1
Q
What is the connective tissue of the brain? where does it arise from?
A
Neuroglia, arises from mainly the ectoderm, one type rises from the mesoderm.
Astroglia, oligodendroglia & peripheral glial cells rise from the ectoderm.
2
Q
What primordial germ layer does connective tissue primarily rise from?
A
The Mesoderm. (only gives rise to the microglia of the neuroglia.)
3
Q
What are the 3 components of connective tissue?
A
- Ground Substance
- Fibers
- Cells
4
Q
What are the extracellular components of the connective tissue called?
What are it’s two components?
A
The matrix
Fibers and Ground Substance.
5
Q
What are the 3 physiological functions of the connective tissue ground substance?
A
- To act as a “sieve” and facilitates diffusion between the blood and tissues.
- A physical barrier to prevent spread of large molecules such as pathogens.
- Acts as support and binds connective tissue cells and fibers.
6
Q
What cells produce the viscous amorphous gel called the ground substance of connective tissue?
A
Fibroblasts.
7
Q
Where are fibroblasts derived from?
A
Embryonic Mesenchyme. (as most connective tissue cells are.)
8
Q
The ground substance of connective tissue contains chains of glycosaminoglycans, proteoglycans and adhesive glycoprotein. What is the most abundant glycosaminoglycan in connective tissue?
A
Hyaluronic acid, also the largest type.
9
Q
What do proteoglycans consist of?
A
90% carbohydrates.
10
Q
What are 3 components of Ground substance in connective tissue?
A
- Water
- Salts- CaPO4 (calcium phosphate.)
- Glycosaminoglycans.
11
Q
What does GAG stand for in relation to connective tissue?
A
Glycosaminoglycans.
12
Q
What creates large hydrated spaces within the extracellular matrix of connective tissue?
A
Hyaluronan. (a glycosaminoglycan which has a unique capacity to bind and retain water.)
a matrix rich in HA is suitable for cell proliferation and migration- may also aid in preventing precocious differentiation ie. cancer.
13
Q
Class of GAG (glycosaminoglycans) which consist of a sulfated-glycosaminoglycan bound to a core protein:
A
Sulfated Proteoglycans.
14
Q
What are the four major classes of Sulfated proteoglycans?
A
- Chondroitin Sulfate.
- Dermatin Sulfate.
- Keratin Sulfate.
- Heparin Sulfate.
15
Q
What are the 4 functions of GAG’s (glycosaminoglycans.)
A
- Contribute to viscosity of the Ground substance.
- Provide support for the connective tissue.
- Act as a medium for diffusion of nutrients and gases.
- exert direct influence on surrounding cells, specific interactions between GAG’s and cell receptors may regulate cell functions- (important for development.)
16
Q
What does precocious refer to in biology?
A
To gaining new abilities.
17
Q
What binds connective tissue cells to the surrounding collagen fibers of the matrix?
A
Structural proteins.
18
Q
What are four structural proteins found in extracellular matrix of connective tissue?
A
- Fibronectin
- Laminin
- Chondronectin
- Osteonectin
19
Q
Structural protein that is a ligand and promotes the attachment of cells to collagen fibers
Also plays a role in cell migration, differentiation, phagocytosis, chemotaxis and cytoskeletal organization of cells which can change their shape/ function.
A
Fibronectin.
20
Q
Structural protein associated with the basement membrane. Attaches epithelial cells to type IV collagen of the basement membrane.
A
Laminin.
21
Q
Structural protein which promotes attachment of cartilage cells to collagen.
A
Chondronectin.
22
Q
Structural protein which promotes attachment of bone cells to collagen.
A
Osteonectin.
23
Q
What is the integumentary system?
A
Skin etc..
24
Q
What are the three types of fibers found in connective tissue?
A
Collagen, Reticular, and Elastic fibers.
Density, Proportion, Arrangement, and occurrence will vary between connective tissues.
25
Most abundant fiber found in all connective tissues, strongest, not very elastic.
Collagen fibers.
26
What is the organization of a collagen fiber?
Polpyeptide chains (tropocollagen)--> Collagen molecule ---> Microfibril ---> Fibril --> Collagen. bundle.
27
What three cells produce tropocollagen?
- Primarily fibroblasts
- Chondroblasts (cartilage)
- Osteoblasts (bone)
28
How many types of collagen are there?
5
29
What is the most abundant collagen type?
Type 1
30
What collagen is found in cartilage and certain eye tissues?
Type 2
31
What type of cartilage is in the GI tract, Skin, Uterus, and Cardiovascular system.
Type 3
Often found associated with reticular fibers.
32
Which collagen is found in the basement membrane?
IV (4)
33
Which collagen is found in fetal tissues, although vestigial amounts may be present in the adult.
Type V (5)
34
Collagen fibers which are arranged into delicate networks?
Reticular fibers.
35
Where are two places that reticular fibers are commonly found?
