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Bio 240 > Unit 1 > Flashcards

Unit 1 Flashcards

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Biology 101 flashcards
1
Q

Is bone tissue alive?

A

yes, bone tissue is dynamic, a living tissue with cells

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2
Q

What is cartilage used for?

A

-component for embryonic, growing, and mature bones
-important for bone development
- connects bones in some areas (ribs and hip bones)
- at the end of bones for protection

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3
Q

What kind of cartilage is at the end of bones?

A

articular hyaline cartilage

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4
Q

What are the types of cartilage?

A

-hyaline
-fibrous/elastic

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5
Q

Where is hyaline cartilage found?

A

-end of bones( articular hyaline)
- epiphysial plate

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6
Q

What is fibrous cartilage?

A

stretchy cartilage

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7
Q

Where is fibrous cartilage found?

A

in between vertebrae
nose and ears

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8
Q

What are the types of connective tissue

A

ligaments and tendons

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9
Q

What is connective tissue?

A

bone and ligament outer membrane

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10
Q

What are tendons?

A

connective tissue that connects muscle to bone

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11
Q

What are ligaments?

A

connective tissue that connects bone to bone

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12
Q

Does cartilage absorb water?

A

yes this helps in protect and cushion the bones

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13
Q

What are the types of bones?

A

-long
-short
-flat
-irregular

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14
Q

What is an example of a long bone?

A

femur or humerous

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15
Q

What is an example of a short bone?

A

tarsals

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16
Q

What is an example of a flat bone?

A

frontal bone

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17
Q

What is an example of an irregular bone?

A

vertebrae

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18
Q

What is a long bone?

A

a bone that is longer than it is wide

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19
Q

What is a short bone?

A

a bone where length is equal to width

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20
Q

What is an irregular bone?

A

a bone that is a complex or elaborate shape

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21
Q

What is a flat bone?

A

a bone with a flat smooth surface, sometimes is curved

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22
Q

What do all bones have?

A

compact and spongey bone

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23
Q

what is compact bone?

A

-white, smooth, solid bone on the outside of bones
- dense or cortical bone

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24
Q

What makes up compact bone?

A

osteons and lamellae

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25
Q

Where is compact bone found?

A

-on the exterior of the bone

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26
Q

What percentage of bone is compact bone?

A

20% of the bone overall, but 80% of the bone weight

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27
Q

What is spongey bone?

A

-cancellous/ trabecular bone
- appears porous

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28
Q

Where is spongey bone found?

A

-internal to compact bone

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29
Q

What makes up spongey bone?

A

-trabeculae
space between trabeculae contains red bone marrow

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30
Q

What makes up the extracellular matrix?

A

Organic and Inorganic tissues

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31
Q

What are the organic tissues that make up the extracellular matrix

A

-osteoid produced by osteoblasts
-a ground substance containing mostly collagen, proteoglycans, and glycoproteins

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32
Q

What is needed for collagen formation?

A

vitamin C

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33
Q

How is organic matter organized?

A

-in a uniform/organized pattern

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34
Q

What does organic matter do for the bone?

A

-contributes to flexibility
- gives in tensile strength by resisting stretching

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35
Q

How much of the bone matrix is organic

A

1/3

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36
Q

How much of the bone matrix is inorganic

A

2/3

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37
Q

How are osteoid produced?

A

by osteoblasts

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38
Q

What is the inorganic bone matrix made of?

A

mineralized crystals (mostly Ca10, PO4. Oh, hydroxyapatite are deposited around collagen fibers resulting in mineralization/ calcification of bone

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39
Q

What does vitamin D help with?

A

propper Ca2+ reabsorbtion

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40
Q

What does the mineralization of inorganic tissue do for bone?

A

accounts for the relative rigidity

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41
Q

How is the bone matrix organized?

A

1st. Collagen is laid down parallel and everything else is laid down after
2. Osteoid (more organic compound) is laid down
3. Proteoglycans and glycoproteins are laid down between the collagen and mineralization occurs
4. hydroxyapatite crystals are laid down between the parallel collagen fibers

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42
Q

What are the skeletal system functions?

A
  • Mobility and movement
  • support and protections
    -hemopoietic
  • storage
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43
Q

How does the skeletal system help with mobility and movement?

