Lecture 6: Connective Tissue Flashcards
(43 cards)
1
Q
Definition of Tissue?
A
- Plentiful extracellular matrix surrounding scattered cells
- (Connective Tissue is one of the 4 types of basic tissues [others are epithelium, muscle, and nervous])
2
Q
4 types of connective tissue?
A
1) Blood
2) Supportive Connective Tissue (cartilage and bone)
3) Adipose Tissue
4) Connective Tissue Proper
3
Q
6 Functions of Connective Tissue?
A
1) Support
2) Packing
3) Diffusion Medium
4) Defense
6) Storage
4
Q
How does connective tissue function as a Diffusion Medium?
A
- Nutrients pass from capillaries to tissues via connective tissue (can be a filter)
- Metabolites pass from tissues back to capillaries
5
Q
How does connective tissue function for defense?
A
- Bacteriostatic (stops movement of bacteria w/in tissues)
- Inflammatory responses (battleground for body’s defense system)
6
Q
2 major components of Connective Tissue Proper?
A
- Expanded Extracellular Matrix (broth and noodles)
- Resident Cells (chicken)
7
Q
3 major components of the Expanded Extracellular Matrix (ECM)?
A
- Amorphous Intracellular Ground Substance (broth)
- Adhesive Glycoproteins
- Fibers (noodles)
8
Q
What is Amorphous Intracellular Ground Substance in general?
A
- colorless semi-fluid gell
- fills spaces between cells and fibers
- indistinguishable with light microscopy
- Contain proteoglycans and glycoprotens
- capacity to retain a large amount of tissue fluid
9
Q
What does Amorphous Intracellular Ground Substance contain?
A
- Proteoglycan monomer
- GAGs
- Cations (Na+, K+, Ca++)
- Hyaluronic acid
10
Q
What is a proteoglycan momomer in ECM?
A
single polypeptide with covalently attached GAGs
11
Q
What are Glycosaminoglycans (GAGs) and what are their functions in ECM?
A
- chains of repeated disacharides
- one sugar is uronic acid, and other is amino sugar
- many amino sugars sulfated (strong - charge)
- bind cations (Na+, K+, Ca++) and water to make ground substance hydrated and viscous
12
Q
What is Hyaluronic acid and what is its function in ECM?
A
- single very long GAG chain
- non-covalently binds proteoglycan monomers to form proteoglycan aggregate
- aggregate occupies large space in ECM, binds collagen fibers to maintain integrity of ECM gel
- Hyaluronidase released by some bacteria, breaks down ECM
13
Q
What are Adhesive Glycoproteins’ general function in ECM?
A
- Important in Binding ECM fibers and cells together
- Present in relatively small amounts
- Have wide distribution
14
Q
What makes up the Adhesive Glycoprotein part of ECM?
A
- Fibronectin
- Laminin
- Integrins
15
Q
What is Fibronectin and what is its function in ECM?
A
- large multifunctional protein
- Domains(distinct polypeptide regions) of fibronectin are recognition sites for cell surface receptors, GAGs, and collagens
16
Q
What is Laminin and what is its function in ECM?
A
- adhesive glycoprotein present in basal laminae
- 3 molecules twisted around eachother
- contains sites for binding integrins, proteoglycans, and collagens
- recognition of laminin by cell surface integrins binds cells to basal laminae (crosslinker)
17
Q
What are integrins and what are their functions in ECM?
A
- transmembrane proteins, are cell surface receptors for fibronectin and other ECM components
- bind to basal laminae
- their cytoplasmic domain links to the cytoskeleton and several enzymes
- Enzyme locations and activities regulate cellular behaviors
- Metastatic movements of cancer cells depend on these integrins and interactions with adhesive glycoproteins. Cell movements through basal laminae and along ECM fibers
18
Q
What are Fibers in ECM?
A
- elongated, formed extracellular protein structures
- 4 types: collagen, reticular fibers, basal lanimae, and elastic fibers
19
Q
What is collagen and what is its function in ECM generally?
A
- Long thin protein-containing extracellular fibers stain blue with triple stain, and pink with H&E
- form chief proteins in bone, tendon, and skin
- Collagenase synthesized by many tumor cells and bacteria, inc invasiveness in CT
20
Q
Most abundant collagens in ECM?