In lymphoid organs and reticular layer of the basement membrane.
36
What are elastin fibers composed of?
Elastin. (stretchy/ not as strong as collagen)
37
What are the cells associated with maintaining the connective tissues?
Permanent cells.
38
What are the four permanent cells of the connective tissues?
Fibrocytes, fibroblasts, adipocytes, and mesenchymal cells.
39
Immature fibrocyte?
Fibroblast- produce all three fiber types and ground substance. Widely distributed.
40
Permanent connective tissue cells which maintain their multipolarity and can develop into other connective tissue cell types during gestation.
Mesenchymal cells.
They can develop into adipocytes, mast cells, smooth muscle etc.
41
What kind of connective tissue is adipose?
Loose connective tissue.
42
What is lipid deposition and mobilization controlled by?
Neuroedocrine secretions.
43
How is the appearance of white fat described?
Unilocular.
44
How is the appearance of brown fat described?
Multilocular.
Brown fat is usually found embryonic/ neonate mammals or mammals which hibernate. It is thermogenic.
45
What is hyperplastic and hypertrophic growth of adipocytes?
Hyperplastic- Increase in #
Hypertrophic- Increase in size- Usually what affects the weight of adults..
46
What are the 5 chemicals produced by mast cells?
- Heparin (anticoagulant)
- Prostaglandins (increase edema)
- Eosinophil Chemotaxic Factor (attracts eosinophils)
- Histamine (increases vascular permeability.)
- Other enzymes which degrade various connective tissue components.
47
What are 2 locations where lymphocytes are more prominent within connective tissue?
The loose connective tissue of the respiratory tract and alimentary canal
48
What is lamina propria where is it found?
A specialized layer of loose areolar connective tissue which connects the apical cells to the smooth muscle below. This is commonly found lining tracts such as respiratory, alimentary canal and urogenital system.
49
What are 4 transient cells within connective tissues?
- Mast Cells
- Lymphocytes
- Plasma Cells
- Macrophages
50
The lamina propria is a layer of areolar connective tissue which lies below the epithelium in various tracts, What are lymphocytes capable of to aid in protection from the external environment (pathogenic invasion)?
Lymphocytes are able to penetrate the epithelium to carry out their immunological functions.
51
What is an activated B-cell Lymphocyte?
Plasma cell, they can be differentiated by their "pinwheel" shaped nucleus.
52
What are plasma cells, what do they secrete?
Activated B-lymphoctyes, they secrete antibodies.
Plasma cells are widely dispersed throughout the connective tissues.
53
What are three places plasma cells (activated B-lymphocytes) commonly reside in?
Within the lamina propria of the respiratory and digestive tract, they are also common in lymphoid organs.
IT IS RARE TO SEE PLASMA CELLS IN THE BLD.
54
Where are macrophages derived from?
The monocyte class of leukocyte which have migrated into the connective tissue from circulation.
55
Long lived, highly mobile phagocytic cells found throughout the connective tissues.
Macrophages.
56
How do macrophages move?
Via diapedesis using pseudopodia.
57
What do mast cells and macrophages have in common?
Cytoplasmic granules.
Only macrophages have pseudopodia.
58
What are substances produced by macrophages?
Digestive enzymes such as lysosomes, immunoregulatory substances: interferon, lysozome, prostaglandins, peroxide and other growth factors.
59
What is a subclass of macrophages?
Dendritic cells.
60
Where do dendritic cells originate from?
Monocytes.
61
What do dendritic cells function to do?
They present the antigen markers of pathogens to lymph nodes to mobilize humoral immunity.
62
What type of connective tissue has mostly a fluid ground substance and fills the space between developing organs?
Mesenchymal tissue.
Mesenchymal cells are stellate shaped.
63
Connective tissue derived from mesenchyme contains collagen fibers and a viscous ground substance- typified by whartons jelly:
Mucus tissue.
64
What connective tissues have a high cell content and low fiber content?
The loose connective tissues:
- Areolar
- Adipose
- Reticular
65
Most common type of loose connective tissue, and supports the epithelium.
Areolar
66
What connective tissue makes up some of the superficial fascia and dermis?
The areolar tissue.
67
What is the stroma?
Connective tissue which supports the function of the parenchyma (functional tissue of an organ.)
68
What tissue commonly composes the stroma of various organs?
Areolar connective tissue.
69
What are the 3 functions of areolar connective tissue?
- Barrier to infection (partly)
- Cushions the body (partly)
- Allows for passage of nerves, blood and lymph vessels.
70
What is the precursor to tropocollagen?
Procollagen.
71
What is something areolar connective tissue will do acting as the stroma in certain organs?
It will form septa and divide the structure into lobes/ lobules.
72
Name three places adipose connective tissue is found?
- Hypodermis.
- Surrounding and protecting certain organs.
- Medullary cavity of long bones.
