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Description
Autumn leaves falling off trees and the beating of your heart are things we expect, take for granted. They are examples of physiological processes which are very precisely controlled. They happen r...egularly. Both processes are controlled partly by the activity of chemical substances. To explain the control of leaf fall experiments on young french bean plants are demonstrated which show that a plant hormone indole acetic acid (IAA) and a simple hydrocarbon gas (ethylene) are produced by leaves and that together they conspire to bring about leaf fall. The mammalian heart is an organ made up of tissues formed of cells. Each heart cell has the inherent ability to contract, Such cells are seen, and we see how finally many cells come to beat together in the heart as it develops to produce the organ whose job is to pump blood. The beating of the mammalian heart is controlled by two chemical substances which produce opposite, antagonistic effects on the heart. These substances are adrenalin and acetylcholine. Experiments shown in the programme demonstrate that adrenalin speeds up the rate and increases the strength of the heart beat. Acetylcholine on the other hand slows the heart beat down and decreases the strength of beat. The experiments are summarised at the end of the programme. N.B. Specialised microscopy sequences prepared and recorded by Roger Jones (BBC)
Autumn leaves falling off trees and the beating of your heart are things we expect, take for granted. They are examples of physiological processes which are very precisely controlled. They happen r...egularly. Both processes are controlled partly by the activity of chemical substances. To explain the control of leaf fall experiments on young french bean plants are demonstrated which show that a plant hormone indole acetic acid (IAA) and a simple hydrocarbon gas (ethylene) are produced by leaves and that together they conspire to bring about leaf fall. The mammalian heart is an organ made up of tissues formed of cells. Each heart cell has the inherent ability to contract, Such cells are seen, and we see how finally many cells come to beat together in the heart as it develops to produce the organ whose job is to pump blood. The beating of the mammalian heart is controlled by two chemical substances which produce opposite, antagonistic effects on the heart. These substances are adrenalin and acetylcholine. Experiments shown in the programme demonstrate that adrenalin speeds up the rate and increases the strength of the heart beat. Acetylcholine on the other hand slows the heart beat down and decreases the strength of beat. The experiments are summarised at the end of the programme. N.B. Specialised microscopy sequences prepared and recorded by Roger Jones (BBC)
| Module code and title: | S101, Science: a foundation course |
|---|---|
| Item code: | S101; 22 |
| First transmission date: | 07-08-1979 |
| Published: | 1979 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:24:00 |
| + Show more... | |
| Producer: | Roger Jones |
| Contributors: | Irene Ridge; Peggy Varley |
| Publisher: | BBC Open University |
| Keyword(s): | Abscission; Leaf fall |
| Subject terms: | Conservation |
| Footage description: | Irene Ridge stands under a tree and examines a branch which has been killed by fire. She contrasts its leaves, which have not fallen, with natural leaf fall in deciduous trees. Shots of individual leaves falling. Time lapse photographs show a young bean plant growing. Irene Ridge, with a three week old bean plant, explains that controlled experiment can be performed for researching the leaf fall (abscission) mechanism. She demonstrates one of the techniques used. Animation over shots of a bean plant shows the movement of auxin hormone (indole acetic acid) through the plant. Irene Ridge performs an experiment, on bean plants, to determine if absence of auxin hormone causes abscission in leaves. Time lapse shots of a coleus plant exposed for several days to ethylene gas. Irene Ridge discusses the role of ethylene in abscission and outlines an experiment to test this. She cuts pieces of bean plant stem in preparation for the experiment. Animations shows the effects of ethylene on the sample stem sections cut above. Ridge concludes that the effects of auxine and ethylene are antigonistic and that plants utilise both to fine tune abscission. In animation over a cellular cross section at the abscission zone of a bean plant is used by Irene Ridge to demonstrate what is happening at a cellular level during abscission. Over shots of single mammalian heart, cells and of a chick embryo, Peggy Varley points out the ability of heart cells and tissue to change shape and contract. Peggy Varley sets up the apparatus for an experiment which will monitor the effect of certain chemicals on the strength and rate of a rabbit heart beat. Shots of a heart being dissected out of a rabbit and prepared for the experiment. Commentary by Peggy Varley. Peggy Varley performs the experiment on the rabbit heart. Adrenalin and then acetylcholine are allowed to enter the heart and their effects on the rate and strength of the heart beat are monitored. |
| Master spool number: | 6HT/72874 |
| Production number: | 00525_1352 |
| Videofinder number: | 1197 |
| Available to public: | no |
