Bone Lecture Flashcards
Sliding Filament Theory Steps
(10 steps)
- Action potential
- Ca2+ ions “pop out” of the terminal cisternae of the sacroplasmic reticulum (SR) into sacroplasm
- Calcium binds/sticks to troponin (protein on actin)
- Binding of calcium causes a rotation/spinning of tropomyosin (protein on the actin)
- Uncovers the binding sites of the actin (binding sites now visible)
- Myosin binds to actin at the binding sight (cross bridge)
- Myosin pulls actin; actin slides inward
- ATP (enery) released the myosin crossbridge & recharges the myosin (reloads/refolds)
- Calcium released from the tropodin & pumped back to the sacroplasmic reticulum (SR)
- Tropomyosin recovers the binding site & the actin relaxes
Recruitment
The increase in the number of motor unites for an action results in an increased force
Skeletal muscle hierarchy (biggest to smallest)
- Muscle “Flesh”
- Fascicles (bundles/ groups in muscle)
- Fibers
- Myofibrils
- Filaments
Tendon
Connects muscles to bones
Epimysium
The muscle “flesh” is covered by a connective tissue called the epimysium (ontop of muscle)
Perimysium
The perimysium covers the fasciles with connective tissue
Endomysium
The endomysium is a connective tissue that covers the sacrolemma
Sacrolemma
The muscle cell’s membrane (covering)
What factors affect bone growth/osteoporosis?
- Gender
- Diet (calcium)
- PTH
- Wolff’s Law
- Bone cells
How does gender affect bone growth/osteoporosis?
- Women and men have hormonal differences
- Women are more likely to develop osteoporosis than men due to:
- Estrogen
- Is an osteoclast inhibitor but when menopause occurs, there is less estrogen therefore more osteoclasts form
- Muscle density
- Men are more muscular therefore their bones are denser as well
- Women have babies
- Breast feeding (milk production)
- Estrogen
Summation
The increased number of stimuli to make a muscle not relax (don’t want the muscle to stop contracting)
What does Wolff’s Law affect bone growth/osteoporosis?
- Wolff’s Laws states:
- If you stress a bone (move it) the bone will increase in density (becomes stronger and less prone to breakage)
- Inactivity causes bones to become brittle
- Activity (weight baring) increases bone density
How does diet and PTH affect bone growth/osteoporosis?
- When you have a diet low in calcium this causes you to have low blood calcium
- Through negative feedback your body releases PTH to retrieve calcium from the bones to put into the blood
- The PTH “break bones” by activating osteoclasts
- A diet low in calcium depletes the bones of calcium resulting in low bone density
- Low bone density results in osteoporsis and hinders bone growth
What are the three types of bone cells?
Osteocytes = normal bone cell
Osteoclast = breaks down bone/ destroyer
Osteoblast = bulids up bone/ builder
Define summation for skeletal muscle contractions
- The process of adding things together
- If a skeletal muscle is stimulated and a second stimulus is applied before relaxation is complete, a second contraction, which develops a greater tension, is fused to the first contraction.
Define recruitment for skeletal muscle contraction
- The successive activation of the same and additional motor units with increasing strength of voluntary muscle contraction
- Motor unit recruitment refers to the activation of additional motor units to accomplish an increase in contractile strength in a muscle. A motor unit consists of one motor neuron and all of the muscle fibers it stimulates.
Summation
- If a skeletal muscle is stimulated and a second stimulus is applied before relaxation is complete, a second contraction, which develops a greater tension, is fused to the first contraction.
Recruitment
- The successive activation of the same and additional motor units with increasing strength of voluntary muscle contraction