73
What are three functions of adipose connective tissue?
- Stores energy.
- Body insulation.
- Cushions body and organs.
74
What is the thermogenic tissue only found in placental mammals?
Brown Adipose tissue.
75
Connective tissue with a delicate modified form of collagen that acts as a supportive framework
Reticular connective tissue
abundant in reticular fibers.
76
Which connective tissue is most abundant in areas that need to be able to stretch?
What four locations when this tissue is likely to be found?
Elastic connective tissues- made of elastic fibers.
Found in: Trachea, Elastic Arteries, Skin and the Uterus.
77
What are the 4 permanent cells of the connective tissue?
- Fibroblasts.
- Fibrocytes.
- Mesenchymal Cells.
- Adipocytes
78
Cells involved with the maintenance of connective tissues?
Permanent connective tissue cells.
79
Cells involved in short term response event within the connective tissues?
Transient connective tissue cells.
80
Permanent connective tissue cell responsible which can produce all three types of fibers and ground substance?
Fibroblast.
81
Permanent connective tissue cell which can aid in repair of the tissue?
Fibrocyte- Mature Fibroblast.
82
Group of connective tissue which have a low cell content and higher fiber content?
Dense connective tissues:
- Dense regular
- Dense irregular
- Elastic
83
Type of connective tissue that has a random weave of fibers (mostly collagen), and low cell content.
Dense irregular connective tissue.
Fibroblasts and fibrocytes most common within.
Found in the sheaths of tendons, nerves, and capsules of organs and the dermis.
84
Where are 4 places most likely to find Dense Irregular Connective Tissue?
- Sheaths of Tendons.
- Sheaths of Nerves.
- Capsules of Organs.
- Dermis.
85
Two most common cell types within the Dense Irregular Connective Tissue?
Fibroblasts and Fibrocytes.
86
What is the purpose of the Dense Irregular Connective Tissue(2)?
To withstand stress from multiple directions and act as a protective barrier.
87
Connective tissue which has a repeating pattern of fibers and very few cells.
Dense Regular Connective Tissue.
88
What is the most common fiber and cell types within Dense Regular Connective Tissue.
- Collagen Fibers
- Fibroblasts and Fibrocytes.
89
What two places is dense regular connective tissue most likely to be found?
Why?
In Tendons and Ligaments.
This is because this tissue has a great resistance to mechanical forces, but only unidirectionally.
90
Dense connective tissue where the dominant fiber is the elastic fiber?
Elastic Connective Tissue.
91
What are two places where elastic fibers are found?
Elastic cartilage and elastic veins which have elastic connective tissue.
92
What are the four mineralized connective tissues?
- Bone
- Cartilage
- Dentin
- Enamel
93
What is the precursor cell between a mesenchymal cell and one of the specialized connective tissue cells (Chondroblast, Osteoblast, Odontoblast, Ameloblast.)
A Scleroblast cell. Derived from the mesenchyme and can become any four specialized connective tissue cell types.
94
What are the four specialized connective tissue cells that scleroblasts can differentiate directly to?
- Odontoblast (Dentin)
- Ameloblast (Enamel)
- Chondroblast (Cartilage)
- Osteoblast (Bone)
95
What specialized connective tissue is not mineralized?
Blood.
96
Specialized type of connective tissue which is highly resilient and can provide strength/ support in body area which require some flexibility?
Cartilage.
97
What are the two type of cartilage cells?
Chondroblasts and Chondrocytes these produce the ground substance and fibers.
98
Which tissue has an amorphous matrix that is "gel-like"?
What is it function?
Cartilage.
It provides weight bearing, resiliency, and high tensile strength.
99
Process of the mesenchyme differentiating into cartilage?
Chondrogenesis.
100
What is the space in which the cells of mineralized connective tissues lie in?
Lacuna/ Lacunae (plural)
101
What two organelles are extensive and well developed within chondroblasts?
Why?
The RER and golgi apparatus.
This is because these cells are responsible for producing fibers and ground substance.
102
What are the two two of cartilage growth? Describe them and what they result in.
Appositional growth: Cells in the perichondrium become chondroblasts., which will secrete matrix material.
Interstitial- This is when a chondrocyte will undergo mitosis and produce a daughter chondrocyte that will produce matrix material. These cells will remain near each other forming isogenic groups/ clusters of twin cells.
103
Membranous structure forming the outer layer of a cartilage organ?
What are it's two layers?
Perichondrium
- Outer layer of fibrous dense irregular c.t.
- Inner layer is a single layer of cells called scleroblasts.
104
What are the 2 main components of the matrix in cartilage?
What are the 2 most abundant chemicals of one of the components?
High component of fibers and proteoglycans (a type of GAG- Glycosaminoglycan.)
Chondroitin sulfate is the most abundant proteoglycan, 2nd is keratin sulfate.
105
What are the two regions of matrix?
