Lecture

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Lecture 8 Introduction to Animal Structure and
Function
Images the two most beautiful cats in the
world, currently, as kittens and grownups
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Key Concepts

• What separates animals from other organisms?
• Introduction to structure and function
  relationships the implications of being
  multicellular
• Hierarchical organization in animals
• Tissues
• Organ systems
• Bioenergetics and metabolic rates

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What do all organisms have to do to make a
living???

• ???

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What do organisms have to do to make a living???

• Acquire resources (food, water)
• Eliminate waste products
• Exchange metabolic gasses
• Control internal conditions (homeostasis)
• Control function
• Control development
• Reproduce (optional for individuals, essential
  for evolutionary success)

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What makes an animal an animal?

• ???

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What makes an animal an animal?

• All are eukaryotic, multi-cellular, aerobic, and
  heterotrophic
• Most are mobile exceptions???
• Most are highly complex with many specialized
  organs exceptions???
• Cells divide by cleavage
• Excess carbohydrate stored as glycogen or
  converted to fats
• Most engage in sexual reproduction, some also
  have asexual reproduction processes

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Structure and Function of Animal Systems

• Focus on human biology, but will use comparative
  approach
• Comparisons between animals of differing levels
  of complexity
• We will correlate structure with function, at all
  levels of organization
• Important theme in biology
• Start with intro to basic principles
• Then discussions of various organ systems

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Critical Thinking

• Life has been on this planet for 3½ billion
  years!
• Until about 700 million years ago, all organisms
  were______________?

Table - the geological time scale
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Its always fun to study the geological time
scale it reveals the history of life on earth
What happened here???
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Critical Thinking

• Life has been on this planet for 3½ billion
  years!
• Until about 700 million years ago, all organisms
  were single celled!!!
• The emergence of multi-cellularity allowed for
  organisms to adapt in complex ways to their
  environment
• The migration to land promoted even more
  diversification about 450 million years ago

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Multi-cellularity imposes limitations, too

• In most multi-cellular organisms, not every cell
  is in contact with the external environment
• Multi-cellular organisms develop complex
  morphologies that reflect their environment
• Multi-cellular organisms develop complex
  mechanisms for resource/waste exchange with their
  environment
• We saw these phenomena with plants animals do
  the same thing

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Critical Thinking

• Terrestrial plants use a tight epidermis and a
  waxy cuticle to retain water
• What is the analogous structure in terrestrial
  animals???

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Critical Thinking

• Terrestrial plants use a tight epidermis and a
  waxy cuticle to retain water
• What is the analogous structure in terrestrial
  animals???
• The skin, and the oils that coat it
• Structure and function are related, and are the
  product of each species long history of
  evolutionary adaptations

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Critical Thinking

• Most animals (even many aquatic animals) urinate.
  Why???
• Do plants pee???

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Critical Thinking

• Most animals (even many aquatic animals) urinate.
  Why???
• Most animals circulate metabolic waste products
  through a filtering system (such as our kidneys)
  and eliminate a liquid waste
• Do plants pee???

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Critical Thinking

• Most animals (even many aquatic animals) urinate.
  Why???
• Most animals circulate metabolic waste products
  through a filtering system (such as our kidneys)
  and eliminate a liquid waste
• Do plants pee???
• Plants dont produce as much metabolic waste
  (they use more nitrogen) and they mostly either
  die back and recycle, or store the waste in
  isolated vacuoles or wood

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Constraints On Size And ShapeThe physical
environment affects animal evolution as it does
with all organisms

• Simple physics
• Flight, soil burrowing, swimming for speed
• The physical environment
• Dense water or soil, thin air
• Often leads to convergent evolution of shape

Images - convergent evolution of spindle-shaped
swimmers
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Constraints On Size And ShapeThe necessity of
exchange with the environment affects animal
evolution.

