Skeletal System Objectives

Question 1

Osteoblasts

Answer 1

Forms new bone, found on the surface of bones in a single layer.
*Activate RANKL to start process of bone remodeling
*secrete osteoid seam to fill in lacunae. Calcium and phosphate deposit on seam and form hydroxyapatite
*osteoblasts that become trapped in bone tissue turn into osteocytes.

Question 2

What is released by osteoblasts to initiate bone remodeling?

Answer 2

RANKL

Question 3

What is released by osteoblasts to turn off bone remodeling?

Answer 3

Osteoprotegerin, binds RANKL and prevents activation of RANK receptors and slows activation of osteoclasts.

Question 4

Osteoclasts

Answer 4

Break down bone by releasing collagenase (digests collagen), also produce hydrochloric acid which dissolves hydroxyapatite into soluble calcium and phosphatase ions.

Question 5

What does RANKL do?

Answer 5

Binds to monocytes which come together to form an osteoclast, helps cells to mature

Question 6

If you have a drop in blood calcium levels, what hormone will be released and from where?

Answer 6

Parathyroid hormone from parathyroid glands, this stimulates osteoblasts to release RANKL to trigger bone resorption which will ultimately lead to calcium being deposited in blood stream, correcting calcium levels

Question 7

What is released and from where when blood calcium levels become elevated

Answer 7

Calcitonin, parafollicular cells
*bone resorption inhibited, decreases amount of calcium in the blood stream

Question 8

Wolffs law

Answer 8

Bones that bear a lot of weight remodel at a high rate

Question 9

What role does vitamin D play in bone resorption?

Answer 9

Stimulates intestinal absorption of calcium, calcitonin increases and inhibits bone resorption.

Question 10

Osteocytes

Answer 10

Basic bone cells, determines strength or weakness of bone and senses movement

Question 11

What is red marrow responsible for?

Answer 11

Hematopoiesis (process of producing blood cells)

Question 12

What is stored in yellow marrow?

Answer 12

Fat

Question 13

Axial skeleton

Answer 13

Central structure (skull, spine, thorax)

Question 14

Appendicular skeleton

Answer 14

Limbs (pelvis, upper and lower extremity)

Question 15

Flat bone examples and structure

Answer 15

Skull, sternum, ribs, scapula
*plates of compact bone running in parallel with small layer of spongy bone in between, decent amount of hematopoiesis

Question 16

Cuboidal bones examples and structure

Answer 16

“Short bones” carpals, tarsals
*primarily spongy bone, thin layer compact covering

Question 17

Irregular bones examples

Answer 17

Vertebrae, mandible, facial bones

Question 18

Articulation

Answer 18

Where two bones meet

Question 19

Facet

Answer 19

Flat surface
Ex) vertebrae

Question 20

Condyle

Answer 20

Rounded surface
Ex) femoral condyle (area where it meets tibia)

Question 21

Protuberance

Answer 21

Protrusion
Ex) chin

Question 22

Process

Answer 22

Prominence feature
Ex) styloid process

Question 23

Tubercle

Answer 23

Small rounded process often site of ligament or tendon attachment
Ex) tubercle of humerus

Question 24

Tuberosity

Answer 24

Rough surface that serves as an attachment point
Ex) tibial tuberosity

Question 25

Crest

Answer 25

Ridge
Ex) iliac crest

Question 26

Fossa

Answer 26

Elongated basin (depression, bowl like)
Ex) mandibular fossa or fossa of the pelvis

Question 27

Fovea

Answer 27

Small pit
Ex) fovea of femoral head

Question 28

Foramen

Answer 28

Hole through bone
Ex) foramen magnum occipital bone

Question 29

Meatus

Answer 29

Opening into canal
Ex) External auditory meatus

Question 30

Sinus

Answer 30

Air filled space in bone
Ex) nasal sinus

Question 31

Trochlea

Answer 31

Smooth grooved structure that allows bone or tendon to slide or articulate, pulley system
Ex) elbow