Do you think ‘The Iceman’ can really will himself to be warmer?

In the next 30 sec, list 5 things you might do to try and warm up if you were him…

Share your list with a partner…

Are there any similarities? Any things you didn’t think of?

How is that animals are able to maintain their temperature in a range of environments?

Ectotherms

Usually at the temperature of their environment

Do not have an internal method of heat production

Lower energy needs and cells function so slowly at low temperatures they are often inactive during winter

Ectotherms

ADVANTAGES

Use less food in respiration

Need less food

Can use more energy from food for growth

DISADVANTAGES

Less active in cooler temps

May not be capable of activity during winter due to the need to hibernate

Heterotherms

Some ectotherms can sometimes function as endotherms

Allows animals to be more active

Endotherms

Maintain a relatively constant body temperature Usually higher than their surroundings

Generate heat by internal metabolic heat production

Have mechanisms by which to regulate loss/gain of heat

Endotherms

ADVANTAGES

Constant temp.

Active in cold temp.

Can inhabit colder countries

DISADVANTAGES Lots of energy used to

regulate body temp.

More food needed

Less energy from food goes into growth so more food needed

Regulatory mechanisms

These include structures: Feathers

Fur

Fat

Physiological mechanisms Hibernation

A note on terminology…

“Cold-blooded” is not correct – their blood will be warm when

the environment is warm.

“Warm-blooded” is also not correct – a hibernating bat

maintains its temperature at about 10 °C.

Explain the graph…

Temperature-regulating Pathways

Thermoregulation

Maintenance of body temperature within a range that enables cells to function efficiently

The maintenance of body temperature in endotherms is an example of dynamic equilibrium

Sensing: Detecting temperature change

Sensing: Detecting temperature change

Involves disturbance and misalignment detectors

Temperature receptors in skin (disturbance)

Misalignment detectors in the hypothalamus

Group of temperature sensitive cells trigger homeostatic responses if blood temperature deviates

Responding: regulating heat exchange

Heat loss

Radiation

Evaporation

Conduction

Loss of body fluids

To the environment

Heat gain

Metabolism

Environmental & behavioural

In a cold environment…

We must conserve body heat and gain heat to maintain body temperature Vasoconstriction – blood vessels near the surface of the skin

narrow, reducing the volume of blood near the surface, reducing the heat lost to the environment from the blood

Shivering – Muscles contract to produce heat via metabolic reactions

Hair-raising – muscles in the skin at the base of each hair contract, raising hairs and trapping air, forming an insulating layer.

Increased metabolic rate – respiration increases to generate more heat

Sweating reduced

Behavioural mechanisms – huddling, sheltering

In a hot environment…

We must lose body heat to maintain our core temperature Vasodilation – Blood vessels near the surface of the skin dilate and

increase in volume, allowing more blood to flow through, radiating heat away through the skin

Sweating – water evaporates from the surface of the skin, using heat energy to turn the liquid into water vapour. Prevalent in humans as we lack body hair. In other mammals this takes place from the tongue and mouth

Body hair flattening – removes the insulating layer

Behaviours – not performing metabolic activity, sheltering

For you to think about…

Why do we go pink when we are hot?

For you to think about…

Over to you…

On a piece of paper, list 2 mechanisms the body can use to regulate temperature in a hot environment and in a cold environment…

Your homework task!

Compare and contrast a central heating system with your body’s temperature control system. What type of feedback control regulates both these systems?

Using Inspiration, illustrate both negative feedback loops involved in thermoregulation. Be sure to include Stimulus, Receptor, Regulator, Effectors. Be detailed and clear. It is up to you whether you present this as a flowchart, picture or concept map!