Bones, joints and cartilage Flashcards
1
Q
What is the musculoskeletal system?
A
It makes up the muscles, skeleton and accessory tissues which together allow locomotion and articulation.
2
Q
What are the two main tissues types the skeleton is composed of?
A
Bone and cartilage.
3
Q
What are the features of bone?
A
It is long, short (usually cuboidal), flat (slightly curved) and irregular and encased within a fibrous periosteum.
4
Q
What is the most common type of cartilage?
A
Hyaline.
5
Q
What are the three types of cartilage?
A
Hyaline, fibro and elastic.
6
Q
What are the features of hyaline cartilage?
A
It is a growth plate, it is on joint surfaces and can act as a temporary scaffold.
7
Q
What are the features of fibrocartilage?
A
It has invertebral discs, menisci pads in joint spaces and no perichondrium.
8
Q
What is perichondrium?
A
A connective tissue that envelops cartilage.
9
Q
What are the features of elastic cartilage?
A
It makes up the external ear, epiglottis larynx.
10
Q
In what areas would have fibrocartilage?
A
Areas that need to be able to withstand lots of pressure.
11
Q
What is the general function of bone?
A
Support, protection, muscle attachment, mineral reservoir, haematopoiesis, lipid storage.
12
Q
What is the general function of cartilage?
A
Template for bone formation, growth of long bones, smooth articulating joint surface.
13
Q
What is the percentage of weight in bone water?
A
20-25%.
14
Q
What is the percentage of weight in cartilage water?
A
75-80%.
15
Q
What makes up bone composition?
A
65% mineral, 30% type I collagen and 5% proteoglycans/glycoproteins.
16
Q
What makes up cartilage composition?
A
65% type II collagen, 20% proteoglycans, 10% glycosaminoglycans and 5% glycoproteins.
17
Q
What are the cell types involved in bone?
A
Osteoblasts, osteocytes and osteoclasts.
18
Q
What are the cell types involved in cartilage?
A
Chondroblasts and chondrocytes.
19
Q
What are osteoblasts involved in?
A
Bone forming.
20
Q
What are osteocytes?
A
They are mature osteoblasts that have become trapped within the bone matrix they produced.
21
Q
What are osteoclasts?
A
They are involved in bone resorbing - breaking down.
22
Q
How many bones are in the human body?
A
206.
23
Q
What is the axial skeleton?
A
The bones of the skull vertebral column and ribs.
24
Q
What is the appendicular skeleton?
A
Bones of the limbs, pelvis, scapula and clavicle.
25
What are the 4 different types of bone shape?
Flat bone, long bone, short bone and irregular bone.
26
Where are long bones located and give an example?
In the appendicular skeleton e.g. the humerus.
27
What are the features of short bones?
Cube like in shape (equal in length/width and thickness). The primary function is to provide support and stability - they are involved in very little to no movement. Example e.g. hand and feet.
28
What are the features of flat bones?
They are thin and flat and in some cases can be slightly curved. They serve as points of attachment for muscles or to protect the internal organs.
29
What are the features of irregular bone?
Bones that do not fit into any of the other categories. They usually have a complex shape such as bones in the vertebrate and they support the spinal cord and protect it from compressive forces.
30
What is the diaphysis?
The shaft of the long bone.
31
What is the epiphysis?
Spongy bone at either end of each bone.
32
What does spongy bone contain?
Red bone marrow where red blood cells are made.
33
What are the other words for spongy bone?
Cancellous bone, trabecular bone.
34
What is the difference between epiphyseal plates and lines?
Called plates when still growing, called line when stopped growing.
35
What is the metaphysis?
It contains the medullary cavity that is the hollowed out core of the bone. Fatty tissue is found here that is used for energy storage, which is sometimes referred to as the yellow marrow.
36
What does articular cartilage allow?
Joints to move more smooth at the end of the bone.
37
What is the basic functional unit within the long bone?
The osteon.
38
What are concentric lamellae in the osteon?
Rings throughout the osteon that are made up of osteocytes.
39
What does the osteon contain in the long bone?
A canal where the blood vessel is located.
40
Why does the lamellae run in opoosite directions in the long bone osteon?
