Communication, homeostasis and energy

Changes in the internal environment?
blood glucose, internal temp, water potential, cell pH
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Changes in the external environment?
humidity, external temp, light intensity, new or sudden sound
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How do animals react to changes in their environment?
through electrical response (neurons) and chemical response (hormones)
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How do plants react to changes in their environment?
a number of chemical communication systems including plant hormones
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Why is coordination needed?
produce the required response, cells have become specialised with functions, coordinating functions causes effective operation
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How are red blood cells coordinated?
Erythrocytes transport oxygen but have no nucleus to replicate, supply maintained by hematopoietic stem cells
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How are muscle cells coordinated?
constantly respire and require oxygen, can't transport it so are dependent on red blood cells
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What are flowering plants coordinated with?
Season and pollinators
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How do flowering plants coordinate?
using light sensitive chemicals to coordinate the development of flower buds
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What is homeostasis?
The function of different cells and organs coordinated to maintain a constant internal environment
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What is cell signalling?
One cell releasing a chemical which has an effect on a target cell
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How is coordination planned?
Through communication at a cellular level - cell signalling
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What can cells do through cell signalling?
transfer signals locally and transfer signals across large distances using hormones
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Example of local cell signalling?
between neurons at a synapse using neurotransmitters
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Example of large distance cell signalling using hormones?
pituitary gland secreting ADH to act on kidneys and maintain water balance
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Example of plant response?
plant stems growing towards light source to maximise rate of PS, achieved through plant hormones
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What must be kept within a narrow range for homeostasis?
concentration of chemicals like glucose, pH, water balance of body fluids, core body temp
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What do systems use to monitor and respond to changes?
chemical and electrical systems
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What is the result of homeostasis?
dynamic equilibrium
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change in the environment
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Sensory receptor?
detect changes in the body and are stimulated to send a message
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Communication system?
cell signalling in nervous/hormonal system to send message from receptor to effector
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Effector cells?
produce response that reverses change detected by receptor cells (release hormones/ move muscles)
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change in behaviour/physiology as a result of stimulus
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Why is it impossible to maintain a living mammal in a completely stable state?
Every factor causes minute changes
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Instead of a completely stable state what does the body aim to achieve?
A dynamic equilibrium with small fluctuations over a narrow range of condition
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How do the sensory and motor neurone work together to create homeostasis?
sensory receptors detect changes in the environment and this information is sent to the brain. Impulses are sent along the motor neurone to effectors to bring about changes to restore equil...
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detects changes in pressure
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detects changes in light
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detects chemical changes (pH)
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detects temperature changes
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What does homeostasis depend on?
sensory receptors detecting small changes in the body and effectors working to restore it
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What do precise control mechanisms in the body depend on?
feedback systems which enable the maintenance of a relatively steady state around a narrow range of conditions
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What is negative feedback?
Restoration to the the dynamic equilibrium, reversing the initial stimulus
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How does negative feedback work?
A small change in one direction detected by sensory receptors, effectors work to reverse change and restore conditions to base level
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Example of negative feedback?
Thermo and glucoregulation
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What is positive feedback?
Change also detected by sensory receptor but effectors stimulated to reinforce change and increase response rather than restore change
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Blood clotting - positive feedback?
Blood vessel damaged, platelets stick to damaged region, release clotting factors initiating clotting and attracting more platelets, adding to pos feedback, continuing until clot formed
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Childbirth - positive feedback?
Head of baby presses against cervix stimulating production of hormone oxytocin, stimulates uterine contractions, pushes head of baby harder against cervix, trigger more oxytocin, cont. until baby born
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Other cards in this set

Card 2


Changes in the external environment?


humidity, external temp, light intensity, new or sudden sound

Card 3


How do animals react to changes in their environment?


Preview of the front of card 3

Card 4


How do plants react to changes in their environment?


Preview of the front of card 4

Card 5


Why is coordination needed?


Preview of the front of card 5
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