• Resource/waste exchange with the environment
• Diffusion at the surface was characteristic of
  the earliest animals
• Limits size
• Limits shape to thin, flat, open
• Limits complexity
• Mostly quite simple animals

Diagram - 2 tissue layers in Cnidarians
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Most animals have much more complex exchange
systems

• Exchange occurs at internal epithelia
• Huge surface area is characteristic
• Fun factoids from humans
• Lungs have 100 m2 of surface area (about ½ as big
  as room)
• Small intestine has surface area of a tennis
  court
• 80 km of tubules in a single kidney
• 100,000 km of blood vessels almost 3x
  circumference of the earth

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Critical Thinking

• How on earth do such large surface areas fit into
  our bodies???

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Critical Thinking

• How on earth do such large surface areas fit into
  our bodies???
• Folding! All these epithelial surfaces are
  highly convoluted

Micrographs - lung and intestinal tissues
Small Intestine Tissue
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Exchange with environment is not direct for most
animals

• Body is covered with waterproof surface
• Complex organ systems exchange materials
• Organ systems are linked together, but not
  usually directly
• Most organ systems are separated by interstitial
  fluid a water-based solution that surrounds all
  cells in the animal body
• Transport occurs through the interstitial fluid

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Indirect exchange between organism and
environment, and between organ systems
Diagram - organization of organ systems showing
indirect exchange through the interstitial fluid
same diagram on 29
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Critical Thinking

• Do nutrients leap from our breakfast cereal to
  our cells???
• Why do animals need nutrients anyways???

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Critical Thinking

• Do nutrients leap from our breakfast cereal to
  our cells???
• No first they are extracted through digestion,
  then they diffuse to the cells through a fluid
  medium
• Why do animals need nutrients anyways???

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Critical Thinking

• Do nutrients leap from our breakfast cereal to
  our cells???
• No first they are extracted through digestion,
  then they diffuse to the cells through a fluid
  medium
• Why do animals need nutrients anyways???
• Same as with plants to build the
  macro-molecules that make the animal work

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Exchange with environment is not direct for
complex animals

• Body is covered with waterproof surface
• Complex organ systems exchange materials
• Organ systems are linked together, but not
  usually directly
• Organ systems are separated by interstitial fluid
  a water-based solution that surrounds all cells
  in the animal body
• Transport occurs through the interstitial fluid

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Indirect exchange between organ systems occurs
via the interstitial fluid one big exception
the Malphigian excretory tubules in insects are
directly connected to the digestive tract
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All complex organisms have a hierarchical
organization
Diagram - cells - organism in a zebra

• Cells
• Tissues
• Organs
• Organ systems
• Organism

Form Reflects Function!!!
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Critical Thinking

• Think of your heart, or this zebras how are
  structure and function related???

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Critical Thinking

• Think of your heart, or this zebras how are
  structure and function related???
• Stretchy chambers to store blood
• Muscular chambers to pump blood
• Connected to vessels
• Result circulation!!!

Yes, it really is often that simple and elegant
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Form and function are correlated from cells ?
whole organism

• We learned about cells in 111.
• Cells
• Tissues
• Organs
• Organ systems
• Organism

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Four major tissue types read more in text
Diagram tissue types
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Epithelial Tissues

• Sheets of cells that cover the body surfaces and
  line many of the internal organs
• Base of epithelial tissue is attached to a
  basement membrane
• The free (exposed) surface has cells that are
  either cuboidal, columnar or squamous (tile
  shaped)
• Shape reflects function!
• Some epithelia waterproof, some leak, some
  secrete, some slough off.

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Epithelial tissues
Diagram sub-types of epithelial tissues
Which do you think are waterproof??? Which
leaky??? Which secrete??? Which slough off???
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Connective Tissues

• Cells held in a fibrous or fluid extra-cellular
  matrix
• Matrix generally secreted by the cells
• Many types and sub-types of connective tissue
• Loose bind and shape
• Adipose store fat
• Fibrous strong connections
• Cartilage cushions
• Bone support system
• Blood connects tissues to resources

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Critical Thinking

• What makes the bones of plants???

