Movement

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Movement Animal may be stationary and have
moving parts, or may be mobile How do animals
move? How do they overcome friction and gravity
in their various environments? What
supportive/protective structures are required?
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What modes of transport are there? in
water on land flying All require a lot of
energy Swimming is the most efficient Larger
animals are more efficient, in terms of body
weight
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Swimming Friction is a big problem in
water Gravity is not (as long as animal is
buoyant) Some animals have fusiform
bodies Others have appendages to help them swim
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Locomotion on land Walking, running,
jumping Appendages Muscles Balance Crawling
(friction, not gravity) How are muscles arranged?
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Flying Lift thrust gt weight drag Wing
design Weight
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Mechanisms of movement Protozoans amoeboid
movement actin-myosin network (microfilaments)
adhesion proteins (also seen in cells in
complex animals that move in the same
way ciliary/flagellar movement
(microtubles) sliding filament model?
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Multicellular animals? muscles Muscles work
against skeletons Three main types of
skeletons hydrostatic exoskeletons endoskeleton
s
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Hydrostatic skeleton Fluid-filled
compartment cnidarians, flatworms, nematodes,
annelids Animals with true body cavities exhibit
peristalsis (longitudinal and circular
muscles) Simpler animals have only longitudinal
muscles
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Exoskeletons Deposited on surface of
animal mollusks, arthropods (Most) mollusks
form shell that increases in size Arthropods
have a cuticle secreted by epidermis protein-chit
in complex Thicker in protective areas, thinner
at joints Animals must molt periodically
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Advantages of exoskeleton? Can support more
weight, but animals are small enough that they
will not collapse under the weight of the
exoskeleton
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Endoskeleton Formed within body Composed of bone
and cartilage Bone is reservoir for calcium and
phosphorus In amniote vertebrates, also site of
blood cell formation
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Cartilage Notochord serves as stiffening device
in protochordates and vertebrate larvae
and embryos Large cells surrounded by elastic
and fibrous tissue Replaced by spinal column
except in hagfishes Cartlaginous skeletons seen
in jawless fishes and elasmobranchs (sharks,
skates, rays)
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Other vertebrates have bony skeletons
interspersed with cartilage (Cartilage overlaid
with bone during development) Hyaline cartilage
most common Some invertebrates (e.g., mollusks)
have tissue similar to cartilage
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Functions of bone (skeleton) Support and
protection Blood cell formation Mineral storage
(calcium especially) Site for muscle
attachment?body movement
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Compact bone osteocytes within lacunae arranged
in concentric circles called lamellae This
surround a central canal complex is
called Haversian system Canaliculi connect
osteocytes to central canal and to each other
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Prenatal development skeleton is mostly
cartilaginous Cartilage cells and then
osteoblasts start to deposit minerals Cartilagin
ous disk (epiphyseal disk) remains in
epiphysis Cells eventually stop dividing
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Adults continually break down and build up
bone Osteoclasts remove damaged cells and
release calcium into blood Osteoblasts remove
calcium from blood and build new matrix. They
become trapped? osteoclasts
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Axial skeleton skull (cranium and facial
bones) hyoid bone (anchors tongue and
muscles associated with swallowing) vertebral
column (vertebrae and disks) thoracic cage
(ribs and sternum) Appendicular
skeleton pectoral girdle (clavicles and
scapulae) upper limbs (arms) pelvic girdle
(coxal bones, sacrum, coccyx) lower limbs (legs)
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Joints Immovable (synarthoses) bones sutured
together by connective tissue skull Slightly
movable (amphiarthoses) connected
by fibrocartilage or hyaline cartilage vertebra
e, rib/sternum joint, pubic symphysis Freely
movable (diarthroses)- separated ligaments- hold
bones together tendons- muscle to bone lined by
synovial membrane
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Skeleton and other systems Skin makes vitamin D
which enhances calcium absorption Skeleton
stores calcium for muscle contraction, nervous
stimulation, blood clot formation Red marrow-
site of blood cell formation Calcium levels
regulated by parathyroid hormone and
calcitonin kidneys (can help provide vitamin
D) digestive system (can release calcium into
blood)
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Vertebrates will have different types of
skeletons depending on their size and
needs Variations in vertebrae number of
ribs usually paired appendages girdles (pelvic,
pectoral) modification of pentadactyl limb
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Posture Larger animals bear stress along long
axis of bone, i.e., more upright
posture Smaller animals bear weight along
transverse axis of bone more crouched posture
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Movement muscle moves against skeleton Skeletal
muscles are attached to bones by tendons (bones
are attached to each other by ligaments) Muscles
are attached in opposing pairs (when on
contracts, the other relaxes) How does
(skeletal) muscle contract? the sliding filament
model is based on microscopic observations of
muscle
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Critical role for calcium in muscle