Territorial Matrix: Extremely basophilic region surrounding the chondrocytes.
Interterritorial Matrix: Weakly basophilic region in between the territorial matrices.
106
Most abundant cartilage, forms bulk of embryonic skeleton in non-chondrichthyan gnathostomata (non-cartilaginous ie. bony fish.)
Hyaline cartilage.
107
What connective tissue makes up majority of the skeletal components of chondrichthyes and agnathans (Cartilaginous fish)?
Hyaline cartilage.
108
Where are 6 places hyaline cartilage is found in non-chondrichthyan gnathostomata?
- Larynx
- Nasal Septum
- Trachea
- Bronchi
- Articular surfaces of joints
- Costal Cartilage.
109
What cartilage provides flexible and weight bearing surfaces and is a pathway to for bone length growth?
Hyaline cartilage.
110
What kind of collagen fibrils are within hyaline cartilage?
Type 2- which does not form bundles- this is why it is not seen.
111
What occurs to Hyaline cartilage as the organism ages?
The tissue becomes infiltrated by calcium, reducing it's ability for interstitial growth and increasing it's rigidity.
At some point only appositional growth is possible.
112
Where are elastic chondrocytes derived from?
Fibroblasts.
Although elastic cartilage is considered a modified hyaline cartilage it's chondrocytes are not derived directly from the mesenchyme like with hyaline cartilage.
113
Name 6 places elastic cartilage is found?
- External ear.
- Auditory Tubes.
- Eustachian Tubes.
- Epiglottis.
- Corniculate Cartilages.
- Cuneiform Cartilages.
(Last two are located in the larynx.)
114
Which cartilage provides extremely flexible support?
Elastic Cartilage.
115
Describe the ground substance of elastic cartilage?
The ground substance is parse and heavily infiltrated with elastic fibers in random arrangement.
116
Combination of Hyaline Cartilage and Dense Regular Connective Tissue
Fibrocartilage.
117
Where do the chondrocytes of fibrocartilage arise from?
Fibroblasts.
118
What is the organization of Hyaline Cartilage and Dense Regular Connective tissue forming Fibrocartilage?
Dense collagen fibers arranged into parallel bundles.
Chondrocytes in rows between the bundles.
119
What is the support fibrocartilage provides?
It combine the stress bearing properties of Hyaline and Dense Regular C.t. For a firm, not rigid, support.
120
Where is fibrocartilage commonly found?
Intervertebral discs, pubic symphysis, certain tendinous insertions.
121
What Cartilage is able to help heal all cartilages?
Fibrocartilage, however this ability reduces with age.
122
What is the densest and least resilient cartilage type?
Where is it found?
Calcified/ Mineralized/ Tessellated Cartilage.
It is found in the jaws of Chondrichthyes (Cartilagenous fish)(especially Sharks and Rays).
123
What occurs to form Calcified Cartilage?
it is a modified Hyaline or Fibrocartilage which becomes perfused with calcium salts, a step in endochondral ossification but it paused before it is too calcified too have diffusion across the matrix
124
What are the two morphologies of bone tissue?
Spongy (Medullary) and Compact (Cortical) bone.
125
What are the intercommunicating projection within spongy bone called?
Trabeculae.
126
Where is bone marrow? What are the types?
Bone marrow resides within the intertrabecular spaces and medullary cavity.
There is Red (RBC's) and Yellow (Adipose) bone marrow.
127
What is Medullary and Cancellous bone located within a long bone organ?
Cancellous bone (Containing Trabeculae) is within the epiphysis and the medullary canal is within the diaphysis. Both contain bone marrow.
128
Layer of specialized connective tissue which lines the external aspect of a bone organ (covering the Cortical bone.).
Periosteum.
129
What are the two layers of the periosteum?
Outer layer is fibrous.
Inner layer is cellular and contains scleroblasts. It allows for remodeling and repair of bone.
130
What do tendons and ligaments attach to?
The periosteum
131
how does the periosteum attach to the cortical/ compact bone?
Through perforating/ sharpey's fibers. These are dense collagen bundles connecting the periosteum into the mineralized bone matrix at the outer circumferential lamellae.
132
Layer of flattened cells with osteogenic potential lining the inner aspect of bone such as the medullary cavity, or intertrabecular spaces?
Endosteum.
133
What does the vascular supply to bone penetrate through and what is this called?
The vascular supply to bone penetrates through the diaphysis by way of the nutrient foramen/ canal and are often accompanied by nerves.
134
What is the system within bone that allows nutrients to get to it's cells?
Haversian systems/ haversian canal in the center.
135
Enclosed in fluid filled joints the articular surfaces of bone are covered by what connective tissue? what is it called specifically in this situation?
Hyaline Cartilage, called articular cartilage.
136
What is the most organized special connective tissue?
Bone.
137
What does bone store?
Bone is a reservoir for minerals, especially Calcium and Phosphate.
