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Created by Julia Hsu Levy – Version 1.5
Chapter 28: Animals
Animal characteristics:
1. Muticellular
2. Heterotroph
3. Eukaryotes
4. NO cell wall
5. Two unique tissue types: muscle (movement) and nervous (response)
6. Mostly sexual reproduction these stages:
Cleavage: many rounds
of mitotic cell division
Blastula: hollow ball
structure
Gastrulation: part of
embryo pinches in,
forming gastrula (pouch)
Specific tissue types
result (endoderm,
ectoderm, sometimes
mesoderm)
7. Some undergo metamorphosis (juvenile  larva  pupa  adult)
8. Hox gene controls animal development from embryonic stage
9. Most have symmetry (except sponges that are assymetrical)
10. Most are acoelomate, pseudocoelomate, or coelomate
Those with symmetrical bodies
these associations:
have
Dorsal: top
Ventral: bottom
Anterior: head
Posterior: tail
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* * * Evolutionary History of Animals * * *
May have evolved from flagellated protists
Classification
P. Porifera
P. Cnidaria
P. Ctenophora
P. Platyhelminthes
P. Nematoda
P. Annelida
P. Mollusca
 C. Gastropoda
 C. Bivalvia
 C. Cephalopoda
P. Arthropoda
 C. Arachnida
 C. Insecta
P. Echinodermata
C. Agnatha
C. Chondricthyes
C. Osteichthyes
C. Amphibia
C. Reptilia
C. Aves
C. Mammalia
 Marsupial
 Monotreme
 Placental
Invertebrate Animal Kingdom Survey
Common examples
Notable traits
Sponges
Asymmetry, pores, filter
feeder, parazoa (lacks true
tissues, only animal like
this)
Jellyfish, sea anemone, hydra Tentacles, radial symmetry,
filter feeder, nematocyst,
eumetazoa (has true
tissues)
Comb jelly
Similar to cnidarian
Flatworm, tapeworm
Bilateral symmetry, flat body,
aceolomate, mouth only
Roundworms, pinworms,
Bilateral symmetry, round
hookworms
body, pseudocoelomate,
mouth and anus
Segmented worms,
Bilateral symmetry, found
earthworms, leeches
body, coelomate,
metanephridia
Body has 3 parts: foot,
Snails
visceral mass, mantle
Clams, oysters, mussels
Squid, octopus
Millipedes, centipedes
Exoskeleton, molting
Spiders, ticks
Insects
Malpighian tubules
Starfish, sand dollar
Water vascular system, tube
feet
Vertebrate Animal Kingdom Survey
Jawless fish
Parasitic on fish
Shark, skates, rays
Cartilaginous, paired fins
Trout, bass, salmon, etc
Boned fish, swim bladder,
operculum
Frogs, toads, salamanders,
Close ties with water, respires
newts
through skin, metamorphic
Lizards, crocodiles, alligators
Amniotic egg, ectotherm
Birds
Light hollow bonds, feathered
Mammary glands, hair
Kangaroo
Pouch
Platypus
Egg-laying
Humans
placenta
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* * * Animal Structure and Function * * *
Anatomy: study of the structures of an organism
Physiology: study of the functions of an organism
Atoms  molecules  molecular structures  cell  tissues  organs  organ
systems
Animal tissues
 Epithelial: forms outer covering and organ linings
 Connective: sparse cells in extracellular matrix
 Muscle: long, excitable cells that can contract
 Nervous: senses stimuli and transmits electrical signals
Epithelial tissue:
 tight junction connections between
cells
 protects against injuries
 classified according to
arrangement of cells
Connective tissue:
 bind and support other tissue
 loose, adipose (fatty), fibrous,
cartilage, bone, blood
Muscle tissue:
 parallel bundles of microfilaments
in cytoplasm (actin and myosin)
 most abundant tissue in animals
 ex: cardiac, striated, visceral
Nervous tissue:
 neuron cell = cell body + dendrites +axons
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* * * Homeostasis * * *
Regulating the internal
environment is dependent upon
control systems.
two
1. Negative feedback: opposite
effect of whatever that is
happening (ex: human body heat)
2. Positive feedback: amplifies
(increases) the same response (ex:
oxytocin and labor)
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* * * Digestive System * * *
Energy derived from food input  digestion  absorption  catabolism
Metabolic rate: total amount of energy an animal uses per unit of time (measured in
kcal or CAL)
 measuring amount of O2 animal uses per unit time
 measuring animal’s heat loss per unit time
 minimal rate: needed to support life
 maximal rate: during peak activity
 rate determined by age, sex, weight, body temperature, etc.

Endotherm: generate own body heat
Ectotherm: generates body heat from
metabolically
environment
Ex: birds and mammals
Ex: fish, amphibians, reptiles, and
Basal metabolic rate (BMR): metabolic
invertebrates
rate measured under resting, fasting, and
Standard metabolic rate (SMR)
stress-free conditions
determined at specific temperature under
resting, fasting, and stree-free conditions
Why is eating important?
o Chemical energy
o Building blocks for other materials
o Essential nutrients
ANIMAL NUTRITION: Most use some combination of extracellular and intracellular
digestion.
