Chapter 7

Question 1

What are the functions of the 💀?

Answer 1

• 💉 formation
• acid-base balance
• electrolyte balance
• protection
• movement
• support

Question 2

What is the💀 system made of?

Answer 2

• 🦴
• cartilage
• ligaments

Question 3

What are long 🦴?

Answer 3

• most important 🦴 for movement

* rigid levers acted on by 💪🏼 for movement (like crowbars)

Question 4

What are some examples of long 🦴?

Answer 4

• humerus
• radius
• ulna
• femur
• tibia
• fibula
• metacarpals
• metatarsals
• phalanges

Question 5

What covers joint surfaces in nature skeleton?

Answer 5

cartilage

Question 6

What holds bones together?

Answer 6

ligaments

Question 7

What attaches muscles to bones?

Hint: similar to ligaments

Answer 7

tendons

Question 8

Where is spongy (cancellous) 🦴 found?

Answer 8

• inside ends of long 🦴
• inside compact 🦴 of long 🦴 shaft
• middle of most flat/irregular/short 🦴

Question 9

How is the skeleton divided between compact & spongy 🦴?

Answer 9

• 3/4 compact

* 1/4 spongy

Question 10

What’s the general anatomy of long 🦴?

Answer 10

• outer shell = dense white osseous tissue AKA compact (dense) bone
• shell around medullary cavity AKA marrow cavity
• ends of bone filled w/spongy (cancellous) tissue
• diaphysis = shaft (middle); leverage
• epiphysis = head (ends); strengthens joints & adds room for tendons/ligaments to attach

Question 11

What is a joint surface?
What’s it covered with?
What’s the purpose of this covering?

Answer 11

• where 🦴 meet
• articular cartilage
• works w/lubricant fluid so joints move easier

Question 12

Periosteum

Answer 12

• external 🦴 sheath covering
• tough/fibrous collagen layer-outer
• osteogenic bone forming cells layer-inner
• provides strong attachment from 💪🏼 > tendon > 🦴

Question 13

Endosteum

Answer 13

• thin layer of reticular tissue
• lines internal marrow cavity
• covers spongy 🦴
• lines canal system in compact 🦴

Question 14

What is the spongy layer of the cranium?

Answer 14

diploe

Question 15

Flat 🦴

Answer 15

•thin curved plates

Ex:
•most cranial 🦴 are flat 🦴 
•paired parietal 🦴 (form dome of top of head)
•sternum (breastbone)
•scapula (shoulder blade)
•ribs
•hip bones

Question 16

What tissues make up 🦴?

Answer 16

• osseous
• 💉
• 🦴 marrow
• cartilage
• adipose
• nervous
• fibrous connective

Question 17

What are the 4 🦴 cells?

Answer 17

Osteogenic cells

• stem cells develop from mesenchyme
• give rise to most bone 🦴 cells
• multiply constantly
• some become osteoblasts
• stimulated by stress/fractures (then multiply faster)

Osteoblasts

• 🦴 forming cells
• cuboidal or angular
• single layer on bone surface under endosteum & periosteum (similar to cuboidal epithelium)
• nonmitotic (don’t recreate except through osteogenic cells)
• synthesize matter in bone matrix which hardens
• stress/fractures stimulate osteogenic cells = more osteoblasts = faster 🦴 repair

Osteocytes

• osteoblasts that get trapped in matrix they made
• stuck in lacunae (cavities)
• lacunae connected by canaliculi
• canaliculi used to send nutrients/chemical signals/pass waste to 💉 cells
• resorb bone matrix/deposit 🦴 matrix
• homeostatic maintenance of 🦴 density & blood concentrations
• strain sensors:
  1) pressure/load applied to 🦴
  2) lacunae & canaliculi flow through ECF
  3) osteocyte cilia stimulated
  4) cells secrete signals to regulate 🦴remodeling

Osteoclasts

• 🦴 dissolving cells
• on 🦴 surface
• develop from 🦴 marrow stem cells that give rise to 💉 cells
• fused stem cells = osteoclasts
• 3 or 4 nuclei (up to 50)
• live in resorption bays

Question 18

What’s the basic structural unit of compact 🦴?

Answer 18

Osteon (haversian system)

Question 19

What is spongy 🦴 made of?

Answer 19

•lattice of spicules & trabeculae

Question 20

What is 🦴 marrow?

Answer 20

•soft tissue occupying…

• marrow cavity of long 🦴
• space amid trabeculae of spongy 🦴
• larger central canals