Download CHAPTER 49

Sensory and Motor
Functions
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Motor systems
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• Cilia, flagella - projections that
extend from eukaryotic cells.
• Both produced from microtubules
organized in ring with 9 groups of 2
microtubules.
• Motor proteins join microtubules
together, consume ATP to drive
sliding movement of microtubules
past each other.
http://www.uic.edu/classes/bios/bios100/summer2002/microtubules.jpg
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• Causes flagella or cilia to move back
and forth - whip-like motion to
drive movement.
• Protist, free-swimming cell (sperm)
flagella movement drives cell
through water.
• Cilia helps to move water over
surface (respiratory tract).
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• In cell - cytoskeleton drives
movement of cytoplasmic contents
from one part of cell to another.
• Organelles can move because
microtubules used as track to drive
organelles (using ATP) around cell.
• Actin microfilaments drive
movement of cytoplasmic contents;
change shape of cell by interacting
with myosin.
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http://ghr.nlm.nih.gov/handbook/illustrations/actin.jpg
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• Amoebas, protists, amoeboid cells
in multicellular organisms (like
macrophages) use actin
microfilaments for cellular motion.
• Cells form pseudopods - extensions
of cytoplasm - help to change shape
of cell - causes movement.
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Hydrostatic skeletons
• Hydrostatic skeleton - fluid held
under pressure in closed body
compartment.
• Muscles that run length of
cnidarian body contract and
shorten body if water chamber
inside sealed – done by closing gut
opening - allows muscles to press
against water resulting in
movement.
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http://biology.unm.edu/ccouncil/Biology_203/Images/Protostomes/Nereis.jpg
• Also in annelid (earthworm)
locomotion.
• Each segment contracts
independently - contraction of
muscles that run around worm,
muscles that run length of worm.
• Contraction of circular muscles
makes worm segments longer and
narrower; contraction of length
muscles makes segments fat and
wide.
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• Earthworms move primarily by
moving muscles against hydrostatic
skeleton.
• Have bristles (setae) in lower part
of each segment to aid in
movement.
• Also help to anchor worm in earth
while muscles push worm ahead.
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http://biology.unm.edu/ccouncil/Biology_203/Images/Protostomes/earthworm.gif
Exoskeleton
• Exoskeleton - hard skeleton that
covers all muscles and organs of
some invertebrates.
• Exoskeletons in arthropods - chitin.
• All exoskeletons made from
material secreted from epidermis.
• Functions in protection; limits
growth of organism.
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http://www.cartage.org.lb/en/themes/sciences/LifeScience/GeneralBiology/Physiology/TheBones/MuscularSkeletal/exoskel.gif
• Periodic molting of old exoskeleton
occurs to allow organism to grow.
• Muscles attached to interior of
exoskeleton between jointed
sections which contract, allowing
movement.
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http://www.dfw.state.or.us/MRP/shellfish/crab/large_images/molt_series.jpg
Vertebrate endoskeleton
• Framework for movement and
support within vertebrate.
• Skeletal muscles attached to bones,
allowing movement when muscle
contracts by bringing 2 bones
together.
• Also provides protection because it
protects vital organs.
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http://img.dailymail.co.uk/i/pix/2007/11_01/elephantDM0711_800x511.jpg
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Cartilage
• Cartilage firm and flexible, not as
hard or brittle as bone.
• Makes up skeleton of lower
vertebrates (sharks, rays).
• Higher animals, cartilage part of
embryonic skeleton, replaced during
development by bone.
• Found in joints in humans; has no
nerves or vessels (longer healing
time).
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Bone
• Bone - skeletons of higher animals.
• Comes from replacement of
cartilage or from direct
ossification (dermal bone - skull).
• Replacement bone, osteoblasts
replace cartilage already formed.
• Hollow cavity formed where bone
marrow ends up (forms red blood
cells)
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• Mature bone constantly being
broken down by osteoclasts,
replaced by osteoblasts.
• In response to hormones; part of
regulation of calcium in blood.
