The Skeletal System Flashcards
(109 cards)
0
Q
What are the 7 components of the structure of a bone?
A
- Diaphysis - the shaft
- Epiphysis - the ends of the bones
- Metaphysis - the transition zone, between the diaphysis and the epiphysis, where the epiphyseal plate/line is.
- Periosteum - tissue that covers the surface of a bone.
- Articular cartilage - hyaline cartilage that covers articulation.
- Medullary cavity - hollow cavity where yellow bone marrow is.
- Endosteum - connective tissue lining the inside of the marrow cavity.
1
Q
What are the 6 key functions of he skeletal system?
A
- Support
- Protection
- Movement
- Mineral content regulation
- Blood cell production - hemopoiesis
- Storage of triglycerides - fat storage
2
Q
What are the contents of the extracellular matrix of bone and what is the ratio of those substances?
A
15% water
30% collagen fibers
55% crystallized mineral salts.
3
Q
What are the main elements that are regulated, stored and released by bone?
A
Calcium is the MOST MAJOR (Ca2+)
Phosphorus (P)
Iron (Fe3+)
4
Q
Where in the bone are blood cells produced?
A
In the red bone marrow in the spongy bone.
5
Q
Where are the triglycerides in the bone stored?
A
In the medullary cavity. Fat tissue in the yellow mine marrow.
6
Q
What is the endosteum?
A
A layer of dense connective tissue that lines the inside of the marrow cavity.
7
Q
What is periosteum?
A
Dense irregular connective tissue that covers the bone and merges with tendons.
8
Q
In regards to being the support system for our body, where does the strength of the skeletal system come from?
A
The strength comes from the microscopic lattice of calcium and phosphate. Ca2+PO4
9
Q
What is the epiphysealial plate?
A
The spot in the metaphysis where long bones grow length during one’s growing years.
10
Q
Within the extracellular matrix, which mineral salt is 2nd most abundant?
A
Calcium hydroxide
11
Q
What is the epiphyseal line?
A
The epiphyseal plate turns to the epiphyseal line when growing is complete.
12
Q
Within the extra cellular matrix, which mineral salt is most abundant?
A
Calcium phosphate Ca3(PO4)2
13
Q
What do the 2 most abundant mineral salts within the extracellular matrix of bone, calcium phosphate and calcium hydroxide, combine to make?
A
Calcium phosphate and calcium hydroxide combine to make hydroxyapatite.
This in turn combines with fluoride and sulphate & Mg2+ I. The process of calcification.
14
Q
What are Sharpey’s fibers?
A
Sharpey’s fibers are thick bundles of collagen that extend from the periosteum into the bone extracellular matrix. They attach the periosteum to the underlying bone.
15
Q
What are the 3 types of cartilage in the body?
A
Hyaline cartilage, fibrocartilage, and elastic cartilage
16
Q
Explain the process of calcification.
A
Calcium phosphate and calcium hydroxide combine to form hydroxyapatite, this in turn combines with fluoride, potassium, sulphate and magnesium.
17
Q
What are the 4 types of cells present in bone?
A
- Osteogenic cells
- Osteoblasts
- Osteocytes
- Osteoclasts
18
Q
What is an osteogenic cell?
A
An osteogenic cell is an unspecialized stem cell. A mesenchymal cell that can undergo mitosis.
19
Q
What is an osteoblast?
A
A bone building cell. Osteoblasts synthesis collagen fibers and initiate calcification. They take Ca2 from blood and put it into bone.
20
Q
What is an osteocyte?
A
An osteocyte is a mature bone cell. It maintains the daily metabolic activities of the bone cell. (Exchanging nutrients, removing waste)
21
Q
What is an osteoclasts?
A
Osteoclasts are cells that destroy bone for resorption. Cells take Ca2 from the bone and put it into the blood.
22
Q
What are the 2 major portions of bone?
A
Compact bone and spongy bone.
23
Q
Where is compact bone found?
A
Compact bone is found in the diaphysis and shaft of the bone. There is also a paper thin layer of compact bone covering all spongy bone.
24
What is lamellae?
Lamellae is the matrix of the bone.
25
How many types of lamellae are there?
| What are they?
There are 3 types of lamellae.
1. Concentric lamellae.
2. Interstitial lamellae.
3. Circumferential lamellae.
26
What are Volkman's canals?
Volkman's canals or perforating canals are perpendicular canals that run superficial to deep that carry blood & lymphatic vessels and nerves that penetrate from the periosteum.
27
What are haversion canals?
Haversian canals or central canals are parallel canals that run deep and longitudinally along the shaft of the bone. Parallel canals also carry blood and lymph vessels and nerves.
