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8/3/2019 LSM3261_Lecture 9 --- Animal Symmetry and ion
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LSM3261 Life Form and FunctionAnimal structure and function
LSM3261 Lectures 08 - 13= Zoology Lectures 1 - 6
LSM3261 Practicals 4 - 6
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Practicals and CA
Practical 4
Body plans and Protection
Arthropod morphology (dissection)
Dissection assessment (2.5%)
Practical 5
Form and function in vertebrates
Setting thinking questions (2.5%)
Practical 6
Support
Practical test based on practicals (15%)
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Not possible to cover the entire range of animal formand function.
Certain aspects are highlighted to initiate a thinkingprocess.
An emphasis on structure and function - i.e.we will focus on structural adaptations and less onbehavioural or physiological ones.
Thematic approach will focus on specific topics.
Course approach
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Plants & Animalsface similar challenges to survival
Gas exchange: Stomata/lenticels in plants Respiratory systems in animals
Internal transport: Vascular system (phloem, xylem, leaf
veins) in plants
Circulatory system in animals
Osmoregulation
Active transport (cellular level) inboth plants and animals
Salt secretion in both plants andanimals
Protection: Epidermis, cuticle, hairs, spines in
plants
Epidermis, exoskeleton, scales, spinesin animals
Common physical and environmental challenges result in similarities inform and function.
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Lecture Number - Topic
08 - Animal diversity and basic designs 09 - Animal symmetry, arthropod morphology
Animal form and function in relation to: 10 - Protection 11 - Support & Locomotion
12 - Locomotion (Flight)
13 - Sensing the environment, Feeding 13 - Other adaptations
Topics for the animal component
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Biology education
Expand your initial introduction to biodiversity (LSM 1103). Explorezoology!
Appreciate a holistic approach to understanding life.
To understand the structure of animals and how they are designed forspecific tasks.
To understand how adaptation facilitates survival.
To appreciate the diversity of structural adaptations displayed bydifferent groups of animals in response to a common problem.
Whats the point of it all?
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General education
Appreciate structure, detect patterns and deducefunction.
Application, analysis, synthesis and judgment.
Other skills and tools, e.g. illustrating ideas,communicating science (especially during thepracticals and the CA).
Life lessons and food for thought.
Dealing with a less structured system.
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Questions from
an active mind Why dont elephants choke when they suck water upthrough their nose (trunk).
Why cant a flying fish fly for long distances?
Why has a sea cucumber become bilaterally symmetricalwhen it started out with radial symmetry?
Isnt it dangerous for cuttlefish to be swimmingbackwards?
Why doesnt the long proboscis of the butterflyinterfere with its flight?
Please ask stupid questions!
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Questions from a lazy mind
What is bilateral symmetry?
How many toes are there in a leg of a horse? What is the mouth part of a butterfly called?
During practicals, we will consult booksand the internet together
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How to do well in this moduleand gain from it
Be curious, inquisitive and observant. Be an active learner - do not ask questions that can be
obtained directly from a text book. Read widely, watch nature documentaries. Dont waste tim on the details.
Essential to understand general concepts so that youcan apply them. Explore with Google and NUS Digital Library.
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http://delicious.com/sivasothi/lsm3261
This is listed under weblinks inIVLE.
It allows you see the additionalreferences I look at whilepreparing lectures.
Check the tags (lsm3261,
locomotion, etc)
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http://del.icio.us/sivasothi/lsm3261http://del.icio.us/sivasothi/lsm3261http://del.icio.us/sivasothi/lsm32618/3/2019 LSM3261_Lecture 9 --- Animal Symmetry and ion
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This year we will use a a
Facebook page - easier for
most of you to follow than amodule blog.
