Provides structural and metabolic support Carries blood vessels; tissue repair Mediates exchange of nutrients/ metabolites/ waste products between tissue & circulation

a glycoprotein; precursor proteins produced by fibroblasts at least 28 different types identified, based on AA sequence Principle fiber in extracellular matrix—provides tensile strength

Connective Tissue Flashcards by Nhukha nguyen

Connective Tissue

Provides structural and metabolic support
Carries blood vessels; tissue repair
Mediates exchange of nutrients/ metabolites/ waste products between tissue & circulation

How well did you know this?

Not at all

Perfectly

where is primitive connective tissue-derived?

derived from mesodermal mesenchyme—contains stellate to spindle-shaped cells, jelly-like extracellular matrix, & occasional fibers

How well did you know this?

Not at all

Perfectly

Mature connective tissue contains?

contains cells& extracellular material secreted by cells

How well did you know this?

Not at all

Perfectly

Fibroblasts structure and function

Structure: pointed, elongate, spindle-shaped cells
Function: Synthesize & maintain proteinaceous ground substance & connective tissue fibers (collagen, elastin, & reticular fibers)

How well did you know this?

Not at all

Perfectly

myofibroblasts

Fibroblasts with contractile ability

How well did you know this?

Not at all

Perfectly

Reticular cells structure, synthesized, and function?

Structure: of lymph nodes & bone marrow; a type of fibroblast
Synthesized: reticular fibers (made of reticulin); by regular fibroblasts in some tissues
Function: may have a phagocytic function;

How well did you know this?

Not at all

Perfectly

what are reticular cells morphologically similar to?

primitive mesenchymal cells; look like branched fibroblasts

How well did you know this?

Not at all

Perfectly

Adipocytes structure and function

Structure: Generally large, balloon-shaped, clear spaces filled with “lipid”
Function: responsible for storage & metabolism of lipids

How well did you know this?

Not at all

Perfectly

Extracellular organic matrix is also known as what?

ground substance

How well did you know this?

Not at all

Perfectly

Extracellular material

Various fibers embedded within matrix (e.g., collagen, reticulin, & elastin)
Each type of fiber has different chemical make-up and characteristics

How well did you know this?

Not at all

Perfectly

Collagen

a glycoprotein; precursor proteins produced by fibroblasts
at least 28 different types identified, based on AA sequence
Principle fiber in extracellular matrix—provides tensile strength

How well did you know this?

Not at all

Perfectly

Type I Collagen

90% of collagen in body

- Loose & dense connective tissue of skin, tendons, ligaments, bone & fibrocartilage

How well did you know this?

Not at all

Perfectly

Type II collagen examples

hyaline and elastic cartilages

How well did you know this?

Not at all

Perfectly

Type III collagen (made of reticulin fibers)

Reticulin fibers; thin, branching, net-like fibers
•For structural support in organs (e.g., liver, spleen, lymph nodes, bone)
•Produced by reticular cells in lymph nodes & bone marrow & by fibroblasts elsewhere

How well did you know this?

Not at all

Perfectly

Argyrophilic

Seen in type III collagen, stains black with silver stain

How well did you know this?

Not at all

Perfectly

Type IV collagen

found in basement membrane; doesn’t form fibers

How well did you know this?

Not at all

Perfectly

Type V

cornea, placenta, dermo-epidermal junctions

How well did you know this?

Not at all

Perfectly

what is the best-known collagenopathy?

Ehlers-Danlos syndrome= Affects Type V collagen; Characterized by hyperextension of joints, skin fragility, & poor wound healing

How well did you know this?

Not at all

Perfectly

Collagen synthesis steps:

synthesized as procollagen form triple helix
Packed into secretory vesicles & secreted into ECS
extracellular enzymatic modification to form tropocollagen monomers
Polymerization of tropocollagen into final formation of collagen microfibrils
Several microfibrils combine to form larger collagen fiber; several fibers make up collagen bundle

How well did you know this?

Not at all

Perfectly

procollagen

composed of three alpha polypeptide chains

How well did you know this?

Not at all

Perfectly

Elastin fibers structure and synthesized

Structure: Highly branched; random coiling pattern allows stretching; arranged in fibers & sheets; refractile
Synthesized: by fibroblasts as tropoelastin precursor; polymerizes in ECM to form elastin

How well did you know this?

