LAB EXERCISE # 9 – METABOLISM AGAIN?
Today, we will examine the hierarchical organization of organs and organ systems of multi-
cellular organisms like ourselves. We will try to connect the study of organs and organ systems with the
cellular concepts that we have studied all semester. In one lab period, we cannot study all the organ
systems and will therefore concentrate on the
digestive, circulatory, respiratory, and excretory
(urinary) organ systems
and will not specifically cover the nervous, skeletal, muscular, endocrine and
reproductive systems. Likewise, we may refer to tissues in the lab but will not cover the study of tissues
(histology) in depth.
Cells are highly organized and, in the end, all physiological processes are cellular in nature. For
example, ultimately all nutrients and wastes enter and leave the cells by way of the plasma membrane;
and ultimately it is the mitochondrion in the cell that provides us with the energy to function as an
organism. In the lab covering photosynthesis, you will learn that the energy supplied by radiant energy
provided the means to make carbohydrates that enter your body in the form of food. This food then
provides the materials for synthesizing proteins and other components of the cells. Other food materials
come from catabolic reactions that breakdown complex molecules.
Tissues are defined as groups of similar cells performing a similar function. Animals also have
four major tissue types, whose primary functions are as follows: epithelial: secrete/absorb -muscle:
facilitate movement - nervous: conduct neural impulses – connective: binding, supporting, forming
blood, storing fats, filling space
Two or more tissues that perform a specialized function are defined as organs. Organs are further
organized into organ systems. Keep in mind that although we may look at the systems individually, the
organ systems for the most part work together. For example, what if you were hungry?
What if you had a hamburger, French fries and a soda sitting in front of you? Have you ever
considered the number of anatomical and physiological processes at all levels that need to be involved in
eating the lunch? You might assume that the digestive system is all that is needed to begin the
breakdown of the food. It actually takes multiple systems working together to satisfy your hunger and to
give you energy to function.
Let us consider partly what it takes. First, the
is informed by the
that you are hungry. But before the stomach is involved, you will need
put the food in your mouth, to bite it, to chew it, and then to swallow it.
Nerves also become directly
involved in the actions of the stomach.
Nerves dilate blood vessels
of the circulatory system to bring
and intestines for activities later related to