138
What is the mineral component of bone called?
Hydroxyapatite (65% of bone matrix.)
139
What are the four most abundant bone minerals?
List three more not as abundant.
- Phosphate
- Calcium
- Carbonate
- Citrate
---
- Fluorine
- Magnesium
- Sodium
140
What is the principle bone mineral?
Calcium Phosphate.
141
What is the hydrated organic bone matrix termed?
What is it primarily composed of?
The Osteoid
95% Collagen
-The other 5% is amorphous ground substance: Proteoglycans such as Chondroitin-4-sulfate & Keratin Sulfate.
142
Where are osteogenic cells located in the adult organism?
in the cellular (inner) component of the periosteum and endosteum.
(osteoblasts)
143
Immature bone cells derived from scleroblasts?
What do they mature into?
Osteoblasts mature into Osteocytes.
144
Where are osteoblasts derived from?
Scleroblasts.
145
What do Osteoblasts secrete?
The osteoid: The hydrated organic bone matrix.
146
What do Osteoblasts indirectly participate in?
Calcification of the matrix.
147
What two organelles are prominent in osteoblasts?
Why?
RER, Golgi Apparatus and secretory vesicles.
This is because they are secretory cells.
148
What is a special group of secretory vesicles in osteoblasts?
What does it contain and aid in?
Matrix Vesicle contain Alkaline Phosphatase and aid in calcification of the matrix.
149
How do osteocytes within lacunae in the compact bone communicate/ receive products from each other?
Since compact bone is impermeable, each lacuna has radiating canals called canaliculi connecting each osteocyte. These also eventually open near a blood supply for nutrients.
150
Where are osteoclasts derived from? what do they do?
Derived from combined monocytes- leaves many nuclei.
Osteoclasts breakdown bone by resorption- this is called osteoclastic resorption.
151
What is the space where the osteoclast is resorbing bone called?
Resorption bay/ Howship's lacuna.
152
How is the cytoplasm of an osteoclast that is located against the surface of bone organized?
The cell has a Ruffled Border and contains catabolic substances, the areas without this ruffling are called the "Clear Zones"
153
What are the 2 activities of Osteoclasts?
- Osteoclastic Resorption.
- Release Ca from Matrix.
154
What are the 2 modes of Bone Resorption?
- Osteoclastic resorption
- Osteocytic Osteolysis
155
Left details from 21 special connective tissues onward.
156
What are the 2 hormones associated with controlling the release of calcium from bone?
- Calcitonin- decreases (Reduces the size of the ruffled border and clear zone.)
- Parathyroid hormone- increases. (Increases the size of the ruffled border and clear zone.)
157
What are the microscopic layers of trabeculae called?
Lamellae.
158
What is the arrangement of Collagen in spongy bone?
Collagen bundles form parallel lamellae which are perpendicular to neighboring lamellae. This arrangement increases the strength of bone.
159
What are the 3 types of lamellar organizations?
- Haversian Lamellae
- Interstitial Lamellae
- Circumferential Lamellae
160
Canals within compact bone containing blood vessels and nerves travelling perpendicular to haversian canals?
What is the lining tissue?
- Volksmann's canals.
- Endosteum.
161
What are the 2 stages of Osteoclasia/ Osteoclastic Resorption?
What carries out this resorption?
Demineralization of Bone: Secretions which increase the solubility of bone mineral salts across the ruffled border.
Degradation of Collagen: newly exposed collagen is now degraded by acid hydrolases released from vesicles.
This is all carried out by Osteoclasts within Howship's Lacunae.
162
Process of bone resorption which is carried out by osteocytes within deep heavily mineralized bone to release calcium?
Osteocytic Osteolysis.
163
Two differences between Osteoclasia/ Osteoclastic Resorption and Osteocytic Osteolysis?
- Osteoclasia is carried out by osteoclasts.// Osteocytic Osteolysis is carried out by resorptive osteocytes.
- Osteoclasia releases Calcium from superficial bone.// Osteocytic Osteolysis releases calcium from deep heavily mineralized bone.
164
Which is more complex: Cancellous Bone or Cortical Bone?
Why?
Cortical (compact) Bone is more complex, this is due to the difficulty of getting nutrients to osteocytes within such a dense extracellular matrix.
Cancellous = Spongy Bone
165
Lamellae arranged concentrically around a canal?
Canal Name?
Lining of the Canal?
Osteon
Haversian Canal
Endosteum.
166
Osteon AKA?
Haversian system
167
What connects Osteocytes to each other and to the haversian canal?
Canaliculi.
168
What do both Haversian and Volkmann's canals Carry?
They both carry Blood Vessels and Nerves.
169
Boundary between interstitial and haversian lamallae?
Cement Lines.
170
Classification of Lamellae that does not have a canal and is a remnant of older partially resorbed osteons?
Interstitial Lamellae.
