5 - MSK

Question 1

Describe the morphology of bones

Answer 1

organic portion (30-40%): collagen (type I) and glycoproteins
inorganic portion (60-70%) minerals, hydroxyapatite

Question 2

Compact (cortical) bone

Answer 2

Osteons formed by concentric rings of extracellular matrix (=collagen and hydroxyapatite crystals)
• Lacunae house osteocytes
• Canaliculi connect lacunae

• Strong, support
• Diaphysis of long bones
• External layer of all bones

Question 3

Spongy (trabecular) bone

Answer 3

Trabeculae support and protect marrow
• Trabeculae are oriented along lines of stress
• Within each trabecula there are lacunae and a lamellated morphology

• Light weight
• Most of epiphysis
• Internal cavity of long bones

Question 4

Describe the cell types found in bone and their function and how they relate to the extracellular matrix

Answer 4

Osteoblasts = main bone producing cells
Osteocytes = mature osteoblasts
Osteoclasts = cells that reabsorb bone

Question 5

Apply the concept of negative feedback to mineral homeostasis

Answer 5

Blood calcium decreases
Parathyroid gland detects lower Ca
PTH gene turned on
Osteoclasts increase bone reabsorption, kidneys retain Ca in blood
Increase in Plasma Ca levels
Controlled variable restored to normal
Return to homeostasis

Question 6

Axial skeleton

Answer 6

Head, spine, rubs/trunk

Question 7

Appendicular skeleton

Answer 7

everything else

Question 8

Short bone example

Answer 8

patella

Question 9

long bone example

Answer 9

Femur

Question 10

flat bone example

Answer 10

scapula

Question 11

irregular bone example

Answer 11

pelvis

Question 12

Diaphysis

Answer 12

the shaft or body of a long bone.

Question 13

Epiphyses

Answer 13

END

form the distal and proximal ends of a long bone.

Question 14

Metaphyses

Answer 14

MID - (between episodes and dia)

are the areas where the epiphyses and diaphysis join.

Question 15

Synovial Joint

Answer 15

bone - articulating cavity - bone

Question 16

Solid Joint

Answer 16

bone - connective tissue - bone

Question 17

Types of joints

Answer 17

ball and socket
pivot
hinge
saddle 
gliding
condyloid

Question 18

Extracellular matrix is composed of organic and inorganic components:

Answer 18

organic portion (30-40%): collagen (type I) and glycoproteins
• tensile strength and resilience
inorganic portion (60-70%): minerals, hydroxyapatite
• hardness and rigidity

Question 19

Myosinmolecule

Answer 19

• two heads, connected by
flexible heads
• motor domain with ATP binding site
• actin-binding site

Question 20

Thick filament

Answer 20

Clusterofmyosinmolecules

Question 21

Thin filament

Answer 21

Actin, tropomyosin, troponin

Question 22

Actin monomers

Answer 22

Binding site for myosin
head
• Myosin binding site is covered by tropomyosin when muscle is at rest

Question 23

Myofibril

Answer 23

Contractile element of a muscle fibre

- a single muscle cell

Question 24

Movement of filaments

Answer 24

• Calcium (Ca2+)enters the cell
• Ca2+ binds to troponin
• Tropomyosin shifts, which exposes the myosin binding sites on actin

Question 25

How do you get the entire motor unit to contract together?

Answer 25

• Depolarization happens at the cell membrane
• Calcium is stored in sarcoplasmatic reticulum
• Transverse tubules are deep invaginations of the cell membrane and are linked with the sarcoplasmic reticulum (SR)
• When the cell membrane depolarizes, Ca2+ is released from the SR along the entire muscle fibre
• When the cell repolarizes, Ca2+ is pumped back into the SR