Bones/skeletal tissue

Question 1

3 types of cartilage + location?

Answer 1

Hyaline: most carrtilage except..
Elastic cartilage (“E..”): external ear, epiglottis, eustacian tube
Fibrocartilage: knee meniscus, pubic symphysis, intervertebral discs

Question 2

Cartilage: vascular or avascular? (so what?)

Answer 2

Avascular: hard to repair

Question 3

Appositional growth vs interstitial growth of cartilage?
length vs thickness?

Answer 3

Appositional: occurs at surface, adds protuberances
Interstitial growth: expanding cartilage from within (increase overall size of cartilage)

Question 4

Cartilage calcification:
Why?
How?

Answer 4

Why: to replace cartilage with bone (as a result of injury/aging)
How: oxygen supply cut off, calcium phosphate deposited into eroded matrix, chondrocytes die + leave space for bone

Question 5

2 textures of bone + functions
Spongy (cancellous/trabecular)
Compact

Answer 5

Spongy: filled with bone marrow (makes new blood cells)
Compact: outer layer, dense (smooth looking without microscope)

Question 6

Inner membrane of bone:
Outer membrane of bone:

Answer 6

Endosteum
Periosteum

Question 7

Lamellae
purpose
orientation (to previous layer)

Answer 7

Purpose: weight-bearing
90 deg. to previous layer

Question 8

Canaliculi: connect what to eachother and to what

Answer 8

Connect lacunae to eachother and to central canal

Question 9

Which orientation are trabeculae aligned in (in spongy or compact bone?)

Answer 9

Trabeculae: spongy bone, direction of physical stress

Question 10

Diaphysis vs Epiphysis
What type of bone
Where is each on the bone?
What type of marrow in each
What divides them
yellow vs red marrow?

Answer 10

Both in long bones
Diaphysis: shaft, Epiphysis: head
Diaphysis: yellow marrow
Epiphyses: red marrow
Epiphyseal line

Question 11

How can you tell if a bone is adult or child?

Answer 11

Epiphyseal PLATE: child, still room for development
Epiphyseal LINE: adult, bone is ossified.

Question 12

Where do nutrients enter the bone?

Answer 12

Nutrient foramina

Question 13

Osteoblasts vs osteoclasts

Answer 13

Osteoblasts: synthesize osteoid (mitotically active) - build bone
Oosteo clasts: reabsorb/break dwon bone matrix

Question 14

2 types of cells produced by osteoblasts?
Difference

Answer 14

Osteocytes: mature bone cells in lacunae
Bone lining cells: mature cells on bone surface
Both maintain bone matrix

Question 15

Is bone primarily organic or inorganic?
Primary inorganic substance (what is it composed of, function)

Answer 15

Inorganic
Hydroxyapatites: calcium phosphare (hardness/resistance to compression

Question 16

How much of the body’s calcium is in bone?

Answer 16

99%

Question 17

what are the 3 stages of bone development (ossification)

Answer 17

1. bone formation (prenatal)
2. post-natal bone growth (until early childhood)
3. bone remodelling/repair (lifelong)

Question 18

Bone formation (prenatal):
Endochondral ossification: how? which bones?
Intramembranous ossification: how? which bones?

Answer 18

Endochondral: bone replaces hyaline cartilage model (bones inferior to skull)
Intramembranous: bone developd from fibrous membrane (skull bones-flat)

Question 19

Endochondral bone formation:
When does it occur
How
Where is bone collar laid down first?

Answer 19

Prenatally
Hyaline cartilage model, as cartilage matrix deterioriates, osteoblasts produce osteoid
Bone collar first laid down on outside of bone

Question 20

Postnatal bone growth
Occurs until when?
Interstitial vs Appositional bone growth
Does thickness of bone change?

Answer 20

Until early childhood
Intersitital: cartilage calcification, FOR BONE LENGTH
Appositional: osteoblasts add rings to outer surface while osteoclasts break down inside FOR BONE THICKNESS
Thickness doesn’t change, only diameter increases

Question 21

Bone remodeling
How much bone mass is recycled weekly (%)
How often is spongy bone replaced (years)
How often is compact bone bone replaced (years)

Answer 21

5-7% weekly
Spongy bone: every 3-4 years
Compact bone: every 10 years

Question 22

Important nutrients for bone deposit (when injured or added strength is needed)

Answer 22

Protein
Vit C, D, A
Calcium
Phosphurus
Magnesium
Manganese

Question 23

Remodeling control: how do you know…
If remodeling will happen
Where remodeling will happen

Answer 23

If: hormones
Where: physics (mechanical/gravitational forces)

Question 24

What do these hormones do?
Growth hormone (GH)
Thyroid hormone (T3/T4)
Sex hormones (est/test)

Answer 24

GH: growth at epiphyseal plate (height increase)
T3/T4: modulate GH activity
Sex hormones: growth spurts, close epiphyseal plate when growth is finished

Question 25

How much calcium is in the body (g)

Answer 25

1200-1400g

Question 26

How are calcium levels regulated

Answer 26

Diet (intestines)
Osteoclasts breaking down bone
Kidneys (amount of Ca released through urine)

Question 27

Which hormone reulgates blood Calcium levels? How

Answer 27

Parathyroid hormone
1. osteoclast -> break down bone
2. osteoblasts -> inhibited
3. Synthesisze calcitrol (vit D) -> inc absorption in small intestine
4. Decrease urine Ca2+ levels

Question 28

Which hormone decreases blood Ca2+ levels, where is it released from

Answer 28

Calcitonin (from thyroid gland, parafollicular cells)

Question 29

What is wolff’s law

Answer 29

A bone grows/remodels in response to forces/demands placed upon it

Question 30

When are all bones ossified by?
When does bone mass begin to decrease?

Answer 30

25
40

Question 31

Types of bone fractures
Comminuted
Compression
Spiral
Epiphyseal
Depressed
Greenstick

Answer 31

Comminuted: 3+ pieces
Compression: crushed (cervical/thoracic vertebrae)
Spiral: excessive twisting (radius/ulna) - sports
Epiphyseal: epiphysis separates from diaphysis along epiphyseal plate
Depressed: skull
Greenstick: only one side of shaft breaks

Question 32

Steps of bone fracture repair

Answer 32

1. Fracture hematoma formed (blood clot)
2. Internal + external callus formed (cartilage)
3. External callus cartilage replaced with bone (bulge formed)
4. Remodelling over time (bone is cast, no forces applied to it)