Chapter 40
BASIC PRINCIPLES OF ANIMAL
FORM & FUNCTION
Problem Solving
 Animals must solve basic challenges of life:
 Obtain oxygen
 Nourish themselves
 Excrete waste products
 Move
 These questions will be addressed throughout
our next unit.
 Unifying themes that will be introduced here:
 Form & function are closely related
Vocabulary
 Anatomy – is the study of the structure of an
organism
 Physiology – is the study of the functions an
organism performs
 Bioenergetics – how organisms obtain,
process, and use their energy resources.
 Homeostasis – regulating internal
temperature
40.1
 Physical laws and the
environment constrain
animal size and shape.
 An animal’s size and
shape (body plan or
design) affect the way
it interacts with its
environment.
Physical Laws
 Physical laws and the need to exchange
materials with the environment place certain
limits on the range of animals forms.
 Examples: Aquatic animals (sleek streamlined
body forms) and flying animals (bones that allow
for the organism to generate enough lift to
become air born)
Exchange with the
environment
 Living cells must be bathed in a aqueous
medium to keep the plasma membrane intact
 Single celled organisms – Surface-to-volume ratio
Fig. 40.3a
Multicellular organisms
 Composed of numerous
cells which also must be in
water
 Saclike body plan
 Hydra Fig. 40.3b
 Flat body plan –
tapeworm
 Both of these put a large surface area in
contact with the environment but do NOT
allow for complexity in internal organization
 Complex body forms allow for: outer
coverings to protect against predators, large
muscles for fast movement internal digestive
organs to break down food gradually,
maintaining relatively stable internal
environment, and for living on land.
40.2
 Animal form and function are correlated at all
levels of organization.
 Tissues are classified into 4 main categories –
pg. 824-826
Epithelial
 Sheets of tightly packed cells
 Where is it found? Epithelial tissue covers the
outside of the body and lines organs and
cavities within the body
 Form & function? Closely joined (tight
junctions between them) so epithelium
functions as a barrier against mechanical
injury, microbes, and fluid loss.
 Types?
 Stratified columnar
 Simple columnar
 Pseudostratified ciliated columnar
 Stratified squamous
 Simple squamous
 Cuboidal
 All have slightly different volumes of
cytoplasm which allow them to perform
different functions.
Connective Tissue
 Sparse population of cells scattered through
an extracellular matrix.
 Where is it found? Everywhere
 Form & function? Bind and support other
tissues
 Types?
 Loose connective tissue – holds organs in place
 Fibrous connective tissue – tendons & ligaments
 Cartilage
 Bone – mineralized connective tissue
 Blood
 Adipose tissue – stores fat
Muscles tissue
 Long cells called muscle fibers
 Where is it found? Everywhere!! Most
abundant tissue in most animals
 Form & function? Contraction brings about
movement
 Types?
 Skeletal – attaches to bones – voluntary movement
 Cardiac – striated – involuntary
 Smooth – lacks striations - involuntary
Nervous Tissue
 Nerve cells
 Organs & organ systems – see table 40.1 pg.
827
40.3
 Animals use the chemical energy in food to
sustain form and function
 Bioenergetics – limits the animal’s behavior,
growth, and reproduction and determines
how much food it needs.
 Fig. 40.7 – After the energetic needs of
staying alive are met any remaining
molecules from food can be used in
biosynthesis (body growth & repair, storage
material such as fat and production of
gametes)
 Metabolic rate – the sum of all the energy-
requiring biochemical reactions occurring
over a given time interval.
 Energy measured in Calories (cal) or kilocalories
(kcal)
 Unit Calorie with a capital C is actually a kilocalorie
 Energy appears as heat so metabolic rate can be
determined by measuring heat.
2 Bioenergetic Strategies
 Endothermic – bodies are warmed mostly by
heat generated by matabolism and body
temperature is maintained within a relatively
narrow range.
 Ectothermic – meaning that they gain their
heat mostly from external sources
Endo or Ectothermic?
Endo or Ectothermic?
Endo or ectothermic?
