BIOL 211 – CELLULAR AND ORGANISMAL BIOLOGY

Lecture Outline for April 1, 2005

 

Topic: homeostasis

Chapter 30 sections 30.2, 30.3; chapter 38 section 38.1

Figures used in lecture: 30.6, 38.1, 38.2, 38.4, 38.5

Additional Resources:

            Homeostasis

            Homoestasis – includes some information on feedback systems for homeostasis

            Thermoregulation in animals

 

Homeostasis

Define/explain: homeostasis

You should be able to explain the basic principle of homeostasis for any physiological condition (eg, temperature, salt balance, pH, etc).  We will examine thermoregulation as an example of homeostasis.

Homeostasis: Maintaining the Internal Environment

Define: homeostasis, set point, sensor, integrator, effector, negative feedback, positive feedback

Be able to explain and give an example of negative feedback and positive feedback.

 

Thermoregulation

Most cellular functions are limited to 0-45oC (thermal limits for life), however, any particular species has a much narrower temperature range that it can tolerate.

Define and give an example of: homeotherm, poikilotherm, heterotherm, ectotherm, endotherm, countercurrent heat exchanger, brown fat.

 

Be able to describe mechanisms for thermoregulation for the following situations:

1. ectotherms

   a) mechanisms for conserving/producing heat

   b) mechanisms for releasing heat

2. endotherms

   a) mechanisms for producing/conserving heat

   b) mechanisms for releasing heat

 

Today’s Lecture (4-1-05)

 

Set point :

 

Sensor:

 

Effector:

 

 

feedback information :

 

            1.  negative feedback

 

 

 

            2.  positive feedback

 

 

 

 

Thermoregulation

 

 

Ectotherm:

 

 

Endotherm:

 

 

 

Mechanisms to control body temp:

1.  behavior

2.  regulate blood flow

3.  generate heat

4.  conserve heat

 

 

Thermoregulation

1.  Behavior

           

 

2. Regulate blood flow

           

 

3.  Generate heat

           

 

4. Conserve heat 

           

countercurrent exchange system :

Fig.  38.2

 

 

Thermoregulation

Heating Mechanisms in endotherms

1.  Shivering - releases ATP energy solely as heat

2.  Brown fat

3.  Insulation

4.  Body shape

 

Cooling mechanisms of endotherms

1.  Evaporation of water

2.  Immersion in water

3.  Carotid rete – cools the brain

 

Fig.  38.4

Fig.  38.5