6. Temperature regulation III Flashcards
(18 cards)
What is selective freezing of extracellular compartments?
Some organisms can allow controlled freezing of areas outside cells.
This adaptation helps organisms survive in extremely cold environments.
Which compound works 200 times better than salt at lowering freezing points?
Glycerol.
Glycerol is used by some organisms to prevent freezing.
What are antifreeze proteins and their function?
Proteins produced in the liver of Arctic fish that bind to embryonic ice crystals to prevent further growth.
These proteins are crucial for survival in freezing temperatures.
What is supercooling?
The phenomenon where pure water can remain liquid down to -20°C under specific conditions.
Found in frogs, spiders, insects, and polar fish.
What are the challenges faced by homeothermic (warm-blooded) animals in cold environments?
Higher metabolic costs due to a higher surface-to-volume ratio.
Smaller animals face greater challenges in maintaining body temperature.
What are the degrees of frostbite?
- First degree: irritation
- Second degree: blisters, no major damage
- Third degree: deeper skin layers affected, permanent damage
- Fourth degree: tissue loss through necrosis, typically at extremities
Each degree indicates the severity of frostbite damage.
Name three strategies for reducing heat loss in cold environments.
- Insulation
- Reducing exposed surface area through posture
- Huddling
Huddling is exemplified by emperor penguins.
What is shivering thermogenesis?
Muscles generate heat through friction.
This is a heat generation strategy in cold environments.
What is non-shivering thermogenesis?
Tissues produce heat directly without movement.
Brown fat tissue is specifically designed for this purpose.
What role does the hypothalamus play in temperature regulation?
Acts as a thermostat with sensors 10x more sensitive than skin.
It triggers cooling and warming mechanisms based on temperature.
What are external thermoreceptors?
Skin sensors responsive to temperature and touch.
They have special adaptations in various species, such as insect antennae.
How do vampire bats utilize thermoreception?
They use thermoreception to locate prey.
This adaptation allows them to detect temperature differences.
What is countercurrent heat exchange?
Arteries and veins run in close proximity to exchange heat, conserving heat in core areas.
Examples include tuna tails and sheep’s nose.
What is daily torpor?
A short-term reduction in metabolic rate and body temperature, common in small animals.
This is an energy-saving strategy during periods of inactivity.
What is hibernation?
Extended metabolic reduction in small mammals during winter, with body temperature dropping to near ambient.
Metabolic rate can reduce to ~7% of normal.
What are the two main types of dormancy states?
- Sleep
- Hibernation
Other dormancy states include daily torpor and estivation.
Fill in the blank: The hypothalamus triggers _______ mechanisms when warm sensors are activated.
cooling.
Cooling mechanisms include sweating and vasodilation.
True or False: Humans are entirely homeothermic.
False.
Humans are partially heterothermic, with variable temperature in extremities.
