Download 11.2 Movement - Ms. Richards IB Biology HL

11.2 Movement
11.2 Movement
Nature of science: Developments in scientific research follow improvements in apparatus—
fluorescent calcium ions have been used to study the cyclic interactions in muscle
contraction. (1.8)
Understandings
• Bones and exoskeletons provide anchorage for muscles and act as levers
• Synovial joints allow certain movements but not others
• Movement of the body requires muscle to work in antagonistic pairs
• Skeletal muscle fibers are multinucleate and contain specialized endoplasmic reticulum
• Muscle fibers contain many myofibrils
• Each myofibril is made of contractile sarcomeres
• The contraction of the skeletal muscle is achieved by the sliding of actin and myosin
filaments
• ATP hydrolysis and cross bridge formation are necessary for the filaments to slide
• Calcium ions and the proteins tropomyosin and troponin control muscle contractions
11.2 Movement
Applications and Skills
• Application: Antagonistic pairs of muscles in an insect leg
• Skill: Annotation of a diagram of the human elbow
• Skill: Drawing labelled diagrams of the structure of a sarcomere
• Skill: Analysis of electron micrographs to find the state of contraction
of muscle fibers
Retro Topics to Review
• Topic 6.5 Neurons and Synapses
• Topic 1.4 Membrane Transport
• Review these topics in your review guide/book, you will be
quizzed/tested on this!
Movement
• Movement is the hallmark of animals. In order to catch food, an
animal must either move through its environment or move the
surrounding water or move air past itself
• A large portion of their time and energy is spent actively searching
for food and escaping from danger and looking for mates
• Locomotion: active travel from place to place
Mode of locomotion
• Diverse modes of movement
• Animals swim, crawl, walk, run, hop, and fly
• Requirements: energy must be expended to overcome friction and
gravity
Cost of Transportation
Cost of Transportation
• Running animals generally consume more energy per meter traveled
than similarly sized animals specialized for swimming because running
demands overcoming gravity
• Swimming is the most efficient mode of transport
• Flying animals use more energy for the same amount of time,
however
• A larger animal travels more efficiently than a smaller species
specialized for the same mode of transport. (E.g. a horse consumes
less energy per kg of body weight than a cat running the same
distance)
Requirements for Movement
1. Muscles arranged as antagonistic pairs (e.g. Flexors and
extensors)
2. A skeleton that provides support and attachment points
for muscles (e.g. endoskeleton made of cartilage/bone;
exoskeleton made of chitin/calcium carbonate; hydrostatic
skeleton).
3. Nervous enervation to stimulate and coordinate muscle
contraction.
Swimming
• Overcoming gravity is less of a problem than for species that
move on land or through air
• However, water is a much denser medium than air.
• Friction (resistance) is a major problem for aquatic animals.
Adaptations for swimming
• Sleek, torpedo-like shape (streamline) is common for fast swimmers.
• Glands in skin of a bony fish secrete a mucus that gives the animal its
characteristic sliminess
• This adaptation reduces drag during swimming.
• Bony fish have swim bladders
• Swim bladder is an air sac that helps control the buoyancy of the fish. Bony
fish can remain almost motionless
Bony Fish Swimming
• Bony fish swim by moving their body and tail from side to side
• They generate a force that pushes the fish forwards by beating the
tail from side to side.
• There are bony projections from the vertebra that are used for
muscle attachment
• The muscle on the left side causes the tail to move to the left while
the muscle on the right side causes the tail to move to the right
Antagonistic muscle bundles
• Bony fish are maneuverable swimmers, their flexible fins are better
for steering and propulsion
Bony Fish Swimming
Flying
• Overcoming gravity is a major problem in
flying
• Wings must develop enough lift to
overcome the downward force of gravity
• Key: shape of the wings which act as airfoils,
structures whose shape creates lift by
altering air currents
• The leading edge is thicker than the trailing
edge and its upper surface is somewhat
convex and its undersurface is concave or
flattened.
• Air passing over the wing travels faster than
air passing under the wing. Low pressure on
top, higher pressure exerted on bottom 
lift
• Birds generate this lift by flapping wings up
and down.
Flying
Adaptions for Bird Flight
• Bones are strong but light
• Internal structure is honeycombed
• To reduce weight, bird has an absence of some organs
• Females have only one ovary
• Modern birds are toothless
• Keen eyesight
Bird Flight
• Providing power for flight, birds flap their wings by
contractions of large pectoral (breast) muscles
anchored to a keel on the sternum (breastbone)
• Pectoralis major pulls the wing down, pectoralis minor pulls the
wings up. The tendon of the pectoralis minor is attached to the upper
surface of the shoulder bone.