A

-bones form lever system that act as attachment sites for skeletal system

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44
Q

How does the skeletal system help with support and protection?

A

-Bones provide a structural framework and protect delicate tissues
- can build bones when growing
- can take bones away (pregnant mothers)

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45
Q

How does the skeletal system help with hemopoiesis?

A
  • formed elements developed in red bone marrow (RBCs WBCs , platelets)
  • yellow bone marrow= fatty
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46
Q

How does the skeletal system help with storage?

A

-mineral storage (99% of body’s Ca2+ phosphate is in bones)
- liquid storage ( adipose tissue is stored in yellow bone marrow)
- bones are mostly calcium phosphate

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47
Q

What does Calcium do?

A

-muscle contraction
-blood clotting
-neurons firing
-tooth enamel

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48
Q

What does phosphate do?

A

ATP and Energy

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49
Q

What are the types of bone cells in the order of formation?

A

-osteoprogenitor cells
-osteoblasts
- osteocytes
- osteoclasts

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50
Q

What are osteoprogenitor cells

A

-Bone cells derived from stem cells
-differentiate into osteoblasts

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51
Q

What are osteoblasts and what do they do?

A

-Blast are the builders
- Synthesize and secrete osteoid
- Regulate osteoclast differentiation and activity
-more cuboidal
-We activate them more when we want to build more bone
- When mineralized it gets trapped and turns into an osteocyte

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52
Q

What is osteoid?

A

-organic portion of tissue matrix
largely collagen
- synthesized secreted from osteoblasts

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53
Q

When do we activate more osteoblasts?

A

when we want to build more bone

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54
Q

What are osteocytes and what do they do?

A
  • mature cell enveloped by calcium osteoid
  • maintains matrix and responds to stress by activating osteoblasts and osteoclast activity
  • Extensions allow communication with other osteocytes through gap junctions
    -still strapped in the matrix, doesn’t add to it, but maintains it through communication
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55
Q

What are osteoclasts and what do they do?

A

-nucleated phagocytic cells formed by the fusion of bone marrow
- digests and dissolves bone matrix through reabsorption into blood
- raises blood calcium levels and releases minerals
-Proteolytic enzymes break down organic material
- HCL dissolves inorganic material
- inhibited by estrogen, so when estrogen drops during menopause bones break down more

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56
Q

What are external circumferential lamellae?

A

-rings of compact bone that surround the entire outer compact bone surface
-not too thick bc you have to be able to get blood vessels through

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57
Q

Where are external circumferential lamellae found?

A

immediately internal to the bone periosteum

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58
Q

What are interstitial lamellae?

A

compact bone remains of a partially reabsorbed osteon
-evidence that bone tissue is constantly regenerating

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59
Q

Where are interstitial lamellae found?

A

found between the newer, complete osteons

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60
Q

What is evidence that bone tissue is constantly regenerating?

A

interstitial circumferential lamellae

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61
Q

What is an osteon?

A

functional unit of compact bone inside of concentric lamellae and the central canal

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62
Q

What are internal circumferential lamellae?

A

-rings of compact bone that line the inner edge of compact bone tissue

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63
Q

Where are internal circumferential lamellae found?

A

-found adjacent to the endosteum

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64
Q

Why are compact bones organized the way they are?

A

-helps blood supply and nutrients be evenly dispersed
- Having the internal circumferential lamellae and external circumferential lamellae means bones can be repaired from inside or outside

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65
Q

What is the periosteum?

A
  • double layer bone covering adjacent to compact bone
  • connected to compact bone through perforating fibers
    -The outer fibrous layer is composed of connective tissue
  • The inner cellular layer contains osteoprogenitor cells, osteoblasts and osteoclasts
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66
Q

What is the outer fibrous layer of the periosteum made of?

A

connective tissue

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67
Q

What is the inner cellular layer of the periosteum made of?

A

osteoprogenitor cells
osteoblasts
osteoclasts

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68
Q

What is the central canal?

A

carries blood vessels and nerves through the center of each individual osteon

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69
Q

What is the perforating canal

A

opening in the bone where vessels and nerves through compact bone, interconnecting the central canal of osteons

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70
Q

What is the nutrient foramen?

A
  • openings in bone where vessels and nerves exit and enter
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71
Q

What is the osteon’s structure?

