Download Ch. 50.5-6 Lecture 50.5

Key Points
• 1.B.1: Organisms share many conserved core
processes and features that evolved and are widely
distributed among organisms today.
Big Ideas
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• 2.A.1: Organisms use free energy to maintain
organization, grow, and reproduce
(e.g. Krebs Cycle  ATP muscle contraction)
• 2.B.1: Cell membranes are selectively permeable due
to their structure
• 2.B.3: Eukaryotic cells maintain internal membranes
that partition the cell into specialized regions (e.g.
sarcoplasmic reticulum)
Big Ideas
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Big Ideas
• 3.E.1: Individuals can act on information and
communicate it to others.
• Organisms exchange information with each other in response to
internal changes and external cues, which change behavior.
(e.g. fight or flight response)
• 3.E.2 d): Animals have nervous systems that detect
external and internal signals, transmit and integrate
information and produce responses.
•
Different regions of the vertebrate brain have different functions. (e.g. vision,
hearing)
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Big Ideas
• 4.A.3: Interaction between external stimuli and regulated gene
expression result in specialization of cells, tissues, and organs.
• 4.A.4 a): Organisms exhibit complex properties due to interactions
between their constituent parts
(e.g. muscle & skeletal/nervous systems/sensory mechanisms)
• 4.A.4 b): Interactions and coordination between systems provide
essential biological activities (e.g. sensory/motor)
• 4.B.2 a.2): Within multicellular organisms, specialization of organs
contributes to the overall functioning of the organism (e.g. communication
& control)
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AP Exam 2008
Skeletal systems
transform muscle
contraction
into locomotion.
Key Points
Movement And Locomotion
(a) Locomotion requires energy to overcome friction and gravity
(b) Skeletons support and protect the animal body and are essential to
movement
(c) Muscles move skeletal parts by contracting
(d) Interactions between myosin and actin generate force during muscle
contractions
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(a) Locomotion requires energy to overcome friction and
gravity.
• A comparison of the energy costs of various modes of
locomotion.
Fig. 49.25
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• Since water is buoyant, gravity is less of a problem
when swimming than for other modes of locomotion.
• However, since water is dense, friction is more of a
problem.
• Fast swimmers have fusiform bodies.
Swimming
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• For locomotion on land, powerful muscles and skeletal
support are more important than a streamlined shape.
• When hopping the tendons in kangaroos legs store and release
energy like a spring that is compressed and released – the tail
helps in the maintenance of balance.
• When walking having one foot on the ground helps in the
maintenance of balance.
• When running momentum helps in the maintenance of balance.
• Crawling requires a considerable expenditure of energy to
overcome friction – but maintaining balance is not a problem.
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• Gravity poses a major problem when flying.
• The key to flight is the aerodynamic structure of wings.
Fig. 34.26
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Movement And Locomotion
(a) Locomotion requires energy to overcome friction and gravity
(b) Skeletons support and protect the animal body and are
essential to movement
(c) Muscles move skeletal parts by contracting
(d) Interactions between myosin and actin generate force during
muscle contractions
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
(b) Skeletons support and protect the animal body and are
essential to movement
• Hydrostatic skeleton: consists of fluid held under
pressure in a closed body compartment.
• Form and movement is controlled by changing the shape of this
compartment.
• The hydrostatic skeleton of earthworms allow them to move by
peristalsis.
• Advantageous in aquatic environments and can support
crawling and burrowing.
• Does not allow for running or walking
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
(b) Skeletons support and protect the animal body and are
essential to movement
• Exoskeletons: hard encasements deposited on the
surface of an animal.
• Mollusks are enclosed in a calcareous exoskeleton.
• The jointed exoskeleton of arthropods is composed of a
cuticle.
• Regions of the cuticle can vary in hardness and degree of
flexibility.
• About 30 – 50% of the cuticle consists of chitin.
• Muscles are attached to the interior surface of the cuticle.
• This type of exoskeleton must be molted to allow for growth.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
(b) Skeletons support and protect the animal body and are
essential to movement
• Endoskeletons: consist of hard supporting elements
within soft tissues.
• Sponges have spicules.
• Echinoderms have plates composed of magnesium
carbonate and calcium carbonate.
• Chordate endoskeletons are composed of cartilage and
bone.
