Transcript Animal Physiology

Animal Physiology
By the end of this class you should understand:
• The system and mechanics of determining
how organisms are related
• How to arrange animals on a phylogenetic
tree
• The purpose and importance of the major
physiological systems of animals
• The physiological differences between
different groups of animals
• Why we must pee in a cup to get a job
Kingdom Animalia
• The first animals (similar to
modern sponges) evolved
around 1 billion years ago
– Probably the first multicellular
organisms
• Like all modern animals, they
had to eat food to grow and
had no cell wall
• Animal diversity was limited
until the Cambrian Explosion
Why the Cambrian Explosion?
• The supercontinent Pannotia
(before Pangaea) broke up,
restricting gene flow and
creating new environments
• Homeotic genes were now
evolved that controlled body
plan
• Oxygen content in the
atmosphere and ocean may
have been rising
– Animal cells all have mitochondria
so this would have benefitted
them
Cambrian Explosion
Morphology and Phylogeny
• Quick Question: Who do you
think is most closely related of
these three organisms?
– Seagull
– Fruit Bat
– Common Rat
• Can you place them into this
phylogenetic tree?
Possible Arrangements
Common Ancestry
• We know the rat and bat are more closely
related because they are both part of class
mammalia
– If you were paying attention yesterday…
• What this means is that they had a common
ancestor with characteristics that they both
have that the other animals don’t have
– These predictions can be made by looking at cell
structures and embryos as well as bones
Identify Common Traits
Prediction of Ancestry
• The common ancestor of all
eukaryotes:
– Had membrane-bound organelles like
nuclei and mitochondria
• The common ancestor of all animals:
– Was multicellular, ate food and had no
cell wall
• The common ancestor of the bilateria
group:
– Had three layers of tissue as an embryo
and had bilateral symmetry
What about Echinoderms?
• It’s true that echinoderms are part of
bilateria and yet they are radially
symmetrical instead of bilaterally
symmetrical
– The embryo of the echinoderm is bilaterally
symmetrical and its opening becomes its
anus
• Evidence suggests that embryo structure
changes more slowly than symmetry, so it
is more likely that echinoderms are closely
related to chordates and lost their
symmetry
– The chance that they are closely related to
jellyfish but their embryos also develop like
chordate embryos is considered very unlikely
Compare These Trees
• If this tree is correct,
• If this tree is correct,
flying evolved twice, but
flying only evolved
having fur and making
once, but having fur
milk for babies evolved
and making milk for
only once
babies evolved twice
Certainty
• Recall that in science nothing is every 100%
certain, all we have is evidence
• The theory of evolution matches all data, and
the tree of life is the best possible fit for all
the probabilities
– New fossils are still being discovered and they
often rewrite the tree of life
– The “missing link” between humans and
chimpanzees was sought for a long time
Circulation
• The most important system in
animal homeostasis is the
circulatory system
– Bring nutrients and oxygen to
all cells
– Removes wastes from all cells
• Nutrients are put in by the
digestive system
• Circulatory system must be
cleaned by the excretory
system (or renal system)
Circulation in Sponges
• The simplest circulatory system is
in sponges
– Probably similar to the first
circulatory system in our common
ancestor
• Seawater is pumped through the
body of the sponge by cells with
flagella
• The cells of the sponge are filter
feeders that grab food out of the
seawater and eat it themselves
– Essentially a colony of animal cells
cooperating
Circulation in Jellyfish
• Phylum cnidaria has a more
advanced circulatory system based
on the fact that they have multiple
layers of tissues in their body
• Prey is paralyzed and dragged into
its gut, and it is then dissolved into
nutrients that diffuse to all the cells
– Moved by seawater through the
tissues of the jellyfish
– Waste products diffuse into the gut,
which eventually expels anything that
wasn’t digested
Circulation in Bilateria
• In the most basic marine animals, ocean water is
used as the circulatory system to allow things to
move to all cells
– This is inefficient, since ocean water doesn’t carry as
much oxygen
• In addition to being bilaterally symmetrical, all
bilateria have circulatory organs that move a
liquid through the body
– Can keep oxygen-transporting materials in this fluid
– Can keep this fluid clean and free of bacteria
Circulation in Annelids
• Annelids like earthworms may
seem very primitive but they
actually have a well-developed
circulatory system
• Blood is kept in blood vessels and
moved by several hearts
– This is known as a closed
circulatory system
• Blood passes around the digestive
tract to absorb nutrients
• Wastes are collected in a pair of
small organs for every segment
and excreted through the skin
Digestive Tract
• An incomplete digestive system has just one
opening (like for jellyfish)
– Same opening used for taking food in and waste out
• A complete digestive tract has two openings and
materials pass in only one direction
– Like ours!