A

-Each osteon has multiple layers of concentric lamellae surrounding the central canal
- Each lamellae is then composed of inorganic crystals between collagen fibers
-within the concentric lamellae each collagen fiber is parallel (collagen fibers are 90degrees away from collagen fibers in adjacent lamellae)

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72
Q

What are osteocytes and what do they do?

A
  • Osteoblasts surrounded by mineralized bone matrix develop into osteocytes
  • Cellular processes extend from the osteocyte cell body through thin small spaces called canaliculi
    • allows cells to communicate with each other where the processes meet through gap junctions
  • the innermost layer of osteocytes extends cellular processes to the central canal blood supply allowing for the exchange of nutrients, wastes, and respiratory gases
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73
Q

Where are osteocytes found?

A
  • in small spaces called lacunae, located btwn adjacent concentric lamella
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74
Q

What are lacuna?

A

spaces that house osteocytes

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75
Q

What are canaliculi?

A
  • thin small spaces housing cellular processes
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76
Q

How to osteocytes communicate?

A
  • connect to other neighboring adjacent concentric lamellae through gap junctions found at their cellular processes
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77
Q

How do osteocytes respond to stress?

A

monitor stress and respond by stimulating osteoblasts, initiating bone deposition.

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78
Q

What are trabeculae

A

an open lattice of narrow rods and plates of bones in spongy bone

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79
Q

What are trabeculae comparable to in compact bone?

A

osteons

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80
Q

Where is spongy bone found?

A

various places dependent on shape of bone

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81
Q

What are trabeculae made of?

A
  • parallel lamellae
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82
Q

Why are trabeculae made of parallel lamellae?

A

makes it thinner so diffusion of nutrients are easier

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83
Q

What is in the spaces between trabeculae?

A

bone marrow and blood vessels

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84
Q

Where does spongy bone get its nutrients?

A

outside (explaining why diffusion is so important)

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85
Q

Where does compact bone get its nutrients?

A
  • central canal
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86
Q

Does compact bone have a periosteum?

A

yes

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87
Q

Does spongy bone have a periosteum?

A

no

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88
Q

Does spongy bone or compact bone have concentric lamellae?

A

compact bone

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89
Q

Does spongy or compact bone have parallel lamellae?

A

spongy

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90
Q

What type of bone has its own anatomy?

A

long bone

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91
Q

What are flat, irregular, and short bones composed of?

A
  • central bone shaft that provides leverage and support
  • exterior that has thick layer of compact bone covered by periosteum
  • interior made of spongey bone
  • no medullary cavity
  • has bone marrow in spongy bone
    -endosteum lines trabecullae of spongy bone
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92
Q

What covers the outer surface of trabeculae in spongy bone?

A

incomplete endosteum

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93
Q

What makes the outer surface of spongy bone?

A

incomplete endosteum

94
Q

Do flat, irregular, and short bones have compact and spongy bone?

A

yes

95
Q

What is dipole in flat bones?

A
  • interior made of spongy bones
96
Q

What type of bone has a dipole?

A

flat bones

97
Q

Does short, flat, and irregular bone have a medullary cavity?

A

no

98
Q

What is a long bone made of?

A

-diaphysis
-epiphysis
-metaphysis
-periosteum
-endosteum

99
Q

What is the diaphysis?

A

-part of the long bone
-central bone shaft that provides leverage and support
-

100
Q

What is the medullary cavity made of?

A
  • exterior made of thick compact bone with thin spicules of spongy bone extending inwards
    -all exterior areas covered with periosteum
    -medullary cavity containing blood vessels and bone marrow?
101
Q

Where in the long bone are blood vessels and bone marrow?

A

medullary cavity

102
Q

What is red bone marrow?

A
  • myeloid tissue that is hemopoietic tissue containing highly active stem cells for the formed elements of blood
103
Q

Where is red bone marrow located?

A
  • at first all bone marrow is red and then slowly converted to yellow as we age.
  • in adults is only in regions of the axial skeleton and a few areas of the appendicular skeleton
104
Q

What is yellow bone marrow made of?

A

adipose tissue

105
Q

What is unique about yellow bone marrow?

A
  • retains the potential to convert back into red bone marrow under stress
  • like severe anemia
106
Q

How many epiphysis’ are there in a long bone?

