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• IB202-8
• 3-31-06
• Form and Function
• Chapt 40 (all)
• Read ahead in Chpt 41 for next week
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Overview: Diverse Forms, Common
Challenges
• Animals inhabit almost every part of the
biosphere AND despite their amazing diversity
they all face a similar set of problems including
how to nourish themselves, gas exchange,
waste removal and reproduction.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Nectar sucking sphinx moth (long proboscis)
•
The comparative study of animals
–
Reveals that form and function are closely correlated. Natural selection can fit
structure (anatomy) to function (physiology) by selecting over many generations,
what works best among the available variations in a population.
Figure 40.1
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• Physical laws and the environment constrain
animal size and shape
• Physical laws and the need to exchange
materials with the environment also place limits
on the range of animal forms and structures.
For example: the ability to perform certain
actions depends on an animal’s shape and
size. An elephant needs certain sized legs to
support its massive weight. The next slide
shows a convergence of the body plan
(fusiform shape) of fast swimming fish, sharks,
penguins and dolphins.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Evolutionary convergence
– Reflects different species’ independent
adaptation to a similar environmental challenge
Tuna speed 80
km/hr.
(a) Tuna
Anglar Fish-large head,
(b) Shark
wait and gulp predator
(c) Penguin
(d) Dolphin
Figure 40.2a–e
(e) Seal
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Exchange with the Environment
• An animal’s size and shape has a direct effect
on how the animal exchanges materials with its
surroundings
•
Exchange with the environment occurs as substances dissolved in the
aqueous medium that surrounds cells. As an example the oxygen in
the air we breath is dissolved in a thin layer of water on the surface of
the aveolar cells (thin walled terminal compartments in the lung where
gas exchange occurs)).
Gases and organic molecules diffuse into aqueous layer and are
transported across the cells’ plasma membranes into the
cytoplasm or the blood.
Importance of distance in diffusion. Time for a molecule to diffuse
through tissues increases as the square of the distance.
1um--10-4 seconds, 10um--10-2 sec, 1 mm --100 sec, 10 mm—3hrs.
Thus distances must be small.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• A single-celled protist living in water
– Has a sufficient surface area of plasma
membrane to service its entire volume of
cytoplasm by simple diffusion
Diffusion
–
50um
Figure 40.3a
(a) Single cell
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• Multicellular organisms with a sac body plan
– Have body walls that are only two cells thick and
again the distances are small enough so that
diffusion is adequate. Mouth
Gastrovascular
cavity
Diffusion
Diffusion
Figure 40.3b
(b) Two cell layers
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Organisms with more complex body plans and
especially large organisms have evolved
specialized organs and surfaces for exchanging
gas and nutrients. Where the plumbing has
reduced the diffusion distance between fluid
compartments.
• The next slide shows an example of a vertebrate
illustrating the systems involved:
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
External environment
Mouth
Food
CO2
O2
Respiratory
system
0.5 cm
Cells
Heart
Nutrients
50 µm
Animal
body
A microscopic view of the lung reveals
that it is much more spongelike than
balloonlike. This construction provides
an expansive wet surface for gas
exchange with the environment (SEM).
Circulatory
system
10 µm
Interstitial
fluid
Digestive
system
The lining of the small intestine, a digestive organ, is elaborated with fingerlike
projections that expand the surface area
for nutrient absorption (cross-section, SEM).
Excretory
System—glomerular cappilaries
Anus
Unabsorbed
matter (feces)
Figure 40.4
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Metabolic waste
products (urine)
Inside a kidney is a mass of microscopic
tubules that exhange chemicals with
blood flowing through a web of tiny
vessels called capillaries (SEM).
• Concept 40.2: Animal form and function are
correlated at all levels of organization
• Animals are composed of cells
• Groups of cells with a common structure and
function
– Make up tissues
• Different tissues make up organs
– Which together make up organ systems
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Tissue Structure and Function
• Different types of tissues
– Have different structures that are suited to their
functions
• Tissues are classified into four main categories
– Epithelial, connective, muscle, and nervous
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Epithelial Tissue
• Epithelial tissue
– Covers the outside of the body and lines
organs and cavities within the body
– Contains cells that are closely joined
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• Epithelial tissue
EPITHELIAL TISSUE
Columnar epithelia, which have cells with relatively large cytoplasmic volumes, are often
located where secretion or active absorption of substances is an important function.
A simple
columnar
epithelium
Lines urethera
Intestinal
lining
A stratified columnar
epithelium
A pseudostratified
ciliated columnar
epithelium
Lines airways,
note cilia
Stratified squamous epithelia
Cuboidal epithelia
Simple squamous epithelia
Kidney
Lungs
K
i
K
Figure
40.5
i
Esophagus
Basement membrane
40 µm
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Vagina, skin
Connective Tissue
• Connective tissue
– Functions mainly to bind and support other
tissues
– Contains sparsely packed cells scattered
throughout an extracellular matrix
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CONNECTIVE TISSUE
• Connective tissue
100 µm
Chondrocytes
Chondroitin
sulfate
100 µm
Collagenous
fiber
Elastic
fiber
Cartilage
Loose connective tissue
Adipose tissue
Fibrous connective tissue
Fat droplets
150 µm
Nuclei
30 µm
Blood
Bone
Central
canal
Red blood cells
White blood cell
Osteon
Figure 40.5
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700 µm
Plasma
55 µm
Muscle Tissue
• Muscle tissue
– Is composed of long cells called muscle fibers
capable of contracting in response to nerve
signals
– Is divided in the vertebrate body into three
types:
– skeletal, (striated muscle)
–
cardiac, (heart cells electrically connected)
– Smooth (non striated, slow contractions)
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Nervous Tissue
• Nervous tissue
– Senses stimuli and transmits signals
throughout the animal
– Incorporate into figure
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Muscle and nervous tissue
MUSCLE TISSUE
100 µm
Skeletal muscle
Multiple
nuclei
Muscle fiber
Sarcomere
Cardiac muscle
Nucleus Intercalated
disk
Smooth muscle
50 µm
Nucleus
Muscle
fibers
25 µm
NERVOUS TISSUE
Process
Neurons
Cell body
Nucleus
Figure 40.5
50 µm
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Organs and Organ Systems
• In all but the simplest animals
– Different tissues are organized into organs
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Organs
• In all but the simplest animals different tissues are
organized into organs. In some organs the tissues
are arranged in layers
Lumen of
stomach
Mucosa. The mucosa is an
epithelial layer that lines
the lumen.
