Musculoskeletal System

Question 1

What is the cartilage matrix made up of?

Answer 1

Chondrin

Question 2

The two types of bone

Answer 2

Compact and cancellous (consisting of trabeculae)

Question 3

What are the shafts and ends of bones called?

Answer 3

Diaphyses and epiphyses

Question 4

What is the epiphyseal plate?

Answer 4

Separates diaphysis and epiphysis and site of longitudinal growth

Question 5

Describe an osteon

Answer 5

Bone structural unit with center = Haversian canal surrounded by lamellae layered with lacunae (which house osteocytes and are connected by canaliculi)

Question 6

Whats’s the hardening of cartilage called?

Answer 6

Endochondral ossification

Question 7

Explain bone remodeling

Answer 7

Osteoclasts break down bone, osteoblasts rebuild.
Calcitonin => inhibits resorption
Parathyroid hormone => enhances resorption

Question 8

What is the synovial capsule?

Answer 8

Encapsulates moving joints, contains synovial fluid

Question 9

Explain the structure of a myocyte

Answer 9

Contractile unit = sarcomere, together form myofibrils. Myofibrils encased in sarcoplasmic reticulum (ER with Ca2+), all of this in sarcoplasm (the cytoplasm). Often many nuclei per cell.

Question 10

Explain red and white muscle fibers

Answer 10

Red have more myoglobin and get energy aerobically, white get energy anaerobically

Question 11

Explain structure of sarcomere

Answer 11

Thick and thin filaments, thick = myosin, thin = actin + troponin + tropomyosin.
M-line: center of thick filaments
H-zone: thick filaments not overlapped by thin
A-band: region of overlap b/w thick and thin filaments
I band: region of just thin filaments
Z-line: ends of contractile unit

Question 12

Explain sarcomere contraction

Answer 12

Release of Ca ions binds troponin, shifting tropomyosin and exposing myosin binding sites on actin. Myosin binds the sites and cocks its head for power stroke. ATP resets to cocked position and makes head detach from actin.

Question 13

Explain muscle single fiber simple twitch phases

Answer 13

Latent period = delay between threshold and contraction as action potential spreads
Contraction period
Refractory period = Fiber restoring resting potential. Absolute is when no amount of stimulus will trigger, relative is when a higher stimulus required to trigger

Question 14

Explain tetanus and frequency summation

Answer 14

Frequent stimulation means no time to relax, contractions begin to combine and become stronger and more prolonged

Question 15

What’s special about smooth muscle activation?

Answer 15

Controlled by autonomic nervous system but can contract without nervous system input, known as myogenic activity

Question 16

Describe smooth muscle key characteristics

Answer 16

1 nuclei per cell, smooth continuous contractions, non-striated

Question 17

Describe cardiac muscle key characteristics

Answer 17

1-2 nuclei per cell, strong forceful contractions, striated

Question 18

What’s key about myoglobin?

Answer 18

Binds oxygen more tightly than hemoglobin

Question 19

What are the two types of ossification?

Answer 19

Endochondral (hardening of cartilage), intramembraneous (undifferentiated embryonic connective tissue [mesenchymal] transforms into bone)