28
What are concentric lamellae?
Concentric lamellae are concentric rings of hard, extracellular bone matrix that surrounds each central or Haversian canal.
29
What are interstitial lamellae?
Interstitial lamellae are lamellae that are located between osteons or Haversian systems. They are fragments of older osteons that have been partially destroyed during bone remodelling.
30
What are circumferential lamellae?
Circumferential lamellae are lamellae that surround the medullary cavity or lie underneath the periosteum along the circumference of the bone. It is not part of the osteon but tends to circle around the other 2 types of lamellae.
31
What are lacunae?
Lacunae are spaces within the lamellae where osteocytes can be found. They are indents like the space in snow made when you make a snow angel.
32
What are canaliculi?
Canaliculi are the small channels that radiate in all directions from each lacunae filled with extracellular fluid. (The arms and legs of the snow angels)
33
What is a Haversian system?
A Haversian system or osteon is a repeating unit of all the components of compact bone around a central canal. It includes the central or Haversian canal, the blood vessels, lymph vessels, the nerves, the lacunae, the canaliculi, the osteocytes and the concentric lamellae.
34
What characteristics does spongy bone have that is different than compact bone?
Spongy bone does not have Haversian systems. The pattern of bone tissue is irregular and less dense in spongy bone. It is less compact, the concentration of bone cells is less concentrated. Spongy bone has more blood supply than compact bone.
35
Where does the blood supply in spongy bone come from?
Red blood cells, white blood cells and platelets are produced within spongy bone.
36
What is trebeculae?
Trebeculae is the lamellae of spongy bone. It has a coral reef appearance.
Trebeculae consists of concentric lamellae, osteocytes in lacunae with canaliculi radiating out from the lacunae.
37
Which bones feature spongy bone tissue?
Spongy bone tissue makes up most of the interior bone of short, flat, sesamoid, and irregular shaped bones. In long bones the epiphysis is made up of spongy bone tissue.
38
What do the terms ossification and osteogenesis refer to?
Ossification and osteogenesis both refer to the creation or formatin of bone that begins at the 6th week of embryonic developement & continues into maturity.
39
When does ossification or osteogenesis begin?
Ossification or osteogenesis begins at the 6th week of embryonic development and continues into maturity.
40
How many types of bone formation are there?
2
41
What are the 2 types of bone formation?
1. Intramembranous ossification.
| 2. Endochondral ossification.
42
How many steps are involved in intramembranous ossification?
What are they?
There are 4 steps.
1. Developement of ossification centre.
2. Calcification.
3. Formation of trebeculae.
4. Development of the periosteum.
43
How does the ossification centre form?
Where bone developes chemical signals will cause mesenchymal cells to cluster and differentiate
44
Describe calcification.
Osteoblasts become osteocytes which extend projections into canaliculi; calcium and minerals are deposited and the matrix hardens.
45
Describe the formation of trebeculae.
The matrix continues to harden and forms trebeculae that fuse with one another to form spongy bone; blood vessels & connective tissue enter spaces and red bone marrow is formed.
46
How does the developement of the periosteum happen?
The outer layer of mesenchymal developes into the periosteum; compact bone replaces spongy bone on the cortex of the bone, spongy bone remains in the middle. Eventually bone conforms into adult size and shape.
47
What is endochondral ossification?
The replacement of cartilage by bone.
48
What are the 2 steps of endochondral ossification?
1. The developement of the cartilage model.
| 2. Growth of the cartilage model.
49
What happens during the developement of the cartilage model?
Chemical messages initiate the mesenchymal cells to develope into chondroblasts, which begins cartilage matrix formation. (Cartilage is formed with perichonrium membrane surrounding the entire model)
50
What happens during the growth of the cartilage model?
Chondroblasts develope into chondrocytes, with further deposition of cartilage extracellular matrix.
Then 2 types of growth occur, interstitial growth and oppositional growth.
51
What 2 types of growth occur during the growth of the cartilage model?
1. Interstitial growth
| 2. Appositional growth
52
What is interstitial growth?
Interstitial growth occurs during the growth of the cartilage model. Replication of chondrocytes accompanying new matrix which results in lengthening.
53
What is appositional growth?
Deposition of extracellular matrix on cartilage surface & periphery resulting in bone growing in width.
54
What happens during the development of the primary ossification?
The nutrient artery penetrates into the middle of the cartilage initiating activity of osteoblasts; perichonrium, becomes periosteum; local cartilage calcifies into bone.
55
What happens during the development of the marrow cavity?
Osteoclastic activity causes a marrow cavity to form within the shaft of the diaphysis.
