Communication: neuronal and hormonal
In order for plants and animals to survive they must react to changes in their external (and internal) environment. Mechanisms are in place to detect changes and bring about responses through communication systems. Whilst animals have both neuronal and hormonal communication mechanisms, plants only have hormone like substances.
Students are often asked to compare the similarities and differences between neuronal and hormonal communication. Obviously this topic links closely with homeostasis and many resources listed in that topic will also be of value here.
Students at A level are required to have a detailed understanding of the structure and function of the mammalian nervous system. Students must appreciate the basic concept that a nerve impulse is specific to a target cell only because it releases a chemical messenger directly onto it, producing a response that is usually rapid, short-lived and localised. Students should also understand how electrical impulses are transmitted along the cell surface membrane, what is meant by resting potential and the sequence of events during an action potential. Some specifications require students to explain the effects of certain drugs on nerve impulses.
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Links and Resources
This two page resource provides a useful, clear and concise summary of endocrine hormones, where they are produced, their function and target cell.
This would be a useful document to photocopy for students or provide electronically for their revision notes.
Alternatively students, or pairs of students, could be given a particular organ or hormone and asked to use the information on this summary as a starter for a 100 word article on the function of that hormone. Students could also be asked to undertake research to add an additional column to the list of any known disorders or diseases that result from an imbalance/malfunction/absence of each hormone.
This website introduces students to the major endocrine glands and hormone function in puberty, the menstrual cycle, pregnancy and growth. Specific examples that are included are insulin, adrenaline, ADH, and plant hormones.
There are some pages of this ten page resource which are too simplistic for A level, but there are other animations, drag and drop and questions which are at the required standard.
The best use of this resource would be as an initial diagnostic activity, to see what students remember/understand from Key Stage Four. Students could work through the pages individually or in pairs. They could either do this as a recall exercise without the use of any other information, or make use of A level textbooks.
This short (three minute) video provides a basic introduction to plant hormones and tropisms. It would be suitable to show at the start of the lesson, with questions added in by the teacher to move the level of understanding from anything that was covered at Key Stage Four to the required level of detail needed at A level.
This video could be used as an introduction to a practical session to investigate the effect of auxin in plants - see the protocol included in this list.
This resource can be used in a number of ways. Firstly the content is appropriate for A level in highlighting the way in which hormones communicate with target cells. Activity sheet one covers this process, providing some challenging questions. Answers are provided, so students could self assess or peer assess their responses.
Activity two continues to explore the process of cell signalling and provides an opportunity for students to carry out some self directed/independent study researching the links provided. This activity is provided to model the way in which scientists would use secondary research.
The third part of the activity then uses this topic to consider the setting up of investigations, looking in detail at hypothesis, variables and reliability. This activity links to the provided video. This would be a good activity for A level students, particularly as a revision exercise. Many exam questions require students to consider factors such as variables and reliability in a given investigation.
This protocol from Science and Plants for School (SAPS) provides opportunities for students to investigate the effects of the hormone auxin (indole acetic acid or IAA) as a plant growth regulator.
There are two sheets provided. One sheet is the actual protocol, presented as a series of five simple diagrams and text. There are two investigations here, students could complete both or half the class could complete investigation one and the other half investigation two.
The second sheet is a question sheet related to the investigation.
This is a good investigation for A level students to work independently-with as little teacher input as possible.
This animation provides a good level of detail and challenge for A level biologists. This is one of two similar animations from the National Learning Network (see other resource on Nervous system: Synapses and Neurons, in this list).
There are several pages to this resource and it would be well worth students going through this page by page, answering the questions on each individual section and also the six question auto answer questions at the very end of the resource.
This resource could be used as an individual self study package, but would also work well as a class activity, with the teacher adding additional information to animations such as the animation with sodium gates.
This animation from the National Learning Network provides a good level of detail and challenge. Its focus is on neurotransmitters and the transmission of impulses at synapses and the neuromuscular junction. It considers how muscle fibres act as motor units and the control of muscle contraction.
This could be used as an initial diagnostic activity at the start of a topic on the nervous system, or it could also be used as a revision activity with students.
This activity would work well as an individual activity, where students would work through the animation, page by page, answering the set multiple choice questions and also completing the final automatic response quiz.
If this is used as a diagnostic activity, students (and the teacher) would be able to note any areas of misconception or weakness from previous learning of this topic at Key Stage Four.
This is a clear and concise four page summary of the nervous system, which includes sections on: functions, key mechanisms and nervous impulse, action potential, propagation and synaptic transmission. There is also a good final section on drugs and the nervous system focusing on caffeine and also the difficulties of drug treatment in Parkinson's disease.
There is a question at the end of the summary which asks students to research the terms agonist and antagonist in terms of drugs and the nervous system. This would make for a suitable research homework question as answers require students to demonstrate an understanding of neurotransmission and many students find the subject of pharmacology an interesting context for the study of physiology.
This Catalyst article provides a good summary of neuronal transmission covering neurones, reflexes, synapses and receptors. The context for this information is how quickly the system is able to react to messages sent from the central nervous system.
This article could be used in a variety of ways. It could simply be a piece of reading for homework, or students could be asked to write a similar article on the endocrine system, highlighting differences and similarities.
The article notes how in certain diseases malfunction of the nervous system is seen, such as in Alzheimer’s syndrome, where the normal mechanism involved in releasing neurotransmitter stays open, flooding the neurone with calcium ions. Students could be asked to research another disease/disorder where neuronal function is in some way impaired, they could then present a summary of this to the class.
This booklet is suitable as a teacher reference guide on the nervous system. It would be a useful guide for any teacher who would like to confirm their understanding of this aspect of physiology before delivering this topic to A level students.
The level of detail within the guide is above what would be required at A level and the format is not particularly user friendly. It may however be possible to use certain paragraphs and diagrams within the classroom.
In this short, (three minute) video from the Royal Institute, scientists at Newcastle University demonstrate how they have been able to listen in to the activity of a locust neuron.
The information provided in the video is interesting and relevant to the topic, but there isn't much detail presented. It would be possible to use this video on its own as a quick starter/introduction to a lesson. There are questions that could be added either during the video or at the end, to challenge thinking and promote understanding about the propagation of the nerve impulse.