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Predicting form
Form and function are closely related. E.g. long extended proboscis of hawk moth (form) for feeding on
nectar in deep tube-shaped flowers (function)
Tremendous diversity of form and function ultimatelyaddresses a set of common general challenges faced by mostanimals:
Obtaining oxygen
Obtaining food Excreting waste
Movement
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Hummingbird hawk moth
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Illustration by John Day; Orchids of the Worldhttp://www.orchids.mu/Species/Angraecum/Angraecum_sesquipedale.htm
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http://www.orchids.mu/Species/Angraecum/Angraecum_sesquipedale.htmhttp://www.orchids.mu/Species/Angraecum/Angraecum_sesquipedale.htm8/3/2019 LSM3261_Lecture 9 --- Animal Symmetry and ion
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The moth ofA. sesquipetale predicted:
Charles Darwin: "[A. sesquipetale has] nectaries11 and a half inches long, with only the lower inchand a half filled with very sweet nectar [...]
it is, however, surprising, that any insect should beable to reach the nectar: our English sphinxes haveprobosces as long as their bodies;
but in Madagascar there must be moths withprobosces capable of extension to a length ofbetween 10 and 12 inches!"
Darwin, 1862. Fertilisation of Orchids, pp. 197-198)
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Th h f A ip l di d
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The moth ofA. sesquipetale predicted:
Alfred Russel Wallacepublished a drawing of what thisbutterfly might look like, concurring with his colleague and added:
"[The proboscis of a hawkmoth] from tropical Africa ([Xanthopan]morganii) is seven inches and a half.
A species having a proboscis two or three inches longer couldreach the nectar in the largest flowers ofAngrcum sesquipedale,whose nectaries vary in length from ten to fourteen inches.
That such a moth exists in Madagascar may be safely predicted,and naturalists who visit that island should search for it with as
much confidence as astronomers searched for the planetNeptune, and they will be equally successful!"
Wallace, 1867. Creation by Law.
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The moth ofA. sesquipetale
predicted:
Nature, 12 June 1873
W. A. Forbes challengedreaders, Can any of your
readers tell me whether mothsof such a size are known toinhabit Madagascar?"
Rotschild & Jordan, 1903
Moth described.
Image Source: KQED QUESTSome rights reserved.
Xanthopan morganii praedicta
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LSM3261 Life Form and Function
Zoology Lecture 2Animal symmetry,internal transmission
and arthropod structure
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LSM 3261 Lif F S & F i
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LSM 3261 Life Form Structure & Function
1st zoology lecture - Animal diversity and basic designs
2nd zoology Lecture Animal symmetry; Transmission of messages/materials within the
animal body
Arthropod structure (practical) Animal form and function in relation to:
No. 3 - Protection
No. 4 - Support & Locomotion No. 5 - Locomotion (Flight) No. 6 - Sensing the environment, Feeding and
other adaptations
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1. Types of animal
symmetry1. Bilateral
2. Radial
3. Pentaradial
4. Metamerism (segmentation)
4.1 Tagmatisation
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BILATERAL SYMMETRY RADIAL SYMMETRY
Can be cut into
two equal lateral halvesalong one (saggital) plane only
Can be cut longitudinally into two
equal halves along more than oneplane through axis of body
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1.1 RADIAL SYMMETRY
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Advantages of radiating configuration
Distance between centre andoutlying points reduced(faster transportation of materials,signals)
Increased surface area
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Is there a solutionto this problem?
Disadvantage
Too many points converging at the
centre causing over-crowding
Solution: Branching
- Maintain radial configuration andsurface area
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Are there radially symmetrical animals thatwhich are branched this reducing
congestion at the centre?
Is there branching in humans?
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1.2 PENTARADIALSYMMETRY
(Echinoderms)Radial symmetry basedon 5 parts or planes
1
2 3
4
5
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Why pentaradial symmetry?
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Pentaradialsymmetry: five
ossicles
Suture planes
Hexaradialsymmetry: six
ossicles
One theory:
Skeleton in primitive echinoderms(radially symmetrical sessile,suspension feeders)
Suture planes: structural weakpoints
Advantageous to NOT have twosuture planes directly opposite
Odd number of surrounding ossicles
But why 5 parts?
