Announcements• Have your “I am a _________ cell” information

ready.• Knowledge survey on-line: check email for link• Personal info (voluntary) due Friday• Group pictures in lab this week• Community of Scholars Research Symposium

– Saturday Sept 12– 10 wks paid research on topic of your choosing!– Summer 2010

The body: A society of interdependent cells, each type with its own needs and contributions.

The Human Body:A Society of Cells

• Imagine you are a cell. Ask yourself:• How did I get here? • What do I do for myself? (What are my special characteristics and

functions?) • What do I do for the person in whom I reside? (What are my

contributions to the whole organism? To homeostasis?) • What do I need simply to survive?• What do the other cells provide for me that I cannot obtain alone?• What governs my actions? • How long will I live?• Can I be replaced? If so, how?• What would happen to the organism if I along with all the other cells

of my type were to fail to function properly?

O2 pHCO2

Temp,[glucose],[Na+],[K+],[Ca++],amino acidsNucleic acids

Cell Membrane: selectively permeable

Capillaries: highly permeable except to proteins

Homeostasis:

• The relative constancy of the internal environment

• Steady state vs. equilibrium

BeggarThessaloniki, Greece

Homeostasis:

• The relative constancy of the internal environment

• Steady state vs. equilibrium

Street vendorThessaloniki, Greece

Homeostasis:

• The relative constancy of the internal environment

• Steady state vs. equilibrium

San womanKalahari Desert, Botswana

Homeostasis:

Camp’s Bay Beach, Cape Town, South Africa

Homeostasis:

Phillip cooling off in waterfall, Vietnam

~37o

C

Homeostasis

• Regulated via reflex arcs and naturally maintained by the process of negative feedback

• Measurement– Which physiological variables?– Averages and ranges

Fig. 01.08Awake AwakeSleep SleepDiurnal cycles

Thermoregulation

The Challenge:# 1: Melt these 6 ice cubes as fast as possible. How to do it?# 2: Make these 6 ice cubes last as long as possible? How to do it?

These are non-living objects: heat exchanges with the environment but they don’t generate heat from metabolism as living things do!

• Conduction

• Convection

• Evaporation

• Radiation

Metabolism generate heat, metabolism is variable!

~37o

C

Modes of Heat Exchange: Conduction Convection Radiation Evaporation

~37oC

Modes of Heat Exchange: Conduction Convection Radiation Evaporation

~37o

C

Modes of Heat Exchange: Conduction Convection Radiation Evaporation

~37o

C

http://www.nws.noaa.gov/os/windchill/windchillglossary.shtml