Cellular Biology Flashcards
1
Q
What is the structure of trabecular bone?
A
→ spongy → interlocking struts with spaces inbetween
2
Q
What are osteocytes?
A
→ Terminally differentiated osteoblasts
3
Q
What is the RANK ligand produced by and what does it do?
A
→ Produced by pre-osteoblasts, osteoblasts and osteocytes → binds to RANK and stimulates osteoclast differentiation
4
Q
State the 7 organisation levels in the body
A
- Organism level
- Systems level
- Organ level
- Tissue level
- Cellular level
- Organelle level
- Chemical level
5
Q
What are the two subtypes of bone marrow cells?
A
→ Mesenchymal cells → Haematopoietic cells
6
Q
What does the RANK receptor binding promote?
A
→ osteoclast differentiation
7
Q
What is a common bone disease?
A
→ Osteoporosis
8
Q
What is ground substance?
A
Substance in the extracellular space that contains all components of the extracellular matrix (ECM)
Mainly water and hygroscopic proteoglycans
9
Q
What happens after the Wnt pathway is activated?
A
→ beta catenin is translocated to the nucleus where it causes transcription
10
Q
What is the structure of trabecular bone?
A
→ spongy → interlocking struts with spaces inbetween
11
Q
What are the three main components of connective tissue
A
- Ground substance or matrix
- Cells
- Fibres (elastin and collagen)
12
Q
What happens after the Wnt pathway is activated?
A
→ beta catenin is translocated to the nucleus where it causes transcription
13
Q
What do haematopoietic stem cells give rise to?
A
→ Lymphoid lineage - lymphocytes → Myeloid lineage - RBC and macrophages
14
Q
How is cortical bone organised?
A
→ In sheet like structures → Surrounding a hollow structure called the Haversian canal
15
Q
What are the 4 main types of connective tissue
A
- Connective tissue proper
- Cartilage
- Bone
- Blood
16
Q
What do OPG and NO do?
A
→ Inhibit the differentiation of osteoclasts
17
Q
What 2 changes occur during osteoporosis?
A
→ Thinning of the cortical bone → Widening of the trabecular bone
18
Q
What are the functions of connective tissue
A
- Binding of organs
- Support
- Physical protection
- Immune protection
- Movement
- Storage
- Heat production
- Transport
19
Q
How is bone continually renewed?
A
→ Old bone is continually resorbed and new bone is laid down → Cycle between osteoclasts digesting old bone and osteoblasts laying down new bone
20
Q
What is the life cycle of osteoclasts controlled by?
A
→ Apoptosis
21
Q
Where are osteocytes found?
A
→ Encased within the bone matrix
22
Q
What is delayed skeletal growth in men linked to?
A
→ Aromatase deficiency
23
Q
An individual skeletal muscle cell
A
Muscle Fiber
24
Q
What are the 5 functions of bone?
A
→ Support and movement → Protection for internal organs → Bone marrow store → Mineral reservoir → Endocrine
25
What do PGE2, NO and ATP promote?
→ Differentiation of osteoblasts
26
Describe simple squamous epithelium
27
What is the function of trabecular bone?
→ Makes bone lighter
28
What does the RANK ligand promote?
→ Promotes the differentiation of osteoclasts
29
Where is cortical compact bone found?
→ On the outside
30
What are the 5 functions of bone?
→ Support and movement → Protection for internal organs → Bone marrow store → Mineral reservoir → Endocrine
31
What are the 3 factors that control bone remodelling?
→ Load bearing exercise → Cytokines and local signals → Endocrine
32
What are the 2 functions of osteoclasts?
→ Bone reabsorbing - digest old bone → Dissolve bone mineral and have enzymes to digest the organic matrix
33
Where is cortical compact bone found?
→ On the outside
34
What is a protease that osteoclasts secrete?
→ Cathepsin K
35
Describe stratified epithelia
* Two or more cell layers (20 or more)
* Regenerate from below
* Basal cells divide, cells migrate to surface
* Mechanism of epidermis replacement
* More durable than simple epithelia
* Physical protection is major role
36
What are lacunae?
