Transcript Basic Principles of Animal Form and Function

Basic Principles of Animal
Form and Function
Taught by Dhruv, Tommy, Zach,
and Butch
Physical Constraints on Size
 Physical laws govern strength, diffusion,
movement, and heat exchange limit the
range of animal forms.
 Ex. Streamlined body, maximum body sizes
Exchange with the
Environment
 Rate of exchange proportional to surface
area, amount proportional to volume.
 Multicellular organization only works if
every cell has access to a suitable aqueous
environment, either inside or outside.
 Ex. Inner, outer layers, flat body shape,
extensively branched or folded exchange
surfaces)
Hierarchical Organization of
Body Plans
 Tissues
 Organs
 Organ Systems
Tissue Structure and Function
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Four types of tissues:
Epithelial Tissue
Connective Tissue
Muscle Tissue
Nervous Tissue
Epithelial Tissue
 Covers the outside of the body and lines
organs and cavities within the body.
 Close packing allows enables it to function
as barrier against mechanical injury,
pathogens, and fluid loss.
 Epithelium (the cells) form active interfaces
with the environment.
Connective Tissue
 functions to bind and support other tissues.
 Sparse population of cells scattered through an extra cellular
matrix.
 Two types of connective tissue cells: Fibroblasts (secrete the
protein ingredients of extracellular fibers) and Macrophages
(cells that roam the maze of fibers, engulfing debris)
 Three types of connective tissue fibers: collagenous (provide
strength with flexibility, made of collagen, are nonelastic and do
not tear easily), elastic (easily stretched but are also resilient,
made of elastin), and reticular (very thin and branched, form
tightly woven fabric that joins connective tissue to adjacent
tissue.
Muscle Tissue
 The most abundant tissue in animals
 All muscle cells consist of filaments
containing actin and myosin, which together
enable contraction.
 Types: Skeletal, Cardiac, Smooth
Nervous Tissue
 Sense stimuli and transmit signals in the
form of nerve impulses from one part of
animal to another.
Regulators vs. Conformers
 A regulator uses mechanisms to regulate the
internal environment in face of external
change.
 A conformer allows its internal environment
to conform to external changes.
Regulator vs Conformer
Homeostasis
 Homeostasis: means “steady state” or
internal balance.
Feedback
Thermoregulation: process by
which animal maintains an
internal temperature within a
tolerable range
Endothermy and Ectothermy
 Endotherm: Warmed mostly by heat
generated by metabolism. Commom
Examples: Mammals, birds and insects.
 Ectotherms: Gain heat mostly from external
sources. Common examples: Lizards,
amphibians, snakes, many fish and
invertabrates
Poikilotherm vs. Homeotherm
 Poikilotherm: Body temperature varies with
the temperature of the environment
 Homeotherm: Body temperature relatively
constant despite temperature changes in the
environment.
Type of heat loss to the Environment
 Insulation reduces Heat Loss to the
Environment. Seen in birds in the form
of feathers, in marine mammals in the
form of blubber and land mammals in
the form of fur
Countercurrent Exchange
 Countercurrent exchange is flow of adjacent
fluids in opposing directions in order to
maximize transfer rates of heat or solutes.
 Antiparallel arrangement so that heat
transfer occurs along entire exchanger
Cooling
 Some animals sweat; as the water evaporates, it
absorbs heat and cools the animal
 Panting is important in many birds and mammals
(birds have a pouch): water evaporates from the
pouch or tongue
 Some animals, like honeybees, flap their wings to
improve evaporation and convection
Thermoregulatory Behavioral
Responses
 Move to warm or cool areas, move into or
out of wind
 Some animals, like honeybees, huddle
together to better retain heat
Metabolic Heat Production
 Shivering raises body temperature
 Some mammals can cause mitochondria to
produce heat instead of ATP
 Some reptiles become endothermic and produce
heat through shivering under special conditions,
such as when incubating eggs
 In insects, wing muscles are very important for
heat production.
Acclimatization
 Adjust to seasons by growing or shedding fur or
feathers
 Ectotherms are better at acclimatization and often
produce variants of enzymes that have the same
function but different optimal temperatures
 Change amount of saturated lipids in membrane;
saturated lipids decrease fluidity and unsaturated
lipids increase fluidity
Hypothalamus and Fever
 Hypothalamus: region of the brain that
functions as the thermostat
 Some endotherms develop fever to kill off a
bacteria infection; some ectotherms seeks
warmer environmental temperatures to kill
off a bacteria infection
Metabolic Rate
 A bigger organism has a higher metabolic rate than a smaller
organism
 For some unknown reason, bigger animals have a smaller
metabolic rate per kg than smaller animals, despite the fact that
a greater percentage of their body mass is devoted to
locomotion. This is all true for both ectotherms and
endotherms.
 Metabolic rate is roughly proportional to body mass to the
three-quarter power
 Animals typically have an average daily metabolic rate that is
2 to 4 times their BMR or SMR. Humans’ average daily
metabolic rate is 1.5 times their BMR- indicating their
sedentary lifestyles
Energy budgets
 Ectotherms have smaller average daily metabolic rates than
endotherms of similar size because they do not spend energy
on thermoregulation
 Smaller organisms must spend more energy on
thermoregulation because they have a high surface to volume
ratio, causing them to lose or gain heat more easily
 Animals, such as penguins, that have to swim to catch their
food spend a large fraction of their energy on movement,
because water has more resistance to movement than air
Energy Conservation
 Torpor: a physiological state in which activity is low
and metabolism decreases
 Hibernation: during the winter; Estivation: during
the summer
Diseases/Disorders
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Amyotrophic Lateral Sclerosis
Ross Syndrome
Parkinson’s Disease
Schizophrenia
Lymphocyte Homeostasis Syndrome