Transcript Animal Form and Function

An Introduction to Animal Structure and Function
• Animal are multicellular, heterotrophic eukaryotes with
tissues that develop from embryonic layers
• 2 types of cells
• Prokaryotic
• Eukaryotic
Structural evidence that supports
relatedness of all eukaryotes (at cellular
level):
membrane-bound organelles
linear chromosomes
endomembrane system
Reproduction
• Most animals reproduce sexually
• Diploid stage dominating the life cycle
Development
• Sperm fertilizes egg zygote cleavage blastula
gastrulation formation of embryonic tissue layers
gastrula
Early embryonic development in animals
1 The zygote of an animal
undergoes a succession of mitotic
cell divisions called cleavage.
2 Only one cleavage
stage–the eight-cell
embryo–is shown here.
3 In most animals, cleavage results in the
formation of a multicellular stage called a blastula.
The blastula, a hollow ball of cells.
Blastocoel
Cleavage
Cleavage
6 The endoderm of
the archenteron develops into the tissue
lining the animal’s
digestive tract.
Zygote
Eight-cell stage
Blastula
Cross section
of blastula
Blastocoel
Endoderm
5 The blind pouch
formed by gastrulation, called
the archenteron,
opens to the outside
via the blastopore.
Ectoderm
Gastrula
Blastopore
Figure 32.2
Gastrulation
4 Most animals also undergo gastrulation, a rearrangement of
the embryo in which one end of the embryo folds inward, expands,
and eventually fills the blastocoel, producing layers of embryonic
tissues: the ectoderm (outer layer) and the endoderm (inner layer).
• Hox genes regulate development of body form
• Hox family of genes has been highly conserved, yet
produces a wide diversity of animal morphology
Paleozoic Era (542–251 Million Years Ago)
• The Cambrian explosion
• Earliest fossil appearance of many major groups of living
animals
• Several current hypotheses
Figure 32.6
Invertebrates
Life Without a Backbone
•
Invertebrates account for 95% of known animal
species
Figure 33.1
Figure 33.2
Eumetazoa
Ancestral colonial
choanoflagellate
Chordata
Echinodermata
Other bilaterians (including
Nematoda, Arthropoda,
Mollusca, and Annelida)
Cnidaria
Porifera
Animal phylogeny
Deuterostomia
Bilateria
Derived Characters of Chordates
• Some species possess some of these traits only during
embryonic development
Dorsal,
hollow
nerve cord
Muscle
segments
Brain
Notochord
Mouth
Anus
Figure 34.3
Muscular,
post-anal tail
Pharyngeal
slits or clefts
Origin of Craniates
• ~ 530 million years ago during the Cambrian explosion
Origin of Tetrapods
• The fins became progressively more limb-like while the
rest of the body retained adaptations for aquatic life in
one line
Bones
supporting
gills
Figure 34.19
Tetrapod
limb
skeleton
Amniotic egg
• 4 extraembryonic membranes
Extraembryonic membranes
Allantois. The allantois is a disposal
Chorion. The chorion and the membrane of the
sac for certain metabolic wastes produced by the embryo. The membrane
of the allantois also functions with
the chorion as a respiratory organ.
allantois exchange gases between the embryo
and the air. Oxygen and carbon dioxide diffuse
freely across the shell.
Yolk sac. The yolk sac contains the
Amnion. The amnion protects
yolk, a stockpile of nutrients. Blood
the embryo in a fluid-filled
cavity that cushions against
mechanical shock.
vessels in the yolk sac membrane transport
nutrients from the yolk into the embryo.
Other nutrients are stored in the albumen (“egg white”).
Embryo
Amniotic cavity
with amniotic fluid
Yolk (nutrients)
Albumen
Shell
Figure 34.24
Archaeopteryx
• Oldest bird known
Wing claw
Toothed beak
Airfoil wing with
contour feathers
Figure 34.29
Long tail with
many vertebrae
Australian convergent evolution
Marsupial mammals
Plantigale
Eutherian mammals
Deer mouse
Mole
Marsupial mole
Sugar glider
Flying squirrel
Wombat
Woodchuck
Wolverine
Tasmanian devil
Patagonian cavy
Kangaroo
Figure 34.35
Animal Form and Function
Structure and function * are closely
correlated
Figure 40.1
Natural selections select for what works best among the
available variations in a population
*
Evolutionary convergence
• Independent adaptation to a similar environmental
challenge
*
(a) Tuna
(b) Shark
(c) Penguin
(d) Dolphin
Figure 40.2a–e
(e) Seal
Exchange with the Environment
• Occurs as substances dissolved in the aqueous medium
transported across membranes
*
* of
• Single-celled protist has a sufficient surface area
plasma membrane to service its entire volume of
cytoplasm
Diffusion
Figure 40.3a
(a) Single cell
• Organisms with complex body plans highly folded
*
internal surfaces
(lg. surface area) specialized for
exchanging materials
*
External environment
Mouth
Food
CO2
O2
Respiratory
system
0.5 cm
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).
