Transcript Presentation

Muscle and movement
Topic 11.2
Assessment statements
11.2.1 State the roles of bones, ligaments, muscles, tendons and nerves in human
movement.
11.2.2 Label a diagram of the human elbow joint, including cartilage, synovial fluid,
joint capsule, named bones and antagonistic muscles (biceps and triceps).
11.2.3 Outline the functions of the structures in the human elbow joint named in
11.2.2.
11.2.4 Compare the movements of the hip joint and the knee joint.
11.2.5 Describe the structure of striated muscle fibres, including the myofibrils with
light and dark bands, mitochondria, the sarcoplasmic reticulum, nuclei and the
sarcolemma.
11.2.6 Draw and label a diagram to show the structure of a sarcomere, including
Z lines, actin filaments, myosin filaments with heads, and the resultant light and
dark bands.
11.2.7 Explain how skeletal muscle contracts, including the release of calcium ions
from the sarcoplasmic reticulum, the formation of cross-bridges, the sliding of
actin and myosin filaments, and the use of ATP to break cross-bridges and reset myosin heads.
11.2.8 Analyse electron micrographs to find the state of contraction of muscle fibres.
Joints
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Articulation or arthrosis, point where two or
more bones contact one another
Arthrology is the scientific study of joints
Rheumatology is the branch of medicine
devoted to joint disease and conditions
Kinesiology is the scientific study of the
movement of the human body
Joints provide mobility and hold the body
together
Include: bones, ligaments, muscles,
tendons, and nerves
Bones (living organs)
Provide a hard framework to support
the body
 Allow protection of vulnerable softer
tissue and organs
 Act as levers so that body movement
can occur
 Forms blood cells in the bone marrow
 Allows storage of minerals, especially
calcium and phosphorus
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Muscles and tendons
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Muscles attached to bones by tendons
Tendons are cords of dense connective tissue
Arrangement of the bones and the design of
the joints determine the type or range of
motion possible in any particular area of the
body
Muscles provide force necessary for
movement by shortening the length of the
fibers or cells
Occur as antagonistic pairs which allow the
body part to return to its original position
after movement
Ligaments and nerves
Ligaments are band-like connective
tissue that serves to strengthen the
joint and provide stability
 Have many different types of sensory
nerve endings which that help to
prevent over-extension of the joint and
its parts
 Proprioceptors in ligaments and
muscles allow constant monitoring of
the position of the joint parts
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Elbow joint
Synovial fluid
is located
within the
synovial cavity.
This cavity is
located within
the joint
capsule. The
joint capsule is
composed of
dense
connective
tissue that is
continuous
with the
membrane of
the involved
bones.
Joint capsule
Ends of bones lined
with cartilage
Synovial cavity
containing synovial fluid
Elbow parts and their functions
Joint part
Function
Cartilage
Reduces friction and absorbs compression
Synovial fluid
Lubricates to reduce friction and provides nutrients to the cells of
the cartilage
Joint capsule
Surrounds the joint, encloses the synovial cavity, and unites the
connecting bones
Tendons
Attach muscle to bone
Ligaments
Connect bone to bone
Biceps muscle
Contracts to bring about flexion (bending) of the arm
Triceps muscle
Contracts to cause extension (straightening) of the arm
Humerus
Acts as a lever that allows anchorage of the muscles of the
elbow
Radius
Acts as a lever for the biceps muscle
Ulna
Acts as a lever for the triceps muscle
Types of joints
Synovial – contain synovial cavity
 Diarthrotic – freely movable
 Hinge – provides an opening-andclosing type of movement
 Ball-and-socket – permits movement in
several directions
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Comparison of the hip and
knee joints
Hip joint
Knee joint
Freely movable
Freely movable
Angular motions in many directions
and rotational movements
Angular motion in one direction
Motions possible are flexion,
extension, abduction,
circumduction, and rotation
Motions possible are flexion and
extension
Bat-like structure fits into a cup-like
depression
Convex surface fits into a concave
surface
Definitions
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Flexion – decrease in angle between
connecting bones
Extension – increase in angle between
connecting bones
Abduction – movement of bone away from
body midline
Adduction – movement of bone toward
midline
Circumduction – distal or far end of a limb
moves in a circle
Rotation – a bone revolves around its own
longitudinal axis
Muscle
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Three types:
Skeletal or striated
 Cardiac
 Smooth or non-striated
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Striated muscle cells
Composed of thousands of cells, which