Submucosa. The submucosa is
a matrix of connective tissue
that contains blood vessels
and nerves.
Muscularis. The muscularis consists
mainly of smooth muscle tissue.
Serosa. External to the muscularis is the serosa,
a thin layer of connective and epithelial tissue.
Figure 40.6
0.2 mm
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Organ Systems
• Representing a level of organization higher
than organs
– Organ systems carry out the major body
functions of most animals
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• Organ systems in mammals
Table 40.1
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• Concept 40.3: Animals use the chemical energy in
food to sustain form and function
• All organisms require chemical energy for
– Growth, repair, physiological processes, regulation,
and reproduction
• The flow of energy through an animal, its
bioenergetics ultimately limits the animal’s behavior,
growth, and reproduction determines how much food it
needs
• Studying an animal’s bioenergetics
– Tells us a great deal about the animal’s adaptations or
“life style”. (Endotherm vs ectotherm).
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Energy Sources and Allocation
• Animals harvest chemical energy from the
food they eat
• Once food has been digested most of the
energy-containing molecules are used to make
ATP, which powers cellular work. Generation
of ATP requires oxygen and produces CO2
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• After the energetic needs of staying alive are met
ie. Ion transport, muscle contraction heat production any remaining molecules from food
can be used in biosynthesis or stored in the form of lipid or carbohydrate
Organic molecules
in food
External
environment
Animal
body
Digestion and
absorption
Heat
Nutrient molecules
in body cells
Carbon
skeletons
Cellular
respiration
ATP
Biosynthesis:
growth,
storage, and
reproduction
Figure 40.7
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Heat
Carbohydrates,
proteins and lipids
Cellular
work
Energy
lost in
feces
Energy
lost in
urine
Oxygen
Heat
Oxidation of reduced
carbon (CH2)- ATP+CO2
Heat
Muscle contraction
Quantifying Energy Use
• An animal’s metabolic rate
– Is the amount of energy an animal uses in a
unit of time and can be measured in a variety
of ways
–
Most common way is measuring oxygen
consumption both in the resting and active
states. Another less well known way is to
measure heat production. (Requires elaborate
equipment).
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• One way to measure metabolic rate
– Is to determine the amount of oxygen consumed
or carbon dioxide produced by an organism
Figure 40.8a,
(a) This photograph shows a ghost crab in a
respirometer. Temperature is held constant in the
chamber, with air of known O2 concentration flowing through. The crab’s metabolic rate is calculated
from the difference between the amount of O2
entering and the amount of O2 leaving the
respirometer. This crab is on a treadmill, running
b at a constant speed as measurements are made.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
(b) Similarly, the metabolic rate of a man
fitted with a breathing apparatus is
being monitored while he works out
on a stationary bike.
Bioenergetic Strategies
• An animal’s metabolic rate
– Is closely related to its bioenergetic strategy
• Birds and mammals are mainly endothermic,
meaning that their bodies are warmed mostly
by heat generated by metabolism. They
typically have higher metabolic rates.
• Amphibians and reptiles other than birds are
ectothermic, meaning that they gain their heat
mostly from external sources. Thus they have
lower metabolic rates.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Size Influences Metabolic Rate
• The metabolic rates of animals are affected by
many factors:
• Metabolic rate per gram
– Is inversely related to body size among similar
animals. Smaller animals have higher
metabolic rate both in endotherms and
ectotherms. In the case of endotherms a
greater surface to volume ration might explain
this relationship, but it is also present in
ectotherms that assume the temperature of the
environment. Effect not presently explained.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Activity and Metabolic Rate
• The basal metabolic rate (BMR)
– Is the metabolic rate of an endotherm at rest
• The standard metabolic rate (SMR)
– Is the metabolic rate of an ectotherm at rest
• For both endotherms and ectotherms
– Activity has a large effect on metabolic rate
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Energy Budgets
• Different species of animals
– Use the energy and materials in food in
different ways, depending on their environment
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• An animal’s use of energy
– Is partitioned to BMR (or SMR), activity,
homeostasis, growth, and reproduction
Annual energy expenditure (kcal/yr)
Endotherms
Activity 340,000
costs
8,000
4,000
Energy expenditure per unit mass
(kcal/kg•day)
60-kg female human
from temperate climate
(a) Total annual energy expenditures
Figure 40.10a, b
Ectotherm
800,000 BasalReproduction Temperature
regulation costs
metabolic
rate
Growth
4-kg male Adélie penguin
from Antarctica (brooding)
0.025-kg female deer mouse 4-kg female python
from temperate
from Australia
North America
438
Human
233
Deer mouse
(b) Energy expenditures per unit mass (kcal/kg•day)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Python
Adélie penguin
36.5
5.5