Influences on metabolic rate
 Size and metabolic rate: amount of energy it
takes to maintain each gram of body weight
is inversely related to body size. (Example –
each gram of a mouse requires about 20
times more calories than a gram of an
elephant)
 Activity and metabolic rate: every animal
experiences a range of metabolic rates. Basal
Metabolic rate (BMR) – metabolic rate of a
nongrowing endotherm that is at rest, has an
empty stomach, and is not experiencing
stress.
 1,600-1,800 kcal per day for adult male
 1,300-1,500 kcal per day for adult female
 Standard Metabolic rate (SMR) – metabolic rate of a
resting, fasting, nonstressed ectotherm at a
particular temperature.
 Maximum potential metabolic rates and ATP sources
– pg. 830 fig. 40.9
 Energy budgets – pg. 831 Fig. 40.10
40.4
 Many animals regulate their internal
environment within relatively narrow limits
 Interstitial fluid (Bernard more than a century
ago) – internal environment of vertebrates –
today homeostasis – steady state
Regulators vs. Conformers
 Regulators – animal is a regulator for a
particular environmental variable is it uses
internal control mechanisms to moderate
internal change in the face of external
fluctuation
 Conformer – an animal is said to be a
conformer for a particular environmental
variable if it allows its internal condition to
vary with certain external changes
 Regulators and conformers are extremes and
no animal is a perfect regulator or conformer
 Some animals may regulate some internal
conditions and conform to external
conditions for others.
Mechanisms of Homeostasis
 Negative feedback – thermostat in your
house pg. 832 Fig. 40.1
 Positive feedback – amplify rather than
reverse the change (child birth)
40.5
 Thermoregulation – process by which animals
maintain an internal temperature within a
tolerable range. Critical because most
biological processes work best at optimal
conditions (plasma membrane)
Ectotherms vs. Endotherms
 Ectotherms include invertebrates, fishes,
amphibians, lizards, snakes, and turtles
 The amount of heat they generate has little effect




on body temperature
Bask in the sun to warm
Seek shade to cool
Can tolerate greater variation in internal
temperature than endotherms
Not “cold-blooded”
 Endotherms include mammals, birds, some
fish, and numerous insect species
 Can use metabolic heat to regulate body
temperature
 Sweating to cool
 Not “warm-blooded”
Advantages & Disadvantages
 Advantages – able to generate a large amount of
heat metabolically – can perform vigorous activity
for much longer than is possible for most
ectotherms, can tolerate extreme temperatures
 Disadvantages – energetically expensive – requires
more food
Modes of heat exchange
 Conduction
 Convection
 Radiation
 Evaporation
Balancing heat loss & gain
 Insulation
 Circulatory adaptations
 Cooling by evaporative heat loss
 Behavioral responses
 Adjusting metabolic heat production
Insulation
 Skin, hair, nails, fur
 Skin houses nerves, sweat glands, blood
vessels, and hair follicles
Insulation
Circulatory adaptations
 Vasodilation (warms skin) – increases in
diameter of superficial blood vessels
 Vasoconstriction (cools skin) – reduces blood
flow and heat transfer by decreasing the
diameter of superficial blood vessels
 Countercurrent heat exchanger – important
for reducing heat loss in many endotherms
Cooling by evaporative heat
loss
 Water absorbs considerable heat when it
evaporates
 Panting
 Sweat glands
 Spreading saliva on body surface
Roxy panting!!
Behavioral responses
 Both ecto and endotherms
 Hibernation
 Migration
 Huddling in cold weather
Adjusting metabolic heat
production
 Endotherms must counteract constant heat
loss
 Heat production is increased by shivering
 NST – nonshivering thermogenesis (produce
heat instead of ATP)
 Feedback mechanisms
controlled by
hypothalamus in the
brain
 Acclimatization – both ectotherms and
endotherms can adjust to new range of
environmental temperatures.
 Shedding, growing a thicker coat
 Heat shock proteins – help maintain integrity of
cell’s proteins when exposed to extreme heat so
they don’t denature
Torpor & energy conservation
 Torpor – a physiological state in which
activity is low and metabolism decreases
 Hibernation – long term torpor to winter cold and
food scarcity
 Estivation – summer torpor
 Daily torpor – adapted to feeding patterns