Not at all

Perfectly

what are the 2 components of elastic fibers

elastin and fibrillin

elastin

protein core similar to collagen, surrounded by microfibrils of fibrillin(structural glycoprotein)

Marfan’s syndrome

Autosomal dominant condition resulting in abnormal elastic fibers
Characterized by tall stature, long limbs, and long, thin fingers
Enlarged aorta, with ↑ regurgitation and ↑ risk of developing a dissecting aneurysm

Glycoproteins

Fibrillin& fibronectinare structural glycoproteins—large polypeptides with branched polysaccharide side chains

Fibronectin location and function

Location: basement membrane Function: aids in adhesion between cell membrane & extracellular matrix, via interaction of adhesion molecules known as integrins

Types of non-filamentous molecules (3)

1. laminin 2. entactin 3. tenascin

laminin

sulfated glycoprotein; major component of basement membrane; produced by most epithelial & endothelial cells

entactin

sulfated glycoprotein; binds with laminin

tenascin

binds cells to extracellular matrix; thought to be important in cell migration in developing nervous system

Ground substance

* Amorphous, transparent material with properties of a semi-fluid gel * Long, unbranched polysaccharide chains of repeating disaccharide units

One of the two sugars is always an amino sugar... what are they

either n-acetyl glucosamine or galactosamine

mucopolysaccharidoses

Non-functional or insufficient lysosomal enzymes => lysosomal storage diseases,

what is glucosaminoglycan(GAG) equalized to?

= mucopolysaccharide(MPS)

sulfated GAG examples

chondroitin sulfate, heparan sulfate

proteoglycans (= mucoproteins)

mostGAG’s covalently bind to protein molecules to form

5 types of GAG's

1. Hyaluronic acid 2. Chondroitin sulfate 3. keratan sulfate 4. dermatan sulfate 5. heparan sulfate

Hyaluronic acid (=hyaluronate)

- found in most connective tissue - Predominant GAG in loose connective tissue - Lacks sulfated side groups - thousand sugars long - Does not form proteoglycans itself, but can bind with them - Ground substance is impervious barrier to microorganisms

Chondroitin sulfate

found in cartilage & bone

keratan sulfate

found in cartilage, bone, cornea & intervertebral disk

dermatan sulfate

found in dermis of skin, blood vessels, & heart valves

heparan sulfate

found in basement membrane, lung, liver

why dont GAG's compact well?

- Negatively charged due to sulfate & carboxyl side groups => hydrophilic => gel formation - Ground substance mostly GAG’s (1’ hyaluronic acid), proteoglycans, & water--Incompressibility of water provides turgor pressure of connective tissue - Reinforced with fibrous proteins

what produces hyaluronidase?

pathogenic bacteria to destroy ground substance barrier and facilitate their spread

Forms of connective tissue (2)

- Loose | - Dense

Loose (areolar) connective tissue

* Sparse fibers & abundant ground substance => viscous, gel-like consistency * Supportive function * Located beneath epithelia & around Nn & vessels

Dense connective tissue

Provides structural support—abundant fibers, moderate # of cells, lesser ground substance

Types of dense connective tissue

1. Regular | 2. Irregular

Regular dense connective tissue

- collagen fibers oriented parallel to each other | - Densely packed fibers & cells arranged in fascicles(e.g., ligaments, tendons, & aponeuroses)

Irregular dense connective tissue

- collagen fibers oriented randomly | - Moderate number of fibers & few cells

what does specialized connective tissue include?

- bone, blood, cartilage, adipose tissue, hematopoietic tissue, & lymphatic tissue - Also mesenchymal & mucus connective tissue (limited to embryo)

Adipose Tissue

- Contains adipocytes—cells derived from lipoblasts—primitive mesenchyme adapted for storing fat (1’ triglycerides) - Fat energetically very active, has rich blood supply - Function: energy storage, thermo regulation & shock absorber

White fat (=unilocular)

- distributed in dermis & around intraperitoneal organs | - Up to 20% of body wt in males, 25% in females

Brown fat (=multilocular)

- highly specialized - present in infants & hibernating animals - Used in thermoregulation to maintain body temperature - In humans, located ~adrenals - Large #’s of mitochondria => heat