Ectotherms

Endotherms

Daphnia

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Oxygen consumption is used as a measure of the rate of respiration.
True
 False
In sea lions the major skin layer involved in temperature regulation will be
adipose tissue
 hairs
 dermis
 capillaries
The part of the brain involved in temperature regulation is
pituitary gland
 medulla
 hypothalamus
 cerebellum
When the body temperature rises heat loss can be increased by
The capillaries expanding in size
 the arterioles dilating to increase blood supply to the skin
 the arterioles moving closer to the skin
 the capillaries moving closer to the skin surface
Raising of the hairs by the erector muscle reduces heat loss by
conduction
 convection
 radiation
 evaporation
Increased activity of the sweat glands increases heat loss by
conduction
 convection
 radiation
 evaporation
The way in which body temperature is normally regulated is an example of
negative feedback
 postive feedback

Ectotherms and Endotherms

These sea lions are on a New Zealand beach in winter. How do endotherms keep their internal temperature constant?

Endotherms

Endothermic animals generate their own body heat. This heat comes from animals metabolism, chemical reactions within the body.

Endotherms require less energy to maintain their body temperature as the temperature of their surroundings increases.

 

Despite this endotherms still need to control heat loss. Without this the body temperature would still fall too low, or high.The skin has a major role in the control of heat loss.

In humans it is the hypothalamus which acts as a thermostat and helps to control body temperature. It is sensitive to the temperature of the blood flowing through it and causes changes in the physiological mechanisms by which we regulate temperature (Revision: what are these?) . The hypothalamus is linked via the autonomic nervous system to the appropriate effectors. The highest critical temperature that a human can tolerate varies according to the humidity of the atmosphere. At the high critical temperature the bodies ability to thermoregulate breaks down. The metabolic rate starts to increase with increasing temperature. Eventually this will lead to a positive feedback situation as the increased body temperature itself increase the metabolic rate which in turn increases body temperature. 42*C is the upper lethal body temperature.