Lecture 3- Energy & Temperature

What term describes organisms that require preformed organic molecules for energy and chemical building blocks?

Heterotrophs

Animals obtain energy primarily by:

breaking the chemical bonds of organic compounds obtained from other organisms

Can animals build their tissues from inorganic matter present in the environment?

NO! Animals build their tissues from matter present in preexisting organic compounds obtained from other organisms

Do animals need chemical building blocks for growth or to replace cells throughout life?

BOTH!

How to animals obtain energy and chemical building blocks?

Eating nutrients, amino acids, fatty acids, minerals, carbohydrates, proteins.

ex. humans requiring linoleic acid and alpha-linoleic acid within their diet.

What is metabolic rate?

The amount of chemical bond energy consumed & converted to heat per day.

What are the three types of food molecules that are used to calculate the metabolic rate? (oxidized)

1. Lipids (fats & oils)

2. Carbohydrates

3. Proteins

What is metabolic rate measured by?

Determining the rate of O2 consumption (when organic matter is oxidized during aerobic metabolism, O2 is used as heat is made, in a one-to-one relationship)

Does physical activity increase metabolic rate?

Yes! It’s the cost of exercise

Basal Metabolic Rate (BMR)

Is measured when animal is in a comfortable thermal environment and has not eaten recently

Does BMR per gram body weight decrease with animal’s size?

Yes! Small mammals need more food per gram of body weight than large mammals do

What are the body fluids that bathe the cells in an animal’s body called"?

Tissue fluids (or interstitial fluids)

Differentiate between an animal's internal environment and its external environment.

The internal environment consists of the tissue fluids surrounding the cells, while the external environment is the outside world.

What process occurs when the internal environment remains constant despite changes in the external environment?

Regulation (or homeostasis)

How does an animal's metabolic rate relate to its environment?

Metabolic rate depends on the ways animals relate to their environment.

Regulators vs. Conformers (temperature wise)

Regulators temp: An animal’s internal environment may be held constant when its external environment changes (birds/humans)

Conformers temp: The internal environment may be permitted to vary so that it matches the external environment (frogs/fish)

What does the term “homeostasis” refer to?

The stability of the internal environment & the mechanisms that maintain it

What is a major disadvantage of homeostasis?

It is energetically expensive

Do humans and many other animals exhibit very little homeostasis

No, they exhibit high degrees of homeostasis

Thermoregulation

Maintains body temperature within a range. Most cells only survive between O^*C and 40^*C

Homeostasis is parallel to what concept?

The concept of regulation; has the same pros and cons

Homeotherms (endotherms)

Animals that maintain a constant internal body temperature (thermoregulation); e.g. mammals & birds

Ectotherms

Body temperatures are variable and are determined by the external temperature

Poikilotherms

Vary widely in their body temperature limits and can control body temperatures through behavior, such as positioning themselves in the sun or shade (behavioral thermoregulation)

• Ex. Lizard “sunbathing” = basking

• Can tolerate extreme tissue temperatures

The difference in metabolic rate for a vertebrate homeotherm and a vertebrate poikilotherm of the same body size.