171
Circumferential Lamellae forming the external and internal lamination of cortical bone?
Circumferential Lamellae.
They are respectively immediately below the periosteum and the endosteum from the outside to inside.
172
Acellular Bone AKA?
Aspidin Bone.
173
How does Aspidin bone develop compared with Compact or Spongy Bone?
Spongy and Cortical done both have osteoblasts which secrete bone matrix and become stuck within lacunae and mature into osteocytes.
In Acellular bone the osteoblasts retreat as the secrete the matrix, leaving it acellular.
174
Where are two places Aspidin bone is found?
The cementum of the tooth.
The bony component of elasmoid scales of teleosts.
175
What is Cementum of the tooth?
The bottom outer layer of the tooth that serves to attach the rooting to surrounding tissue.
176
What are elasmoid scales?
The most common type of fish scale and are found on teleosts (Ray Finned Fishes), they are partially mineralized scales, but still flexible allowing movement.
177
Type of bone which responds to hormonal influences?
Metaplastic Bone.
178
Where is metaplastic bone usually seen?
What is it usually driven by?
In the skull of certain avains and non-avian dinosaur species. Usually affected by sex hormones ie. testosterone.
179
What is osteogenesis also called?
Ossification.
180
What are the two types of osteogenesis/ ossification?
- Intramembranous Ossification.
- Endochondral Ossification.
181
Where does Intramembranous Ossification usually occur?
In the membranous bones. Membranous bones defined as being made via Intramembranous ossification, these are usually flat shaped bones such as skull bones, mandible, clavicles, turtle shells, and fin rays (Lepidotrichia.) (not ribs.)
182
Ossification process by which mesenchyme forms the model of a bone organ, Mesenchymal cells produce scleroblasts, which produce osteoblasts which begin osteogenesis.
Intramembranous Ossification.
183
Ossification process by which Hyaline cartilage forms the model of a bone organ, the cartilage is then degraded and replaced by bone tissue.
Endochondral ossification.
184
Where does endochondral ossification usually occur?
Within majority appendicular and axial skeleton.
185
Is Dentin acellular?
No, this is because it's odontoblasts reside just within the visceral side of the tissue.
186
What is dentin produced by?
Odontoblasts.
187
What two tissues are produced by odontoblasts.
Dentin and Enameloid.
Enameloid is a modified dentin.
188
What are the "canaliculi-like" structures within Dentin?
What causes them?
Dentin Tubules.
They are caused by odontoblasts as they retreat through the dentin have cytoplasmic processes within them.
189
Where is Dentin found?
What is dentin frequently found with?
Only in the Dermis.
Found in teeth and scales.
Frequently coated by enamel or enameloid (modified dentin).
190
What is the difference between enamel and enameloid?
Enamel is produced by ameloblasts.
Enameloid is not enamel, as it is produced by odontoblasts, not ameloblasts.
191
What is the densest the tissue in ion vertebrates?
Enamel.
192
What gives rise to Enamel?
Ameloblasts.
193
What gives rise to ameloblasts?
Scleroblasts.
194
What germ layer gives rise to Ameloblasts/ Enamel?
The ectoderm.
195
What gem layer gives rise to the dentin, enamel and enameloid?
Enamel- Ectodermal.
Dentin- Mesodermal
Enameloid- Debated to have components from both, but likely mesodermal.
196
What layer of "skin" is the dentin, enamel and enameloid?
Enamel- Epidermis.
Enameloid- Dermis.
Dentin- Dermis.
197
Connective tissue full of free cells within a tissue matrix?
Blood.
198
What is something blood generally lacks except during clotting?
Fibers.
199
What are the two components of blood?
Fluid- Plasma.
Cellular- Formed elements.
200
What are the three main components of plasma?
- Water.
- Inorganic Salts.
- Plasma Proteins.
201
What are the 3 Plasma Proteins?
- Albumin.
- Fibrinogen.
- Globulins.
202
What are the two Globulins common in the plasma?
What are their functions in the plasma?
- Gamma Globulins: Contains antibodies.
- Beta Globulins: Used in transport of hormones, lipids, and metal ions.
203
What are the two microscopic particles contained within plasma?
Chylomicra- Fatty Bodies- Increases after a fatty meal.
Hemoconia- Poss. Fragments of cells.
204
What are the three classes of formed elements within blood?
- Erythrocytes- RBC.
- Leukocytes- WBC.
- Thrombocytes- Platelets.
205
Process by which the formed elements arise?
Hemopoiesis.
206
Hemopoietic Tissue AKA?
Myeloid Tissue.
207
What are the four hemopoietic organs in the vertebrate embryo?
What about the adult?
- Spleen.
- Liver.
- Bone Marrow.
- Yolk Sac.
- Adults become primarily restricted to the Red Marrow.
208
What cell do the formed elements arise from?
The Hemocytoblast.
