2.7 Bones, Joints

Question 1

What are the functions of bones?

Answer 1

Support
Mineral storage (Ca2+, PO4-)
Lipid storage
Blood cell production
Protection
Leverage for muscles

Question 2

What are the bones of the axial skeleton?

Answer 2

Skull
Hyoid bone
Ribs 
Sternum
Vertebral column

Question 3

Name the 8 cranial bones

Answer 3

Occipital
Frontal
Pariental (2)
Temporal (2)
Sphenoid
Ethmoid

Question 4

What are the 6 cranial sutures?

Answer 4

Frontonasal suture – between the frontal and nasal bones
Coronal suture – between the frontal and the parietal bones
Sagittal suture – between the two parietal bones
Squamosal sutures (2) – between the parietal and temporal bones
Lambdoid suture – between the parietals and occipital bone
(NOTE: metopic suture is in the middle of the frontal bone in development)

Question 5

What are he 14 facial bones?

Answer 5

Mandible
Maxilla (2)
Zygomatic (2)
Nasal bones (2)
Lacrimal (2)
Inferior nasal conchae (2)
Palatine (2)
Vomer

Question 6

What are the bones of the orbit?

Answer 6

frontal bone
sphenoid bone
zygomatic bone
maxilla
lacrimal bone
ethmoid bone
palatine bone

Question 7

What is the purpose of the paranasal sinuses?

Answer 7

cavities in some skull bones
Are clustered around and drain into the nasal cavity
Lighten the skull, resonate sound, produce mucus

Question 8

Name the paranasal sinuses

Answer 8

Frontal – superior to nasal cavity
Ethmoidal – superior to nasal cavity
Sphenoidal – posterior to nasal cavity
Maxillary (2) – lateral to nasal cavity

Question 9

Name the regions of the vertebral column. How many bones in each.

Answer 9

Cervical – 7 vertebrae
Thoracic – 12 vertebrae
Lumbar – 5 vertebrae
Sacrum – 5 fused vertebrae
Coccyx – 4 partially fused vertebrae

Question 10

What are the two components of an intervertebral disk?

Answer 10

Annulus fibrosus – outer layer of fibrocartilage

Nucleus pulposus – inner gelatinous core

Question 11

Describe a herniated disc

Answer 11

nucleus pulposus protrudes through the annulus fibrosus due to excessive compression
May put pressure on spinal cord and nerves

Question 12

What are primary vs secondary spinal curvatures?

Answer 12

Primary – appear during fetal development and are present at birth, convex posteriorly
Thoracic
Sacral
Secondary – develop later, concave posteriorly
Cervical
Lumbar

Question 13

What are kyphosis, lordosis, and scoliosis?

Answer 13

Kyphosis – exaggerated thoracic curvature, hunchback
Lordosis – exaggerated lumbar curvature, swayback
Scoliosis – lateral curvature of the spine

Question 14

What is the os coxa?

Answer 14

The hip bones- made of the ischium, ileum, and pubis

Question 15

What are the regions of long bones?

Answer 15

Epiphysis – ends
Metaphysis - neck
Diaphysis - shaft
Medullary cavity – center of bone filled with bone marrow

Question 16

What are endosteum and periosteum?

Answer 16

Endosteum – internal lining of flattened cells

Periosteum – superficial external lining of fibrous CT and cells

Question 17

What are the two types of bone marrow? Function?

Answer 17

Red bone marrow: forms blood cells

Yellow bone marrow: adipose (fat) tissue for lipid storage

Question 18

What makes up bone matrix?

Answer 18

Collagen fibers: (“steel”)
1/3 of total bone weight, flexible, strong, resist compression
Calcium Phosphate: (“concrete”)
2/3 of total bone weight, hard, brittle
calcium phosphate, hydroxyapatite crystals
Ca10(PO4)6(OH)2
other: calcium carbonate, sodium, magnesium, fluoride

Question 19

What are the 4 types of bone cells?

