Biology F214: Homeostasis

All organisms must detect?
Stimulus (change in their surroundings)
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2 communication systems animals have?
The Nervous System and Endocrine System (hormonal)
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What secretion is one of the 4 ways of cell signalling? and at what distances?
Paracrine secretion over short distances
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What cells use what impulses over large distances?
Nerve cells use electrical impulses
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What do they release where they terminate?
Chemicals
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Other type of secretion (3 out of the 4 types)
Endocrine secretion
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The cell signalling that begins at the brain
Neurosecretion
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2 physiological factors controlled in homeostasis?
Core body temperature, blood glucose concentration
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another 2?
Concentrations of ions in the blood and water potential of the blood
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Homeostasis is the..
maintenance of near constant internal conditions
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What is ambient temperature?
Temperature of the organisms surroundings
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Endotherms can..
Conserve and generate heat in their bodies
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If endotherms are hot, they have..
mechanisms to cool the body down
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Ectotherms cannot produce their own..
heat
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Instead they rely solely on their..
Surroundings for heat energy
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They use what methods for homeostasis?
Behavioural
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Example on a hot day, a lizard would do what to raise the core body temp?
Bask in the sun
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In order to regulate temperature you need three components:
Receptors, control centre and effectors
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The thermoregulatory centre is situated where?
In the Hypothalamus
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The frontal part responds to what?
Increases in temperature by promoting heat loss
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What is the set point?
The value of the physiological factor the body is keeping constant
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The hypothalamus keeps the distance between actual body temperature and the set body temperature..
as small as possible
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Controlling the physiological factor is called?
Negative Feedback
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What are the receptors on the surface of the skin detecting temperature called?
Peripheral temperature receptors
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Blood temperature levels are detected by what?
Central temperature recetors
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Where are these found (2 locations)
Spinal Cord and Hypothalamus
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When body temperature rises, what does the hypothalamus stimulate?
Loss of Heat
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4 methods of losing heat
Less sweating, vasodilation, reduced metabolism in liver, relaxation of erector pili muscles in skin
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What does the relaxation of erector pili muscles do?
It makes the hairs lie flat, meaning less air is trapped, allowing more heat loss
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What do animals do (not humans) for heat loss?
Shallow Breathing (panting) - increased evaporation
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Behavioural method of reducing heat in animals
Lying in a shaded area
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When the temperature of the surroundings decreases, the hypothalamus stimulates the..
conservation of heat
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2 ways heat is conserved in humans
Reduced sweating, vasoconstriction of arterioles
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If the blood temperature further falls, the hypothalamus will stimulate..
the production of heat
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2 ways heat is produced in humas
Increased liver metabolism (heat is by-product), Muscle Shivering
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How does muscle shivering produce more heat?
Respiration in the muscle cells produces heat as a by-product
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In young mammals, what sort of tissue is used to produce heat?
Brown Fat Tissue - lots of mitochondria that produce heat
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What behavioural changes do animals do to conserve heat?
Curl up (reduces the surface area exposed to the air)
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What can humans do to do to generate heat (behavioural)
Drink something hot
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Positive Feedback is a control mechanism that detects a difference between the..
Physiological factor and its Set Point
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What does this lead to the effectors doing?
Increasing that difference
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An example of positive feedback
Heat Stroke
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What does it not increase, but instead increases?
Does not increase sweat production, increases metabolism in liver
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Positive Feedback can be very..
Dangerous
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Other cards in this set

Card 2

Front

2 communication systems animals have?

Back

The Nervous System and Endocrine System (hormonal)

Card 3

Front

What secretion is one of the 4 ways of cell signalling? and at what distances?

Back

Preview of the front of card 3

Card 4

Front

What cells use what impulses over large distances?

Back

Preview of the front of card 4

Card 5

Front

What do they release where they terminate?

Back

Preview of the front of card 5
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