Why not 7 or 9 parts?
Why not 3 parts?
Why pentaradial symmetry?
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Bilaterally Symmetrical Animals
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B l l d h
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Fast-moving animals:
Are they radially or bilaterally symmetrical?
Bilateral symmetry associated with: General lengthening of body.
Cephalisation increasing specialisation of anterior endof animal with concentration of sensory structures (i.e.development of a well-defined head!).
Bilateral symmetry and cephalisation
Adaptations for locomotion; associated with increasedeffectiveness of reacting to environment (e.g. find food,detect enemies).
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Radial symmetry
ADV: Defend in all directions!
Slow, nerve net not centrallycontrolled.
Bilateral symmetry
Move faster (advantage foirdirected locomotion),
predation, cephalisation, etc.
Advantages?
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Radial symmetry Bilateral symmetry
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y y
Vast majority sessile - anchored to thesubstrate.
All lateral surfaces equally likely to
interacting with the environmentmeaningfully; oral/aboral
Top and bottom of the organismhave very different functions.
Lower surfaces often modified for astable, concrete point of attachmentto some solid surface.
Upper surfaces modified for thegathering of resources (usually food).
Lateral organization is relativelyunimportantVertical organization is meaningful, Symmetry around the central vertical
axis becomes the most useful body
plan.
y y
An adaptation to a moving, directionalexistence.
Up and down, left and right, top and
bottom, front and back.
Anterior portion encounters theenvironment first.
Differentiation of sense organs(cephalization) in the anterioreventually becomes significant
Locomotion by providing a propulsiveforce against air or water or thesurface of the earth
Can wegeneralise?
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Barnacles
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Not all sessileanimals
are radially symmetrical
Sea squirt or Tunicate
Giant clams
Sea pen
Barnacles
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Not all radiallysymmetrical animals
are sessile
Feather star
Brittle star Jellyfish
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BILATERAL
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BILATERALSYMMETRY?
PENTARADIAL OR BILATERAL SYMMETRY?
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Asymmetry in the Pleuronectiformes
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Asymmetry in the Pleuronectiformes
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This process involves extensive remodeling of the skull.
Bones soften and degenerate,epithelial and connective tissue thickens
and pushes the eye socket around,and just in general many bones,
including those of the jaw,end up oddly skewed.
Larval metamorphosis
Later stages:calcification
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BILATERAL OR RADIAL SYMMETRY?
White-spotted puffer,Arothron hispidus
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Unequal bilateral symmetry
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The Ups and Downs of a Sea Anemone
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The Ups and Downs of a Sea Anemone
Most animals are in theBilateria.
Sea anemones - radialsymmetry.
The starlet sea anemone,Nematostella vectensis.
Burrows through mud! John Finnerty
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the starlet sea anemone
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the starlet sea anemone,Nematostella vectensis
A cross section of the adult shows not radialsymmetry, as dogma would predict, but a plane
of bilateral symmetry (known as the "directiveaxis") that traverses the pharynx at right anglesto the primary oral-aboral (mouth-foot) bodyaxis.
"Enhanced: The Ups and Downs of a Sea Anemone,"by Peter Holland. Science, 304 (5675): 1255 - 1256.
Commenting on Finnerty et al., 2004.Origins of Bilateral Symmetry: Hox and Dpp
Expression in a Sea Anemone. Science, 304(5675): 1335.
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Anthozoan bilaterals
The bilateral symmetry of anthozoans (andnot other cnidarians) was noted by Hyman(1940).
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Origins of bilateral
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If sea anemones possess bilateral symmetry,is it homologous to our own bilateral
symmetry or did it arise by convergentevolution?
I. e. ... did bilateral symmetry originate earlierin our ancestry than is commonly believed or
did anthozoans evolve from a radial ancestorand develop bilaterality independently?