• The bones of the mammalian skeleton are connected at joints by
ligaments.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Movement And Locomotion
(a) Locomotion requires energy to overcome friction and gravity
(b) Skeletons support and protect the animal body and are essential
to movement
(c) Muscles move skeletal parts by contracting
(d) Interactions between myosin and actin generate force during
muscle contractions
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
(c) Muscles move skeletal parts by contracting
• Muscles come in antagonistic pairs.
Fig. 49.30
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Key Points
The physical
interaction of
protein filaments
is required for
muscle contraction.
• Cellular and Skeletal Underpinning of Locomotion.
• On a cellular level all movement is based on
contraction (flexion & extension).
• Either the contraction of microtubules or the
contraction of microfilaments.
See Figure
50.26: Myofibril Structure
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Illustrative Examples:
1. Sliding Filament Model (Actin-Myosin Interactions)
2. Regulation of Skeletal Muscle Contraction
• Structure and Function of
Vertebrate Skeletal Muscle.
• sarcomere is the
functional unit of muscle
contraction.
• thin filaments consist of
two strands of actin and
one tropomyosin coiled
about each other.
• thick filaments consist of
myosin molecules.
Fig. 49.31
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Movement And Locomotion
(a) Locomotion requires energy to overcome friction and gravity
(b) Skeletons support and protect the animal body and are essential
to movement
(c) Muscles move skeletal parts by contracting
(d) Interactions between myosin and actin generate force during
muscle contractions
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Illustrative Examples:
1. Sliding Filament Model (Actin-Myosin Interactions)
2. Regulation of Skeletal Muscle Contraction
(d) Interactions between myosin and actin generate
force during muscle contractions
• The “sliding-filament model” of muscle contraction.
See Figure
50.28:
Fig.Sliding
49.33 Filament Model
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(d1) Calcium ions and regulatory proteins control
muscle contraction
• At rest tropomyosin blocks the myosin
binding sites on actin.
• When calcium binds to
the troponin complex
a conformational change
results in the movement
of the tropomyosintroponin complex and
exposure of actin’s
myosin binding sites.
(See handout)
Fig. 49.34
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• But, where do the
calcium ions come
from?
• Follow the action
potential.
• When an action
potential meets the
muscle cell’s
sarcoplasmic
reticulum (SR),
stored Ca2+ is
released.
Fig. 49.35
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• Review of skeletal muscle contraction.
Fig. 49.36
See Figure
50.30: Contraction System
(see Movement & Locomotion handout)
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(d2) Diverse body movements require variation in
muscle activity
• An individual muscle cell either contracts completely or not
all.
• Individual muscles, composed of many individual muscle
fibers, can contract to varying degrees.
• One way variation is
accomplished by varying
the frequency of action
potentials reach the
muscle from a single
motor neuron.
Fig. 49.37
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• Graded
muscle
contraction
can also be
controlled by
regulating the
number of
motor units
involved in the
contraction.
Fig. 49.38
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• Fast and Slow Muscle Fibers.
• Fast muscle fibers are adapted for rapid, powerful
contractions.
• Fatigue relatively quickly.
• Slow muscle fibers are adapted for sustained
contraction.
• Relative to fast fibers, slow fibers have:
• Less SR  Ca2+ remains in the cytosol longer.
• More mitochondria, a better blood supply, and myoglobin.
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• Other Types of Muscle
• In addition to skeletal muscle, vertebrates have
cardiac and smooth muscle.
• Cardiac muscle: similar to skeletal muscle.
• Intercalated discs facilitate the coordinated contraction
of cardiac muscle cells.
• Can generate there own action potentials.
• Action potentials of long duration.
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Fig. 40.4
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• Smooth muscle: lacks the striations seen in
both skeletal and cardiac muscle.
• Contracts with less tension, but over a greater range of
lengths, than skeletal muscle.
• No T tubules and no SR.
• Ca2+ enters the cytosol from via the plasma membrane.
• Slow contractions, with more control over contraction
strength than with skeletal muscle.
• Found lining the walls of hollow organs.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Movement And Locomotion
(a) Locomotion requires energy to overcome friction and gravity
(b) Skeletons support and protect the animal body and are essential
to movement
(c) Muscles move skeletal parts by contracting
(d) Interactions between myosin and actin generate force during
muscle contractions
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings