Big Idea #2:Cellular Processes and

CommunicationBiological systems utilize free energy and molecular building blocks to grow, to reproduce, and to maintain dynamic homeostasis.

Questions to ponder…What is human body temperature in

Celsius?Is there an average body temperature for

animals?How does the body use feedback order to

maintain a constant body temperature?Can we connect properties of water to

thermoregulation?

What is the optimal temperature range?

Mammals 36-38 C ; Birds 39-42 CAmphibians & Reptiles: varies greatlyThermoconfomers:

Fish: within 1-2 C of surrounding water Invertebrates: with some exceptions (bees)

Role of Water PropertiesDefine

High specific heat? Explain in terms of the

structure of water.

Apply

Air vs. water temp?Connect to marine

vs. land animals?Role in daily and

seasonal change?Animal adaptations?

EctothermsHeat transfer

occurs easilyMetabolic rate has

little effect on body temperature

Invertebrates, fishes, amphibians, reptiles

Endotherms Body warmer

than the environment

Due to high metabolic rate

Birds, mammals, bees and moths

Why aren’t they called cold blooded or warm-

blooded?

Who has an advantage? Endotherms

Can perform vigorous activity for long periods of time.

Can tolerate winter and hot environments

Ectotherms: Cost of food Human: Metabolic

resting rate of 1300 kcal/day

Alligator: Metabolic resting rate of 60 kcal/day

Investigating a Negative Feedback Loop

StimulusSensorSet PointResponseNegative Feedback

Evaporative Cooling Panting, Sweating,

Bathing Water absorbs heat when

it evaporates which has a cooling effect. Summer topor: low

metabolism due to high temperatures

Daily topor: animals go inactive when temperature isn’t ideal

Vasodilation/Vasoconstriction

Vasodilation: increase in the diameter of superficial blood vessels (cools)

Vasoconstriction: decrease in the diameter of blood vessels (warms)

Metabolic Change Movement, shivering

increase muscle contraction.

Heat is a waste product of metabolism

NST (nonshivering thermogenesis)

Brown Fat: tissue specialized for using mitochondria for heat production instead of ATP

Human Thermoregulation

Formative Assessment

Formative AssessmentPart of Feedback Loop? Cross country skiing on a

warm day. You have dressed in layers and you have just climbed your first incline.

Part of Feeback Loop? Oops…you didn’t dress

for the weather. You are out cross country skiing and stopped to take a break. Suddenly, clouds cover the sky and the wind picks up. You have forgotten your hat and gloves.

What is postive feedback then?

Does positive feedback happen?

Let’s look at an example with water and climate change.

More feedback loopsPreview the role of

the thyroid:

How does the brain and the thyroid control metabolism?

How does the thyroid and parathyroid control blood calcium?

More on Water PropertiesFor each property of water:

Description Structure Meets Function

Implications

What is the property?

How does the structure of water cause this property?

How does this impact life on Earth?-At the organism level?-At the ecological level?