Introduction to Animal Systems

Before we begin to study different organ systems in animals,  we need to learn some of the important foundations of animal anatomy and physiology:

• Homeostasis 
• Negative Feedback Loops

Homeostasis

Animals are trying to create a stable internal environment (homeostasis) so that their cells, tissues and organs can function  properly.  The problem is that our external environment can fluctuate wildly.  In this picture,  you can see that humans are able to live in very extreme temperature environments, but our internal temperature will stay around 98.6 ^o F (with some fluctuations)

 What are other examples of homeostasis (stable internal environment) in an animal's body?

Negative Feedback Loops and Flow of Information 

How does our body maintain these stable internal conditions? We  have a series of automatic controls that can 

• • • Sense a change in the internal environment- done with receptors
    • Send a signal to reverse the change - can be via the nerves or hormones 
    • Return to normal conditions. - usually done by actions of muscles or glands. 

Here is a sketch showing the generic process

 Using our example of body temperature, the sensors would detect a decrease or increase in body temperature. If the body temperature is too low, then we begin to shiver. This muscle movement generates heat and our body temperature rises and we stop shivering. If the body temperature is too high, then we begin to sweat. This will cool us down and we stop sweating. 

 Both parts of  this process together equal the negative feedback loop. 

Tissues, Organs and Organ Systems.

The body of an animal can be broken down into the organ systems, that are composed of different organs. We will examine the

• • • Digestive System
    • Immune System
    • Endocrine System: the  hormone system
    • Lymph System: a subset of your circulatory system that helps with immune function

The organs are made up of different tissues, which are made up of different cell types.   Here are some examples of different tissues that you can find in an animal's body

• • • Muscle tissue
    • Nervous tissue
    • Connective tissue (bone, tendon, but also blood)
    • Epithelial tissue (these are tissues that line the inside or outside of organs. 

Core Concept: Biological Organization

In this section of the course, we will focus on the Biological Organization. As you remember, this is the idea that to understand a whole organism, you need to examine the parts that make up the organism: the organs, tissues, cells and even organelles.

We will examine the organs that compose the Digestive System. Then we will look at the two organs that are part of the Endocrine System, the pancreas and the liver. We will delve down to the cell level to understand how the control Blood Glucose levels.  Each of these topics will require us to think about the whole organism, organ systems, organs, tissues, cells and molecules.