A

-proximal and distal

107
Q

What is the epiphysis?

A
  • enlarges surface ends “knobs” composed of a thin outer compact bone layer surrounding inner bone marrow filled spongy bone
108
Q

What is at the end of the epiphysis?

A

-articular cartilage

109
Q

Where is articular cartilage found?

A

at the end of the epiphysis

110
Q

What is articular cartilage?

A
  • protective hyaline cartilage layer found on some bone ends such as where joints occur
    -reduces friction and absorbs shock in moveable joints
111
Q

What is the metaphysis?

A
  • the region that widens and transfers weight between the diaphysis and epiphysis
  • once growth ceases bone tissue replaces all of the cartilage and epiphyseal line (composed of a thin line of compact bone) remains
112
Q

What does the metaphysis contain?

A
  • cartilage containing the epiphyseal plate, or growth plate, responsible for lengthwise growth in bones
113
Q

What is the periosteum?

A
  • a double layer sheath that covers the outside of bones
114
Q

What does the periosteum do?

A
  • protects bone from surrounding structures
    -anchors blood vessels and nerves
  • acts as attachment site for ligaments and tendons
115
Q

Where is the periosteum not found?

A
  • patella and joint surface of long bones covered by articular cartilage
116
Q

What are the parts of the periosteum?

A

-outer fibrous layer
-inner cellular layer
- perforating fibers

117
Q

What does the outer fibrous layer of the periosteum do?

A

-anchors blood vessels (nutrient foramen) and nerves to bone surface
- attachment site for ligaments and tendons

118
Q

What does the inner cellular layer of the periosteum contain?

A

osteoprogenator cells
osteoclasts
osteoblasts

119
Q

What are the perforating fibers of the periosteum?

A

tuffs of collagen that fuse the periosteum to the outer compact bone layer

120
Q

What is the endosteum of the long bone?

A
  • an incomplete cellular layer containing osteoprogenitor cells, osteoblasts, and osteoclasts
  • lines canals of compact bone
    -covers medullary cavity of long bone
  • covers spongy bone tissue
121
Q

Where is endosteum found?

A
  • lines canals in compact bones
  • covers spongy bone tissue
  • lines medullary cavity of long bone
122
Q

Where is the extracellular matrix found?

A

cartilage and bones

123
Q

What is the bone equivalent of agricans?

A

hydroxyapatite crystals

124
Q

What is the bone equivalent of chondroblasts

A

osteoblasts

125
Q

Is cartilage calficied?

A

no

126
Q

What is the bone equivalent of chondrocytes?

A

osteocytes

127
Q

What is the cartilage equivalent of osteoclasts?

A

none- they cant destroy themselves

128
Q

What is the bone equivalent of mesenchymal stem cells?

A

osteoprogenitor cells

129
Q

Does bone or cartilage have a bigger lacuna?

A

cartilage

130
Q

Why does cartilage have a bigger lacuna?

A
  • it fits the whole cell including chondroblasts and chondrocytes
  • bone lacuna only has osteocytes and the processes stick out into canaliculi
131
Q

Can cells go back through mitosis in cartilage?

A

yes

132
Q

Can cells go back through mitosis in bone

A

no

133
Q

Is cartilage vascularized?

A

no

134
Q

Is bone vascularized?

A

yes

135
Q

Does cartilage have processes?

A

no

136
Q

Does cartilage have organized layers?

A

no, no separation of space

137
Q

Does bone have organized layers?

A

yes, highly organized

138
Q

What is the extracellular matrix of cartilage?

A
  • avascular mature tissue
  • a gel-like protein matrix that includes aggrecan, a proteoglycan
139
Q

What are proteoglycans?

A

water absorbing sugars giving cartilage the gel-like matrix, elasticity, helps with diffusion

140
Q

What are the types of cartilage tissue cells?

A
  • mesenchymal stem cells
  • chondrocytes
  • chondroblasts
141
Q

What is the perichondrium?

A
  • dense irregular connective tissue made of mostly collagen fibers that cover the cartilage surface
    -most of the region has fibroblasts, the deepest layer has mesenchymal stem cells
142
Q

What are mesenchymal stem cells?

A
  • only found in deepest layer of perichondrium
    -divides and forms chondroblasts
143
Q

What are chondrocytes?