A
Types I, II, III, and IV
21
Q
What is type I collagen and where is it found?
A
- regular or irregularly arranged bundles and layers in dense CT
- have high tensile strength
- do not stretch, tough to break
- synthesized by the fibroblast
- found in dermis, fascia, bone, ligaments and tendons
22
Q
What does type II collagen form and where?
A
- Fibrils (not fibers) in hyaline and elastic cartilage
23
Q
What does Type III collagen form and where?
A
- form reticular fibers
- found in skin, blood vessels, glands, lymphoid tissues
24
Q
Where is type IV collagen found?
A
- basal and exterminal laminae of epithelia, muscle, fat and nerve tissues
25
What does extracellular processing of collagen include?
* _proteolysis_ of _end peptides_
* _spontaneous assembly_ of fibrils of tropocollagen
* enzymatic _crosslinking_ of tropocollagen by lysine oxidase
26
What is the order of parts (smallest to largest) that make up collagen?
1. Fibrils: are regular arrays of long _tropocollagen_ molecules. bind with eachother and other ECM proteins to form:
2. Collagen Fibers
3. Collagen bundles
27
What are Reticular Fibers made of and where are they found in ECM?
* Contain type III collagen fibrils and glycoproteins
* thin fibers stained by silver stains
* lie beneath basal lamina and surround muscle and other cells
* support and bind cells
28
What does the Basal Laminae consist of and what is its function?
* contain collagen type IV (doesn't assemble into fibrils, assemble into an open network that is 2D scaffold for assembly of other proteins into basal laminae)
* support all epithelia and in external laminae surrounding muscle fibers and Schwann cells
* along with the underlying reticular lamina, make up the _Basement membrane_
29
What do Elastic Fibers contain and what is their function in ECM?
* highly refractile
* branch and contain protein, elastin (gives them their elasticity
* _stain yellow-orange with triple stain_
30
What does Elastin contain and what is its function?
* contain many hydrophobic amino acids
* when stretched, avoid aqueous environment, and fold back when tension is released (elasticity)
31
What are the 3 resident cells (non-motile) of Connective Tissue Proper?
1. Fibroblasts
2. Mast cells
3. Fat cells (store fat)
32
What do Fibroblasts do in ECM?
* most common cell
* involved in synthesis of CT fibers and ground substance
* structural function
33
What do Mast Cells do in ECM?
* secretes pharmacologically potent mediators when stimulated _(histamine_ and _heparin_)
* important in allergic responses (defense function)
* resemble blood basophil in structure
34
What are the 4 Immigrant Cells of Connective Tissue Proper?
1. Macrophages
2. Plasma Cells
3. Neutrophils
4. Other blood cells (lymphocytes, eosiniphils [stain intense red])
35
What are Macrophages' role in ECM?
* arise from blood monocytes
* involved in phagocytosis, play critical role in immunity (defense)
36
What does phagocytosis involve?
* involves extension of cytoplasmic projections
* surround a target, incorporate it into a vesicle that fuses with granules and lysosomes containing lytic enzymes
37
What are Plasma Cells' role in ECM?
* Found in subepithelial connective tissue
* derived from B-lymphocytes
* produce antibodies (immunologic function)
38
What are Neutrophil's role in ECM?
* other phagocytic cell of the immune system (defense function)
* most numerous
* most important cellular component of innate immune response
39
What are the 3 subtypes of Irregularly Arranged Adult Connective Tissue Proper?
1. Loose Connective Tissue (ex. areolar)
2. Dense Connective Tissue
3. Special Connective Tissue
40
What is the most widely distributed irregularly arranged connective tissue?
Loose Connective Tissue
| (more cells, less fibers)
41
Where is Dense Irregular Connective Tissue found?
* found in organ capsules, dermis of skin, joint capsules, and aponeuroses
* (more fibers[thicker], less cells)
42
What are the two types of Special Irregular Connective Tissue?
1. Adipose (loose CT, fat cells predominate)
2. Reticular (reticular fibers abundant)
43
What is a well organized (fibers arranged in same direction) type of connective tissue where fibers predominate, and where is it found?
* Regularly Arranged Dense Connective Tissue
* found in tendons and ligaments