• Spongy bone located in central
portions of bone; consists of
network of hard spicules separated
by marrow-filled spaces where
blood cells produced.
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http://www.web-books.com/eLibrary/Medicine/Physiology/Skeletal/compact_spongy_bone.jpg
• Spongy bone - cannot withstand lateral
stress.
• Compact bone located on outer surfaces
and articular surfaces; responsible for
hardness of bone.
• Consists of Haversian systems - cells
embedded in matrix of inorganic
material which gives bone its hardness.
• Cells surround central blood vessel
within Haversian canal.
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http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/B/Bone.html
http://www.sirinet.net/~jgjohnso/skeletonorg.html
• Bones held together by sutures or
joints (movable and immovable).
• Movable joints (hip joint) ligaments that serve as bone-tobone connection; tendons - skeletal
muscle to bones - help bend
skeleton at movable joints.
• Axial skeleton - midline skeleton
(skull, vertebrae, ribs);
appendicular skeleton (appendages,
pelvis.)
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Fig. 49.28
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Attachments and joints
• Origin of muscle - attachment to
stationary bone; insertion - bone
that moves during contraction.
• Extensor extends or straightens
bones at joint.
• Flexor bends joint to an angle.
• Joints held together by ligaments
(bone to bone), tendons (bone to
muscle).
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http://www.cartage.org.lb/en/themes/Sciences/LifeScience/GeneralBiology/Physiology/Muscular/Joints/joints1.gif
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Types of muscle
• Muscle contraction in all types of
muscles depends on movement of
actin and myosin filaments passed
each other using ATP.
• 1Skeletal muscle (voluntary)
produces intentional movement;
controlled by somatic nervous
system
• Each fiber has >1 nucleus.
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http://www.web-books.com/eLibrary/Medicine/Physiology/Muscular/muscle_structure.jpg
• Striations in muscle formed by
overlapping strands of proteins
actin and myosin.
• Thin filaments – actin; thick
filaments -myosin.
• Contractile unit - sarcomere contains myosin in middle and
overlapping actin filaments on each
end.
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• Muscle contraction results in
myosin filaments sliding over actin
filaments - sarcomere shrinks in
length.
• Contraction of skeletal muscle
regulated by troponin-tropomyosin
proteins that bind to actin
filaments.
• Absence of calcium - block myosin
from binding to actin.
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• Motor neuron fires action potential
that reaches synapse of nerve with
skeletal muscle cell (neuromuscular
junction), muscle has action
potential that spreads across whole
cell - causes calcium to be released
from internal stores in sarcoplasmic
reticulum.
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http://www.arn.org/docs/glicksman/090104%20fig2%20actin.jpg
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• Calcium causes troponintropomyosin to change shape; allows
myosin to bind actin, moving
filaments past each other.
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• 2Smooth muscle involuntary; found
in visceral organs.
• Innervated by autonomic nervous
system.
• Each muscle fiber - 1 nuclei; muscle
not striated.
• Release calcium into cytoplasm to
trigger contraction - do not use
troponin-tropomyosin system.
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http://static.howstuffworks.com/gif/muscle-smooth-contracted.jpg
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• 3Cardiac muscle striated - 1 nuclei.
• Nervous system monitors heart
beat of cardiac muscle.
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http://virtual.yosemite.cc.ca.us/randerson/Lynn%27s%20Bioslides/126.jpg
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Sensory Systems
• Sensory cells receive information,
use action potentials to transmit
information to nervous system.
• Brain determines nature of sensory
information based on what cell it
came from and what region of brain
receives it.
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http://www.cartage.org.lb/en/themes/Sciences/Zoology/Biologicaldiverstity/AnimalsI/flatworm.gif
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Vision
• Eye in invertebrates (flatworms) patches of cells on surface - light
sensitive.
• Can move towards or away from
light, cannot form image.
• Arthropods - compound eyes with
many sections gathering light from
different directions.
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• Mollusks (squid) - more complex
eyes to allow for image forming.
• Human eye detects light, transmits
information about intensity, color,
and shape to brain.