To help give the bone the ability to withstand impact.
41
What are the features of trabeculae?
They have no blood vessels or central canal and contains lamellae like the osteon but are parallel to each other and do not run in opposite directions.
42
What does lacuna contain?
Osteocytes.
43
What are the spaces in between traceculae important for?
They contain bone marrow which is important in blood cell formation.
44
How does spongy bone obtain nutrients?
Through pores in the bone surface.
45
What are osteogenic cells?
They are highly undifferentiated and have high mitotic activity.
46
Where are immature osteogenic cells found?
In the periosteum and bone marrow.
47
What do osteogenic cells form?
Osteoblasts when they have differentiated.
48
Where are osteoblasts found?
In the endosteum - the growing portion of the bone.
49
What do osteoblasts do?
They do not divide but they synthesise and secrete organic compounds and calcium salts. As the secreted matrix calcifies, the osteoblasts become trapped within the bone matrix and they can then differentiate into an osteocyte.
50
Where are osteocytes found?
Lacuna - surrounded by bone tissue.
51
What are the features of osteoclasts?
They are multinucleated cells derived from the macrophage. They can secrete acid and enzymes to breakdown the bone.
52
What is the word for bone development?
Ossification.
53
Where does the skeleton develop from?
Embryonic mesenchyme.
54
What is the embryonic mesenchyme?
Lossely packed, unspecialised cells in a gel-like matrix that are derived from the embryonic mesoderm.
55
What are condensations?
Small clusters.
56
What happens when mesenchymal cells migrate?
They form condensations.
57
What are the two forms of ossification?
Intramembranous ossification and endochondral ossification.
58
What is intramembranous ossification?
When bone forms directly within the condensation.
59
What is endochondral ossification?
When a cartilage template forms within the condensation and the cartilage anlage is subsequently replaced by bone.
60
Which is the most common form of ossification?
Endochondral ossification.
61
When does intramembranous ossification occur?
Week 6 of gestation.
62
What are the 4 main steps in intramembranous ossification?
There is the development of the ossification centre, calcification occurs, formation of the trabeculae and the development of the periosteum.
63
What is the first (detailed) step of intramembranous ossification?
Cells come together and start aggregating and replicating and then differentiate into osteoblasts. These come together to form the ossification centre.
64
What do osteoblasts produce?
Osteoid - new bone tissue.
65
What happens to the osteoid after a few days?
It begins to harden to form the bone.
66
What is calcification?
When osteoblasts become trapped in the centre and will differentiate into osteocytes. The osteoid will begin to harden
67
What happens after the osteoid is deposited in a random fashion around the blood vessels?
Trabeculae is eventually formed.
68
What happens in the last phase of intramembranous ossification?
The lamellae of compact bone begins to form which replaces the trabeculae on the outside edge.
69
What is the first step in endochondral ossification?
Chondrocytes at the centre of the growing cartilage model enlarge and then die as the matrix calcifies.
70
What is the second step of endochondral ossification?
Newly derived osteoblasts cover the shaft of the cartilage in a thin layer of bones.
71
What is the third step in endochondral ossification?
Blood vessels penetrate the cartilage and new osteoblasts form a primary ossification centre.
72
What is the fourth step in endochondral ossification?
The bone of the shaft thickens and the cartilage near each epiphysis is replaced by shafts of bone.
73
What is the fifth step of endochondral ossification?
Blood vessels invade the epiphysis and osteoblasts form secondary centres of ossification.
74
How does the bone elongate in post-natal growth?
The cartilage expands towards the epiphysis and the bone elongates.
75
What happens at the same time as bone elongation in post-natal growth?
The older cartilage is calcified and replaced by bone which is remodelled resulting in the expansion of the medullary cavity of the diaphysis.
76
What is the net result of the processes that occur in post-natal growth in length?
An epiphyseal plate that remains uniform in thickness through time but is constantly moving toward the epiphysis, resulting in elongation of the bone.
77
How is the length of growing bones increased?
Interstitial growth - the epiphyseal plates gradually lengthen.
78
What happens to older chondrocytes in post-natal growth in length?
They enlarge and the cartilaginous matrix hardens. They are replaced by bone.
79
How does post-natal growth occur in terms of width?
