Bone Tissue Flashcards

1
Q

Attributes of Bone

A

Makes up the hard parts of the skeleton with hard ECM to provide structure to the body, anchor skeletal muscles,
protect the CNS, heart, + lungs.
This connective tissue also devevlops blood, stores calcium in the ECM + triglycerides in adipose.

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2
Q

Primary components of the ECM in bone

A

Collagen
Calcium Phosphate

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3
Q

Osteoprogenitor cells

A

Stem cells that produce new osteoblasts
They live between periosteum and bone.

osteoblasts: Cells that make bone’s ECM

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4
Q

Osteoblasts

A

Cells that make bone’s ECM - type of fibroblast

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5
Q

Osteocytes

A

Mature osteoblast cells that have moved to the mature part of the bone to maintain the ECM.

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6
Q

Osteoclasts

A

Specialized cell that breaks down bone ECM. Unrelated to the other types of bone cells because they’re white blood cells (macrophage)

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7
Q

Compact bone

Solid bone

What, where, components

A

Located on the outside of bones without any visible holes.
Components:
* Osteons
* Lamellae → Lacunae → Osteocytes + Canaliculi
* Central Canal
* Perforating canals

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8
Q

Osteons

A

Circles of tissue in compact bone with a large channel running up the middle and along the axis of long bones.
They act as pillars for baring the weight of the bone.
Lamellae, lacunae, osteocytes, + canaliculi are found in these circles.

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9
Q

Lamellae

A

Visible concentric circles of ECM around the central canal.

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10
Q

Lacunae

A

Small holes in the spaces between the lamellae
Osteocytes live here to maintain the bone and touch little extensions though the canaliculi.

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11
Q

Canaliculi

A

Tiny canals touching eachother in bone ECM that connects lucanae to each other + to the central canal.
Gasses and nutrients are exchanged through these extensions.

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12
Q

Central Canal

A

Hole running through the middle of osteon containing blood vessels, lymph vessels + nerves.

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13
Q

Perforating canals

A

Channels that run perpendicular to osteon and carry blood between the central canals and blood outside the compact bone.

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14
Q

Spongy bone

What, where, components

A

Recognized by large visible holes giving it the appearance of a sponge. Located inside of bone.
Components:
* Bone marrow
* Trabeculae
* Lacuna
* Canaliculi + osteocytes
No central canal or osteons

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15
Q

Trabeculae

A

The hard web-looking part of spongy bone.
The different angles + multiple directions provide support to the bone.
Lacuna, canaliculi + osteocytes also live here.

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16
Q

Yellow marrow

A

Composed of adipose tissue storing triglycerides.

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17
Q

Red marrow

A

Blood cells (red + white) development site.

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18
Q

Long bone structure

A
  • 2 Epiphysis
  • Articular cartilage
  • Diaphyis
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19
Q

Epiphysis

A

Long bone head with a proximal + distal end
Made of thin compact bone around the outside + has spongy bone with red bone marrow inside.

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20
Q

Articular cartilage

A

Located on either end of long bones.
It’s composed of hyaline cartilage that forms the base of joints with other bones.

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21
Q

Diaphyis

A

Also known as the long shaft of long bone
Composed of compact bone around the outside, Spongy bone only at the ends, and a medullary cavity filled with yellow bone marrow.

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22
Q

Medullary cavity

A

The empty space in diaphyis filled with yellow bone marrow.

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23
Q

Flat, irregular, + short bones structure similarities

A

Compact bone is around the outside
Mostly filled with spongy bone on the inside
Hyaline cartilage where joints will be connected.

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24
Q

Periosteum

A

Membrane of dense irregular connective tissue that lines the outer surface of all bones. Blood vessels + sensory neurons cen be found in this membrane.

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25
Q

Endostium

A

Membrane of dense irregular connective tissue that line the inside of bone, trabeculae in spongy bone + inside of the medullar cavity.

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26
Q

What is cartilage’s relavance?

A

The other connective tissue found in the skeleton that’s strong but more flexible than bone with no calcium in the ECM. Cartilage has no blood vessels or neurons.

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27
Q

Chondroblast

A

Fibroblast cells in growing cartilage that make cartilage ECM

28
Q

Chondrocytes

A

Mature fibroblasts living in mature cartilage to maintain the cartilage ECM

29
Q

Lacunae

Definition + Properties

A

Holes in the cartilage ECM where chondrocytes live.
* ECM in cartilage
* Has lots of collagen and polysaccharides
* Some types have elastin
* No calcium
* Gel substance is salt

30
Q

Perichondrium

Definition + Purpose

A

Membrane that surrounds cartilage.

Cartilage gets nutrients + oxygen from blood cells in the perichondrium by diffusing through the ECM to osteocytes.

31
Q

Types of cartilage tissue

A
  1. Hyaline
  2. Elastic
  3. Fibrocartilage
32
Q

Hyaline Cartilage

What is it? Where is it?

A
  • Most common cartilage with an ECM of mostly collagen
  • Tough + flexible
  • Most common form of it is articular cartilage located at the ends of bones to form joints.
    1. Costal cartilage - in rib cage
    2. Nasal cartilage - in nose
    3. Respiratory cartilage - in tachea
33
Q

Elastic Cartilage

What is it? Where is it?