are called muscle fibers b/c of their
elongated shape
 Blood vessels and nerves penetrate the
muscle body
 Each muscle fiber contains multiple
nuclei that lie just inside the plasma
membrane, which is called the
sarcolema
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Sarcolemma has multiple tunnel-like
extensions that penetrate the interior
of the cell called transverse or T
tubules
 cytoplasm of muscle fibers is called the
sarcoplasm
 Sarcoplasm contains large numbers of
glycosomes that store glycogen
 Sarcoplasm also contains large
amounts of myoglobin
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Sarcoplasmic reticulum is a fluid-filled
system of membranous sacs
surrounding the muscle myofibrils
 Myofibrils are rod-shaped bodies that
run the length of the cell and are the
contractile elements of the muscle cell
 Myofibrils run parallel to one another
and have numerous mitochondria
squeezed between them
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Myofibrils
Made up of sarcomeres which allow
movement
 Often described as banded:
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Z lines mark the ends of the sarcomere
 A bands are dark in color and extend the
entire length of the myosin filaments;
narrow H band occurs in the middle
containing only myosin, no actin;
supporting protein occurs in the middle of
myosin producing M line
 I bands are light in color and contain only
actin, no myosin
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Two types of filaments or myofilaments
that cause the banded appearance of
the muscle fiber
 These two myofilaments are composed
of two contractile proteins, actin and
myosin
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Actin
Myosin
Thin filaments (8 nm in diameter)
Thick filaments (16 nm in diameter)
Contains myosin-binding sites
Contains myosin heads that have
actin-binding sites
Individual molecules form helical
structures
Individual molecules form a
common shaft-like region with
outward protruding heads
Includes two regulatory proteins,
tropomyosin and troponin
Heads are referred to as crossbridges and contain ATP-binding
sites and ATPase enzymes
Muscle Contraction
Explained by the sliding filament theory
proposed by Hugh Huxley in 1954
 States that muscles contract when actin
myofilaments slide over myosin
myofilaments
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Sliding Filament Theory
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Motor neuron carries an action potential until
it reaches a neuromuscular junction
Neurotransmitter called acetylcholine is
released into the gap between the axon
terminal and the sarcolemma of the muscle
fiber
Acetylcholine bines to receptors in the
sarcolemma
Sarcolemma ion channels open and sodium
ions move through the membrane
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Muscle action potential is generated
Muscle action potential moves along the
membrane and through the T tubules
Acetylcholine is broken down by
acetylcholinesterase
Muscle action potential moving along T tubule
causes release of calcium ions from the
sarcoplasmic reticulum. Calcium ions flood into
the sarcoplasm
Calcium ions bind to troponin on the actin
myofilaments. This exposes the myosin-binding
sites
10. Myosin heads include ATPase which splits ATP
and releases energy
11. Myosin heads then bind to the myosin-binding
sites on the actin with the help of the protein
called tropomyosin
12. Myosin-actin cross-bridges rotate toward the
center of the sarcomere. This produces the
power or working stroke.
9.
13. ATP
once again binds to the myosin head
resulting in the detachment of myosin from
the actin
14. If there are no further action potentials, the
level of calcium ions in the sarcoplasm falls.
The troponin-tropomyosin complex then
moves to its original position, thus blocking
the myosin-binding sites. The muscle then
relaxes.
Useful websites
http://3dotstudio.com/zz.html
 http://www.blackwellpublishing.com/M
atthews/myosin.html
 http://entochem.tamu.edu/musclestruc
contractswf/index.html
 http://highered.mcgrawhill.com/sites/0072495855/student_vie
w0/chapter10/animation__sarcomere_c
ontraction.html
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Rigor mortis
After death, calcium ions leak out of
the sarcoplasmic reticulum and bind to
troponin
 This allows actin to slide, but lack of
ATP production prevents myosin heads
from detaching from the actin
 Result is rigidity for about 24 hours
unter further muscle deterioration
occurs
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Electron Micrograph
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When the muscle is maximally contracted, the H
zone disappears, the Z lines move closer
together, the I bands are no longer present, and
the A bands appear to run the complete length
of the sarcomeres
Can be in various states of partial contraction
This causes a difference in the position of the
sarcomere parts
The number of muscle fibers in a muscle going
through contraction determines the overall
strength of a muscle contraction