Your Professor:

ZOOLOGY 422/423

Spring, 1999

Your Professor:: Dr. William J. Higgins

On to the Syllabus!

Prerequisites:

ZOOL 211 and CHEM 233
Textbook(s)
Recitation/Lab Manual

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Our Web Home Page: http://www.life.umd.edu Get the syllabus and the lecture outlines ahead of time now!

Exams & Grades: be sure to review these now!

Higgins's Three Rules of Biology:

Testosterone makes you stupid.

Exercise is bad for you (we'll explain later).

Life depends upon molecules changing shape.

In the end, entropy always wins.

Recitations and Laboratories
Begin NEXT Week: 1 February 1999

A Few Suggestions:

Come to Class (on time)!
Recopy Your Notes
Use the Sample Problems
Answer the Recitation Questions
Study Groups
Slow me down??

A FEW MORE SUGGESTIONS:

ASK

ASK!

First Assignment:

See the syllabus and review the prerequisite background materials. Now, please.
Conduct a review of membrane and action potentials. See the textbooks and the course manual for explanations and sample problems.

Why Multicellularity?

Specialization
Size
Isolate Interior vs. Exterior

Problem:
Diffusion Distances

As diffusion distance (X) increases, the time required for diffusion increases proportional to X²

To overcome diffusion distance,
move part of the extracellular fluid among the cells and the environment.
Use it as a shuttle.

Internal Fluid Compartments

extracellular

plasma (vs. serum)

cerebrospinal fluid

interstitial fluid

intracellular

The internal fluids must all be at some constant conditions compatible with life.

The composition of this fluid also reflects the condition or state of the cells.

HOMEOSTASIS

maintenance of a constant, optimal internal environment

Thus, you utilize energy to combat ENTROPY!

Your organ systems evolved and function to maintain homeostasis so you can survive and remain in the gene pool!

To maintain homeostasis, organisms have evolved a control system: negative feedback, closed loop system. Notice how the input influences the output; it actually corrects or offsets it.