Brown fat and heat regulation college block 2.3
Temperature
‘measure of heat’
ppt.
If the ambient temperature increases, the oxygen consumption increases as well, and the energy
expenditure as well: all the processes are going faster.
The most of the energy that you put in to exercise is being converted into heat: heat production.
A reptile has a fixed temperature: he can do this behaviourally.
We have a stable temperature.
When we get in a cooler environment, our metabolic processes go up (red line): we need to stay
warm.
Via decreased perfusion in the extremities, we can reduce heat loss. In a hot environment, we have a
lot of perfusion in the extremities: get rid of heat.
Thermoneutral zone: temperature range at which we can remain our core temperature at a level by
perfusion: 28-32 degrees. When we are having clothes on, this shifts to the left: we live in a room of
about 21 degrees.
Between 28-32 is the comfort zone of ambient air.
In a cool environment, the most of the blood is in the core of the body: much in the intestines which
have a big store of blood. In a hot environment, a lot of the blood is distributed to the extremities.
Heat production and exchange mechanisms
- metabolism: you can only have heat production.
- conduction.
- convection.
- radiation,
with these 3 you can produce and loos heat.
- evaporation: lose heat.
You measure heat production in indirect calometrie.
Heat conduction
Energy that is transported. Normally this isn’t that important.
The heat transmitted from the hand to the air for example.
Heat convection
You get a sort going on process with the combination of conduction and convection. With convection
you lose about 15%. It’s a combination of temperature and wind.
Because you warm up air (conduction) this air is flowing, and you all the time warm up new air
(convection) combination is important.
Heat radiation
This is an important one: upto 60% of heat loss.
Evaporation
Temperature
‘measure of heat’
ppt.
If the ambient temperature increases, the oxygen consumption increases as well, and the energy
expenditure as well: all the processes are going faster.
The most of the energy that you put in to exercise is being converted into heat: heat production.
A reptile has a fixed temperature: he can do this behaviourally.
We have a stable temperature.
When we get in a cooler environment, our metabolic processes go up (red line): we need to stay
warm.
Via decreased perfusion in the extremities, we can reduce heat loss. In a hot environment, we have a
lot of perfusion in the extremities: get rid of heat.
Thermoneutral zone: temperature range at which we can remain our core temperature at a level by
perfusion: 28-32 degrees. When we are having clothes on, this shifts to the left: we live in a room of
about 21 degrees.
Between 28-32 is the comfort zone of ambient air.
In a cool environment, the most of the blood is in the core of the body: much in the intestines which
have a big store of blood. In a hot environment, a lot of the blood is distributed to the extremities.
Heat production and exchange mechanisms
- metabolism: you can only have heat production.
- conduction.
- convection.
- radiation,
with these 3 you can produce and loos heat.
- evaporation: lose heat.
You measure heat production in indirect calometrie.
Heat conduction
Energy that is transported. Normally this isn’t that important.
The heat transmitted from the hand to the air for example.
Heat convection
You get a sort going on process with the combination of conduction and convection. With convection
you lose about 15%. It’s a combination of temperature and wind.
Because you warm up air (conduction) this air is flowing, and you all the time warm up new air
(convection) combination is important.
Heat radiation
This is an important one: upto 60% of heat loss.
Evaporation
