topic 11 - coordination and response Flashcards
what is the excretory product of the lungs
CO2 and water
excretory product of kidneys
urea
excretory product of skin
sweat
why do animals need to respond to changes in the environment?
to coordinate the activities of internal organs
how do animals maintain their internal environment?
through a process called homeostasis
5 examples of what homeostasis controls
- water content (of an individual cell or of the body fluids of an organism)
- temperature
- pH
- blood pressure
- blood glucose concentration
2 communication systems in mammals
- the nervous system
- the endocrine system
what is homeostasis?
the control or regulation of the internal conditions of a cell or organism
what is required for a co-ordinated response?
- stimulus - change in environment (heat)
- receptor - what detects stimuli (hand)
- coordination centre - brain, spinal cord
- effector - muscle or gland that brings response (muscle contracts)
- response - body’s reaction (withdraw hand)
why do plants grow in response to light?
- plants need to be able to grow in response to light, to ensure their leaves can absorb light for photosynthesis
- they also need to be able to grow in response to gravity, to ensure that shoots grow upwards and roots grow downwards
what is a tropism?
The directional growth responses made by plants in response to light and gravity
what is a positive tropism?
when the growth is towards the stimulus
what is a negative tropism?
when the growth is away from the stimulus.
what is a response to light called?
phototropsim
what is a response to gravity called?
geotropism
what is geotropism and what are the positive and negative responses?
- growth towards or away from a gravitational pull
- a positive geotropic response is growth towards gravity e.g. the roots
- a negative geotropic response is growth away from gravity e.g. the shoot
what is phototropism and what are the positive and negative responses?
- growth towards or away from a light source
- a positve phototropic response is growth towards light e.g. shoots
- a negative phototropic response is growth away from the light e.g. roots
what are auxins?
plant growth regulators (similar to hormones in animals) produced by plants to coordinate and control directional growth responses such as phototropism’s and geotropism’s
where are auxins produced?
the tip of the shoots and the roots
how is the distribution of auxins affected?
- in the shoots is affected by light and gravity
- in the roots is primarily affected by gravity alone
what are auxins like in the shoots?
- the lower side grows faster than upper side (more auxin = more cell elongation), so the shoot grows upwards
- they stimulate the cells in this region to elongate; the more auxin there is, the faster they will elongate and grow
what are auxins like in the roots?
In the roots, the lower side grows slower than the upper side (as auxin inhibits cell elongation and growth in roots), so the root grows downwards
what happens when the sun shines directly on the tip of a plant?
- auxin is distributed evenly throughout and the cells in the shoot grow at the same rate - this is what normally happens with plants growing outsidew
what happens when the sun is shining predominantly on one side of the plant?
the auxin produced in the tip concentrates on the shaded side, making the cells on that side elongate and grow faster than the cells on the sunny side
4 facts about the nervous system
- information is sent through the nervous system as electrical impulses – these are electrical signals that pass along nerve cells known as neurones
- these impulses travel along neurones at very high speeds, allowing rapid responses to stimuli
- the nervous system coordinates the activities of sensory receptors, decision-making centres in the CNS, and effectors such as muscles and glands
- the nervous system is used to control functions that need instant (or very rapid) responses