Origins of bilateral
symmetry
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Comparison of gene expression patterns
data suggests that
the main oral-aboral body axis
of a sea anemone, running frommouth to foot, is homologousto the anterior-posterior axisof bilaterians,
whereas a precursor of thedorsoventral axis runs throughthe directive axis.
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Nematostella has perfectly good Hox genes that are expressed in astaggered anterior-posterior pattern. It's not quite as tidy as the
vertebrate or athropod patternthere's a lot of overlap, as you canseebut it's good enough to see the canonical Hox arrangement.
PZ Myers commenting on the paper (2006); this and previous slides.
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Boloceroides mcmurrichioff Changi
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Boloceroides swims up, down, or horizontallyapparently equally well. Often it swims in anearly straight line, but sometimes theswimming course is rather erratic.
The tentacles apparently beat in planeswhich are slightly inclined to the oral-aboralaxis, for the anemone usually rotates aboutits longitudinal axis as it swims, making acomplete revolution every 6-20 strokes.
This rotation probably stabilizes swimmingto some extent. ...
See Video and additional text here:
http://tinyurl.com/2cq46n
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Boloceroides mcmurrichioff Changi
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During swimming the tentacles arefunctionally organized as a series ofconcentric rings on the oral disk.
During the downstroke portion of the cycle,the most lateral tentacles, the smallest of thecrown, are the first to beat.
The inner tiers follow in a regular fashionwith a brief delay before the onset of lashingin each. The tentacles near the mouth are thelast to respond."
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During swimming the tentacles are
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g gfunctionally organized as a series ofconcentric rings on the oral disk.
During the downstroke portion of the cycle,the most lateral tentacles, the smallest of thecrown, are the first to beat.
The inner tiers follow in a regular fashionwith a brief delay before the onset of lashing
in each. The tentacles near the mouth are thelast to respond."- Josephson, R. K. & S. C. March, 1966. The
Swimming Performance of the Sea-Anemone Boloceroides. Journal of
Experimental Biology, 44: 493-506.
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1 4 Metamerism (Segmentation)
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Repetition of similar body segments along longitudinal axis of body
Allows for specialisation.
External and internal segmentation
Each segment referred to as ametamere or somite
Clearly represented insegmented worms (annelids) segments separated by internal
walls (septa).
Organs repeat themselves (e.g.excretion). Some are notrepeated (e.g. digestive).
1.4. Metamerism (Segmentation)
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Ad f i
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Advantage of metamerism
Hydrostatic skeleton improves - efficiency ofmovement/burrowing efficiency improves.
Elongate different parts of body at differenttimes - better control of movements.
Safety factor of built in redundancy.
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C t th i h lf
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Cut an earthworm in half
What happens? Why?
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Metamerism,segmentation and tagma
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Segment - clearly differentiatedsubdivision of an animals body
Metamere - homologous segment inlongtitudinal series; copies
Tagma? (pl. - tagamata) -arthropodan divisions,e.g. spider cephalothorax and opsithosoma;crab: cephalothorax and abdomen.
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By the way....
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2005 - New species Glyphidrilus singaporensis
Four new records - Glyphidrilus horstiStephenson, 1930,
Amynthas gracilis (Kinberg, 1866),
Amynthas minimus (Horst, 1893), and
Polypheretima taprobanae (Beddard, 1892)
Three unidentifiable Drawida species
Total of 19 species of terrestrial earthworms that arenow known from the island.
Most dominant species - the exotic Pontoscolexcorethrurus (Mller, 1856)
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1.4.1 Tagmatisation
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Tagmatisation -- grouping/fusion of segments of similarstructure, function and appendages to allow
specialisation
Most obvious e.g.: cephalisation Other examples:
head, thorax, abdomen (insects) cephalothorax, abdomen (chelicerates, some
crustaceans)
clitellum (some annelids)
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Evolved three times?
