Bone Lecture

Question 1

Sliding Filament Theory Steps

(10 steps)

Answer 1

1. Action potential
2. Ca²⁺ ions “pop out” of the terminal cisternae of the sacroplasmic reticulum (SR) into sacroplasm
3. Calcium binds/sticks to troponin (protein on actin)
4. Binding of calcium causes a rotation/spinning of tropomyosin (protein on the actin)
5. Uncovers the binding sites of the actin (binding sites now visible)
6. Myosin binds to actin at the binding sight (cross bridge)
7. Myosin pulls actin; actin slides inward
8. ATP (enery) released the myosin crossbridge & recharges the myosin (reloads/refolds)
9. Calcium released from the tropodin & pumped back to the sacroplasmic reticulum (SR)
10. Tropomyosin recovers the binding site & the actin relaxes

Question 2

Recruitment

Answer 2

The increase in the number of motor unites for an action results in an increased force

Question 3

Skeletal muscle hierarchy (biggest to smallest)

Answer 3

• Muscle “Flesh”
• Fascicles (bundles/ groups in muscle)
• Fibers
• Myofibrils
• Filaments

Question 4

Answer 4

Tendon

Connects muscles to bones

Question 5

Answer 5

Epimysium

The muscle “flesh” is covered by a connective tissue called the epimysium (ontop of muscle)

Question 6

Answer 6

Perimysium

The perimysium covers the fasciles with connective tissue

Question 7

Answer 7

Endomysium

The endomysium is a connective tissue that covers the sacrolemma

Question 8

Answer 8

Sacrolemma

The muscle cell’s membrane (covering)

Question 9

What factors affect bone growth/osteoporosis?

Answer 9

1. Gender
2. Diet (calcium)
3. PTH
4. Wolff’s Law
5. Bone cells

Question 10

How does gender affect bone growth/osteoporosis?

Answer 10

• 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)

Question 11

Summation

Answer 11

The increased number of stimuli to make a muscle not relax (don’t want the muscle to stop contracting)

Question 12

What does Wolff’s Law affect bone growth/osteoporosis?

Answer 12

• 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

Question 13

How does diet and PTH affect bone growth/osteoporosis?

Answer 13

• 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

Question 14

What are the three types of bone cells?

Answer 14

Osteocytes = normal bone cell

Osteoclast = breaks down bone/ destroyer

Osteoblast = bulids up bone/ builder

Question 15

Define summation for skeletal muscle contractions

Answer 15

• 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.

Question 16

Define recruitment for skeletal muscle contraction

Answer 16

• 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.

Question 17

Answer 17

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.

Question 18

Answer 18

Recruitment

• The successive activation of the same and additional motor units with increasing strength of voluntary muscle contraction