Musculoskeletal System

Question 1

What is a sarcomere? What are thick and thin filaments made up of?

Answer 1

A sarcomere is a contractile unit of the fibers in skeletal muscle
Thin filaments contain actin
Thick filaments are made of myosin

Question 2

What are the different zones of a sarcomere?

Answer 2

H-zone is just the thick filaments
A-band is all of the thick filaments
I-band is just the thin filaments

Question 3

What is the initiation of a contraction?

Answer 3

Depolarization of a neuron leads to an action potential

Question 4

How does the sarcomere shorten during contraction

Answer 4

• Sacroplasmic reticulum releases Ca2+
• Ca2+ binds to troponin on the actin filament
• Tropomyosin shifts, exposing myosin-binding sites
• Myosin binds, ATPase activity allows myosin to pull thin filaments towards the center of the H zone, then ATP causes dissociation

Question 5

How does the sarcomere relax after contraction?

Answer 5

Ca2+ is pumped back into the sarcoplasmic reticulum

Question 6

What is an osteoblast?

Answer 6

Builds bone

Question 7

What is an osteoclast?

Answer 7

Breaks down bone

Question 8

Reformation vs. Degradation (resorption)

Answer 8

Reformation is when inorganic ions are absorbed from the blood for use in bone
Resorption is when inorganic ions are released into the blood