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Annelida
external segmentation marked; muscles segmented;
segmentally arranged ganglia.
Arthropoda
segments more specialised for a variety ofpurposes, forming functional groups (tagmata).
head/trunk; head, thorax, abdomen; cephalothorax,abdomen
Chordata if present, restricted to outer body wall.
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2 T i i f d
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2. Transmission of messages and
materials within the animal body
Nervous system
Internal transport
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2.1 Nervous system
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Transmission of information throughout animalsbody vital for survival maintenance of internalenvironment (homeostasis)
Animal must respond rapidly to external andinternal changes (stimuli that trigger response) All animals except sponges have at least a network
of nerve cells (neurons) that respond to stimuli
Neurons transmit electrical and chemical signals
y
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cerebral
Crustacean
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Flatworm
cerebral
ganglia
(simple
brain)
longitudinal
nerve cords
with
transverse
nerves
Hydra nerve net,suitable for radially
symmetrical animals
Bilaterallysymmetricalanimals have
more complexnervoussystems
AnnelidInsect
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Messages received have to be transmitted, analysed, and a
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g , y ,suitable response elicited:
RECEPTION detecting a stimulus (by neurons and
specialised sense organs)
TRANSMISSION sending messages along a neuron, to
other neurons and/or to muscle or gland
INTEGRATION messages sorted and interpreted,
appropriate response determined
RESPONSE appropriate response effected
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Neurons highly specialised cells designed to receive
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stimuli, and produce and transmit electrical signals (nerveimpulses or action potentials)
nucleus
axon
dendrite
myelin sheath
terminal branches(gap betweenbranch and next
neuron = synapse)E.g., motor neuron
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Synapse betweensensory and interneuron
Reception
Transmission
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Receptor
Sensory neuron
Nerve cell body
of sensory neuron
sensory and interneuron
Interneuron
Nerve cell bodyof motor neuron
Muscle
Reflex action coordinated, involuntaryresponse to stimulus
Integration
Response
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Trends in evolution of
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Increased number of nerve cells
Concentration of nerve cells into ganglia, brain,nerve cord, nerves
Specialisation of function (afferent, efferent)
Cephalisation (formation of head)
Increased complexity
the nervous system
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Trends in evolution of
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To survive, animals have to respond to changes in theirinternal and external environment.
Simple nervous system - general responses only (can onlyprocess information in a limited way_, e.g. the commonfreshwater Hydra.
Hydra has a nerve net of neurons between the outerand inner layers of a sac-like body.
The nerve net transmits impulses in all directions withno means of processing the information to make aspecific response.
the nervous system
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Flatworms (e g planaria) i l t li d
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Flatworms (e.g. planaria) - simple centralizednervous system.
Neurons organized into ganglia which receive stimulifrom the sensory structures and transmit them by wayof a ladder-like arrangement of nerves to muscle cells.
This makes specific responses to stimuli possible, e.g.turning away from light, or curling up when touched.
Higher invertebrates (e.g. annelids, arthropods, andmolluscs) - more complex nervous system, more highlydeveloped sensory structures.
This allows the animals to receive, process, andrespond to stimuli in a greater variety of ways.
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E d f i t d i f ti
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E.g. compound eyes of insects: send sensory informationthrough nerve fibers to the ganglia in the head that serve
as the brain.
Information relayed to the other parts of the bodythrough the ventral nerve cord.
E.g. rapid escape response of flies when you try toswat.
E.g. Octopus,
Well developed eyes and a central concentration ofnerve cells.
Responses are highly specific, and it has the ability tolearn how to perform complex tasks.