• Flapping rate varies with species. Shape and arrangement of feathers
form wing into airfoil.
Crawling: earthworm
• Earthworms move by peristaltic locomotion
• Earthworms have a hydrostatic skeleton (fluid held under pressure in
a closed body compartment).
• They control their form and movement by using muscles to change
the shape of the fluid-filled compartments
• Peristalsis is a type of locomotion produced by rhythmic waves of
muscle contractions passing from head to tail
• Earthworms have 2 sets of muscles- one elongates the body (circular)
while the other shortens (longitudinal) it. It also has bristles
(chaetae) that will hold the substrate
Earthworm: Peristalsis
Walking: Extensors vs Flexors
• Extensors- muscles cause extension
• Flexors- muscle causes flexion
• Extension: Increasing the angle of articulation
• Flexion: Decreasing the angle of articulation
Walking: Arthropods
• Arthropods are segmented, have a hard exoskeleton (also called a
cuticle) made of chitin and jointed appendages
• Cuticle is thick over some parts of body but paper thin and flexible in
joints (think of a lobster or crab)
• Muscles are attached to knobs and plates of the cuticle that extend
into the interior of the body.
• Exoskeletons are shed with growth. Crabs (an arthropod) walk by
flexing (bending) and extending (straightening) the segments of their
legs.
Application: Antagonistic pairs of muscles in
an insect leg
Application: Antagonistic pairs of muscles in
an insect leg
Endoskeletons
• Endoskeleton consists of bones
either fused (think of skull
bones) or connected at joints by
ligaments that allow freedom of
movement (think
elbow/hip/shoulder)
• Muscles are connected to bones
by tendons
Human Joints
Role of bones, muscles, nerves, tendons, and ligaments
1.
2.
3.
4.
5.
Bones: Provide an anchorage for muscles, aid in movement by giving
muscles something firm to work against, they act as levers, changing the
size or direction of forces generated by muscle.
Muscles: Muscles move skeletal parts by contracting. The ability to move
parts of the body in opposite directions requires that muscles be attached
to the skeleton in antagonistic pairs, each muscle working against the
other.
Nerves: stimulate muscles to contract. They stimulate each of the
different muscles used in locomotion to contract at the correct time so
the movement is coordinated.
Tendons: attach muscles to bone.
Ligaments: connect bone to bone, restricting movement at joints and
helping to prevent dislocation.
Skill: Annotation of a diagram of the human elbow
Bones
• Humerus- upper arm bone, provides a
firm anchorage for the muscles. Acts a
lever.
• Ulna- lower arm bone, transmits forces
from the triceps through the forearm
• Radius- lower arm bone, which transmits
forces from the biceps through the
forearm.
• Radius is bone closest to your thumb; ulna
is your “funny bone”. Both act as levers.
Skill: Annotation of a diagram of the human elbow
Muscles
• Biceps- flexor muscle used to bend the arm at the elbow
• Triceps- extensor muscle used to straighten the arm.
Connective tissues
• Tendons which attach muscle to bone
• Ligaments which connect bone to bone, are tough cords of tissue and
prevent dislocation.
Skill: Annotation of a diagram of the human elbow
Radius
Ulna
Synovial Cavity
• Feature of freely movable joints
(synovial joints). The synovial cavity
separates the articulating bones
• Another characteristic of such joints is
the presence of articular cartilage.
Articular cartilage covers the surfaces of
the articulating bones but does not bind
the bones together
• The cartilage is a layer of smooth and
tough tissue that covers the ends of the
bones where they meet to reduce
friction
Synovial Cavity
• A sleevelike articular capsule surrounds
and encloses the synovial cavity and
unites the articulating bones.
• The capsule is both flexible and strong,
also resisting dislocation. The outer
fibers of this capsule extend and make up
the ligaments.
• The inner layer of this capsule is formed
by a synovial membrane. It secretes
synovial fluid which fills the synovial
cavity, lubricates the joint, and provides
nourishment for the articular cartilage.
Knee Joint
• Knee (like the elbow) is also a hinge joint which
means that movement is primarily in a single
plane.
• Bones: upper femur, lower tibia, and fibula
• Movement is usually flexion and extension
• Flexion decreases the angle between articulating
bones. Extension increases the angle between
articulating bones, often to restore the leg to its
anatomical position after it has been flexed.
Side View
Hip Joint
•
The hip joint between the ball-like surface of the
femur and the cuplike depression of the pelvic bone
(ball and socket joint), allows movement in 3 planes:
1. Flexion and extension or protraction (movement
forward on a plane parallel to the ground) /retraction
(movement of a protracted part of the body
backward on a plane parallel to the ground).
