Movement Generating Mechanisms

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• Movement Generating Mechanisms
• I. Selective Forces
• -- animals must move to find food, suitable
  habitat, mates, etc.
• -- basic principle
• use energy from ATP to cause protein fibers to
• slide past one another causing contraction
• most common fibers actin, myosin

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II. Amoeboid Movement -- involves pseudopodia
-- found in all Sarcodina many Mastigophorans
amoebocytes of Poriferans mammalian phagocytes
etc.
pseudopodia
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II. Amoeboid Movement A. Structure of
pseudopod
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Amoeboid Movement
trailing edge
leading edge
actin-fiber meshwork
plasmalemma
(Fig. 11-12 p. 217)
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II. Amoeboid Movement A. Structure of
pseudopod B. Mechanism of movement
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Amoeboid Movement
trailing edge
leading edge
actin-fiber meshwork
myosin head head
(Fig. 11-12 p. 217)
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Amoeboid Movement
trailing edge
leading edge
E
Membrane adhesion proteins
(Fig. 11-12 p. 217)
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III. Cilia and Flagella A. Structure 9
2 arrangement of microtubules (cellular
organelles) composed of tubulin
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Flagella and Cilia
(peripheral pairs)

(Fig. 29-11 p. 637)
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III. Cilia and Flagella B. Function
sliding microtubule hypothesis
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Flagella and Cilia

(Fig. 29-11 p. 637)
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Flagella and Cilia

(Fig. 29-11 p. 637)
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IV. Muscles -- muscle cell muscle fiber
-- specialized for generating contractions --
contain actin and myosin -- found in all phyla
from Cnidaria ? Chordata
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IV. Muscles A. Types of muscle fibers
(muscle cells) 1. Striated muscle fibers
a. characteristics -- skeletal
(voluntary) muscle -- controlled by somatic
nervous system -- elongated cylindrical
multinucleated -- contractile fibers
arranged in sarcomeres -- produce rapid,
powerful contractions for locomotion --
fatigue more easily
(Fig. 29-13 p. 638)
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IV. Muscles A. Types of muscle fibers
1. Striated muscle fibers b.
Functional types of striated fibers
(vertebrates) 1) slow oxidative fibers
-- slow, sustained contractions of skeletal
muscles (posture) -- fatigue slowly
-- extensive blood supply -- lots of
mitochondria lots of myoglobin -- red
muscle
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• IV. Muscles
• A. Types of muscle fibers
• 1. Striated muscle fibers
• b. Functional types of striated fibers
  (vertebrates)
• 2) fast fibers specialized for producing
  fast, powerful contractions
• fast glycolytic fibers
• -- produce rapid, powerful, brief contractions
• -- low blood supply low mitochondria little
  myglobin (white meat)
• -- function anaerobically (glycolysis)
• -- accumulates large oxygen debt
• -- fatigue quickly

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• IV. Muscles
• A. Types of muscle fibers
• 1. Striated muscle fibers
• b. Functional types of striated fibers
  (vertebrates)
• 2) fast fibers
• fast oxidative fibers
• -- produce rapid, powerful, sustained
  contractions
• -- rich blood supply high in mitochondria
  myglobin rich O2 supply
• -- function aerobically (oxidative)
• -- fatigue slowly (walking long-distance
  running migration)

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IV. Muscles A. Types of muscle fibers
1. Striated muscle fibers b.
Functional types of striated fibers
(vertebrates) 3) mix of fiber types
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IV. Muscles A. Types of muscle fibers
2. Smooth muscle fibers -- organized in sheets
around internal organs -- involuntary
movement (peristalsis blood vessel
constriction) -- controlled by autonomic
nervous system hormones -- spindle
shaped uninucleated -- lack
striations -- maintain prolonged or
rhythmical contractions with little
energy expenditure -- fatigue very
slowly
(Fig. 29-13 p. 638)
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IV. Muscles A. Types of muscle fibers
3. Cardiac muscle fibers -- only in
vertebrates -- striated uninucleated --
controlled by autonomic nervous
system hormones -- spontaneous
rhythmical contractions (myogenic) --
tireless
(Fig. 29-13 p. 638)
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IV. Muscles B. Muscle structure
(striated) 1. fasciculus

Connective tissue
(Fig. 29-14 p. 639)
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IV. Muscles B. Muscle structure
(striated) 2. muscle fiber a. sarcolemma
b. sarcoplasmic reticulum c. T-tubules
(Fig. 29-14 p. 639)
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IV. Muscles B. Muscle structure
(striated) 3. myofibrils -- chain of
sarcomeres
(Fig. 29-14 p. 639)
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IV. Muscles B. Muscle structure
(striated) 4. sarcomere (contractile unit of
muscle) a. Z- lines
Z-line
Z-line
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IV. Muscles B. Muscle structure
(striated) 4. sarcomere (contractile unit of
muscle) b. actin filaments
Z-line
Z-line
actin
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IV. Muscles B. Muscle structure
(striated) 4. sarcomere (contractile unit of
muscle) b. actin filaments 1)
reactive sites 2) tropomyosin 3)
troponin
reactive sites
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IV. Muscles B. Muscle structure
(striated) 4. sarcomere (contractile unit of
muscle) c. myosin filaments
myosin head
Z-line
Z-line
myosin
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IV. Muscles C. Sarcomere contraction
(sliding filament hypothesis) 1. starts with
nervous impulse at neuromuscular junction
motor neuron releases acetylcholine (in
vertebrates).
sarcolemma
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IV. Muscles C. Sarcomere contraction
(sliding filament hypothesis) 2. causes
electrical response in sarcolemma
sarcoplasmic reticulum spreads
throughout fiber by T-tubule system.
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IV. Muscles C. Sarcomere contraction
(sliding filament hypothesis) 3.
sarcoplasmic reticulum releases Ca 4.
Ca binds with troponin conformational shift
moves tropomyosin off actin reactive
site
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• myosin head uses ATP to bind with reactive sites
  bends inward 45o release, reattach, repeat
  cross-bridge cycling

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IV. Muscles C. Sarcomere contraction
(sliding filament hypothesis) 6. Z-lines are
pulled inward and sarcomere contracts
myosin head
Z-line
Z-line
myosin
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IV. Muscles C. Sarcomere contraction
(sliding filament hypothesis) 7. When nerve
impulse ends -- Ca pumped back into
sarcoplasmic reticulum -- troponin returns to
original shape -- tropomyosin moves back over
actin reactive site -- elasticity of
connective tissue within muscle pulls
sarcomeres and fibers back into relaxed position
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IV. Muscles D. Energy for
Contraction 1. ATP -- generated from
breakdown of glucose (C6H1206) -- glycolysis
net gain of 2 ATP -- aerobic respiration net
gain of 36 ATP
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IV. Muscles D. Energy for
Contraction 2. mechanisms for replenishing
ATP a. glucose 1 glucose ? 36 ATP
b. glycogen animal starch polysaccharide
of glucose c. creatine phosphate
(phosphocreatine) high energy phosphate
compound that quickly converts ADP to ATP
invertebrates use phosphoarginine.
Creatine phosphate
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IV. Muscles D. Energy for
Contraction 3. contraction under anaerobic
conditions during prolonged or heavy
exercise -- muscles fibers (esp. fast
oxidative) use O2 supply faster than blood
can deliver it. -- Krebs cycle stops ATP for
contraction supplied by glycolysis (fast
glycolytic fibers rely almost entirely on
glycolysis for ATP) -- glucose is degraded to
lactic acid leads to muscle exhaustion --
muscles develop O2 debt, because O2 needed to
oxidize lactic acid -- after heavy exercise,
we continue to breathe hard to oxidize lactic
acid