Osteoblasts deposit new bone on the outside of the bone shaft and the osteoclasts breakdown tissue from the medulla to maintain the thickness of the bone.
80
What are the distinct stages of the bone redmodelling cycle?
The reversal step, the bone formation step, the mineralization sep, the resting bone surface step and the resorption.
81
What happens in the resting step of the bone remodelling cycle?
All the lining cells that are inactive osteoblasts are attached to the bone surface. Release of certain substances can activate the lining cells and interact with receptors that trigger pre-osteoclast fusion and form multi-nucleate osteoclasts.
82
What happens in the resorption stage in the bone remodelling cycle?
Osteoclasts gather together and they dissolves the matrix of the bone and release lysosomal enzymes to degrate the organic components of the bone.
83
What happens in the reversal stage of the bone remodelling cycle?
These cells remove the debris produced during resorption - following this there is a release of several growth factors that recruite osteoblasts.
84
What occurs in bone formation step in the bone remodelling cycle?
Once osteoblasts are generated, alkaline phosphate is produced to help form a new bone matrix. The matrix is mineralised with calcium and phosphorus to form new bone and it returns to the resting phase - this process is continually occurring within the body.
85
When does bone mass stop increasing?
Between the ages of 25-30.
86
What is the fracture threshold?
The theoretical bone density below which fractures can occur.
87
What happens to bone mass during the menopause?
It decreases. Osteoclast apoptosis is regulated by oestrogen so when these levels decrease, osteoclasts can live longer and breakdown more bone.
88
What are the main steps in fracture healing?
Hematoma formation, callus formation, callus ossification and bone remodelling.
89
What are the key points in hematoma formation in fracture healing?
Blood is released from damaged blood vessels to form a hematoma.
90
What are they key points in callus formation in fracture healing?
The internal callus forms between the ends of the bones and the external callus forms a collar around the break. The blood clot is replaced by fibril cartilage.
91
What occurs in callus ossification in fracture healing?
Woven, spongy bone replaces the internal and external callus.
92
What occurs in bone remodelling in fracture healing?
Compact bone replaces woven bone and part of the internal callus is removed, restoring the medullary cavity.
93
Where do joints occur?
The joins between two or more bones.
94
What are the three common types of joints?
Synovial joints, fibrous joints and cartilaginous joints.
95
What classifies the type of joint?
The range of motion they exhibit and the types of tissue that holds the bone together.
96
What is the largest and most important type of joint?
Synovial - they allow free movement.
97
What are the six subtypes of synovial joint?
Planar, hinge, pivot, condyloid, saddle and ball and socket.
98
What are uniaxial joints?
Can only move along a single axis.
99
What are biaxial joints?
Move about 2 distinct axis.
100
What are polyaxial joints?
They can move through all 3 axis.
101
What are the basic features of the planar joint?
It only allows movement along the plane of articular surface. It allows the bones of the joint to slide along each other.
102
What are the basic features of the hinge joint?
There is only one motion along the x axis (only flextion and extension).
103
What are the basic features of the condyloid joint?
It is a biaxial joint.
104
What are the basic features of the pivot joint?
It is uniaxial only along the y axis.
105
What are the basic features of the saddle joint?
It is biaxial to form a saddle structure and allows movement along two axis, but this movement is not indepepdent.
106
What are the basic features of the ball and socket joint?
It is round and the only polyaxial joint - most mobile of the joint types.
107
What is articular cartilage?
It is the cartilage covering the ends of the bones. It is a smooth, lubricating surface that resists compression.
108
What are the two layers in the joint capsule?
The outer fibrous layer and the inner elastic (synovial) membrane.
109
What are the features of the fibrous joint capsule?
It is a fibrous layer attached to the periosteum of the articulating bone.
110
What are the features of the inner synovial membrane within the joint capsule?
It is the site of production of synovial fluid.
111
What is a joint cavity filled with?
Viscous synovial fluid - the viscosity increases with applied force.
112
What happens to the joints in rheumatoid arthritis?
The synovial membrane becomes swollen and inflamed and there is bone erosion.
113
What happens in osteoarthritis?
There is thinned cartilage and the bone ends rub together.
