Download Option E Neurobiology and Behaviour

Option E
Neurobiology and Behaviour
Section
Core Material
Stimulus and Response
Perception of Stimuli
Innate and Learned Behaviour
Neurotransmitters and Synapses
Extension Material
The Human Brain
Further Studies of Behaviour
Self-test quiz
Answers to Self-test quiz
Appendix – Explanation of the Hermann Grid
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IB Biology Option E 2012
Stimulus and
Response
Core Material
™
Stimulus and Response
Stimulus
A change in the internal or external environment that
is detected by a receptor and causes a response.
Response
A change in an organism as a result of a stimulus.
Reflex
A rapid and unconscious response to a stimulus.
Animal Response to Stimuli
synapses
pain receptors –
specialised nerve
endings
relay
neuron
cell body of sensory
neuron in dorsal root
ganglion
central canal carrying
cerebro-spinal fluid
dorsal root
sensory
neuron
spinal
nerve
muscle
(effector)
motor
neuron
ventral root
cell body of motor
neuron in grey
matter
grey matter with
synaptic
connections
white matter with ascending
and descending tracts of
neurons carrying impulses
to and from the brain
spinal cord
Key components
¾ Receptor
• Specialised cell or nerve ending;
• Detects a specific stimulus;
• Detects internal and external stimuli.
¾
Sensory neuron
• Carries nerve impulses from the receptor to the central nervous system.
¾
Relay neuron
• Carries nerve impulses from the sensory to the motor neuron;
• Links up with other relay neurons to carry information up and down the spinal cord, eg to the
memory centres of the brain.
¾
Motor neuron
• Carries nerve impulses from the central nervous system to the effector.
¾
Synapses
• Connect neurons together;
• Control how the information is passed from one neuron to the next;
• Uses chemicals called neurotransmitters.
¾
Effector
• Muscle or secretory gland;
• Carries out a response to the stimulus.
IB Biology Option E 2012
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Stimulus and
Response
The Role of Natural Selection in Response
Key points
¾ Responses may increase survival and reproduction;
¾ Responses show adaptive significance by improving fitness;
¾ Fitness is the genetic contribution of an individual to later generations;
¾ Natural selection acts on differences that have a genetic basis;
¾ Response patterns that improve fitness get passed on to offspring. (Darwinian
principle of evolution).
Examples of Responses
Egg laying
¾
¾
¾
¾
The Blue tit, Cyanistes caeruleus, and the Great tit, Parus major, are birds
commonly found through Great Britain and other parts of Europe;
They feed mainly on insects;
As temperatures have risen insects are appearing earlier in spring;
Both species have responded by breeding earlier in the year as shown by egg
laying data in the tables and graphs below.
Blue tit, Cyanistes caeruleus.
Variable
Period
(yrs)
Years
Clutch size
Brood size
Laying date
37
37
37
1968-2005
1968-2005
1968-2005
Mean
Trend
annual
sample
131
Linear decline
220
Curvilinear
173
Linear decline
Modelled
in first year
Modelled
in 2005
9.41 eggs
8.04 chicks
May 3
8.57 eggs -8.9%
7.01 chicks -12.7%
Apr 26
- 7 days
Change
Photo George H. Higginbotham
Baillie, S.R., Marchant, J.H., Crick, H.Q.P., Noble, D.G., Balmer, D.E., Barimore, C., Coombes, R.H.,
Downie, I.S., Freeman, S.N., Joys, A.C., Leech, D.I., Raven, M.J., Robinson, R.A. & Thewlis, R.M. (2007)
Breeding Birds in the Wider Countryside: their conservation status 2007.
BTO Research Report No. 487. BTO.
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IB Biology Option E 2012