56
What happens during the development of the secondary ossification centres?
The epiphyseal plate is formed from penetration of epiphyseal arteries; growth occurs outwards from the epiphysis, cartilage continues to be converted into bone.
57
What happens during the formation of articular cartilage and epiphyseal plate.
The final stage of ossification where hyaline cartilage becomes the articular cartilage we see in adulthood.
58
What is the epiphyseal plate?
A hyaline layer of cartilage in the metaphysis that consists of 4 main zones, from which new bone is laid down. This becomes the epiphyseal line after the person has stopped growing in length.
59
What are the 4 main zones in the epiphyseal plate?
1. The resting cartilage zone.
2. The proliferating cartilage zone
3. The hypertrophic cartilage zone
4. The calcified cartilage zone
60
What is the resting cartilage zone in the epiphyseal plate?
The resting cartilage zone is the layer nearest to the epiphysis. It consists of small chondrocytes that anchor the epiphyseal plate to the bone. The cells are "resting" because they are not involved in bone growth.
61
What is the proliferating cartilage zone of the epiphyseal plate?
In the proliferating cartilage zone large chondrocytes replicate and divide to replace old and dying chondrocytes. They appear like stacks of coins.
62
What happens in the hypertrophic cartilage zone of the epiphyseal plate?
Large mature chondrocytes are situated in columns. (Growing in size)
63
What happens in the calcified cartilage zone of the epiphyseal plate?
In the calcified cartilage zone there are mostly dead chondrocytes, the area is calcified and osteoblasts invade to lay down new extracellular bone matrix to convert it from calcified cartilage to new diaphysis and new blood vessels are formed.
64
What is bone remodelling?
The process of removing old bones cells and rebuilding bone in places of stress, damage and cell death.
65
What is resorption?
The process by which osteoclasts (bone resorption cells) will break down and destroy portions of bone extracellular matrix. This process occurs as part of normal growth where bones need to shape themselves into tubercles, fossae, grooves, foramens, etc... Or as a part of the healing stages after fractures.
66
What is deposition?
Deposition is the process by which osteoblasts (bone building cells) will lay down minerals and collagen fibers to create the extracellular matrix.
67
In remodelling why do resorption and deposition work simultaneously?
In remodelling resorption and deposition work simultaneously in response to changes in various forms of stress on the bones.
68
What is Wolf's law?
Wolf's law states that bone will lay down along lines of stress.
69
What are some exams of Wolf's law?
Exercise will strengthen microscopic bone fibers.
Trauma - broken bones will heal.
Infection - osseous tissue can encapsulate the infection.
Cancer - uncontrolled differentiation of osteoblasts or other types of bone cells.
Aging - abnormal growth to compensate for instability and weakness.
70
What are some factors that affect bone growth?
Minerals, vitamins and hormones
71
What minerals affect bone growth?
Calcium, phosphorus, fluoride, magnesium, manganese
72
What vitamins affect bone growth?
Vitamin A promotes osteoblasts, vitamin C is needed for collagen formation, vitamin D helps with absorption of calcium in the GI tract, vitamin K and B12 help build bone proteins.
73
Which hormones affect bone growth?
T3 & T4 from the thyroid & insulin like growth factors in response to hGH (human growth hormone) all promote bone growth.
74
In regards to bone growth what does vitamin A do?
Vitamin A promotes osteoblasts.
75
In regards to bone growth what does vitamin C do?
Vitamin C is needed for collagen formation.
76
In Regards to bone growth what does vitamin D do?
Vitamin D helps with calcium absorption in the GI tract.
77
In regards to bone growth what do vitamin K and B12 do?
Vitamin K and B12 help build bone proteins.
78
Why are most areas of the bone rich in blood supply?
Blood is formed in the bones.
79
What are Periosteal arteries/veins?
They enter through Volkman's canals and they carry blood to and away from the outer portion of the compact bone and periosteum.
80
What are nutrient artery/veins?
The nutrient artery and veins enter through the foramen in the diaphysis and supplies blood to the inner portion of the compact bone and also to proximal parts of the spongy bone.
81
What are metaphysial arteries/veins?
Metaphysial arteries/veins enter at the metaphysis portion to supply blood to the metaphysis and red bone marrow.
82
What are epiphyseal arteries/veins?
Epiphyseal arteries/veins enter at the epiphysis portion to supply blood to the epiphysis and red bone marrow.
83
In what ways does calcium playa role in maintaining homeostasis in the body?
1. Calcium acts as a cofactor in numerous chemical reactions in the body.
2. Calcium is deeply involved in the blood clotting process. It can be part of a clot or the enzyme to initiate or assist the clotting cascade.