Answer 19

Osteocytes mature bone cells, majority of bone
in lacunae, divots within bone matrix
Osteoblasts: bone building cells, secrete bone matrix
Osteoclasts: bone “crushing” cells, absorb and remove bone matrix
Osteogenic cells: stem cells undergo mitosis to make osteoblasts

Question 20

Describe calcium homeostasis

Answer 20

stimulus: calcium ion concentration in blood
IF TOO LOW:
parathyroid hormone (PTH) response  increase blood Ca2+:
stimulate osteoclasts to breakdown bone matrix
increase small intestine calcium absorption via calcitriol (active Vitamin D)
decrease kidney excretion of calcium ions
IF TOO HIGH:
calcitonin hormone response  decrease blood Ca2+:
inhibit osteoclasts
increase kidney excretion of calcium ions

Question 21

What are the 2 types of ossification? When do they begin and and?

Answer 21

endochondral ossification:
long bones
hyaline cartilage framework, then ossification
intramembranous ossification:
flat bones
form within fibrous connective tissue
Begins 6 weeks after fertilization, ends at about 25 yrs

Question 22

What are the epiphyseal plate and line?

Answer 22

Epiphyseal plate
Disc of hyaline cartilage at the epiphysis-diaphysis junction
Allows bone to grow in length
Epiphyseal line
Remnant of the epiphyseal plate in adults
Thin line of compact bone

Question 23

Where does endochondral ossification occur? What are the steps?

Answer 23

hyaline cartilage framework, then 7 Steps:
chondrocyte disintegration
blood vessels and osteoblasts
primary ossification center – shaft
shaft remodeling
secondary ossification center – epiphysis
epiphyseal plate growth
epiphyseal closure

Question 24

How does HGH affect epiphyseal plate activity?

Answer 24

Growth Hormone and Thyroid Hormone stimulate bone growth through increasing all cell division and activity throughout the body
chondrocytes and osteoblasts stimulated

Question 25

How do sex hormones affect epiphyseal plate activity?

Answer 25

Estrogen and Androgens (testosterone and others) levels stimulate osteoblast activity
bone replaces faster than chondrocytes can divide
complete epiphyseal plate closure varies across individuals and in different bones, but usually by age 25.
estrogens close plate faster (women often shorter stature)

Question 26

What are the steps in intramembranous ossification?

Answer 26

Flat bones in the skull, mandible, and clavicles from via intramembranous ossification
bone forms within fibrous connective tissue of dermis
osteoblasts form ossification centers in mesenchymal tissue
spicules of bone form
blood vessels increase
spicules form flat, spongy bone
compact bone forms on edges

Question 27

In what tissue does endochrondral ossification happen? intramembranous?

Answer 27

Endochondral- In hyaline cartilage

intramembranous- in fibrous CT

Question 28

What hormones are requires for bone growth?

Answer 28

Parathyroid Hormone
Calcitonin
Estrogen
Androgens
Growth Hormone

Question 29

What is osteoporosis?

Answer 29

high osteoclast activity, especially in spongy bone can lead to excessive disintegration of bone
fracture risk, especially hips, wrist, vertebrae
lack of weight bearing exercise
hormones and chemical mediators: estrogen, androgen, vitamin D, parathyroid hormone, interleukins, prostaglandins, tumor necrosis factor

Question 30

What is osteopenia?

Answer 30

early stages – thinning of bone matrix

Question 31

What are the steps in bone repair?

Answer 31

Day 1:
hematoma and inflammation blood clot closes off injury, inflammation reaction
Upto Week 2:
granulation tissue: fibroblasts increase, vascular tissue increases
4-16 weeks:
callus – osteoblasts and chondrocytes, cartilage formation externally, spongy bone internally stabilizes area
spongy bone replaces cartilage
compact bone formed and thickened, remodeled by osteoblasts and osteoclasts
3-6 months:
remodeling by osteoclasts and osteoblasts