→ cell sized holes within the bone matrix
37
What is sclerosteosis caused by?
→ Mutation of the SOST gene → Inactivating sclerostin protein
38
What is OPG?
→ A soluble protein produced by osteocytes
39
What does OPG do?
→ Acts as an antagonist → binds to RANK ligand and prevents it from binding to the receptor
40
What do osteocytes do?
→ They lay down bone matrix (organic material that becomes mineralised)
41
What is bone mineral?
→ Hydroxyapatite → Calcium and Phosphate
42
What do OPG and NO do?
→ Inhibit the differentiation of osteoclasts
43
What are the steps for activating Wnt?
→ The frizzled receptor → and the co-receptor called LRP5/6 have to interace
44
What is the composition of bone in %s?
→ Protein : organic osteoid matrix 25% → Mineral : 75% → Cells
45
What is RANK?
→ A surface receptor on pre-osteoclasts that stimulates osteoclast differentiation
46
What do PGE2, NO and ATP promote?
→ Differentiation of osteoblasts
47
How do osteocytes extend?
→ Via multiple dendrites via minute canals in the bone matrix
48
What is the function of bone mineral?
→ Gives bone rigidity and compressive strength
49
What do sclerostin, DDK and SFRP1 inhibit?
→ Inhibit the differentiation of osteoblasts
50
Where is trabecular bone found?
→ Near the head of the bone
51
How is cortical bone organised?
→ In sheet like structures → Surrounding a hollow structure called the Haversian canal
52
Where are osteocytes found?
→ Encased within the bone matrix
53
What are the 3 main types of connective tissue proper
1. Areolar connective tissue
2. Dense connective tissue
3. Adipose connective tissue
54
In what gender is osteoporosis more common in?
→ Women
55
What is osteoporosis?
→ Loss of bone mass above a certain threshold
56
Broadly describe muscular tissue as a category of tissue class
* Excitable
* Specialised for contraction
57
What is the role of estrogen in bone remodelling?
→inhibits osteocyte apoptosis → Promotes osteoclast apoptosis → essential for skeletal health
58
What is the effector of the Wnt pathway?
→ beta catenin
59
What are the two subtypes of bone marrow cells?
→ Mesenchymal cells → Haematopoietic cells
60
What does process does estrogen favor?
→ Formation over resorption
61
What do haematopoietic stem cells give rise to?
→ Lymphoid lineage - lymphocytes → Myeloid lineage - RBC and macrophages
62
Where are osteoblasts found?
→ Lining the inner surface of bone
63
What is osteoporosis?
→ Loss of bone mass above a certain threshold
64
What is osteopetrosis caused by?
→ Inactivating the RANK ligand → overgrowth of bone
65
Role played by a skeletal muscle acting to slow or stop a movement
Antagonist
66
What are the 2 functions of osteoclasts?
→ Bone reabsorbing - digest old bone → Dissolve bone mineral and have enzymes to digest the organic matrix
67
A flat sheet like fibrous tissue that connects muscle or bone to other tissues
Aponeurosis
68
What do osteoclasts secrete?
→ Acid and proteases that are active in acidic environments
69
What are the steps for activating Wnt?
→ The frizzled receptor → and the co-receptor called LRP5/6 have to interace
70
What is a common bone disease?
→ Osteoporosis
71
How does bone remodelling occur?
→ The leading edge is where cells differentiate into osteoclasts → Behind that the new osteoblasts differentiate into new bone → As the osteoblasts lay down the new bone some of them will stay in it where they are encased in lacunae
72
What is the function of the organic protein matrix?
→ Gives flexibility and tensile strength
73
What are the 3 functions of osteoblasts?
→ Bone forming cells → Secrete osteoid collagen matrix of bone → Promote mineralisation of the osteoid
74
What is OPG?