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Critical Thinking

• What makes the bones of plants???
• Lignin gives rigid structure
• Cellulose allows positive pressure to build to
  keep cells plump
• Ground tissue gives additional structure to
  herbaceous plants

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Critical Thinking

• How about the blood???

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Critical Thinking

• What makes the blood of plants???
• Resources are transported in the vascular tissues
• Some are circulated in phloem

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Muscle Tissue

• Composed of cells that can contract
• Skeletal enable movement, attached to bones by
  tendons
• Voluntary under conscious nervous system
  control
• Cardiac forms the heart
• Involuntary
• Smooth or visceral surround the digestive
  tract, other organs
• Involuntary

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Nervous Tissue

• Transmits messages from one part of body to
  another
• Nerve cells have a central cell body appendages
  that carry messages toward or away from the cell
  (dendrites/axons)
• Appendages may be a meter long in humans!

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Critical Thinking

• Do all animal tissue types have directly
  analogous tissue types in plants???
• Epithelial???
• Connective???
• Muscle???
• Nervous???

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Critical Thinking

• Do all animal tissue types have directly
  analogous tissue types in plants???
• Epithelial certainly, though not internal
• Connective sort of (vascular, ground)
• Muscle not really remember plants move by
  growing, other motions are related to water
  potential changes
• Nervous no plants respond primarily based on
  chemical signals

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Organs

• Composed of two or more types of tissues
  organized into a functional unit
• Tissues are often in layers, or they may be
  integrated throughout the organ
• Stomach has layers of epithelial, connective,
  muscle, connective
• Skin has layers of epithelial, connective, muscle
• All tissues have blood vessels and nerve tissues
  integrated

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Most animals have body cavities

• These are fluid filled spaces that cushion and
  suspend organs
• Sometimes they also give the body shape
• In vertebrates, many organs are held in place in
  the body cavity by layers of connective tissues
  (mesenteries) and sheets of muscle (diaphragm)

Diagram body cavities
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Organ Systems groups of related organs that
maintain various body functions

• Complex organ systems are present in all higher
  animals
• All organ systems are interdependent
• Functions are coordinated (ex digestive
  vascular)
• All systems work together to maintain homeostasis
  (constant internal conditions, more on this
  later)

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Organ Systems most complex animals have 11
major organ systems image search for a table
like this one
Table all the organ systems found in a complex
animal
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Diagrams closeups of the major organ systems
similar diagrams on next 4 slides
Digestive
Circulatory
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Respiratory
Immune
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Excretory
Endocrine
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Nervous
Reproductive
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Skeletal and Integumentary
Muscular
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Organ systems are integrated in both structure
and function to produce the whole organism
Diagram summary of organ systems
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Bioenergetic Principles Regulate Organism Activity

• Bioenergetics the flow of energy through the
  animal
• Controlled by energy sources vs. energy uses
  (food intake vs. metabolism)
• Metabolic rates vary based on size, activity
  levels, homeostasis strategy and thermoregulation
  strategy
• Important selection pressures include the
  physical environment and interactions with other
  organisms

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Energy management food supplies energy to fund
metabolism, maintain homeostasis, and support
activity
Diagram bioenergetics in an organism
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Influences on Metabolic Rate

• Body size
• Inverse relationship between size and metabolic
  rate per unit mass
• Evidence is clear explanation is unclear
• Activity level
• Homeostasis strategy
• It costs more to regulate
• Thermoregulation strategy

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Influences on Metabolic Rate

• Body size
• Inverse relationship between size and metabolic
  rate per unit mass
• Evidence is clear explanation is unclear
• Activity level
• Homeostasis strategy
• It costs more to regulate
• Thermoregulation strategy

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Homeostasis

• Maintenance of constant internal conditions
  (actually, within a range of tolerance)
• Various control systems regulate temperature,
  salt concentrations, water content, pH, blood
  sugar, etc
• Most control systems rely on negative feedback
  loops the results of a process inhibit that
  process
• process is self limiting

