Transformations of Energy and Matter: Nutrition and Homeostasis

Lecture 2

Heterotrophs

organisms that require preformed organic molecules as sources of energy/chemical building blocks

How do heterotrophs obtain energy?

by breaking the chemical bonds of organic compounds obtained from other organisms

How do heterotrophs build their tissues?

from matter present in preexisting organic compounds

Second law of thermodynamics

any organized system, left to itself, tends to lose organization and become more random

How does the second law of thermodynamics relate to animals?

animals need to obtain energy so they can do work to maintain their organization; it takes energy to create and maintain organization

Types of feeding

1. predation

2. suspension feeding

3. symbiosis

Nutrition

study of how animals meet their needs for both chemical substances and energy

The molecules in an animal’s body are made from…

the molecules in the animals food

Essential nutrients

required but cannot be synthesized by the animal

Standard amino acids

20 amino acids animals need to build proteins; animals can synthesize some of these (nonessential)

Essential amino acids

ones that cannot be synthesized and must come from food

Essential fatty acids

omega-3 and omega-6

The eight essential amino acids for humans

• PVT TIM HALL

• Phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histidine, leucine, lysine

Essential Vitamins

vitamin A, vitamin K

Essential minerals

chemical elements that animals require

How can energy content of food be measured?

by the amount of heat the food produces when completely burned in the presence of O₂ producing CO₂ and H₂O

Calories

amount of heat needed to raise 1 gram of H₂O by one degree

Metabolic rate

amount of chemical bond energy consumed and converted to heat per day

Types of food molecules

1. lipids: fats and oils

2. carbohydrates

3. proteins

Relationship between metabolic rate and food need

metabolic rate increases = food need increases

How can metabolic rate be measured?

determining the rate of O₂ consumption

Relationship between metabolic rate and activity

activity = metabolic rate increases

BMR

• basal metabolic rate

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

Scaling relationships

animal characteristics as functions of body size

Relationship of BMR and size

• BMR per gram body weight decreases = animal size increases

• small mammals need more food per gram of body weight than large mammals do

Interstitial fluids

tissue fluids that the animal’s internal environment are bathed in; regulates temperature

Regulation

occurs when the internal environment stays constant even as the external environment changes

Regulators

• animals that can maintain constant internal conditions

• provides stability but is energetically expensive

Conformers

• internal environment varies so that it always matches the external environment

• external T increases = internal T increases

• energetically cheap, but cells must be able to cope w/ changes

Animal bodies are mostly…

water

Intracellular fluid

fluid inside of cells

Extracellular fluid

the rest of the fluid within the body; includes blood plasma and interstitial fluid

Epithelium

sheet of epithelial cells; covers a body surface/organ or lines a body cavity

Simple epithelium

single layer of cells; nonliving basement membrane; lines all blood vessels, intestines, and other tubules

Functions of the epithelium

1. pumps ions between fluids on either side

2. secretes substances (hormones, mucus, sweat, milk, digestive enzymes)

3. absorbs nutrients

4. sensory functions

Cell membranes are…

thin layers separating the extra- and intracellular fluids

Roles of membranes

1. pumps ions

2. producing and receiving physiological signals

3. controls diffusion

Tissue

assemblage of cells of similar type

Organ

2+ types of tissues w/ a defined structural relationshop to each other

Multi-organ system

multiple organs working together