11.2:
Muscles & Movement
Which structure is responsible
for passing messages directly
to effector organs?
11.2.1 State the roles of ...in human
movement.
• Bones
– Lever for movement
–
–
–
–
Frame to support body
Protect tissue/organs
Form blood cells (marrow)
Store minerals
• Ligaments
– Strengthen joint
– stabilize bone to bone connections
• Muscles
– Provide force for movemt by contracting
– Shortening length of cells
– Occur in antagonistic pairs
• Tendons
– Attach muscle to bone
• Nerves
– Sensory ends @ ligaments and muscles
– Help prevent over-extension @ joints
– Coordinate muscle contraction
11.2.2 Label a diagram of human elbow joint:
cartilage, synovial fluid, joint capsule, named
bones (humerus, radius, ulna), antagonistic
muscles (biceps, triceps)
11.2.2 Label a diagram of human elbow joint:
cartilage, synovial fluid, joint capsule, named
bones (humerus, radius, ulna), antagonistic
muscles (biceps, triceps)
http://www.asmi.org/sp
ortsmed/anatom
y/elbow.html
www.Click4biology.co
m
11.2.3 Outline the functions of the
structures in the human elbow joint.
• Hinge joint
• Synovial fluid w/in synovial cavity, w/in joint
capsule—dense connective tissue, continuous
w/bone membranes
www.heinemann.co.uk/hotlinks 4242P; weblink 11.1
Joint part
Cartilage
Synovial fluid
Joint capsule
Tendons
Ligaments
Biceps
Triceps
Humerus
Radius
Ulna
Function
Reduces friction, absorbs compression
Lubricates to reduce friction; provides nutrients
to cells of cartilage
Surrounds joint; encloses syn cavity; unites
connecting bones
Attach muscle to bone
Connect bone to bone
Contracts  flexion (bending) of arm
Contracts  extension (straightening)
Lever, allows anchorage of elbow muscles
Lever for biceps
Lever for triceps
11.2.4 Compare the movements at the hip
and knee joint.
Hip Joint
Freely movable
Angular motions in many
directions & rotational
movements
Motions possible:
flexion, extension,
abduction, adduction,
circumduction, and
rotation
Ball-like structure fits into
a cup-like depression
(ball-and-socket joint)
Knee Joint
Freely movable
Angular motion in one
direction
Flexion and extension only
Convex surface fits into a
concave surface (hinge joint)
11.2.4 Compare the movements at the hip
and knee joint.
11.2.5 Describe the structure of striated muscle fibers:
myofibrils w/light and dark bands, mitochondria,
sarcoplasmic reticulum, nuclei, sarcolemma
• Skeletal movement
• Muscle fibers = cells
– Multinucleate
– Plasma membrane = sarcolemma
• T tubules = “tunnels” penetrating cell’s interior
– Cytoplasm = sarcoplasm
• LOTS of stored glycogen (glycosomes)
• LOTS of myoglobin (protein)
– SR = sarcoplasmic reticulum = smooth ER
– Myofibrils = rod-shaped bodies, run length of cell
• Lots, packed parallel to each other, lots mitochondria in b/w
• Contractile units of the muscle cell; give it striated pattern
• “muscle” = 1000s of cells, nerves, vessels
11.2.6 Draw and label a diagram to show structure of a
sarcomere: z lines, actin filaments, myosin filaments with
heads, and resultant light and dark bands.
• Myofibrils:
– Sarcomere = unit of movemt
– Z lines @ ends
– A bands (dArk), length of myosin filaments
– H band (narrow) @ middle of A band (myosin
only, no actin) w/M line in middle—supporting
protein for myosin filaments
– I bands (LIght), only actin—no myosin
– http://entochem.tamu.edu/musclestruccontrac
tswf/index.html
11.2.6 Draw and label a diagram to show structure of a
sarcomere: z lines, actin filaments, myosin filaments with
heads, and resultant light and dark bands.
Actin
Myosin
Thin (8nm diam)
Thick (16 nm diam)
Contains myosinbinding sites
Contains myosin
heads that have
actin-binding sites
Individual
molecules form
helical structures
Individual molecules
form a common shaftlike region w/outward
protruding heads
Includes 2
regulatory proteins
(tropomyosin &
troponin)
Heads referred to as
cross-bridges, contain
ATP-binding sites and
ATPase enzymes
11.2.7 Explain how skeletal muscle contracts, including the release of
calcium ions from the SR, the formation of cross-bridges, sliding
action of actin and myosin filaments, and use of ATP to break cross
bridges and re-set myosin heads.
• Sliding filament theory
• Actin myofilaments slide over myosin
myofilaments—they don’t shorten!
• The sarcomere shortens when they slide
over each other
• http://3dotstudio.com/zz.html
• www.thelifewire.com
Sliding Filament Theory:
1.
2.
3.
4.
5.
6.
7.
Motor neuron carries action potential
to NMJ (neuromuscular junction)
Neurotransmitter, acetylcholine,
released into gap b/w axon terminal
and sarcolemma of muscle fiber
ACh binds to receptors on
sarcolemma
Sarcolemma ion channels open,
Na+ move through
Generates muscle action potential
Moves along membrane, through T
tubules
ACh broken down by
acetylcholinesterase to make sure
one nerve action potential causes
only one muscle action potential
Sliding Filament Theory:
8. Muscle action potential going through T tubules causes release of
Ca ions from SR. Flood into sarcoplasm.
9. Ca ions bind to troponin on actin—exposes myosin-binding sites
10. Myosin heads include ATPase which splits ATP and releases
energy
Sliding Filament Theory:
11. Myosin heads bind to myosin-binding sites on actin with help of
tropomyosin (protein)
12. Myosin-actin crossbridges rotate toward center of sarcomere,
producing the “power stroke”
13. ATP binds again to myosin head, resulting in detachment of myosin
from actin
14. If no more action potentials, Ca ion level in sarcoplasm falls.
Troponin-tropomyosin complex moves to its original position,
blocking myosin binding sites...muscle relaxes.
WHOAAAA....
•
When you die...Ca++ leak out of SR, bind to
troponin...allows actin to slide. But, no ATP produced
when you’re dead, so myosin heads can’t detach from
actin: RIGOR MORTIS! Lasts ~24 hrs until muscles
deteriorate.
•
Muscle filaments don’t change in length during
contraction.
•
The sarcomere shortens (Z line to Z line)...can see in
electromicrographs.
11.2.8 Analyze electron micrographs to find
the state of contraction of muscle fibers.
• Which is relaxed, which is contracted?
• You should also be able to label this!