2. Abduction (movement of bone away from the
midline) and adduction (movement toward the
midline)
3. Rotation (bone moves in a single plane around its
longitudinal axis).
Vertebrate Skeletal Muscle
• Vertebrate skeletal muscle is striated muscle
because of the repeating pattern of light and dark
bands seen under the microscope
• It is characterized by a hierarchy of smaller and
smaller parallel units
• Muscle consists of a bundle of long muscle fibers
running the length of the muscle.
• Each fiber is a single cell with many nuclei which
reflects its formation by the fusion of many
embryonic cells.
Two types of Skeletal Muscles
• Slow twitch (type I) muscle fibers- slower but help in long-endurance
exercises like running distances
• Fast twitch (type II) muscle fibers- faster but fatigue quicker and are
used for sprinting
Vertebrate Skeletal Muscles
• Each fiber is itself a bundle of smaller myofibrils arranged
longitudinally
• The myofibrils are composed of two kinds of myofilaments
1. Thin filaments consist of two strands of actin and one strand of a
regulatory protein, tropomyosin, coiled around one another
2. Thick filaments are staggered arrays of myosin molecules
Vertebrate Skeletal Muscle
• The repeating unit of the myofibril is called a sarcomere, the basic
contractile unit of the muscle.
• The borders of the sarcomere are called the Z-lines
• The thin filaments are attached to the Z lines and project toward the
middle of the sarcomere.
• The thick filaments are centered in the sarcomere.
• Around each myofibril is a special type of endoplasmic reticulum
called the Sarcoplasmic reticulum
• There are also mitochondria between the myofibrils
Skill: Drawing labelled diagrams of the
structure of a sarcomere
Remember to use a ruler when labeling!
Light band
(I band)
Dark band (A band)
Light band
(I band)
Muscle Contraction
• At rest: the thick and thin filaments
do not overlap by much
• During contraction: the length of
each sarcomere is shortened
(distance from one Z line to the next
becomes shorter).
• These changes can be explained by
the sliding filament model of
muscle contraction.
Skill: Analysis of electron micrographs to find
the state of contraction of muscle fibers
1. You must state whether sarcomere is
more or less relaxed, or more or less
contracted.
2. You must back this up with 2
measurements: Z line to Z line; size of
the light band.
Muscle Contraction
• Sliding Filament Model: Based on the
interaction of the structural protein molecules
that make up thin and thick filaments.
• Myosin consists of a long, fibrous “tail region”
with a globular “head” region sticking off to
one side (golf club).
• The tail is where the individual myosin
molecules cohere to form the thick filament
• Myosin head is the center of bioenergetic
reactions that power muscle contractions.
Muscle Contraction
• Skeletal muscle only contracts when
stimulated by a motor neuron
• When the muscle is at rest the myosin
binding sites on the actin molecules are
blocked by the regulatory protein
tropomyosin
• Another set of regulatory proteins, the
troponin complex, controls the position
of tropomyosin on the thin filament. For
a muscle cell to contract, the myosin
binding sites on the actin must be
uncovered
Muscle Contraction
• The myosin binding site is uncovered when calcium ions bind to
troponin
• This alters the interaction between troponin and tropomyosin
• The calcium binding rearranges the tropomyosin-troponin complex,
exposing the myosin binding sites on actin
• Calcium concentration in the cytosol of the muscle cells is regulated
by the sarcoplasmic reticulum (SR). The membrane of the SR
actively transports calcium from the cytosol into the interior of the
reticulum, which is thus an intracellular storehouse for calcium.
Muscle Contraction
• The stimulus leading to the contraction of a skeletal muscle cells is an
action potential in a motor neuron that makes a synaptic connection
with the muscle cell
• Synaptic terminal of the motor neuron releases neurotransmitter
(acetylcholine) at the neuromuscular junction
• The postsynaptic muscle cell is depolarized triggering an action
potential in the muscle cell
• The action potential is the signal for contraction. The action potential
spreads deep into the interior of the muscle cell along infoldings of
the plasma membrane called T (transverse) tubules
Muscle Contraction
• When T tubules contact the
sarcoplasmic reticulum, the action
potential changes the permeability of
the sarcoplasmic reticulum, causing it
to release calcium ions
• Calcium ions bind to troponin
allowing the muscle to contract
Cross Bridge Formation
1. The myosin head can bind ATP and hydrolyze it into ADP and
inorganic phosphate (the head has ATPase activity)
2. Some of the energy released by cleaving ATP is transferred to the
myosin, which changes shape to a high-energy configuration.
