Information comes to this area from our senses and the brain sorts it out in the light of past experiences. As a result, motor impulses are sent along the nerves to cause an appropriate action to take place.
For example, the eyes and ears, receptors in muscles and tendons, pressure sensors on the feet all provide signals about the position of the body in space. The cerebrum of the brain interprets all of these signals and sends messages to various effectors to balance the body in space.
Walking involves several receptors, including the eyes, gravity receptors in the ears, pressure sensors in the feet and position receptors in the joints. These receptors are connected to the brain by neurones and the brain interprets the signals it receives. The brain sends messages to the muscles and other effectors to coordinate the process of walking.
The importance of the brain in the coordination of animal behaviour is highlighted when parts of it are damaged. The paralysis that follows a stroke, or the shaking movements of people with Parkinson’s disease, are signs of damage to the brain. In people with these conditions, muscular contractions are no longer coordinated by the brain.

Question 5

identify that a nerve is a bundle of neuronal fibres

Answer 5

A nerve is a bundle of axons or neuronal fibres bound together like wires in a cable.

A neurone is a nerve cell. A typical neurone consists of a cell body, dendrites and an axon covered by an insulating myelin sheath.
Neurone

You can find out more about neurones at the web site Neuroscience for Kids (external website) University of Washington, Seattle, Washington, USA.