Circulation in Mollusca
• Mollusks have a large diversity in
their circulatory systems
• Gastropods (snails) and Bivalves
(clams) have an open circulatory
system
– A heart pumps fluid through their body
but it is not contained in vessels and is
called hemolymph
• Cephalopods have a closed
circulatory system for more efficient
delivery of nutrients
– Nutrients leave the blood when it goes
through capillaries
Circulation in Arthropoda
• Arthropods all have an open
circulatory system
– Their exoskeleton is made of chitin,
which is a dense carbohydrate that
makes their bodies impermeable to
water
– Their organs are bathed in hemolymph
which nourishes their cells
• Their circulation is poor since their
heart is just stirring their fluids
through their body
Circulation in Echinodermata
• Echinoderms are similar to early
chordates but have developed radial
symmetry
• Like sponges and unlike more
advanced invertebrates, they use
seawater as their circulatory system
– They use a water vascular system to
nourish their body
• They also use the water vascular
system to move by pumping water
through tubes in their arms to make
themselves move
Circulation in Fish
• Fish and other vertebrates all have a
closed circulatory system
• Fish have a two-chambered heart
which pumps blood over their gills
and through their body in one big
squeeze from the ventricle
– Advantage: blood is always
oxygenated when it enters the body
– Disadvantage: blood flow through
body is slower since it has already lost
a lot of its pressure on the gills
Circulation in Amphibians and Reptiles
• Amphibians and most reptiles
have a three-chambered heart
• Blood collects in two collecting
chambers, one from the lungs
or gills and the other from the
body, then pumped by the
well-muscled ventricle into
tubes that lead back to both
– Advantage: better circulation in
body
– Disadvantage: some blood is not
oxygenated
Circulation in Birds and Mammals
• Crocodiles, birds and mammals
have a four-chambered heart,
which is the most advanced heart
system for maximum efficiency
• Blood from the body is pumped to
the lungs, blood from the lungs is
pumped to the body
– Advantage: best oxygen delivery
and best circulation
– Disadvantage: requires a higher
metabolism
Excretory System Needs
• All organisms must remove
waste chemicals in some way
– The #1 waste to remove is
ammonia, which is produced
when protein is metabolized to
sugar or fat
• Marine organisms can simply
secrete the ammonia into the
water around them
– Land animals cannot do this
because it wastes too much
water
Behold the Kidney!
• The kidney is an organ that collects and
stores wastes like ammonia (can be
turned into urea to save water)
– Can usually also secrete water or salt to
keep the salt/water balance in the blood
safe
– Blood or hemolymph filtrate is called
urine and is essentially all the wastes
from blood
• Human kidneys are very effective since
they must also balance water and salt
levels
Advanced Excretory System
• The more an animal must go without
water, the better its excretory system
must be
– Human kidneys are very good but no
match for desert animals!
• A better excretory system is also needed
when an animal eats a lot of protein for
energy
– This is part of why the Atkin’s diet can
mess up your kidneys
– Cats often develop kidney problems as
they age, since most other carnivores they
are related to eat plants as well as meat
Why Pee In A Cup?
• When we take chemicals into our
body that do not belong, they are
broken down by the liver
• These drug by-products collect in the
kidney and are removed by urination
– Drug tests are basically a test for these
drug metabolites in the urine
– These tests can be fooled by drinking a
crapload of vitamins and minerals, but
that is super bad for your kidneys and
they’ll know you did that anyway
See you in lab!
• More plants in lab today!