6. General Functions
• Shape and Support
• Protect soft organs
• Working with muscles to
produce movement
• Storage of minerals: Ca and P
• Produce blood cells
10. Knee and Hip Joint
Knee –
– Hinge Joint – one way movement… Flex and
extend
– Bones involved: Femur, tibia, fibula, patella
Hip
- Ball and Socket Joint – multiple movement:
Flex, Extend, Adduction, Abduction, Rotation
- Bones involved – Pelvis and Femur
22. Types of Muscle – Skeletal/Striated
• LARGE…contain…blood vessels, nerves,
and connective tissue.
• Voluntary movement.
• Fibers contain striations.
• Have many nuclei
• Sarcoplasmic reticulum – ER in muscle
cells. Stores and pumps CALCIUM.
• Sarcolemma – cell membrane of muscle
plus collagen
23. The EM View of the Skeletal Muscle
You must be able to draw this:
26. Structure of a Skeletal Muscle
• Muscle tissue is made up of 2 types of
proteins
– Actin – molecules that form LONG, THIN
chains. (Light Band)
– Myosin – molecules that bundle together to
form THICK fibers. (Dark Band)
• Actin and Myosin are arranged in
structures called SARCOMERES
• In a muscle, sarcomeres group to form a
threadlike structure: MYOFIBRIL
• Mitochondria between myofibril
27. Muscle Contractions – Building of
Muscle
• Many myofibrils bundle together with cell
organelles to form a MUSCLE CELL
• Muscles cells grouped together to form a
FASCICLE.
• Groups of Fascicles = whole muscle
• Membrane around muscle = sarcolemma
_________________________________
Actin and myosin sarcomere myofibril muscle cell
Fascicle muscle
34. Stages in Muscle Contraction
• A sarcomere is the functional unit of
muscle contraction.
• When muscle cells contract the light and
dark bands get closer.
– Why? – myosin and actin filaments
interact to shorten the length of a
sarcomere.
• Two proteins on actin: tropomyosin
and troponin regulate the binding of
actin and myosin.
37. Stages in Muscle Contraction
Relaxed Skeletal Muscle: protein – tropomyosin blocks
binding sites on actin.
Regulatory Proteins (Troponin & Tropomyosin) In Skeletal Muscle Fibers
When a motor neuron stimulates a muscle fiber:
• “Stimulus” – Ca+ ions released from sarcoplasmic
reticulum.
• Ca+ ions bind to protein - troponin --- causes
tropomyosin to move to expose binding sites on
actin
• This allows the myosin heads to bind…..
CONTRACTION:
• Myosin filaments have “heads” which form CROSS
BRIDGES when attached to binding sites on actin.
38. Stages: Mechanism of Muscle
Contraction
• ATP attaches to myosin head and causes them
to break the cross bridges by detaching them
from the binding site.
• ATP is hydrolyzed. Causes he myosin head to
change its “angle” The heads are “bent” and
store the energy released.
• The heads attach to binding sites on actin that
are further from the center of the sarcomere.
• The heads push the actin inward toward the
center of the sarcomere: POWER STROKE!
39. Stages: Mechanism of Muscle
Contraction
The synchronized shortening of
sarcomeres along the whole muscle fiber
causes the fiber….the whole muscle to
contract.
When thousands of actin and myosin
filaments interact… the entire muscle
shortens.
THIS IS THE SLIDING FILAMENT THEORY
Muscle contraction
44. Structure of Human Bones
• Made of living cells, collagen, and
inorganic compounds.
• Bone Cells are arranged:
• Periosteum – outer layer of connective tissue
• Contain blood vessels
• Compact Bone – thick layer. Dense.
• Haversian Canals – in compact bone. Contain blood vessels
and nerves.
• Spongy Bone – less dense. Found ar the end of most long
bones. Helps to add strength without mass.
• Bone Marrow – inside bone cavities. Yellow( fat cells) and
Red (makes blood cells)
• Ossification – Bone formation
thin filaments (myofibrils) extending from sarcomere ends (Z lines) toward center (M line) mysosin: thick filaments (myofibrils) extending from sarcomere center (M line) toward ends (A band = length of myosin) cross-bridge formation: myosin filaments overlap with actin filaments mysosin arms attach to actin, forming cross-bridges movement and breakage: movements of myosin arms ratchet along actin, contracting sarcomere myosin breaks attachment, reattaches to actin, and repeats ratcheting contraction of sarcomere ATP: ATP phosphorylation of myosin heads provides energy for ratcheting power stroke of muscle contraction Ca2+ ions: released from sarcoplasmic reticulum in response to neural depolarization attach to troponin