A
  • maintains cartilage matrix
  • found in individual lacunae
  • forms chondroblasts and may create more chondroblasts
144
Q

Whats the difference when looking at chondrocytes and chondroblasts?

A

-1 nucleus in lacuna = chondrocyte
- 2 nucleus in lacuna= chondroblast

145
Q

Where are chondrocytes found?

A

individual lacunae

146
Q

What are chondroblasts and what do they do?

A
  • produces cartilage matrix
    -matures into chondrocytes
    -found in shared lacuna
147
Q

Where does appositional growth occur?

A
  • at the perichondrium (outside of tissue)
148
Q

What does appositional growth do?

A

increases width

149
Q

Where does the perichondrium surround cartilage?

A

costal cartilage, between spinal vertebrae, nose

150
Q

How does appositional growth occur?

A
  • Meiotic activity happens in mesenchymal stem cells within the deepest layers of perichondrium
  • forms chondroblasts
  • Chondroblasts secrete cartilage matrix, pushing each other further apart
    • Hence why it adds
  • chondroblasts mature into chondrocytes
151
Q

Where and when does interstitial growth occur?

A
  • occurs when internal chondrocytes divide
  • occurs at epiphyseal plate
152
Q

What does interstitial growth do?

A
  • increases length
153
Q

How does interstitial growth occur?

A
  • A chondrocyte in the lacuna starts showing
  • Chondrocyte cellular division forms 2 new chondroblasts in 1 lacuna
    -each cell produces a new cartilage matrix and starts separating from its neighbor
  • previously secreted matrix matures, further separating individual cells in there own lacunae
154
Q

When does skeletal development start?

A

8 weeks

155
Q

How many bones do you start with and then end up with?

A

starts with 300 and ends with 206 because the bones fuse together

156
Q

What does skeletal development start with?

A

-mesenchyme tissue
- startic material for all skeletal structures?

157
Q

What are the two ways ossification can occur?

A

intramembranous or endochondral

158
Q

What is intramembranous ossification?

A

when vascularized mesenchymal membrane becomes ossified

159
Q

What bones does intramembranous ossification create?

A
  • flat bones of the skull, some facial bones, mandible, central part of the clavicle
  • doesn’t have growth plates
160
Q

What are the steps to intramembranous ossification?

A
  1. Ossification centers form within thickened regions of the mesenchyme
  2. Osteoid undergoes calcification forming the ossification center
  3. Woven bone (primary bone) and bone membranes begin to form
  4. Lamellar bone (secondary bone) forms
161
Q

How do ossification centers form within thickened regions of the mesenchyme?

A

mesenchyme cells become osteoprogenitor cells which differentiate into osteoblasts which secrete osteoid

162
Q

How does osteoid undergo calcification and form the ossification center?

A
  • calcification of matrix causes osteoblasts to become osteocytes
  • Osteoblasts remain at the periphery continuing to deposit osteoid and allow for expansion of the bone deposition
163
Q

What is woven bone?

A

newly formed bone

164
Q

Describe woven bone

A

-newly formed bone
- poorly organized
-weaker

165
Q

Does woven bone have lamellae?

A

no

166
Q

How do woven bone and bone membranes begin do form?

A
  • mesenchyme tissue condenses and forms the membranes
  • when it condenses it form the periosteum
    -endosteum begins to form
  • blood vessels move through space.
167
Q

What does lamellar bone do?

A

replaces woven bone

168
Q

What are the types of lamellar bone?

A

lamellar compact and lamellar spongy

169
Q

When are the endosteum and periosteum fully developed?

A

in lamellar bone

170
Q

What is endochondral ossification?

A
  • when hyaline cartilage model becomes ossified
171
Q

What does endochondral ossification produce?

A

most bones of the skeleton including long bones (upper and lower limbs, pelvis, vertebrae, ends of clavicle

172
Q

What are the steps of endochondral ossification?

A
  1. Fetal hyaline cartilage develops and perichondrium forms
  2. Periosteal bone collar forms
  3. Primary ossification center forms
  4. Secondary ossification centers form in epiphysis
173
Q

Hoe does fetal cartilage develop and the perichondrium form?

A
  • perichondrium turns into periosteum
174
Q

How does the periosteal bone collar form?