• Cornea (transparent) at front of
eye bends, focuses light rays - pass
through opening (pupil) whose
diameter controlled by muscular iris
(colored part of eye).
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• Iris responds to intensity of light.
• Increased light - pupil constrict.
• Light continues through lens
(behind pupil) - focuses image onto
retina.
• Retina has photoreceptors that
change light into action potentials.
• Muscle attached to lens can stretch
to change focus to view far or near
objects.
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• 2 types of photoreceptors in retina:
cones and rods.
• Cones - high-intensity illumination,
sensitive to color.
• Rods - low-intensity, important in
night vision.
• 3 different types of cones with
different color sensitivity.
• Color blind people lack one or more
pigments.
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http://www.mediacollege.com/lighting/colour/images/ishihara7.gif
A deficiency in cones is responsible for
color-blindness
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• Rhodopsin (protein) receives visual
signal, has retinal group bound to it.
• Retinal group changes when hit by
photon - changes structure of
rhodopsin; starts cascade of signal
transductions that lead to action
potential.
• Photoreceptor cells synapse onto
bipolar cells - synapse onto ganglion
cells.
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http://cas.bellarmine.edu/tietjen/HumanBioogy/Sensory/Rhodopsin.gif
• Axons of these ganglion cells
bundle to form optic nerves - send
visual messages to brain.
• Interpretation of messages done in
cerebral cortex.
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Fig. 49.15
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Hearing and balance
• Ear responsible for transforming
impulses into sound as well as
maintaining balance.
• Sound waves pass through 3 regions
as they enter ear.
• Outer ear consists of auricle
(pinna), auditory canal.
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• At end of auditory canal - tympanic
membrane (eardrum) of middle ear.
• Vibrates at same frequency as
incoming sound.
• 3 bones - mallus, incus, stapes amplify stimulus and transmit it
through oval window to fluid-filled
inner ear.
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http://www.palaeos.com/Vertebrates/Bones/Ear/Images/Incus2.gif
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• Inner ear - cochlea and semicircular
canals.
• Cochlea contains organ of Corti specialized cells (hair cells).
• Vibration of bones exerts pressure
on fluid in cochlea which stimulates
hair cells to change pressure into
action potentials.
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http://www.2ears2hear.org.uk/images/P_cochlear-noConsole.jpg
• Action potentials travel (via
auditory nerve) to brain for
processing.
• Frequency of sound detected by
position of cochlea of hair cells
that are stimulated; volume
detected by number of signals
received.
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Fig. 49.17
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Fig. 49.18
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
• Semicircular canals are used for
balance.
• Each of 3 semicircular canals in
inner ear is perpendicular to other
2 and filled with a fluid endolymph.
• At base of each canal - chamber
with sensory hair cells.
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http://www.daviddarling.info/images/semicircular_canals.jpg
• As head rotates, endolymph in one
of canals displaced - puts pressure
on hair cells in it.
• Changes nature of impulses sent by
vestibule nerve to brain.
• Brain interprets this information to
determine position of head.
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Fig. 49.19
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Taste and smell
• Chemosensor detects chemicals in
environment.
• Taste and smell both involve
chemosensors.
• Taste buds located on tongue, soft
palate, and epiglottis.
• Outer surface of taste bud has
taste pore where microvilli are
located.
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• Nerve fibers located in taste buds
that are stimulated by taste buds.
• These neurons transmit impulses to
brainstem.
• 4 taste sensations: sour, salty,
sweet, and bitter.
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http://www.nature.com/nature/journal/v444/n7117/images/nature05401-f1.2.jpg
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• Olfactory receptors found in
olfactory membrane in upper part
of nostrils.
• Receptors - specialized neurons
from which olfactory hairs project.
• Substances enter nasal cavity and
bind to receptors in cilia which set
off receptors.
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http://upload.wikimedia.org/wikipedia/commons/thumb/3/3a/Head_olfactory_nerve.jpg/250px-Head_olfactory_nerve
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• Axons from olfactory receptors
join to form olfactory nerves form direction to olfactory bulbs in
base of brain.
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