Biology
Home > Biology > Options > Communication > Communication: 7. Interpretation of signals
9.5 Option – Communication: 7. Interpretation of signals
Extract from Biology Stage 6 Syllabus (Amended October
2002). © Board of Studies, NSW.
[Edit: 17 Aug 04]
perform a first-hand investigation using stained prepared slides and/ or electron micrographs to gather information about neurones and nerves
- This activity requires you to gather
information about neurones and nerves using a
microscope and prepared slides of neurones. Try to identify
individual cells and draw labelled diagrams of a few of them.
Alternatively, you can observe electron micrographs or
photomicrographs of neurones at the web sites
Neuroscience for Kids Cell Gallery
University of Washington, Seattle, Washington, USA or
Histology on the Internet Stritch
School of Medicine, Loyola University, Chicago, Illinois,
USA.
identify that a nerve is a bundle of neuronal fibres
- 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.
- You can find out more about neurones at the web site
Neuroscience for Kids University of
Washington, Seattle, Washington, USA.
identify neurones as nerve cells that are the transmitters of signals by electro-chemical changes in their membranes
- 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.
present information from secondary sources to graphically represent a typical action potential
- The action potential of a neurone can be graphically represented by the graph below.
define the term threshold and explain why not all stimuli generate an action potential
- 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.
Animation of an action potential
University of Washington, Seattle, Washington, USA.
perform a first-hand investigation to examine an appropriate mammalian brain or model of a human brain to gather information to distinguish the cerebrum, cerebellum and medulla oblongata and locate the regions involved in speech, sight and sound perception
- This activity requires the examination of the brain of a mammal, which can be obtained from a local butcher. Alternatively, you can examine a model of a human brain.
- Perform a first-hand investigation by examining the brain so that hazards are minimized. Identify and use safe work practices during this investigation.
- Draw a diagram to show the various structures you observe.
- Use the diagram below to identify the cerebrum, cerebellum and medulla oblongata.
- Prepare notes to explain how you minimised hazards, disposed safely of any waste materials.
- Note that the cerebrum or cerebral cortex is involved in thinking and reasoning, as well as the perception of the senses, including speech, sight and sound perception.
The following websites show dissections of a sheep's brain.
Dissection of a sheep's brain The
University of Scranton, Pennsylvania, USA.
Sheep brain dissection Exploratorium,
The museum of science, art and human perception, USA.
identify those areas of the cerebrum involved in the perception and interpretation of light and sound
- 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.
Brain lobes University of Central
Florida, Florida, USA.
explain using specific examples, the importance of correct interpretation of signals by the brain for the coordination of animal behaviour
- 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.
|