A
  • nutrient foramen starts to develop and interior cartilage breaks down due to mineralization
175
Q

What is the bone collar?

A

when it starts going from perichondrium to periosteum

176
Q

How does the primary ossification center in endochondral ossification form?

A
  • Periosteal bud blood vessels enter diaphysis
  • cartilage in diaphysis ossifies and bone development extends in both directions toward epiphysis as bone replaces degenerating cartilage
177
Q

How

A
178
Q

How do the secondary ossification centers form?

A
  • cartilage in epiphysis calcifies, and chondrocytes die
  • Blood vessels enter carrying osteoprogenitor cells which become osteoblasts
  • the woven bone in the diaphysis interior is removed by osteoclasts forming the medullary cavity
179
Q

Where does lengthwise growth occur?

A
  • at epiphyseal plate until bone is fully grown
180
Q

What are epiphyseal growth plates?

A

-plates where cartilage is instead of bone

181
Q

Can there by multiple epiphyseal growth plates on one bone?

A

yes

182
Q

Do all epiphyseal plates fuse at the same time?

A

no, they fuse progressively depending on regions, gender affects when these close

183
Q

Do males or females have their growth plates close sooner?

A

females

184
Q

How can we use growth plates in forensics?

A

to determine age of death

185
Q

What type of growth occurs from the epiphysis to the diaphysis?

A

-interstitial/endochondral

186
Q

What are the Zones of bone growth?

A
  • resting cartilage
    -zone of proliferation
    -zone of hypertrophy
    -zone of calcification
  • zone of ossification
187
Q

What is the resting cartilage zone?

A
  • mature cartilage that secures epiphysis to epiphyseal plate
188
Q

What happens in the zone of proliferation?

A
  • chondrocytes undergo rapid mitotic division producing longitudinal columns of parallel flattened bone
189
Q

What happens in the zone of hypertrophy?

A
  • chondrocytes cease to divide and begin to hypertrophy
    -walls of lacunae thin
190
Q

What happens in the zone of Ossification?

A
  • Lacunae cells break down capillaries and osteoprogenitor cells enter as new bone matrix deposited on the calcified cartilage matrix
  • sex hormones play a role in allowing this to happen
191
Q

Which zones of bone growth are cartilage?

A
  • resting cartilage
  • hypertrophy
    -calcification
    -proliferation
192
Q

What happens in the zone of calcification?

A
  • minerals deposited between lacunae killing chondrocytes
193
Q

What is bone deposition?

A

adding bone tissue

194
Q

What is bone resorbtion?

A

taking away bone tissue

195
Q

Where does bone deposition and resorption occur?

A
  • periosteum
    -endosteum in compact bone and spongy bone trabeculae
196
Q

Why does deposition occur?

A
  • remodeling
  • bone growth
  • bone repair
197
Q

Why does resorption occur?

A
  • remodeling or Calcium needs
198
Q

What helps with bone deposition?

A

osteoblasts that secrete osteoid

199
Q

What helps with bone reasoprtion?

A
  • osteoclasts
  • proteolytic enzymes fo for organic matrix
  • HCL goes for inorganic matrix
200
Q

How does TH regulate bone growth?

A
  • needed for proper development of GH which is needed for skeletal muscular growth
    -The hypothalamus releases TRH which stimulates the pituitary gland to release TSH (directly stimulating bone growth and indirectly stimulating the secretion of TH)
    -needed during skeletal development for recruitment and maturation of cartilage and bone cells
    -especially important during childhood for promoting synthesis of bone matrix by increasing metabolic rate of bone cells
201
Q

What does the hypothalamus release?

A

TRH

202
Q

What does the pituitary gland release?

A

TSH
GH

203
Q

What does GH do for bone growth?

A

-plays a bigger role in childhood
- released by the pituitary gland stimulating the production of IGF in the liver
- GH and IGF work synergistically so 1+1=3
- has a really strong effect on cartilage within the epiphyseal plate region, stimulating the elongation of the long bone

204
Q

What do sex hormones do during bone growth?

A
  • Hormone levels increase dramatically during puberty which has a large impact on an epiphyseal plate by stimulating bone and cartilage cells
  • The bone rate of growth is greater than cartilage growth causing the closure of the epiphyseal plate and formation of the epiphyseal line
  • Postmenopausal women don’t produce significant amounts of estrogen leading to a risk of osteoporosis
205
Q

What are gluccocorticoids?

