Homeostasis Lesson 1: Part 2 Flashcards
What is thermoregulation?
The process in which animals maintain an internal temperature within a tolerable range
It is critical to survival because biochemical and physiological processes are sensitive to changes in temperature
—> enzymatic reactions
—> properties of membranes
One of two ways to maintain Body Temperature?
Poikilothermy: body temperatures is not controlled but varies with ambient temperature, as in invertebrates and most fishes. Poikilotherms do not necessarily have widely fluctuating body temperatures
Homeothermy: maintenance of constant body temperature that is usually high! Here consistency matters over heat!
Modes of heat exchange? —> Explain them!
Radiation
Evaporation
Convention
Conduction
Balancing heat loss and gain
1- insulation
2- circulatory adaptations
3- cooling by evaporative heat loss
4- adjusting metabolic heat production
Insulation
feathers, hair or fat layers
Reduces the flow of heat between an animal and its environment
Lowers energy cost of staying warm
Most land animals and birds react to cold by raising fur or feathers
—> traps a thicker layer of fur
—> increasing its insulating power
Goosebumps?
Raise hair on body
Inherited by ancestors
We rely on a layer of fat underneath the skin
Circulatory adaptations
We can alter the amount of blood (hence heat) flowing between the body core and skin
Vasodilation
Muscles in superficial blood vessels relax
Increases the diameter of vessels = more blood
Increases heat transfer, releasing heat energy to surroundings
Vasoconstriction
Muscles in superficial blood vessels contract
Smaller diameter of blood vessels = less blood
Reduces heat transfer: preventing heat loss
Keeps blood (and heat) in interior of body where it’s needed
Evaporative heat loss
When environmental temperatures are above body temperature animals
Sweat, pant, bathe, spread saliva over body surfaces
Heat is carried away with water molecules as they change into a gas
Adjusting metabolic heat production
Shivering and moving —> heat production is increased by muscle activity
Non shivering thermogenesis (NGT) certain hormones can cause mitochondria to increase their metabolic activity and produce heat instead of ATP
What is the insulating material for mammals
The integumentary system (hair,skin,nails)
What regulates our temperature?
Hypothalamus - contains a group of nerve cells
that function as a thermostat
Illustrate what happens in a cold or hot response?
Slideshow 1: 30-31
