Histology of Connective Tissue Flashcards
Connective tissue is derived from _ germ cell layer
Connective tissue is derived from mesoderm germ cell layer
* Mesoderm also gives rise to muscle tissue
Two categories of connective tissue include _ and _
Two categories of connective tissue include connective tissue proper and specialized connective tissue
* Connective tissue proper is protecting and supporting organs/tissues/structures
* Specialized connective tissue has additional roles
Four types of connective tissue proper
Connective tissue proper provides resistance to pulling, stretching
Four types:
1. Dense regular connective tissue
2. Dense irregular connective tissue
3. Loose (areolar) connective tissue
4. Reticular connective tissue
Four main types of specialized connective tissue:
Four main types of specialized connective tissue:
1. Blood transports nutrients and oxygen
2. Cartilage provides template for bone growth
3. Bone home for hematopoietic precursor cells
4. Adipose tissue stores energy in form of lipids
How does the composition of connective tissue differ from epithelial, muscle, and nerve tissue?
Connective tissue (especially connective tissue proper) has abundant extracellular matrix
* The ECM carries out its main functions
* ECM is composed of fibers and amorphous ground substance
Fibers in the ECM are made of _ and they are really good at resisting _ forces
Fibers in the ECM are made of proteins and they are really good at resisting tensile forces
* Fibers run parallel in tendons to resist forces in the direction that the muscle produces force
Two types of fibers are _ and _
Two types of fibers are elastic and collagen
Elastic fibers are thin, structural proteins that allow for incredible elasticity due to a protein called _
Elastic fibers are thin, structural proteins that allow for incredible elasticity due to a protein called elastin
* Elastin forms the inner core of elastic fibers
* It is composed of short peptide chain that are cross-linked in a way that allows for extension and retraction
The cross-links of elastin are composed of two amino acids, _ and _
The cross-links of elastin are composed of two amino acids, desmosine and isodesmosine which are only found in elastin
Elastic fibers are found in tissues that need to stretch, expand, and return their shape such as _
Elastic fibers are found in tissues that need to stretch, expand, and return their shape such as walls of arteries, bronchi, bronchioloes, ligaments
The most common type of fiber found in the ECM is _
The most common type of fiber found in the ECM is collagen
Type _ collagen is found in bone, skin, tendons, dentin, ligaments, fascia, scar tissue, fibrocartilage, organ capsules, cornea
Type I collagen is found in bone, skin, tendons, dentin, ligaments, fascia, scar tissue, fibrocartilage, organ capsules, cornea
Type _ collagen is the most common among the collagen subtypes and makes up about 90% of the collagen in our body
Type I collagen is the most common among the collagen subtypes and makes up about 90% of the collagen in our body
The key function of type I collagen is to _
The key function of type I collagen is to resist tension
The stripy appearance to collagen is due to a complex, staggered arrangement of small molecules called _
The stripy appearance to collagen is due to a complex, staggered arrangement of small molecules called tropocollagen
Type _ collagen is found in the hyaline cartilage matrix
Type II collagen is found in the hyaline cartilage matrix
The nucleus pulposus of vertebral discs and the vitreous body of the eye is type _ collagen
The nucleus pulposus of vertebral discs and the vitreous body of the eye is type II collagen
The primary function of type II collagen is to _
The primary function of type II collagen is to resist pressure
* These fibers are thin
Hyaline cartilage appears smooth and glassy due to a blend between type II collagen and _
Hyaline cartilage appears smooth and glassy due to a blend between type II collagen and glycosaminoglycans
Type III collagen fibers are extremely fine and delicate; they provide structural support to _
Type III collagen fibers are extremely fine and delicate; they provide structural support inside hematopoietic organs like bone marrow, spleen, lymph nodes
Collagen III fibers are also called _
Type III collagen fibers are also called reticulin or reticular fibers
* Latin for network
* * Can be seen seen with silver stain
Vascular Ehlers-Danlos syndrome is a genetic disorder of connective tissues; specifically, EDS is a defect in _
Vascular Ehlers-Danlos syndrome is a genetic disorder of connective tissues; specifically, EDS is a defect in transcribing DNA/ translating mRNA that encodes type III collagen
What are the signs/symptoms of Ehlers-Danlos Syndrome?