Cells
Heart
Nutrients
Circulatory
system
10 µm
Interstitial
fluid
Digestive
system
Excretory
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).
Anus
Unabsorbed
matter (feces)
Figure 40.4
50 µm
Animal
body
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).
Cellular respiration
Electron shuttles
span membrane
CYTOSOL
MITOCHONDRION
2 NADH
or
2 FADH2
2 NADH
2 NADH
Glycolysis
Glucose
2
Pyruvate
2
Acetyl
CoA
+ 2 ATP
by substrate-level
phosphorylation
Maximum per glucose:
Figure 9.16
6 NADH
Citric
acid
cycle
+ 2 ATP
2 FADH2
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
+ about 32 or 34 ATP
by substrate-level by oxidative phosphorylation, depending
on which shuttle transports electrons
phosphorylation
from NADH in cytosol
About
36 or 38 ATP
Excretory Processes
• Urine produced by refining a filtrate derived from body
fluids
Capillary
Filtrate
Excretory
tubule
1 Filtration. The excretory tubule collects a filtrate from the
blood.
Water and solutes are forced by blood pressure across the
selectively permeable membranes of a cluster of capillaries and
into the excretory tubule.
2 Reabsorption. The transport epithelium reclaims valuable substances
from the filtrate and returns them to the body fluids.
3 Secretion. Other substances, such as toxins and excess ions, are
extracted from body fluids and added to the contents of the excretory
tubule.
Urine
Figure 44.9
4
Excretion. The filtrate leaves the system and the body.
Vertebrate Kidney
Posterior vena cava
Renal artery and vein
Kidney
Aorta
Ureter
Urinary bladder
Urethra
(a) Excretory organs and major
associated blood vessels
Figure 44.13a
Nephron
Cortical
Juxtamedullary nephron
nephron
Afferent
arteriole
from renal
artery
Glomerulus
Bowman’s capsule
Renal
cortex
Proximal tubule
Peritubular
capillaries
Collecting
duct
SEM
20 µm
Renal
medulla
Distal
tubule
Efferent
arteriole from
glomerulus
To
renal
pelvis
Collecting
duct
Branch of
renal vein
Loop
of
Henle
Descending
limb
Ascending
limb
Vasa
recta
Figure 44.13c, d
(c) Nephron
(d) Filtrate and
blood flow
• Glomerulus of Bowman’s capsule proximal tubule
the loop of Henle distal tubule collecting duct
Filtrate becomes urine
1
Proximal tubule
NaCl Nutrients
HCO3
H2O
K+
H+
NH3
4
Distal tubule
H2O
HCO3
NaCl
K+
H+
CORTEX
2
Filtrate
H2O
Salts (NaCl and others)
HCO3–
H+
Urea
Glucose; amino acids
Some drugs
Descending limb
of loop of
Henle
3 Thick segment
of ascending
limb
NaCl
H2O
OUTER
MEDULLA
NaCl
3 Thin segment
of ascending
limb
Figure 44.14
Collecting
duct
Urea
Key
Active
transport
Passive transport
5
NaCl
INNER
MEDULLA
H2O
• The mammalian kidney’s ability to conserve water is a
key terrestrial adaptation
Antidiuretic hormone (ADH)
• Increases water reabsorption in the distal tubules and
collecting ducts
Osmoreceptors
in hypothalamus
Thirst
Hypothalamus
Drinking reduces
blood osmolarity
to set point
ADH
Pituitary
gland
Increased
permeability
Distal
tubule
H2O reabsorption helps
STIMULUS:
The release of ADH is
triggered when osmoreceptor cells in the
hypothalamus detect an
increase in the osmolarity
of the blood
prevent further
osmolarity
increase
Collecting duct
Homeostasis:
Blood osmolarity
) Antidiuretic hormone (ADH) enhances fluid retention by making
the kidneys reclaim more water.
(a
Figure 44.16a