1. Ingestion: eating
2. Digestion: breaking food down (chemically or physically) into smaller particles and
molecules
3. Absorption: uptake of molecules
4. Elimination: passing out of digestive system undigested materials
Undernourished: not enough nutrients
Overnourished: too many nutrients (severe
obesity)
Malnourished: improper nutrients (missing
essential nutrients)
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1. Mouth: ingestion and digestion
(salivary enzymes)
2. Esophagus: peristalsis motion
3. Stomach: digestion (peptic
enzymes), controlled with sphincter
muscle
4. Small intestine: chemical
digestion and absorption
5. Large intestine: water
absorption, E. coli digestion and
vitamin production
6. Anus: elimination, controlled
with sphincter muscle
Alimentary canal: continuous tube with two openings (mouth and anus)
Feeding Mechanisms
o Suspension feeders: sift small food particles from water (ex: clam, oysters)
o Substrate feeders: live in or on food source (ex: leaf miners)
o Deposit feeders: eating way through dirt (ex: earthworms)
o Fluid feeders: sucking nutrient-rich fluids from living host (ex: mosquitoes, leech)
o Bulk feeders: eat large pieces of food (ex: humans)
Hydra captures prey
with stinging tentacles.
The prey is pushed
into a gastrovascular
cavity where enzymes
are released.
Phagocytosis and
intracellular hydrolysis
complete digestion.
The protist
Paramecium uses only
intracellular digestion,
where chemicals
secreted break down
food particles..
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Crop and stomach = storage
Gizzard = grinder
Pharynx = throat
Intestine = chemical digestion
Anus = elimination
Ruminents:
(1) When the cow first chews and swallows a mouthful of grass, boluses enter the
rumen and (2) the reticulum.
• Symbiotic bacteria and protists digest this cellulose-rich meal, secreting
fatty acids.
• Periodically, the cow regurgitates and rechews the cud, which further
breaks down the cellulose fibers.
(3) The cow then reswallows the cud, which moves to the omasum, where water is
removed.
(4) The cud, with many microorganisms, passes to the abomasum for digestion by the
cow’s enzymes.
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* * * Circulatory System * * *
CIRCULATION: Diffusion is too slow to move materials. Circulation reduces the
amount of time necessary to transport vital chemicals and gases.
Open circulatory system:
hemolymph (body fluid)
bathes internal organs
directly while moving
through sinuses
Closed circulatory
system: blood is confined
to vessels and distinct
interstitial fluid present
Circulatory system: heart
+ blood vessels + blood
Heart: cardiac muscle
Comparing Circulatory Systems
2-chambered
Ex: fish
One atrium, one ventricle
3-chambered
Ex: amphibians
Two atria, one ventricle
4-chambered
Ex: humans
Two atria, two ventricles
Systole: heart contracts
Diastole: heart relaxes,
chambers fill with blood
Heart rate: number of heartbeats per
minute
Sinoatrial (SA) node: controls heart
muscle
1. Oxygenated blood out of left ventricle to the
body.
2. O2 into body, CO2 into blood
3. Deoxygenated blood back to heart into right
atrium, right ventricle, and to the lungs.
4. CO2 exhaled, O2 inhaled
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5. Oxygenated blood back to heart into left atrium, left ventricle (repeat #1).
Arteries away from heart
Veins back to heart
Blood pressure: hydrostatic force that blood exerts against a vessel wall
Capillary exchange: exchange of materials between blood through capillary walls and
interstitial fluid
Blood components:
1. Plasma: fluid for blood,
electrolytes+proteins+90%
water
2. Red blood cells: erythrocytes
3. Leukocytes: white blood cells
4. Platelets: clotting factors
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* * * Respiratory System * * *
Gas exchange: movement of O2 and CO2 between animal and environment
Gas exchange over
entire body surface
Ex: protozoan and
unicellular organisms
Plasma membrane of
every cell has contact
with outside
environment
Ex: sponges,
flatworms, cnidarians
Isolated cells from
environment,
respiratory surfaces
are generally thin with
moist skin over bed of
capillaries
Region of body
surface with lots of
folds to increase
surface area for gas
exchange
Ex: humans
Ex: earthworms,
amphibians
Diaphragm: muscle that raises and lowers to decrease and increase lung capacity
Medulla senses pH of blood. Increased CO2 levels
drops pH. Lower pH raises rate of breathing to
exhale excess CO2.
Hemoglobin: four subunits each with heme group that bonds O2 with an iron atom
CO2 transported in blood dissolved in plasma, bound to hemoglobin, or as bicarbonate
ion.