→ A soluble protein produced by osteocytes
75
What is sclerosteosis caused by?
→ Mutation of the SOST gene → Inactivating sclerostin protein
76
Contraction accompanied by lengthening of a muscle
Eccentric
77
A connective tissue sheath that envelops each primary bundle of muscle fibers.
Perimysium
78
What 2 changes occur during osteoporosis?
→ Thinning of the cortical bone → Widening of the trabecular bone
79
What does process does estrogen favor?
→ Formation over resorption
80
What are the 4 types of bone cells?
→ Osteoblasts → Osteoclasts → Osteocytes → Bone marrow cells
81
What ratio controls osteoclast differentiation?
→ Ratio of RANK ligand to OPG
82
Describe simple cuboidal epithelium
83
In what two forms can the RANK ligand exist in?
→ Surface bounds → Soluble form that is secreted from osteocytes
84
How is bone continually renewed?
→ Old bone is continually resorbed and new bone is laid down → Cycle between osteoclasts digesting old bone and osteoblasts laying down new bone
85
Why is osteoporosis more common in women?
→ dramatic loss of estrogen due to menopause
86
Where is sclerostin expressed and what does it do?
→ Expressed in osteocytes → stops osteoblast differentiation
87
What is the life cycle of osteoclasts controlled by?
→ Apoptosis
88
What are the 4 types of bone cells?
→ Osteoblasts → Osteoclasts → Osteocytes → Bone marrow cells
89
Role played by a skeletal muscle to cause a movement
Agonist
90
In what two forms can the RANK ligand exist in?
→ Surface bounds → Soluble form that is secreted from osteocytes
91
What is the function of bone mineral?
→ Gives bone rigidity and compressive strength
92
What is the function of the organic protein matrix?
→ Gives flexibility and tensile strength
93
What is RANK?
→ A surface receptor on pre-osteoclasts that stimulates osteoclast differentiation
94
Describe the basic function of 'cyte' cells and give and example
"Cyte" cells
Mature form; maintains/recycle/breaks down ground substance
Chondrocytes in cartilage
Osteocytes in bone
95
What is the RANK ligand produced by and what does it do?
→ Produced by pre-osteoblasts, osteoblasts and osteocytes → binds to RANK and stimulates osteoclast differentiation
96
What do mesenchymal stem cells make?
→ Osteoblasts and osteocytes
97
Where are osteoblasts found?
→ Lining the inner surface of bone
98
Where is trabecular bone found?
→ Near the head of the bone
99
Name the four categories into which tissues are classified
* Nervous
* Muscular
* Epithelial
* Connective
100
Where is sclerostin expressed and what does it do?
→ Expressed in osteocytes → stops osteoblast differentiation
101
The ability to contract or shorten
Contractility
102
Describe simple epithelia
* Three main types
* One layer of cells
* Basement membrane
* Different shape nuclei
* Basal/apical specialisation
* No blood vessels
103
What are the 3 functions of osteoblasts?
→ Bone forming cells → Secrete osteoid collagen matrix of bone → Promote mineralisation of the osteoid
104
A wave of symmetrical squeezing of the digestive tract walls that occur during digestion
Peristalsis
105
What is the function of the lacunocanalicular system?
→ Maintains communication between the bone surface and blood vessels
106
What is osteopetrosis caused by?
→ Inactivating the RANK ligand → overgrowth of bone
107
Describe the basic function of clast cells, and give and example
“Clast" cells – break down of connective tissue
* Osteoclast in bone
* Chondroclast in cartilage
108
How do osteocytes extend?
→ Via multiple dendrites via minute canals in the bone matrix
109
What is the Wnt pathway regulated by?
→ DKK and Sclerostin
110
What is a rare bone disease?
→ Osteomalacia
111
What is the function of trabecular bone?
→ Makes bone lighter
112
What does the RANK receptor binding promote?
→ osteoclast differentiation
113
What do mesenchymal stem cells make?
→ Osteoblasts and osteocytes
114
What do osteoclasts secrete?