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Most organisms regulate at least some components
of their internal environment
Diagram homeostasis
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Homeostasis

• Maintenance of constant internal conditions
  (actually, within a range of tolerance)
• Various control systems regulate temperature,
  salt concentrations, water content, pH, blood
  sugar, etc
• Most control systems rely on negative feedback
  loops the results of a process inhibit that
  process
• Process is self limiting

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Feedback Loops thermostats and furnaces are a
non-living example
Diagram a mechanical representation of a
negative feedback loop
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Many similar strategies for regulation of blood
chemistry, blood sugar, body temperature, etc etc
etc
Diagrams representations of biological negative
feedback loops
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Homeostasis is dynamic.

• All feedback loops are constantly monitored and
  levels are fluctuating within range
• Not all animals maintain stable internal
  conditions
• Regulators expend metabolic energy to maintain
  stability
• Conformers dont internal values vary with
  external conditions
• Some animals regulate some conditions, conform to
  others

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Influences on Metabolic Rate

• Body size
• Inverse relationship between size and metabolic
  rate per unit mass
• Evidence is clear explanation is unclear
• Activity level
• Homeostasis strategy
• It costs more to regulate
• Thermoregulation strategy

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Thermoregulation

• All biochemical processes are sensitive to
  temperature
• Extreme temperatures can denature proteins or
  alter membrane function
• Animals regulate their internal temperature to
  maintain metabolic function
• Two main strategies have emerged
• Ecothermy
• Endothermy

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Thermoregulation

• Ectothermic animals gain heat from the
  surrounding environment
• Most invertebrates, fishes, amphibians and
  reptiles
• Low metabolic rate when cold
• Not always able to be active
• Behavior is often used to regulate body
  temperature

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Critical Thinking

• Are ectothermic animals cold blooded???

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Critical Thinking

• Are ectothermic animals cold blooded???
• NO!!! An ectotherms body temperature reflects
  its environment (with some exceptions)

Graph body temp vs. environmental temp in
ectotherms vs. endotherms
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Critical Thinking

• What are the costs and benefits of ectothermy???

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Critical Thinking

• What are the costs and benefits of ectothermy???
• Cost limited activity and endurance
• Animals must remain warm to maintain active
  cellular respiration
• When their body is cold, they cannot produce
  enough ATP to be active
• When cold, they cant forage or escape!
• Benefits low energy cost

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Thermoregulation

• Endothermic animals use energy to maintain a
  constant body temperature
• Primarily mammals and birds
• High metabolic rate generates waste heat that
  keeps the body warm
• Most endotherms also gain some heat from their
  surroundings or behaviors
• Some endotherms vary body temperature by season
  or time of day (hibernation, estivation,
  diurnation)

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Critical Thinking

• What are the costs and benefits of endothermy???

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Critical Thinking

• What are the costs and benefits of endothermy???
• Cost uses lots of energy
• 10-30x more than same size ectotherm
• Benefits allows for constant activity
• Always able to forage
• Always able to escape

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Most endotherms are terrestrial

• Moving on land requires more energy than moving
  in water (water supports)
• Land T fluctuates more than water T (high heat
  capacity of H2O)
• The development of endothermy was an important
  adaptation to the colonization of land
• Many terrestrial animals are ectothermic, but few
  aquatic animals are endothermic

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Always active Slow when its cold
Graph body temp vs. environmental temp in
ectotherms vs. endotherms
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Both endos and ectos have many strategies to
regulate body temperature

• Insulation
• Adjusting the rate of heat exchange with the
  environment
• Evaporative cooling
• Behavior
• Adjusting metabolic rate

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Diagram adipose tissue as insulation
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Many strategies to regulate body temperature

• Insulation
• Adjusting the rate of heat exchange with the
  environment
• Evaporative cooling
• Behavior
• Adjusting metabolic rate

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Adjusting the rate of heat exchange with the
environment

• Constriction or dilation of surface blood vessels
• Raising of fur or feathers
• Fat accumulation
• Countercurrent heat exchange

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Critical Thinking

• How would changing blood vessel diameter change
  the rate of heat exchange???