3. Calcium is involved in muscle contraction. It is the key ion responsible for muscle contraction.
84
Calcium is tightly regulated and controlled in the body. What must the concentration be?
The concentration of calcium in the blood must remain between 9-11mg/100ml of blood.
85
What happens if the concentration of calcium goes above 11mg/100ml of blood?
If the concentration of calcium rises above 11mg/100 ml of blood the heart contracts and does not uncontract. ie- the heart stops and death occurs.
86
What happens if the concentration of calcium drops below 9mg/100ml of blood?
If the concentration of calcium drops to below 9mg / 100 ml of blood breathing stops because not enough muscle fibres are stimulated to have breathing occur.
87
How is the concentration of calcium controlled?
The concentration of calcium is controlled by the para-thyroid hormone, PTH and thyroid parofollicular cells which produce calcitonin.
88
How does para-thyroid hormone control calcium concentration levels?
A negative feedback system kicks in, in which, as calcium concentration levels in the blood drop PTH increases.
Para-thyroid hormone is secreted by the parathyroid cells, PTH increases Ca2 levels in the blood.
89
What are the physiological effects of para-thyroid hormone?
1. PTH increases the activity of osteoclasts and decreases the activity of osteoblasts. Bone matrix is broken down by osteoclasts (resorption), and calcium is released into the blood stream.
2. PTH increases the formation of calcitrol (a form of vitamin D) which helps increase the absorption of calcium from our diet. (GI tract)
3. PTH stimulates the kidney cells to pull back and retain calcium from urine. This way less calcium is lost in urination and blood Ca2 levels go up.
90
How do thyroid parofollicular cells work to regulate the concentration of calcium in the blood?
Thyroid parofollicular cells produce calcitonin, (a hormone) which has opposite effects than those of PTH. Calcitonin increases osteoblasts and decreases osteoclastic activity. Bone resorption decreases and bone formation increases.
91
What is a fracture?
Any break in bone. There are varying types, severities, locations and ethologies.
92
What is an open or compound fracture?
Broken ends of the bone will protrude out thru the skin.
93
What is a closed or simple fracture?
Broken ends of the bone will not protrude out through the skin.
94
What is a comminuted fracture?
Bone splinters and fragments at the site of impact are trapped between the fractured bone.
95
What is a green stick fracture?
A partial fracture. 1 side of the bone is broken and the other side is bent. This happens in kids due to immature cells.
96
What is an impacted fracture?
One bone is forced into the other bone.
97
What is a Pott's fracture?
Pott's fractures occur only in the legs (tibia). It is a closed fracture with damage to to the ankle articulation.
98
What is a Colle's fracture?
A Colle's fracture occurs in the hands and wrist where falls drive the carpals posteriorly.
99
What is an avulsion fracture?
An avulsion fracture happens when the forceful tearing of muscles and tendons pull portions of the bone off.
100
What is a stress fracture?
Stress fractures are microscopic tears in the fissures of the bone commonly not detected by X-rays. This usually occurs due to repetitive and strenuous activities.
101
What is osteoporosis?
A pathology of loss of bone mass associated with the deterioration of the micro architecture of bone tissue. Bone resorption outpaces bone deposition and a lack of calcium is the main culprit.
It affects women more than men and people over the age of 50 more commonly.
102
What are ricketts or osteomalacia?
The failure of bones to calcify. Called rocketts in children and osteomalacia which means bone softening in adults. This occurs from a lack of vitamin D.
103
How many steps are there in bone fracture repair?
There are 4 steps in the repair of bone fractures.
104
What are the 4 steps in bone fracture repair?
1. Formation of fracture hematoma.
2. Fibrocartilaginous callus formation.
3. Bony callus formation.
4. Bone remodelling.
105
What happens during the formation of fracture hematoma?
Exposed blood vessels form a clot at site of fracture, blood flow stops and bone cells located here die. Inflammation occurs in response to dead cells. Phagocytes and osteoclasts move in to remove debris. This lasts several weeks and is called the reactive phase.
106
What happens during fibrocartilaginous callus formation?
Fibroblasts invade the site and lay down collagen fibres. Chondrocytes invade from periosteum and produce fibrocartilage. Callus is formed. This is called the repairitve phase A.
107
What happens during bony callus formation?
Osteogenic cells become osteoblasts which converts the fibrocartilage into spongy bone. This takes 3-4 months and is called repairitve phase B.
108
Bone remodelling
Osteoclasts move into resorption Any remaining fragments. Compact bone eventually replaces the spongy bone around the periphery.
