The document discusses how plants and animals coordinate responses to changes through hormonal and nervous systems, explaining that plants use chemical growth factors like auxins and gibberellins rather than hormones transported by glands; it also examines the inflammatory response process in animals involving chemical mediators like prostaglandins and histamine that cause redness, warmth, pain and swelling at sites of injury.

1. Coordination
Lesson Objectives:
•How do hormonal and nervous coordination differ?
•What are the chemical mediators and how do they work?
•What changes to plants respond to?
•How do plants respond to change?
•What are plant growth factors?

2. No body system can work in isolation
• Draw the outline of a
body.
• Draw one system on the
body e.g reproductive.
• For that system to work
what other systems
does it rely on?
• Annotate you diagram.

3. Comparing nerves and hormones.
Copy and fill in the table using page 157
Hormonal System Nervous System

4. Chemical Mediators
• Act locally on cells that produce them and
other cells in the immediate area.
• Released by injured or infected cells.
• Cause arteries and small arterioles to dilate.

5. Inflammatory Response
• Redness
• Warmth
• Pain
• Swelling

6. Prostaglandins
• Are mediators of the first three characteristics.
• Released from damaged cells at the site of injury.
• Have several important effects including:
 Vasodilatation of arterioles – this allows more blood to
flow to the area and more phagocytic white blood cells.
 Promoting blood clotting – minimises blood loss and
entry of microbes.
• Pain is a result of pressure on nerve endings and
pressure receptors due to an increase of blood.

7. Histamine
• Not produced by damaged cells but by mast
cells in the area.
• Acts on the capillary walls allowing them to
dilate and become more leaky.
• This allows some of the plasma, including
protein molecules to leave the blood.
• Increases the volume of liquid in the tissues
causing swelling.
• The ‘leakiness’ makes it easier for phagocytes
to exit the blood and enter the tissues.

8. Pus
• The liquid in the tissues.
• Dead phagocytes
continuing
bacteria/dead cells they
have engulfed.
• Escape from the
inflamed site as ‘pus’.

9. Histamine

10. Do plants have hormones?
• They have chemical messengers, but they aren’t
secreted by glands and don’t travel in a transport
system.
• They are called plant growth factors.
• They include:
– Auxins
– Gibberellins
– Abscisic acid
– Cytokinins
– Ethene

11. Auxins
• Best known growth factor as they were the
first to be discovered.
• There are several different auxins but they are
all similar, chemically, to indole acetic acid
(IAA).

12. Control of phototrophic response by
IAA
• The way auxins, including IAA act has only
recently been discovered.
• They act on growth genes turning them on
and stimulate cell division and cell elongation.
• The growth towards light from one side is a
result of the auxin being redistributed to the
shaded side of the root.

13. Control of phototrophic response by
IAA

14. Gravitrophic Response
• Auxins inhibit growth in roots.
• It is the absence or low concentrations of
auxins that bring about growth.
• If a seedling is placed horizontally and left, the
roots grow downwards and the shoot
upwards.

15. Gravitrophic Response
• In both root and shoot the auxin is
redistributed to the lower side.
• In the shoot the auxin stimulates growth, so
the cells on the lower side grow faster than
those on the upper side causing upwards
curvature.
• In the root auxin inhibits growth, so cells on
the lower side grow more slowly than those
on the upper causing a downward curvature.

16. Darwins Experiments 1880
Read pages 158-160 and answer the questions.