contraction Calcium must bind to actin so that
myosin binding sites are exposed Regulated by
sequestration of calcium in the sarcoplasmic
reticulum of muscle cell Sarco prefix refers
to muscle cells
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Muscle contraction is graded Action potentials
can be summated many cells contract Skeletal
muscles are innervated by motor units (one
neuron can stimulate many muscle fibers)
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A single somatic motor neuron can produce an
axon with several terminal branches. Each
stimulates a different muscle fiber. Motor unit-
a motor neuron and the muscle fibers it
innervates
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Control of skeletal muscle contraction number of
fibers stimulated size of muscle number of
motor units size of motor unit how many times
fiber is stimulated (summation) length of
muscle at time of contraction (longest at rest
more cross bridges can form)
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Energy requirements of skeletal muscles At rest,
most energy obtained from fatty acids Exercise
glycogen and glucose also used ATP is used for
movement of cross bridges pumping of calcium
into sarcoplasmic reticulum (i.e., for
contraction AND relaxation)
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Oxidative phosphorylation (O2-dependent) blood d
eep breathing myoglobin Glycolysis glycogen fat
igue depletion of glycogen accumulation of
lactic acid Creatine phosphate- first source
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Not all muscles have the same contraction
speed Slow-twitch- red fibers lots of myoglobin
and blood supply back and legs (in
humans) Fast-twitch- fewer capillaries and less
myoglobin (white fibers)- anaerobic activity
(glycolysis) tend to be larger in
diameter arms Intermediate fibers- fast twitch
but with high oxidative capacity. Resistant to
fatigue
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Upper motor neuron control Spinal reflex
activity Output from primary motor
cortex Multineuronal system (posture,
movement of trunk and limbs) Modulated by motor
cortex, cerebellum and basal nuclei Information
delivered by muscle spindles (muscle
length) Golgi tendon organs (tension)
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Cardiac and smooth muscle Cardiac-
striated muscle cells can produce impulses and
contract simultaneously gap junctions allow
impulses to be conducted from cell to
cell can produce action potential
simultaneously usually originate from SA
node autonomic innervation
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Smooth muscle Often arranged circularly,
sometimes longi- tudinally as well No
sarcomeres, lots of actin. Myosin arranged so
cross bridges can form along its length Muscle
can contract when stretched
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Regulation of calcium is different not much
sarcoplasmic reticulum Smooth muscles capable of
graded depolarization Contractions are slower
and more sustained than in skeletal muscle. Can
work more efficiently (doesnt need as much
ATP)
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Single unit and multiunit smooth
muscles Single-unit- cells have many gap
junctions function as unit (most smooth
muscles) pacemaker activity neurotransmitter
release to one cell can diffuse to
others Multi-unit- each cell is innervated
separately ciliary muscles attached to eye
lens A single nerve fiber can synapse with
many smooth muscle cells (varicosities
allow release of neurotransmitter all along axon)
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Smooth muscle can maintain tension even when
stretched Can relax when stretched (to original
level of tension) Is energy efficient compared
to skeletal muscle Connective tissue keeps it
from stretching too much
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Muscle cells in other animals Arthropod muscles
are very similar to vertebrate muscles Flight
muscles can act more like autonomic muscles
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Integument- protective barrier skin and
structures associated with it Protection from
what? injury infection loss of
fluid inability to regulate body
temperature Sensory receptors May have excretory
and/or respiratory functions Secretions may play
role in sexual attraction or other kinds of
signaling
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Integument in invertebrates Protozoans- plasma
membrane or pellicle Other invertebrates-
epidermis cuticle may secrete mucus Mollusk
epidermis has glands that secrete calcium
carbonate for shell Arthropod integument also
serves as skeleton
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Arthropod cuticle is tough but flexible and
soft found this way in larvae and
microcrustaceans Hardened either by
calcification (decapods crabs and lobsters) Or
sclerotization (protein-chitin complexes)
which are tough but light Molting epidermal
cells divide and secrete enzymes that digest
cuticle materials are reabsorbed New cuticle is
made and hardened
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Vertebrate integument and derivatives Epidermis
and dermis form outer layers epidermis gives
rise to hair, feathers, claws hooves outermost
layers are keratinized (calluses, scales of
reptiles and birds dermis contain support
structures such as capillaries and nerve
endings bony structures are derived from
dermis (fish scales, crocodilians, turtle
shells)
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Coloration Usually produced by pigments May be
produced by structure of surface tissue such
that it reflects and absorbs light (structural
color many insects, birds and a few
fishes) Some animals are iridescent color
changes depending on angle at which it is seen
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Pigments more common Melanins (esp. in mammals),
carotenoids, etc. iridiophores- silvery
metallic ommochromes and pteridines Mammals are
generally the least colorful of the
bunch Melanin also helps protect from UV
irradiation Many animals have protective fur,
feathers or other structures Some must simply
hide!