BIO 7:  Lecture 17 Preview

Your individual work on poster topics 1-5 is due today.  You will have some time at the end of lecture to meet.

Living things are made of molecules, which function best under specific conditions; temperature and water concentration are especially important conditions.  Homeostasis is the process of maintaining fairly constant internal conditions.

• Very high temperatures "cook" proteins; very low temperatures slow down molecules and change water to ice.
• Lack of liquid water prevents other ions and molecules from moving around freely
• Living things have structures and activities that help them function under fairly constant conditions.

For homeostasis gain = loss

Water is gained and lost differently in water and on land.

Larger animals have internal mechanisms to maintain water content.  Humans have an excretory (or urinary) system.

Heat is gained and lost in different ways in water and on land.

Some mechanisms for gaining and losing heat.

Endotherms (mainly birds and mammals) keep their body temperature fairly constant;  ectotherms' body temperatures vary with the outside temperature.

Energy is required to maintain a constant body temperature.  What is the endotherm's advantage?

 The integumentary system helps to regulate temperature and prevent water loss.