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2.2 Internal transport
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A cell requires:
a continuous supply of nutrients, oxygen
removal of waste products Mainly through diffusion across cell
membrane
Cells bathed in interstitial fluid (aqueousmedium between cells for diffusion ofoxygen, nutrients, waste materials)
p
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Circulatory System
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Diffusion effective across short distances feasible for internal transport in small, simple invertebrates
(e.g., sponges, cnidarians, flatworms)
Larger animals require specialised circulatory systems
Transport oxygen, nutrients, hormones, metabolic wastes toand from interstitial fluid
A circulatory system reduces diffusion distance of materials
interacts with all organ systems (and constituent tissues andcells) in the body
Circulatory System
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CIRCULATORY SYSTEM
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Blood - connective tissue containing cells &cell fragments in fluid (plasma)
Pumping organ (usually a heart) System of tubes (blood vessels) or spaces
through which blood flows
C CU O S S
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INVERTEBRATES
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INVERTEBRATES
No circulatory system
Open circulatory system
Closed circulatory system
VERTEBRATES
Closed circulatory system
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NO CIRCULATORY SYSTEM
Small aquatic invertebrates:
Flatworms
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Small, aquatic invertebrates:
Flattened, not more thanfew layers of cells thick
Branched intestine circulates nutrients/oxygento all cells
SpongesCnidarians73
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OPEN CIRCULATORY SYSTEM- Pumping mechanism presentBlood vessels not continuous throughout body blood flowsinto large spaces or sinuses (haemocoel)
- Blood bathes tissues directly- Blood and interstitial fluid not distinguishable (haemolymph)
Haemolymph returns directly to heart:- through openings in heart (arthropopds)
- through open-ended vessels leading to gills (molluscs)
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Stomach
Ventricle
Atrium
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Gills
Artery Ostia Tubular heart
OPEN CIRCULATORY SYSTEM
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CLOSED CIRCULATORY SYSTEM
- Continuous circuit of blood vessels- Smallest blood vessels (capillaries): sufficiently thin walls toallow diffusion of materials
-Tissues not directly bathed by blood
-Blood pumped through system by muscular heart or bodymuscles
- Annelids, cephalopods, echinoderms, vertebrates-
Network based on a main blood vessel taking bloodto the entire body and another taking blood back to the heart
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CLOSED CIRCULATORY SYSTEM
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Dorsalvessel
Contractileblood vessels
Ventralvessel
Lateralvessels
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AtriumVeins from thebody
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SINGLE CIRCULATIONSYSTEM IN FISH
gills
heart
Ventricle
Aorta
Heart to gills to rest of body, back to
heart (2 chambered heart: oneventricle, one atrium)
Rest
ofbody
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AMPHIBIAN d bl i l
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AMPHIBIAN double circulatory system
Heart to lungs to heartHeart to body to heart
(3-chambered heart: two atria, one ventricle partialmixing of oxygenated and deoxygenated blood)
REPTILE double circulatory system
(3-chambered heart: two atria, one ventricle, partiallyseparated, minimal mixing of oxygenated and
deoxygenated blood cf. amphibian)
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DOUBLE CIRCULATIONSYSTEM IN AMPHIBIA Incomplete
partitionof theentricle
Reptile heart
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lungs
Veins fromthe body
Ventricle
Pulmonary vein Pulmonaryartery
Aorta
Partitionseparating atria
Atria
ventricle
Amphibian heart
Rest ofbody
3-chambered heart: twoatria, one ventricle, mixingof oxygenated and
deoxygenated blood
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DOUBLE CIRCULATION SYSTEM INBIRDS AND MAMMALS
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lungs
Veins fromthe body
Right atrium
Ventricles
Leftatrium
Pulmonaryartery
Aorta
4-chambered heart: two atria, twoventricles, no mixing of oxygenated and
deoxygenated blood
Rest ofbody
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Aorta
Left pulmonary arteries
Superior vena cava
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Right pulmonaryarteries
Pulmonary valve
Right atrium
Pulmonary veins
Right ventricle
Inferior vena cava
Pulmonary artery
Pulmonary veins
Left atrium
Left ventricle
Interventricular septum
Aorta
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