1. John Stein Office Hours (SFH 354) -Thursdays 5-6 pm
-Friday 12-1:00pm (lunch)
-Friday 1-3pm (SFH 354)
-or by appointment
- After class on Wed and Fridays

2. Tips for success… Look at the readings before class.
Pay careful attention to the content and questioning that occurs in class, lab and homework assignments.
Go back to readings to reinforce what was covered in class. (Lectures Slides will be posted)
Some exam questions will cover content while others will involve analysis, critical thinking skills and application of knowledge; the kind of stuff we do in class, lab and homework assignments.
(Freeman often does this as well!)

3. Physiology – the study of body functions Anatomy - the study of body structure
“Function follows Form” – if it looks interesting there must be a reason.
Much more meaning when we study physiology in light of what we know about evolution and molecular and cellular biology
Comparative Physiology
Relate to Adaptation, Natural Selection

4. Major Recurring Themes
Constrained by laws of chemistry and physics
Diffusion and Surface area to volume ratio
Homeostasis
Evolutions role in developing diverse physiological systems.

5. Today’s Goals Layout of organisms
Issues encountered as body size increases
Internal environment and maintaining homeostasis
Role of negative feedback in maintaining homeostasis
Analytical skills and asking good scientific questions with body temp/torpor example
Cell communication via Endocrine and Nervous Systems – Introduction…maybe.

6. To Maintain HOMEOSTASIS!
literally means “alike-standing.”
does NOT always mean “keeping oneself the same”.
(chemical & physical states kept within a tolerable range)
can be seen at many levels throughout an organism…from whole organism (temperature) to cellular/molecular level (enzymes, transcription factors).

7. Multicellular Organisms
What does this cell need?
Hospitable Environment
What defines hospitable?
Some cells are more particular than others when it comes to pH, temp, oxygen, etc.
Brain cells – very finicky
Muscle cell – more tolerant

8. Homeostasis “alike-standing”
Water
Oxygen
Carbon Dioxide
pH (-log [H+])
Temperature
Osmolarity
Nutrients
Wastes
Pathogen-free
environment
Normal Range Lethal
98.60F
(370C) ( C) (18-430C)
(Sodium)
142mM
( for humans )

9. Hierarchy of Organism Cell (cardiac muscle cell) Tissue (muscle)
Epithelial
Connective
Nervous
Muscle
Organ (Heart)
Organ System (Cardiovascular)
Organism (Elephant Seal)

10. Diffusion is a major concern for multicellular organisms
Diffusion is a major concern for multicellular organisms. Bulk Movement for large distances

11. Surface area : Volume BUT!!
surface area of structures like lungs and blood vessels are proportional to volume of animal!
S.A. = L2 * 6
Vol. = L3

12. Surface Area to Volume Ratio (and body temperature)
65 kg human walks from shadow to sun with little effect on body temp
10 mg fly moves from shadow to sun and body temp increases 10 0 C in 10 seconds!

13. Surface Area to Volume Ratio (for different sized cats)
0.1 square meters of skin on 1 kg cat (0.1/1) 0.46 square meters of skin on 10kg cat (0.046/1) 1.53 square meters of skin on 60kg cat (0.0255/1)
This ratio is significant in maintaining proper body temperature
(e.g. small animals cool more quickly than large animals.)
How can small animals reduce surface area to volume ratio?

14. Negative Feedback Set point (desired temp) Integrator (desired - current = ? If not = 0 then…) Effector (make current = desired temp)

15. Heating and Cooling cost energy and resources!

16. “Warm Blooded” & “Cold Blooded”
Endotherms & Ectotherms
(heat from within) (heat from outside)
Homeotherms & Heterotherms
(same temp) (different temp)
There are no hard and fast rules here.
(e.g. some insects are endotherms and some mammals are ectotherms)

17. Is the body temp of this very small (~20 grams) mammal under homeostatic control?

18. Is the body temp of this very small (~20 grams) mammal under homeostatic control during torpor?