→ Acid and proteases that are active in acidic environments
115
A fine protective sheath of connective tissue around a skeletal muscle fiber
Endomysium
116
What are the function of Haversian canals?
→ Allow for blood vessel penetration
117
What are the 3 phases of bone remodelling?
→ Activation : promotion of differentiation of new osteoclasts → Resorption : duration of osteoclast activity → Reversal : osteoclast apoptosis, terminating activity
118
What do osteoclasts look like?
→ They are large and multinucleate
119
What are the function of Haversian canals?
→ Allow for blood vessel penetration
120
A bundle of muscle fibers
Fascicle
121
The ability to respond to a stimulus
Irritability
122
What are the two basic classifications of epithelial tissue
123
Broadly describe nervous tissue as a category of tissue class
* Excitable
* Specialised for rapid signal conduction
124
Broadly describe epithelial tissue as a category of tissue class
* Cover organs, form glands
* Protect, secrete and absorb
125
What ratio controls osteoclast differentiation?
→ Ratio of RANK ligand to OPG
126
What do osteocytes do?
→ They lay down bone matrix (organic material that becomes mineralised)
127
What is a protease that osteoclasts secrete?
→ Cathepsin K
128
What are lacunae?
→ cell sized holes within the bone matrix
129
The outermost sheath of connective tissue that surrounds a skeletal muscle
Epimysium
130
What is the effector of the Wnt pathway?
→ beta catenin
131
What do sclerostin, DDK and SFRP1 inhibit?
→ Inhibit the differentiation of osteoblasts
132
What does the RANK ligand promote?
→ Promotes the differentiation of osteoclasts
133
What is bone mineral?
→ Hydroxyapatite → Calcium and Phosphate
134
Describe simple columnar epithelium
135
What does OPG do?
→ Acts as an antagonist → binds to RANK ligand and prevents it from binding to the receptor
136
What do osteoclasts look like?
→ They are large and multinucleate
137
What are the 3 phases of bone remodelling?
→ Activation : promotion of differentiation of new osteoclasts → Resorption : duration of osteoclast activity → Reversal : osteoclast apoptosis, terminating activity
138
What are osteocytes?
→ Terminally differentiated osteoblasts
139
What are the repeating units of cortical bone?
→ Osteons
140
What is delayed skeletal growth in men linked to?
→ Aromatase deficiency
141
What is the function of the lacunocanalicular system?
→ Maintains communication between the bone surface and blood vessels
142
What are the repeating units of cortical bone?
→ Osteons
143
What is a rare bone disease?
→ Osteomalacia
144
A type of contraction that involves no change in muscle length
Isometric
145
How does bone remodelling occur?
→ The leading edge is where cells differentiate into osteoclasts → Behind that the new osteoblasts differentiate into new bone → As the osteoblasts lay down the new bone some of them will stay in it where they are encased in lacunae
146
In what gender is osteoporosis more common in?
→ Women
147
What is the composition of bone in %s?
→ Protein : organic osteoid matrix 25% → Mineral : 75% → Cells
148
What is the role of estrogen in bone remodelling?
→inhibits osteocyte apoptosis → Promotes osteoclast apoptosis → essential for skeletal health
149
A type of contraction that results in shortening of a muscle
Concentric
150
151
What are the 3 factors that control bone remodelling?
→ Load bearing exercise → Cytokines and local signals → Endocrine
152
The delicate membrane surrounding each striated muscle fiber
Sarcolemma
153
Broadly describe connective tissue as a category of tissue class
•Support, bind and protect organs
154
What is the Wnt pathway regulated by?
→ DKK and Sclerostin
155
Why is osteoporosis more common in women?
→ dramatic loss of estrogen due to menopause
156
Describe the basic function of 'blast' cells and give an example
"Blast" cells
* Immature form; mitotically active; secrete ground substance and fibers
* Fibroblasts in connective tissue proper
* Chondroblasts in cartilage
* Osteoblasts in bone