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* * * Immune System * *
Robert Koch was the first to connect certain diseases to specific bacteria (anthrax, TB)
Koch’s postulates:
(1) The researcher must find the same pathogen in each diseased individual
investigated,
(2) Isolate the pathogen form the diseased subject and grow the microbe in pure
culture,
(3) Induce the disease in experimental animals by transferring the pathogen from
culture, and
(4) Isolate the same pathogen from experimental animals after the disease develops.
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* * * Controlling Internal Environment * * *
Osmoconformers: animals that do NOT actively adjust internal osmolaroty
Ex: saltwater animals, body fluids isotonic with the environment
Osmoregulators: animals that regulate internal environment by regulating water intake
and excretion
Ex: freshwater animals, all terrestrial animals, many saltwater animals
Planarian excretion:
* * * Excretory System * * *
Earthworm excretion:
Human nephrons:
Insect excretion:
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Flatworms: fluid passes through flame bulb, cilia
brushes into tubule, fluid drains into excretory
ducts
Earthworm: fluid passes through
metanephridium and empties into storage body
outside the body through nephridiopore
Insect: waste removed from hemolymph into
tubules, waste accumulates, water follows, fluid
passes to hindgut to rectum, salts and water
reabsorbed, solids excreted
Nitrogenous waste:
1. Ammonia: aquatic animals
2. Urea: mammals and most adult amphibians, requires lot of water to dilute or
otherwise toxic
3. Uric acid: land snails, insects, birds, and reptiles (paste-like consistency)
Mammalian excretory system: nephrons
1. filter blood: Bowman’s capsule, glomerulus
2. secretion: proximal and distal tubules
3. reabsorption: tubules and loop of Henle
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* * * Endocrine System * * *
Hormones; endocrine or neurosecretory cell secretions
that affect a target cell
Neurosecretory ell: nrueons that receive signals from
other nerve cells and release hormones as a result
Target cell: cell that can respond to a particular hormone
Endocrine gland: ductless glands that secrete hormones
Exocrine gland: glands that produce a variety of
substances and send products through ducts (ex: sweat,
mucus, etc)
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* * * Reproductive System * * *
Parthenogenesis: egg development with fertilization
Hermaphroditism: solution for animals that have difficulty finding mates
o Sequential hermaphroditism: an individual reverses its sex during its lifetime.
(ex: clearner shrimp)
Asexual reproduction (mostly in invertebrates)
o Fission: asexual reproduction in which a parent separates into two or more
approximately equal sized individuals.
o Budding: asexual reproduction in which new individuals split off from existing
ones.
o Gemmules of sponges are an example of a type of asexual reproduction that
involves the release of specialized cells that can grow into new individuals.
o Fragmentation: the breaking of the body into several pieces, some or all of
which develop into complete adults.
o Requires regeneration of lost body parts.
Sexual reproduction:
o Internal fertilization: favorable conditions for copulation (quality over quantity)
o External fertilization: moist habitat to protect eggs from drying out (quantity over
quality)
Pheromones: chemicals that attract mates (ex: bombykol of female moth)
Sperm anatomy:
Middle piece = lots of ATP to
flagella
supply
Acrosome: enzymes that digest
the outer layer of the egg during
fertilization
away
Produced in the testes (gonad)
the scrotum
held in
Fertilization takes place in
the Fallopian tubes
(oviduct)
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Oogenesis:
Spermatogenesis:
Female hormones:
Male hormones:
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* * * Nervous System * * *
1. Resting state: sodium channels closed, + outside and - inside
2. Threshhold: all or nothing response, inside much reach certain + voltage before
response can “fire”
3. Depolarization state: sodium channels open, Na+ ions flood inside the nerve cell,
inside goes + while outside goes +
4. Repolarization state: sodium channels close, Na+ blocked but K+ let in, makes inside
– against and outside +
5. Undershoot: Na+ continues to flood out with K+, membrane voltage becomes very
negative, creates
the refractory
period
Repeat for the the
next section of the
nerve axon.
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Synapses: spaces between two nerve cells that receive electrical or chemical signals to
fire the next neuron
Examples of neurotransmitters: acetylcholine, epinephrine, norepinephrine, dopamine,
serotonin, gases (NO, CO)
Nerve nets:
Cephalization: head development
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Cerebral cortex: thoughts
Medulla oblongata: reptilian brain (controls basic body functions – breathing, heart rate,
etc)
Cerebellum: balance
Pituitary gland: master gland that produces hormones
Hypothalamus: controls the pituitary gland
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* * * Skeletal-Muscular System * * *
Sliding-filament model
.
1. At rest tropomyosin blocks the myosin binding sites on actin.
2. When calcium binds to the troponin complex a conformational change results in the
movement of the tropomyosin-tropinin complex and exposure of actin’s myosin binding
sites.
3. Myosin sites on actin bind to tropomyosin, forming a cross-bridge.
4. The two filaments slide, causing a muscle contraction.
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