Transcript Slide 1

Lecture #8 – Introduction to Animal
Structure and Function
1
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
2
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
8
It’s always fun to
study the
geological time
scale – it reveals
the history of life
on earth
What happened here???
9
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
11
Critical Thinking
• Terrestrial plants use a tight epidermis and
a waxy cuticle to retain water
• What is the analogous structure in
terrestrial animals???
12
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
13
Constraints On Size And Shape:
The physical environment affects animal
evolution – as it does with all organisms
• Simple physics
Flight, soil burrowing,
swimming for speed…
Images - convergent
evolution of spindleshaped swimmers
• The physical environment
Dense water or soil, thin air
• Often leads to convergent
evolution of shape
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Hands On
• Think of some other adaptations to habitat,
food source or predators
• Name an animal – speculate on adaptive
characteristics
What selection pressure might have resulted in
a structure or function?
What structures or functions are phylogenetic?
18
Constraints On Size And Shape:
The 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 and branching! 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???
25
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???
26
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 macromolecules 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 Malpighian
excretory tubules
in insects are
directly connected
to the digestive
tract
29
All complex
organisms have
a hierarchical
organization
•
•
•
•
•
Diagram - cells - organism in a zebra
Cells
Tissues
Organs
Organ systems
Organism
Form Reflects Function!!!
30
Critical Thinking
• Think of your heart, or this zebra’s – how
are structure and function related???
31
Critical Thinking
• Think of your heart, or this zebra’s – 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
Let’s talk
about
tissues!!!
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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….
35
Epithelial
tissues
Diagram – sub-types of epithelial tissues
Which do you
think are
waterproof???
Which
leaky???
Which
secrete???
Which slough
off???
36
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
37
Critical Thinking
• What makes the “bones” of plants???
38
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
39
Critical Thinking
• How about the blood???
40
Critical Thinking
• What makes the “blood” of plants???
• Resources are transported in the vascular
tissues
• Some are “circulated” in phloem
41
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
42
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!
43
Critical Thinking
• Do all animal tissue types have directly
analogous tissue types in plants???
• Epithelial???
• Connective???
• Muscle???
• Nervous???
44
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
45
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
Skin has layers of epithelial, connective,
muscle
All tissues have blood vessels and nerve
tissues integrated
46
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
47
Organ Systems:
groups of related organs that maintain various
body functions
• Complex organ systems are present in
most 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
50
Respiratory
Immune
51
Excretory
Nervous
52
Reproductive
Endocrine
53
Skeletal and
Integumentary
Muscular
54
Organ systems
are integrated in
both structure
and function to
produce the
whole organism
Diagram – summary of organ systems
55
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:
Diagram – bioenergetics in an organism
food supplies
energy to fund
metabolism,
maintain
homeostasis,
and support
activity
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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
60
Most organisms regulate at least some
components of their internal environment
Diagram – homeostasis
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Homeostasis mechanisms primarily
control the interstitial fluid – the inside of
the cell is very dynamic, depending on
metabolic activity
Freeman is not completely accurate on this issue…..
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 don’t – internal values vary with
external conditions
Some animals regulate some conditions,
conform to others
66
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
67
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
69
Critical Thinking
• Are ectothermic animals cold blooded???
70
Critical Thinking
• Are ectothermic
animals cold
blooded???
• NO!!! An
ectotherm’s body
temperature
reflects its
environment (with
some exceptions)
Graph – body temp vs. environmental
temp in ectotherms vs. endotherms
71
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 can’t forage or escape!
• Benefits – low energy cost
73
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)
74
Critical Thinking
• What are the costs and benefits of
endothermy???
75
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
77
Always
active
Graph – body temp vs. environmental
temp in ectotherms vs. endotherms
Slow
when it’s
cold
78
Both endo’s and ecto’s have many
strategies to regulate body temperature
• Adjusting the rate of heat exchange with
the environment
• Adjusting metabolic rate
79
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
• Behaviors
80
Critical Thinking
• How would changing blood vessel diameter
change the rate of heat exchange???
81
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
82
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
• Behaviors
83
Critical Thinking
• How would raising the fur or feathers
change the rate of heat exchange???
84
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
85
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
• Behaviors
86
Diagram – adipose tissue as insulation
87
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
• Behaviors
88
Countercurrent Exchange: arterial blood is warmer
(comes from body core); warms adjacent venous
blood in extremities
Diagram – countercurrent blood
flow in bird’s leg and dolphin’s fin
89
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
90
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
• Behaviors
91
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 – dragonflies
positioned for max or
min solar exposure
92
Sweating, panting, licking,
spraying….often linked to
behaviors….
Images – animals panting and spraying
93
Many strategies to regulate body
temperature
• Adjusting the rate of heat exchange with
the environment
• Adjusting metabolic rate
94
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
95
Graph – change in a moth’s thorax
temperature with pre-flight shivering
96
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
97
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
98