Chapter 14 - Homeostasis

• homeostasis= the maintenance of a constant internal environment

CONTROL OF BODY TEMPERATURE

• endothermic animals= can keep their body temperature constant. They can get heat energy from within themselves (e.g. mammals and birds)>
• ectothermic animals= can't keep their body temperature constant. 

• If internal body temperature can be kept at around 37 celsius, than enzymes can always wor efficiently, no matter what the outside temperature is. This means an endothermic animal can be active in cold weather whereas a ectothermic animal wouldn't be able to move.
• Endothermic animals get their heat energy from food. Due to this, endothermic animals have to eat far more food than ectothermic ones. 

• The skin is the most important organs involved in temperature regulation in mammals. 
• The top layer of the skin is the epidermis.
• The lower layer of the skin is the dermis. 
• The cells in the epidermis are always dividing by a type of cell division called mitosis. 

• Most of the dermis is made of connective tissue. It also contains sweat glands. Sweat helps in temperature regulation. 
• Underneath the dermis is a layer of fat, called adipose tissue. This fatty tissue is made up of cells which contain large drops of oil. This layer helps to insulate the body against heat loss, and also acts as an energy reserve. 

• The hypothalamus is a…