10 Coordination
- Created by: cvrla
- Created on: 17-04-16 16:40
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- Coordination
- Plant growth factors
- light, gravity and water
- plant growth factors
- exert their influence by affecting growth
- made by cells located throughout the plant
- some affect the tissues that release them rather than distant cells
- Chemical mediators
- chemicals released from certain mammalian cells that have effect on cells on their immediate vicinity
- histamine - stored in certain white blood cells and released as a response to an injury or allergen
- causes dilation of small arteries and arterioles and increased permeability of capillaries, leading to localised swelling, redness and itching
- prostoglandins - found in cell membranes and also cause dilation of small arteries and arterioles
- causes increased permeability of capillaries, affect blood pressure and neurotransmitters, in doing so affecting pain sensation
- histamine - stored in certain white blood cells and released as a response to an injury or allergen
- chemicals released from certain mammalian cells that have effect on cells on their immediate vicinity
- Control of tropisms by IAA (indoleacetic acid)
- IAA in shoot tip, causes elongation (increases growth)
- e.g. IAA moves to shaded side of shoot which increases concentration therefore the shoot grows faster and elongates on the shaded side so the shoot grows towards light
- IAA in root tip decreases growth; bends towards gravity
- IAA in shoot tip, causes elongation (increases growth)
- Principles of coordination
- the nervous system
- stimulate cells by secreting neurotransmitters directly onto them
- rapid transmission
- response is localised, rapid and short lived
- effect is temporary
- the hormonal system
- produces chemicals that are transported in the blood plasma to their target cells which they then stimulate
- relatively slow transmission
- response is widespread, slow and long lasting
- the nervous system
- Plant growth factors
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