A

Similar to hyaline but has lots of elastic fibers (look like black lines) + make it flexible
Most flexible type of cartilage
Found in: ear + epiglottis

34
Q

Fibrocartilage

A
  • Toughest cartilage
  • Dense bundles of collagen fibers with a stiff gel substance and lacunae within the chondrocytes, all going the same direction (similar to dense irregular tissue)
    Found in: between vertebrae, pubic bones + meniscus in the knee
35
Q

Bone Development Process

A
  1. Bones develop from hyaline cartilage or from fibrous membrane
  2. Ossification
  3. Endochondral ossification
  4. Intramembranous ossification
36
Q

First step of the bone development process

A

Bones develop from hyaline cartilage or from fibrous membrane
* Softer than bone tissue making it easy to make, grow + control shape
* Lay out the initial structure of the bone

37
Q

Ossification

Definition + Process in bone development

A

The formation of bone from other tissues.
* ECM replaced with bone ECM - introducing Ca++
* Blood vessels, lymphs + nerves grow in bone
* Starts at 8 weeks of gestation

38
Q

Endochondral ossification

A

Inside/cartilage (hyaline) turns into bone - almost all bones below the skull.

39
Q

Primary ossification center

A

Where ossification starts and spreads out from
1. Osteoblasts form around diaphysis
2. Bone collar
3. Start making bone ECM

40
Q

Bone Collar

A

Ring of bone around diaphysis and made of compact bone.

41
Q

Chondrocytes purpose in bone development

A

To calcify the cartilage ECM and die.
ECM inside bone starts to break down, leaving holes in the calcified cartilage ECM.

42
Q

Periosteal bud

A

Inside/ bone like growing plant → other tissues that move into bone together
* Blood vessels, lymph nodes, nerves, bone marrow, osteoblasts + osteoclasts
- Osteoclasts break down remaining cartilage ECM, Osteoblasts start building the bone + spongey bone inside

43
Q

Medullary cavity

A

Forms from the periosteal bud.
* Osteoclasts break down spongy bone to form a cavity
* Diaphysis + epiphyses continue to grow

44
Q

Secondary Ossification Centers

A

Centers form in the epiphyses.
The ossification of epiphysis is similar to the ossification of the diaphysis.
After ossification:
Most of bone is bone
Still have hyaline cartilage in a few places as Articular Cartilage and Epiphysial plates.
After ossification at the epiphysial plate:
New cartilage is produced at the epiphysial side, pushing epiphysis out at the epiphysial side
Cartilage is converted to bone on the epiphysial side
Appositional growth is now possible

45
Q

Articular Cartilage

A

Is found at the end of bones - where bones form synovial joints with other bones

46
Q

Epiphysial plate

A

Also known as a growth plate - consists of a band of hyaline cartilage between epiphyses + diaphysis

47
Q

Appositional growth

A

Refers to how bones get wider.
1. New compact bone is laid down around the outside by osteoblasts.
2. On the inside, bone is broken down so they don’t get too heavy
3. Sometimes replaced by spongey bone (dependent on its location)

48
Q

Intramembranous ossification

A

Process in which membrane made of fibrous connective tissue is converted into bone
* Created the bones of the skull and clavicles
* Connective tissue ECM is converted to bone by osteoblasts

49
Q

Why is old bone broken down and replaced by new bone?

A
  • To replace old bone so bone doesn’t become too old + brittle
  • To repair broken bone
  • To change the shape of bones
  • Ca++ homeostasis
50
Q

Bone Remodeling process basics

A
  1. Bone restoration: osteoclasts come in and break down old bone, releasing Ca++
  2. Bone deposition: osteoblasts lay down new bone in appropriate position
51
Q

Calcitonin & Parathyroid hormone

A

Hormones that regulate Ca++ homeostasis in the body.
Big effect on body’s deposition + reabsorption

52
Q

Calcitonin

A

Hormone released when blood Ca++ is high.
* From the thyroid gland
* Stimulates bone deposition
* Stores Ca++ in bone
Negative feedback for homeostasis:
Ca++ high → calcitonin → -Ca++

53
Q

Parathyroid Hormone

A

Hormone released when blood Ca++ levels are low.
* From parathyroid glands
* Stimulates osteoclasts + reabsorption
* Ca++ being released from bone
Negative feedback for homeostasis:
Ca++ low → parathyroid → +Ca++

54
Q

Wolf’s Law

A

Bone grows where stress is greatest - to resist damage

55
Q

Forces that cause mechanical stress:

A
  1. Tension: bone is pulled on, stretching
  2. Compression: bone is squeezed
    Both forces are strongest in the middle of the diaphysis - where the bone is thickest
56
Q

Transverse Fracture

A

fracture across bone →

57
Q

Linear fracture

A

Runs along the long axis of bone - parallel to the diaphysis ⇡

58
Q

Oblique fracture

A

fracture at an angle ↗↘

59
Q

Spiral fracture

A

break is spiraling around the bone ꩜

60
Q

Greenstick fracture

A

One side breaks, one side bends ➦➥

61
Q

Open / compound fracture

A

Bone goes through the skin ⏯

62
Q

Bone repair process

A
  1. Hematoma - clotting to fill inflamed wound
  2. Fibrocartilgainous callus fills the space and connects the broken bones
  3. Bony callus holds broken bones together
  4. Bone remodeling
63
Q

Hematoma

A

A big pool of mostly clotted blood to fill an inflamed wound. Very painful!

64
Q

Fibrocartilgainous callus

Definition + attributes

A

A matrix of cartilage and fibrous connective tissue that fills the space and connects the broken bones
Attributes:
* Bulges out from the bone
* New blood vessels grow into the bone
* Made by fibroblasts + chondroblasts

65
Q

Bony callus

A

Spongy bone that holds broken bones together
The fibrocartilaginous callus is converted into bone - Made by osteoblasts

66
Q

Bone remodeling for repairs

A

Osteoclasts break down bone where you don’t need it
Osteoblasts build up bone in other places it’s needed