Myosin head is “cocked”
3. This energized myosin can bind to a specific site on actin, forming a
cross bridge
Cross Bridge Formation
4. When this happens, the stored energy is released and the myosin
head relaxes to its low-energy configuration
5. This relaxation changes the angle of attachment of the myosin head
to the tail. So as the myosin bends inward on itself, it exerts tension on
the thin actin filament to which it is bound, pulling the thin filament
toward the center of the sarcomere.
6. When a new molecule of ATP binds to the myosin head, the crossbridge is broken. In a repeating cycle, the free head can then cleave
the new ATP to revert to the high energy configuration and attach to a
new binding site on another actin molecule farther along the thin
filament.
Relaxation
• Muscle contractions stop when the sarcoplasmic reticulum pumps the
calcium back out of the cytosol into SR
• Tropomyosin-troponin complex again blocks the myosin binding sites
as the concentration of calcium falls
• Acetylcholinesterase breaks down acetylcholine in the synapse.
Membrane Potential
• Every cell has a voltage or membrane potential across its plasma
membrane- this is an electrical charge difference.
• Membrane potential exists because of the different concentration of
ions on the inside and outside of a cell
• Anions are more concentrated inside the cell and cations are more
concentrated in the extracellular fluid
• The plasma membrane is negatively charged on one side than on the
other: it is polarized
• Membrane potential is measured by using microelectrodes connected to
a voltmeter or oscilloscope
• Remember this stuff from SL?
6.5.1 Neurons transmit electrical impulses
6.5.2 The myelination of nerve fibers allows for salutatory conduction
• What is a neuron?
• Neurons carry messages in the form of electrical impulses at high
speeds and for long distances
• What is myelination?
• Some neurons has myelin sheath and helps in nerve impulses
• There are spaces between the myelin sheaths called nodes of Ranvier
allowing the impulse to jump from node to node
• What is this process called?
• Saltatory conduction
Diagram of a neuron
What is a synapse?
• Synapse is a junction
between a neuron and
another neuron or a
receptor or effector cell
• Synaptic cleft is the fluid
filled space between the
two neurons
• How are messages
transmitted?
• They are transmitted via
neurotransmitters across
the synapse from presynaptic neuron to postsynaptic neuron
Explain how synapses function:
1. Nerve impulse reaches the end of the pre-synaptic neuron
2. Depolarization of the pre-synaptic membrane causes neurotransmitter
vesicles to move to the membrane and fuse with it. Neurotransmitters
are released into the synaptic cleft by exocytosis
3. Neurotransmitter diffuse across the synaptic cleft and binds to receptors
on the post-synaptic membrane. These receptors are transmitter-gated
sodium channels
4. When the neurotransmitter binds, the sodium channels open and
sodium ions diffuse into the post-synaptic neuron leading to the
depolarization of the post-synaptic membrane
5. Depolarization moves down the post-synaptic neuron as an action
potential
6. Neurotransmitters are broken down to prevent continuous transmission
Resting Potential
• What is a resting potential?
• The voltage across the plasma membrane of a neuron when it is not
conducting a nerve impulse
• Explain the sodium-potassium pumps
• Sodium is pumped out and potassium is pumped in
• The charge on the inside of the neuron is…
• Negative
• What is the voltage of a resting potential?
• -70mV
Action Potential
Action Potential
• Action potential is the depolarization and repolarization of the plasma
membrane
• This is due to the movement of ions across the membrane by facilitative
diffusion
• The membrane potential rises from -70mV to -50mV, voltage-gated sodium
channels open and sodium ions (Na+) diffuse in from high to low
concentration
• This causes a net positive charge on the inside of the neuron = depolarization
• This causes potassium channels to open allowing potassium ions (K+) to diffuse
down their gradient
• This causes a net negative charge on the inside of the neuron thus resorting
the potential = repolarization
Propagation
•
•
•
•
•
•
•
•
•
Nerve impulse is an action potential that travels along an axon
An action potential will occur when what threshold is reached?
-50mV
How are action potentials propagated?
Action potential in one part of the axon triggers an action potential in the
next part
Sodium ions (Na+) diffuse between a region with an action potential and
the next region at a resting potential
What is this called?
Local currents
It changes the voltage from -70mV to -50mV
Propagation
Passive Transport
• What is passive transport?
• Moving from high to low concentration, down the gradient
• No energy is needed
Active Transport
• What is active transport?
• Movement from low to
high concentration,
against the gradient
• ATP is needed
• Think
A- Active transport,
A- ATP,
A- Against the gradient