Connective T Flashcards
What is connective tissue
Comprises a diverse group of cells within a tissue-specific extracellular matrix
What are the functions of the connective tissue
Providing support and connections
Defense (site of inflammatory and immune reactions, physical barrier)
Nutrition (reservoir for water and electrolytes, stores energy in form of triglycerides (adipocytes), support blood vessels, passageway for nutrients and gases)
Energy is stored in the connective tissue in the form of
Triglycerides (adipocytes)
What is the structure of loose/areolar CT?
What is the purpose of loose/areolar CT?
Loosely arranged cell/ ground substances/ fibers
Supports epithelial tissue, surrounds blood vessels, fills spaces between muscles
Diffusion of oxygen/carbon dioxide and nutrients/wastes
Inflammatory and immune reactions
Provides structural support
In what form of connective tissue is diffusion of oxygen/co2 and nutrients/waste happening?
Loose/ areolar CT
What are the ground substances of connective tissue?
Glycosaminoglycans (GAGs)
Proteoglycans
Structural glycoproteins (laminin, Fn)
Water
What are the fibers that make up the connective tissue
Collagen fiber system(collagen & reticular fibers)
Elastic fiber system
Dense CT fibers structure
Prominent fibers, little ground substance
What is the purpose of the dense regular CT?
Where is the dense CT located?
Transmit force of muscle contraction
Attach muscles to bones
Protection
Tendons, ligaments, cornea
What is the purpose of the dense irregular CT?
Where is it located?
Provide tensile strength
Protection
Skin, GI tract
What are the resident cells in the CT?
Fibroblast
Macrophages
Adipocytes
Mast cell
Adult stem cells
What are the wandering cells in the CT?
Lymphocytes
Plasma cells
Neutrophils
Eosinphils
Basophils
Monocytes
What is the most abundant type of fibers in connective tissue?
Collagen fibers
How would you describe collagen fibers?
Are they flexible? What is their level of strength?
Wavy structures with variable width
Flexible
High tensile strength
What is the hydroxylation of collagen dependent on?
Vitamin C
Collagen polypeptides are initially synthesized in the ______ and then send to the _______ for multimeter assembly, which results in ______
Rough ER, Golgi, pro collagen
Procollagen is processed into ________ which can be used for ________ or the _______
Tropocollagen
Collagen fiber, collagen network
What is deficient in those affected by Scurvy?
What are the characteristics of this disease?
Vitamin C (ascorbic acid)
Bone disease in growing children and hemorrhages and healing defects in both children and adults
Vitamin C is a required cofactor for the addition of _____ groups to the ____ and ___ residues
Hydroxyl, proline, lysine
How does scurvy present in the oral cavity?
Symmetrical lesions without infection
What type of collagen make up reticular fibers?
Do these form a bundle or network
Type III
Network
How do we stain reticular fibers? Why
Silver salts because of the high content of sugar
Where are reticular fibers found?
What produces these fibers?
Support hematopoietic and lymphoid organs (except thymus)
Reticular fibers
What does type I collagen form?
Where is it found?
What purpose does it serve?
Fibers
Dermis, tendon, bone, fibrocartilage
Resistance to tension
What does type II collagen form?
Where is it found?
What is its purpose ?
Fibers
Hyaline cartilage, Intervertebral disc
Resistance to pressure
What does type II collagen form?
Where is it found?
What is its purpose ?
Fibers
Hyaline cartilage
Intervertebral disc
What does type III collagen form?
Where is it found?
What is its purpose?
Fibers
Reticular connective tissue
Maintenance of expansible organs
What does type IV collagen form?
Where is it found?
What is its purpose?
Networks
Basal lamina
Supports delicate structures and filtration
In relation to other collagen fibers, elastic fibers are ____ (thicker/thinner)
Thinner
What is the purpose of elastic fibers?
Responsible for elasticity, resilience, and shape control
Allow tissues to respond to stretch and distension
What is the structure of an elastic fiber?
Core protein = elastin
Two unique AA = desmosine & isodesmosine which covalently link elastin monomers together
What is the cause of osteogenesis imperfecta?
What are the symptoms ?
Defective synthesis of collagen (normally type I)
Brittle bones, blue sclera
What are the clinical features of Ehlers-Danlos syndromes?
What is defective?
Fragile, hyperextensible skin vulnerable to trauma
Hyper mobile joints
Poor wound healing
Defects in collagen synthesis or assembly
What defect causes Marfan syndrome?
What are the clinical features?
FBN1 gene (encodes fibrin) = lack of resistance in tissues rich in elastic fibers
Tall stature, long fingers, bilateral subluxation of lens, mitral valve prolapse (**heart problems)
What is ground substance?
What is the purpose
Colorless, hydrated
Fills space between cells and fibers
What are the functions of ground substance?
Lubricant (high viscosity)
Allows diffusion of water soluble molecules
Anchors cells through cell-ECM adhesion
path for cell migration
binds/retains growth factors
via cell adhesion molecules information is transmitted across the PM
What types of macromolecules make up ground substance?
Glycosaminogylcans (GAG)
Proteoglycans
Glycoproteins
What are examples of GAG in the ground substance?
Dermatan sulfate
Keratin sulfate
Hyaluronic acid
What purpose does dermatan sulfate serve?