(Multi-Potential Hemapoietic Stem Cell.)
209
Where is the Hemocytoblast derived from?
The mesenchymal Cells.
210
What are the 2 stem cells a hemocytoblast will differentiate into?
* Myeloid Progenitor: Megakaryoblast, Pronormoblast, Myeloblast.
* Lymphoid Progenitor: Lymphoblast, Lymphoid Dendritic Cell.
211
What is the most numerous formed element?
What is special about it?
Erythrocytes.
One of the few cells that have color without staining. -Red.
212
What group of vertebrates have anucleated erythrocytes?
Only Mammals.
213
Largest to smallest red blood cells of 5 vertebrate classes?
Largest
1. Amphibian (salamanders.)
2. Reptile
3. Fish
4. Avian
5. Mammal- Anucleated.
Smallest.
214
Why do mature erythrocytes usually lack most organelles?
In order to carry more oxygen on their heme group.
215
What is the iron containing prosthetic group within an erythrocyte?
What is the protein containing it?
Heme group
The iron and oxygen give blood its "Rusty" color.
Hemoglobin: Globular Quaternary Protein, heme group on each of the four sub units.
## Footnote
Prosthetic Group: a Non-Peptide Molecule Tightly bound to a Protein, Usually Covalent Bond (Strongest).
EX: Heme, Biotin, Flavin, etc.
216
Which protein forms the subplasmalemmal framework of microfilaments which provides flexibility, allowing erythrocytes to travel through the tiny capillaries?
Spectrin Proteins.
217
How are erythrocytes able to travel through very small capillaries?
Due to a subplasmalemmal network of microfilaments made of the protein Spectrin.
Allowing for Flexibility of the Erythrocyte.
218
What is the process of producing erythrocytes called?
Where does this occur in the mature vertebrate?
Erythropoiesis.
Occurs in the red marrow of mature vertebrates.
219
What hormone stimulates erythropoiesis?
Erythropoietin.
-Produced in the kidneys in response to a decrease in erythrocyte numbers.
220
What are the cellular steps of erythropoiesis (9)?
1. Mesenchyme.
2. Hemocytoblast.
3. Myeloid Progenitor.
4. Proerythroblast/ Pronormoblast.
5. Basophilic Erythroblast.
6. Polychromatophilic Erythroblast.
7. Orthochromatic Erythroblast/ Normoblast.
8. Polychromatophilic Erythrocyte/ Reticulocyte.
9. Erythrocyte (Complete/ Mature.)
221
What do Proerythroblasts differentiate into?
Process?
Basophilic Erythroblasts.
Smaller/ condensed nucleus and develops more ribosomes, rRNA is what causes the basophilic staining.
222
What do Basophilic Erythroblasts Develop into?
Process?
* Polychromatophilic Erythroblasts.
* The basophilic staining ribosomes (rRNA) begin to synthesize hemoglobin (eosinophilic).
* So the cell will begin staining more eosinophilic, but not by much.
* The nucleus is further reduced & non-functional.
## Footnote
Mostly Basophilic Staining.
223
What do Polychromatophilic Erythroblasts Develop into?
Process?
* Orthochromatic Erythroblasts/ Normoblasts
* The Nucleus continues to be reduced and the chromatin becomes "clumped".
* Stage where most hemoglobin Synthesis occurs.
224
What do Normoblasts develop into?
Process?
## Footnote
Normoblast AKA: Orthochromatic Erythroblast.
* Reticulocyte/ polychromatophilic erythrocytes
* Once the normoblasts extrudes its nucleus.
* The cell is polychromatic, hence alt. name.
* Barely more eosinophilic than normoblast due to minor amount of hemoglobin synthesis still occuring.
## Footnote
Hemoglobin (Eosinophilic).
225
What do Reticulocytes develop into?
Process?
* Mature erythrocytes.
* Membrane remodeling and loss of organelles & rRNA.
* Will no longer stain with H&E & will appear red due to the iron oxidation.
* Normally: 1-2% of RBC's in circulation are reticulocytes.
226
Mature Erythrocyte cycle?
Once they reach senescence (~120 days) after running out of ATP. The cell becomes fragile and is phagocytized by the liver, spleen, and bone marrow.
227
What happens to phagocytized erythrocytes?
They are degraded, the hemoglobin is broken Down into bilirubin and iron is released.
-Fe will be complexed W/ protein for storage as Ferritin (Primary Storage) or Hemosiderin Both can recycle into Erythropoiesis.
## Footnote
Hemosiderin is more common with excess iron.
227
What are the only complete cells of the formed elements in mammals?
Leukocytes.
228
What are the two groups of leukocytes?
Granulocytes and Agranulocytes.
228
What are the two features of Granulocytes, what three leukocytes are in this group?
- Visual Cytoplasmic Granules.
- Lobed Nucleus.
Includes:
Basophils.
Eosinophils.