EDS causes thin, easily buised, fragile skin that can sometimes be excessively stretchy
* Also causes hyperflexible joints
* Sometimes causes emergent rupture of bowel or large arteries since type III usually surrounds smooth muscle cells
Type IV collagen’s main function is to form _
Type IV collagen’s main function is to form meshwork of fibers in the basal lamina of basement membranes
* Functions to support and anchor epithelial cells
* Also aids filtration
* Scaffold for cell migration
_ is a watery, gelatinous, clear material that fills the space between fibers of the ECM and connective tissue cells
Ground substance is a watery, gelatinous, clear material that fills the space between fibers of the ECM and connective tissue cells
* Structured such that small molecules and metabolites can diffuse through it
* It acts as a barrier to invaders
* Also good lubricant
Ground substances also contain large molecules called glycosaminoglycans (GAGs), most of which are bound to _ to form _
Ground substances also contain large molecules called glycosaminoglycans (GAGs), most of which are bound to proteins to form proteoglycans
* Proteoglycans act as stabilizer and barrier for connective tissue
Ground substance also contains glycoproteins like _ which is a key protein in the basal lamina and fibronectin
Ground substance also contains glycoproteins like laminin which is a key protein in the basal lamina and fibronectin
What is fibronectin?
Fibronectin is an ECM component involved in wound repair, embryogenesis, and cell-to-cell adhesion
Macrophages, lymphoid cells, plasma cells, and granulocytes are all types of (transient/ resident) cells of the connective tissue
Macrophages, lymphoid cells, plasma cells, and granulocytes are all types of transient cells of the connective tissue
Pericytes, adipocytes, mast cells, and fibroblasts are all examples of (transient/ resident) cells of connective tissue
Pericytes, adipocytes, mast cells, and fibroblasts are all examples of resident cells cells of connective tissue
Pericytes
Pericytes are pluripotent cells that are similar to fibroblasts and play a role in modifying capillary blood flow
Fibroblasts
Fibroblasts are the “master chef”; they have the ability to make collagen, elastic fibers, other parts of the ground substance
How do we know if fibroblasts are active or inactive based on appearance?
Inactive fibroblasts have an oval nucleus with many nucleoli
Active fibroblasts have a fusiform shape and many golgi complexes and an extensive RER
(True/False) Fibroblasts normally undergo mitosis
False; Fibroblasts do not normally undergo mitosis
* Except when wound healing
We find dense regular connective tissue proper mainly in _ and _
We find dense regular connective tissue proper mainly in ligaments and tendons
* Parallel orientation makes dense regular good at withstanding tension in one direction
What are the key histologic features of dense regular?
Dense regular:
* Densely packed
* Parallel bundles of Type I
* Few fibroblasts and scant ground substance
What are the key histologic features of dense irregular?
Dense irregular:
* Densely packed
* Randomly oriented bundles of type I
* Few fibroblasts and scant ground substance
* Collagen bundles are in random/irregular directions
Where do we mostly find dense irregular connective tissue proper?
Dense irregular is normally found in organ capsules and the deep dermis of the skin
* Places that are susceptible to multidirectional pulling forces
What are the key histologic features of loose (areolar) connective tissue?
Loose (areolar) connective tissue:
* Numerous fibroblasts and fine collagen fibers interspersed with areas of clear ground substance
* Contains numerous cell types (fibroblasts, plasma cells, macrophages)
Where do we find loose (areolar) connective tissue?
Loose (areolar) tissue is mostly in the lamina propria of the GI tract, around vessels and nerves, upper dermis
What are the key histologic features of reticular connective tissue?
Reticular connective tissue:
* Type III collagen fibers in net-like arrangement
Where do we find reticular connective tissue?
Reticular connective tissue is found in the bone marrow, lymph nodes, and spleen
* Delicate, supportive framework
The most prevalent form of connective tissue in the body is _
The most prevalent form of connective tissue in the body is loose (areolar) connective tissue
* It serves as a packing material that fills in otherwise unoccupied spaces in the body
Reticular connective tissue is composed of type _ collagen
Reticular connective tissue is composed of type III collagen (reticulin) fibers, arranged in an interwoven, net-like pattern