Meditation of wound repair, fibrosis
What purpose does keratan sulfate serve?
Related to cell motility, axonal guidance and embryo implantation
What purpose does hyaluronic acid serve?
Very important in development because it is a major component of mucous connective tissue which is found in the umbilical cord
Major component of cartilage (resists compression, promotes flexibility, shock absorber)
important for immobilizing growth factors
insulator, prevents diffusion
What are some examples of Proteoglycans in the ground substance?
Aggrecan, syndecan
What is the purpose of aggrecan?
Related to hydration of the ECM
What is the purpose of syndecan?
facilitated interaction between the proteins of the ECM and the actin cytoskeleton
What are some examples of glycoproteins in the ground substance/
Integrity, fibronectin, laminin
What is the purpose of integrin?
Binds cells to ECM
What is the purpose of fibronectin?
Binds many ECM components, attach to integrins
What is the purpose of laminin?
Mediating attachment to the basement membrane
Glycosaminoglycans appear in the ground substance as ___
Unbranched polysaccharide chains
Proteoglycans appear in the ground substance as ___
Large macromolecules with protein core
How is HA present in the ground substance?
What other ground substance element does it binds to and what do they form?
Free carbohydrate chain; not covalently bound to protein
Proteoglycans, forms giant aggregates
Mutliadhesive glycoproteins facilitate attachment between ________________
Cell to CT element
CT element to CT element
What are hyaluronidases?
What are their functions?
What can release these?
Enzymes that degrade hyaluronic acid (lowers the viscosity of the CT - increases tissue permeability)
bacteria will release in order to infiltrate cell
What are the outcomes of degradation of HA by hyaluronidases?
Lowers the viscosity of CT and therefore increases tissue permeability
What is the most common cell type
Fibroblasts
What is the structure of fibroblasts?
Spindle shaped cells with elliptic nucleus, thin cytoplasm
How often do fibroblasts divide?
When would they do this?
Rarely
In response to injury and inflammation
(Myofibroblasts)
What are macrophages and what are their purpose?
Phagocytic cells that contain lysosomes and residual bodies
Initiate immune response
Secrete hydrolytic enzymes
How do macrophages initiate an immune response?
Releases cytokines
Present antigens to lymphocytes
What is the structure of Mast cells?
Where do they arise from?
What do they express on their surface?
Oval to round cells with microvilli, nucleus central
Multipotent hematopoietic stem cells in bone marrow
IgE
What are the functions of adipose tissue?
Main energy stores (depot for triglycerides)
-Insulates body against heat loss
Fills space between tissues
-Provides cushions (shock absorption) : soles of feet, around kidney, in the orbit around eye
paracrine and endocrine substances
-secretes leptin (regulate food intake and energy consumption)
Where would you find adipose tissue In the body?
Soles of feet, around kidney, in the orbit around the eye
What type of stem cells to adipocytes originate from?
What are the two types?
Mesechymal stem cells
Unilocular/white & multiocular/brown
What are the purpose of white adipocytes?
What do they look like?
Metabolic energy storage, insulation, cushioning, hormone production
Flattened nucleus on periphery, one large lipid droplet surrounded by a ring of cytoplasm
What are the purposes of brown adipocytes?
What do they look like?
When are these present?
Heat protection/thermogenesis
Multiple lipid droplets, eccentric nucleus & numerous mitochondria
Fetal life and first decade after birth
What are the ‘wandering cells’ in the CT
Eosinophils, basophils, monocytes, lymphocytes, neutrophils
What are plasma cells derived from?
What do they look like?
What is their purpose
Lymphocyte derived
Oval cell, eccentric “wheel/clockface” nucleus ; little cytoplasm
“golgi ghost”=light staining area next to nucleus
Antibody producing cells
How do leukocytes (WBC) get into connective tissue?
When does this process increase?
Diapedesis : WBC leaves blood by migrating between epithelial lining of capillaries to enter CT
During inflammation
How do leukocytes (WBC) get into connective tissue?
When does this process increase?
Diapedesis : WBC leaves blood by migrating between epithelial lining of capillaries to enter CT
During inflammation
where is embryonic CT?
when does it disappear?
umbilical cord, after birth
the lamina propia is made of which type of connective tissue?
loose CT
how can you differentiate loose CT from dense?
loose has more cells, more ground substance, and fewer fibers
in h& e staining, loose connective tissue stains _____ than other CT because
Less (lighter appearance)
less fibers = less red
where are elastic fibers synthesized by fibroblasts?
chondroblasts ?
smooth muscle?
skin and tendons
in elastic cartilage
large blood vessels
why are elastic fibers present in the aorta?
blood pressure changes drastically, allows it to stretch and recover easily
giant aggregates of proteoglycans and HA are hydro______
philic
what are matrix metalloproteinases? (MMPs)
what releases them?
tissue remodeling/ depredations of ECM
cancer cells!
tumor invasion, metastasis, tumor angiogenesis require participation of MMPs (expression increases in association with tumorigenesis)
what do monocytes differentiate into? Where are the monocytes found?
macrophages
bone marrow—->blood (differentiate in tissues)
how do mast cells appear?
what can they contain?
lots of secretory granules!
secrete heparin,histamine, vasoactive mediators, chemotactic factors
Asthma/allergies are related to which cells?
mast cells (secrete histamine)