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Critical Thinking

• How would changing blood vessel diameter change
  the rate of heat exchange???
• Alters the amount of warm blood that reaches the
  surface of the skin
• Constricting holds heat
• Dilating releases heat

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Adjusting the rate of heat exchange with the
environment

• Constriction or dilation of surface blood vessels
• Raising of fur or feathers
• Fat accumulation
• Countercurrent heat exchange

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Critical Thinking

• How would raising the fur or feathers change the
  rate of heat exchange???

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Critical Thinking

• Why would raising the fur or feathers change the
  rate of heat exchange???
• Adds more of an insulating boundary layer around
  the skin

Image fluffed bird
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Adjusting the rate of heat exchange with the
environment

• Constriction or dilation of surface blood vessels
• Raising of fur or feathers
• Fat accumulation
• Countercurrent heat exchange

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Countercurrent Exchange arterial blood is warmer
(comes from body core) warms adjacent venous
blood in extremities
Diagram countercurrent blood flow in birds leg
and dolphins fin
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Adjusting the rate of heat exchange with the
environment

• Some ectotherm fishes maintain higher
  temperatures in their deep swimming muscles with
  a heat exchanging pattern of blood flow
• Increases aerobic respiration (thus ATP
  production) in those muscles
• Partial endotherms

Diagram countercurrent flow in deep muscles of
fish
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Many strategies to regulate body temperature

• Insulation
• Adjusting the rate of heat exchange with the
  environment
• Evaporative cooling
• Behavior
• Adjusting metabolic rate

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Sweating, panting, wetting.often linked to
behaviors.
Images animals panting and spraying
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Many strategies to regulate body temperature

• Insulation
• Adjusting the rate of heat exchange with the
  environment
• Evaporative cooling
• Behavior
• Adjusting metabolic rate

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Behavior

• Moving to shade/sun
• Moving into/out of water
• Restricting activity to night/day
• Regulating body posture to manage solar exposure
• Migrating
• Social behavior to share heat (bees)

Image dragonfly positioned for minimum solar
exposure
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Many strategies to regulate body temperature

• Insulation
• Adjusting the rate of heat exchange with the
  environment
• Evaporative cooling
• Behavior
• Adjusting metabolic rate

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Adjusting metabolic rate

• Increases or decreases in muscular activity
  (shivering, active motion)
• Acclimation many animals adjust to temperature
  changes throughout the seasons by changing enzyme
  type and quantity, altering lipids to keep
  membranes fluid
• Torpor some animals react to predictable
  temperature and food supply fluctuations by
  entering a state of reduced metabolism
  (hibernation, etc)
• Daylength is the likely trigger

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Graph change in a moths thorax temperature
with pre-flight shivering
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Adjusting metabolic rate

• Increases or decreases in muscular activity
  (shivering, active motion)
• Acclimation many animals adjust to temperature
  changes throughout the seasons by changing enzyme
  type and quantity, altering lipids to keep
  membranes fluid
• Torpor some animals react to predictable
  temperature and food supply fluctuations by
  entering a state of reduced metabolism
  (hibernation, etc)
• Daylength is the likely trigger for seasonal
  torpor

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REVIEW Both endos and ectos have many
strategies to regulate body temperature

• Insulation
• Adjusting the rate of heat exchange with the
  environment
• Evaporative cooling
• Behavior
• Adjusting metabolic rate

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REVIEW Key Concepts

• What separates animals from other organisms?
• Introduction to structure and function
  relationships the implications of being
  multicellular
• Hierarchical organization in animals
• Tissues
• Organ systems
• Bioenergetics and metabolic rates