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9.7 Option - Pharmaceuticals: 1. The nervous system
| Syllabus reference(October 2002 version) | ||
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| 1. The central nervous system and peripheral nervous system are responsible for the detection and interpretation of signals from outside and inside the body. | Students learn to: |
Students: |
Extract from Senior Science Stage 6 Syllabus(Amended 2002).© Board of Studies, NSW.
[Edit: 2 June 09]
Prior learning: Stage 5, Structures and Systems 5.8.4 9 (a).
Background: All information received
from the environment outside the body and from within it is processed
by the nervous system.
| The nervous system consists of:
- the brain (B) - the spinal cord (SC) - a huge network of nerves running to all other parts of the body (N). |
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describe the central nervous system as comprising the brain and spinal cord
- The brain is the main processing organ for information received from the body and its environment. It is housed and protected in the skull.
- The spinal cord relays "messages" in the form of small electrical impulses to and from the brain via the nerves. It is housed in and protected by the spinal column (backbone).
- Nerves consist of bundles of many nerve cells, called neurones.
describe the peripheral nervous system as the nerves that emanate from and connect to the central nervous system
- The peripheral nervous system (PNS) consists of all the nerves situated outside the brain and spinal cord.
- The PNS receives information from inside the body and from its surface. This information is passed to the central nervous system (CNS) where it is processed.
- Processed information from the CNS returns via the PNS to muscles and glands of the body, controlling activities in these systems.
gather and process information from secondary sources to identify the main components of the nervous system and their functions
- Information about the structure and function
of the nervous system is available in many junior and senior science
texts and from the World Wide Web. A comprehensive description of the
nervous system can be found in Neuroscience
for Kids
; a site maintained by Erick Chudler at the University of
Washington. Links to other relevant sites are provided.
- When gathering your information,
the following table format would assist efficient data collection.
Central nervous system Peripheral nervous system Brain Spinal cord Structure Function - When processing, you can evaluate the validity of data by checking if a number of sources consistently provide the same information.
describe the general role of sense organs
- The general role of sense organs is to detect stimuli from inside and outside the body.
- Special sense organs detect specific stimuli.
Extra information
The eyes are the organs of sight and contain millions of light sensitive receptors. These receptors convert light energy into electrical impulses that are transmitted to the brain, where they are interpreted as an image.
The ears are the organs of hearing and balance. Sound vibrations are transferred from the outer ear to the cochlea where they are detected by fine hairs. Body movements are detected by receptors in the semicircular canals.
The nose is the organ of smell and contains the olfactory nerves. These nerves detect odours and account for most of the differing flavours and sensations of substances taken into the mouth. The shape of an odour-causing chemical molecule determines the nature of the odour of that molecule or substance. There are seven types of smell receptors - camphorlike, ethereal (like dry-cleaning fluid), floral, musky, peppermintlike, pungent and putrid. The molecules of an odour combine with specific cells in the nose or with chemicals within those cells, triggering an impulse by the olfactory nerve that is perceived as the odour by the brain.
The tongue is the primary organ of taste and it contains receptors, called taste buds, which detect four qualities of substances - sweetness, sourness, saltiness, and bitterness. Taste buds are flask-shaped and are located on the surface and sides of the tongue. Some are also located the roof of the mouth and the entrance to the pharynx (throat). Each taste bud contains an opening at its base through which nerve fibres enter. These fibres transmit impulses directly to the brain. In order for a substance to stimulate these impulses it must be in solution, which is mostly achieved by saliva.
- General senses include touch, pressure, pain, temperature and vibration. These senses are more widely spread around the body than the special senses.
distinguish between the roles of sensory neurones, motor neurones and interneurones
Recall that neurones are nerve cells that conduct
- Sensory neurones carry signals from the sensory areas of the body to the CNS.
- Motor neurones take signals away from the CNS to muscles and glands of the body.
- Interneurones are neurones situated totally within the CNS and relay messages between the sensory and motor neurones.
distinguish between the responses of muscles and glands as effectors.
- Effectors are the organs of the body,
either muscles or glands, which carry out the body's actions in response
to motor neurone signals.
- Muscles respond to motor neurone signals by
thickening and contracting, resulting in movements.
(Because muscles cannot lengthen, there must be paired muscles that work together to allow opposite movements)
- Glands respond to motor neurone signals by releasing special chemicals, called hormones, into the bloodstream. Hormone affect the way in which the organs of the body function. For example, insulin regulates blood glucose levels; testosterone causes sexual development and growth spurt and maintains proper functioning of male reproductive system.
outline the pathways from a stimulus through the reflex arc to a response and its interpretation by the brain.
A reflex arc is a pathway
through which impulses pass when a sensory receptor receives a stimulus
that requires an immediate response to prevent harm to the body.
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outline
briefly the relationship between
- the synapse
- the chemical messenger
- the continuation of the "message"
- A synapse is a microscopic junction between two neurones through which a chemical messenger, called a neurotransmitter, passes to transfer an impulse.
- The neurotransmitter is released from the end of one neurone when it is stimulated and received by the next one.
- The neurotransmitter then causes the receiving neurone to convert the message back into an electrical impulse to be sent to the next neurome.
- The electrical signal (the message) then
passes along the second neurone to its destination.
plan, choose equipment or resources for, and perform a first-hand investigation to gather first-hand data (to) demonstrate differences in reaction time and relate this to the sequence of events involved
Reaction time is the time taken between a stimulus being received and a voluntary response occurring by an individual.Reaction times may be determined by the traditional metre stick method.
On-line methods for measuring reaction times in milliseconds
can be found, Test your reaction time
Erick Chudler at the University of
Washington and Reaction Tester at Berend Meijer's Home Page.
- In planning your investigation, you should consider how your design would allow valid and reliable data to be collected. Validity can be achieved by ensuring that a reasonable and representative number of people are tested and that each person is tested in exactly the same way. Reliability can be achieved by carrying out multiple trials of a task for each person.
- When choosing equipment or resources for the investigation, you should identify and set up the most appropriate equipment or combination of equipment needed to undertake the investigation. In this investigation, very simple equipment might be appropriate. Consider the degrees of accuracy needed for differences in reaction time for a number of people to be demonstrated. In designing your procedure, consider the measurements required for valid conclusions to be made.
- When performing the investigation, consider if the planned procedure is achieving useful data. If not, make modifications and analyse the effect of these adjustments before recommencing testing.
- Gather data accurately during the investigation by writing down measurements and observations in an accessible and recognisable form, such as a data table. Carry out repeat trials as planned or if a particular trial is disrupted.
- Once differences are demonstrated, remember to relate your findings to the sequence of events involved.
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