A

-steroid hormones released from the adrenal gland that regulate blood glucose levels

206
Q

What do glucocorticoids do for bone growth?

A

-High levels cause increased bone loss and impair growth of the epiphyseal plate
-can be prescribed as anti-inflammatory medications (asthma) so patients must be monitored because it could potentially negatively impact child bone growth

207
Q

What does calcitrol do?

A

-stimulates the absorbtion of calcium from the small intestine into the blood

208
Q

Where does calcitriol form?

A
  • in kidney
209
Q

What does PTH do for Calcitrol?

A
  • Calcitriol forms more regularly in the presence in PTH
  • Calcitriol and PTH work synergistically to increase blood calcium levels
210
Q

What is the calcitriol formation cycle?

A
  • precursor is converted to vitamin D3
  • which is then converted to calcidiol in the liver when an oh group is added
  • Calcidiol goes to calictrol in the kidney when another OH is added
211
Q

How is calcitonin released?

A
  • Blood calcium levels rise then calcitonin is released by the thyroid
    -specifically during exercise
212
Q

What happens if blood calcium levels are too high?

A
  • intestines and kidneys decrease the resorbtion of calcium since we already have too much
  • this inhibits osteoclast activity and stimulates osteoblast activity
213
Q

What does PTH do?

A
  • ## enhances production of calcitriol with hormones working together to increase blood Calcium levels
214
Q

When is PTH released?

A
  • In response to decreased blood calcium levels, stimulates bone reabsorption, resulting in an increase in blood calcium levels
  • stimulates osteoclast proliferation and reabsorption of bone by osteoclasts
  • promotes reabsorbtion of Ca2+
    -indirectly increases Ca2+ absorption by the small intestine
215
Q

What is wolfe’s law?

A
  • Hormones affect skeletal system but then bones respond to mechanical stress put upon them by strengthening so they can support that stress
    -shows how bones adapt to their environment?
216
Q

What are stresses placed on bone?

A

-gravitational forces
-skeletal contraction; muscles and body weight pull on bone

217
Q

How does the bone respond to mechanical stress?

A
  • Stress is detected by osteocytes which communicate to osteoblasts and trigger an increased synthesis of osteoid which adds bone strength
  • Osteoblasts lay down more osteocytes
218
Q

what does the removal of stress do to bone?

A
  • reduces collagen formation and causes demineralization and reduces some bone mass
  • immobilization (cast) or microgravity environment (space) can cause this
219
Q

What are the types of bone breaks?

A
  • complete fracture
  • stress fracture
  • compound fracture
  • pathological fracture
220
Q

What is a complete fracture?

A

bone is completely separated due to break

221
Q

What is a stress fracture?

A
  • thin break caused by repetitive actions
222
Q

What is a compound fracture?

A

1 or more region of the bone is sticking out
- more susceptible to infections
- will need surgical alignment

223
Q

What is a pathological fracture?

A
  • break in bones that were already weakened by disease
224
Q

What population group has fractures heal the fastest?

A

kids

225
Q

What are the steps to bone healing?

A
  1. a hematoma forms from broken blood vessels
  2. A fibrocartilaginous (soft) callus forms as collagen fibers (fibroblasts) and dense connective tissue from chondroblasts aggregate
    -basically the body’s way of doing an internal splint
    - all about alignment
  3. a hard callus (Bony) callus formas as adjactent osteoblasts produce bone tissue
  4. remodeling
226
Q

When does bone density peak?

A

30

227
Q

When does most bone deposition occur?

A

in childhood

228
Q

Which type of bone is more susceptible to aging?

A
  • spongy bones
    -so vertebrae, mandible, epipysis
  • causes height, tooth loss and fragile limbs
229
Q

What is aging’s impact on bone compostition?

A
  • reduced tensile strength due to a decrease in osteoblast activity and protein production
  • alters ratio of organic and inorganic resulting in brittle bones with increased fracture risk
    -increased demineralization resulting in insufficient ossification and thinner, weaker bones (ostepenia)
230
Q

What is osteopenia?

A
  • demineralization resulting in insufficient ossification and thinner weaker bones
231
Q

Is osteopenia normal?

A

yea

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