1. 11.2: Muscles & Movement

2. Which structure is responsible for passing messages directly to effector organs?

4. 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 ligaments and muscles
Help prevent joints
Coordinate muscle contraction

5. Label a diagram of human elbow joint: cartilage, synovial fluid, joint capsule, named bones (humerus, radius, ulna), antagonistic muscles (biceps, triceps)

6. Label a diagram of human elbow joint: cartilage, synovial fluid, joint capsule, named bones (humerus, radius, ulna), antagonistic muscles (biceps, triceps)

8. 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
4242P; weblink 11.1

9. Joint part
Function
Cartilage
Reduces friction, absorbs compression
Synovial fluid
Lubricates to reduce friction; provides nutrients to cells of cartilage
Joint capsule
Surrounds joint; encloses syn cavity; unites connecting bones
Tendons
Attach muscle to bone
Ligaments
Connect bone to bone
Biceps
Contracts  flexion (bending) of arm
Triceps
Contracts  extension (straightening)
Humerus
Lever, allows anchorage of elbow muscles
Radius
Lever for biceps
Ulna
Lever for triceps

11. 11.2.4 Compare the movements at the hip and knee joint.
Hip Joint
Knee Joint
Freely movable
Angular motions in many directions & rotational movements
Angular motion in one direction
Motions possible: flexion, extension, abduction, adduction, circumduction, and rotation
Flexion and extension only
Ball-like structure fits into a cup-like depression (ball-and-socket joint)
Convex surface fits into a concave surface (hinge joint)

12. 11.2.4 Compare the movements at the hip and knee joint.

16. “muscle” = 1000s of cells, nerves, vessels
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

18. Myofibrils: Sarcomere = unit of movemt Z lines @ ends
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 ends
A bands (dArk), length of myosin filaments
H band 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

21. 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 myosin-binding sites
Contains myosin heads that have actin-binding sites
Individual molecules form helical structures
Individual molecules form a common shaft-like region w/outward protruding heads
Includes 2 regulatory proteins (tropomyosin & troponin)
Heads referred to as cross-bridges, contain ATP-binding sites and ATPase enzymes

23. Sliding filament theory
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

24. Sliding Filament Theory:
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

25. 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

26. 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.

29. 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.

30. 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!