Neutrophils.
228
What are the two features of Agranulocytes, what two leukocytes are in this group?
- Lacking Visual Cytoplasmic Granules.
- Spherical Nucleus.
Includes:
Lymphocytes
Monocytes.
228
Production of Leukocytes from the red bone marrow.
Myelopoiesis.
229
What are the three differentiations a hemocytoblast can become that become leukocytes?
- Myeloblast.
- Monoblast.
- Lymphoblast.
230
What does a Myeloblast develop into?
Any of the three granulocytes:
- Basophils.
- Eosinophils.
- Neutrophils.
231
What does a Monoblast develop into?
Monocyte.
232
What does a Lymphoblast develop into?
Lymphocyte.
233
Where do granulocytes mature?
In the red bone marrow.
234
What is the most abundant Leukocyte- Granulocyte?
Neutrophils
235
Chemical substances which attract or repel cells?
Chemotactic Factors.
236
Granulocyte which is attracted to chemotactic facets released by Inflammation and phagocytized bacteria, etc.
Neutrophil.
237
Granulocyte with a highly lobed nucleus (3-5) and both small pink granules and larger blue/purple granules?
Neutrophil.
238
Bilobed granulocyte with many pink/ orange/ red granules?
Eosinophil.
The granules will often obscure parts of the nucleus.
239
What are the four components of the granules of eosinophils?
- Arylsulphatase.
- Histaminase metabolizes histamines.
- Hydrocortisone- Hormone.
- Major Basic Protein.
240
What does MBP do when released by eosinophils?
Major Basic Protein is released onto the surfaces of parasites and promotes and antibody mediated immune response.
241
Which granulocyte is rare in the blood stream, and more commonly found in the connective tissue of the digestive and respiratory tract?
What are their functions?
Eosinophils.
- They will phagocytize antigen antibody complexes (Think how they also contain MBP which marks parasites for immune response.)
- Chemotactically attracted to areas of allergic RXN, think inflammation.
242
Bilobed "U-shaped" granulocyte with basophilically staining granules.
Basophils.
Granules contain substances which can promote inflammation and some glycosaminoglycans. (GAG's)
243
What are the 2 functions of basophils?
- Increase Vascular permeability by secreting histamines and heparin.
- Binds to immunoglobulin & antibody IgE which can activate the basophil.
244
Where do granulocytes develop and mature?
They develop within the red bone marrow but may also mature elsewhere.
245
Highly phagocytic cell which is a precursor to macrophages?
Monocyte.
Circulate 1-2 days then,
They may also go through mitosis before differentiating into a macrophage within the connective tissues.
246
Which cells contain numerous small granules but they are not visible under the light microscope?
Which group is it in?
Monocytes and Lymphocytes.
Agranulocyte.
247
Agranulocytes: which has a kidney shaped nucleus and which has a slightly indented nucleus?
Kidney shape: Monocyte.
Indented: Lymphocyte.
248
What are the two types of lymphocytes?
B & T.
249
Long living leukocytes which mature in the thymus
T-Lymphocytes.
250
What are the two types of cells B & T lymphocytes can become?
Effector or Memory Cells.
251
Leukocytes with varying longevity, undetermined where they mature.
In Aves they mature in the Bursa of Fabricius.
B-Lymphocytes.
"Bursa-equivalent."
252
What are effector B-Lymphocytes called?
Function?
Plasma cells- Activated B-Lymphocytes.
Secrete antibodies.
253
How is a plasma cell made?
When a B-Lymphocyte is exposed to an antigen it will undergo mitosis and some of the cells will become effector B-cells/ AKA: Plasma Cells and secrete antibodies specific to that antigen.
254
T-Lymphocytes can undergo mitosis and differentiate into what 3 cells?
- Cytotoxic T-Cells.
- Helper T-Cells.
- Suppressor T-Cells.
255
Function of Cytotoxic T-Cells?
Recognize cells with foreign antigens on their cell membranes and lyse them.
256
Function of Helper T-Cells?
Assist B&T Cells.
In response to antigens will secrete factors which stimulate B cells and other leukocytes to destroy the "invader.".
257
Function of Suppressor T-Cells?
Suppress the immune response.
258
Function of memory Cells?
Has a "Memory" for previously encountered pathogens and alerts the immune system to initiate a swift response.
259
What is the smallest formed element?
Thrombocyte/ Platelet.
260
Where are thrombocytes derived from?
The are fragments of the Megakaryocyte- This is why they do not have any organelles. (endomitosis.)
261
What are the two regions of thrombocytes?
Granulomere: Central Purple staining portion
Hyalomere: Peripheral pale blue/ purple staining portion.
262
Where is 1/3 of the body's thrombocytes stored?
Spleen- This can be part of a trauma response to help with bleeding.
263
Where are platelets/ Thrombocytes derived from?
Megarkaryocytes Via Endocytosis.
