Connective Tissue Flashcards by sophia cordova

Elements of connective tissues

Extracellular matrix
- ground substance
- protein fibers (collagen, elastic, reticular)

Resident cells
- mesenchymal
- macrophages
- adipocytes
- fibroblast

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Connective tissue functions

Matrix to support and physically connect tissues to form or
Metabolic support
Diffusion of nutrients and waste
Defense
Protect
repair

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What does connective tissue drive from?

Mesenchyme

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Types of connective tissue

Proper: loose/dense and regular/irregular

Special properties: adipose, elastic, mucous, hematopoietic

Supporting: cartilage and bone

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Loose connective tissue

Low collagen
High cells
High ground substance

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Dense connective tissue

High collagen
Low cells
Low ground substance

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What is the most abundant type of connective tissue

Loose connective tissue
- Most cell types present

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Where is loose connective tissue located

Under epithelia
- forms storma (non essential)

Fills space between tissue and organs
Sheaths lymphatics and blood vessels

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Dense regular vs dense irregular CT

Dense regular ct:
- collagen bundles are aligned in parallel
- tendons and ligaments

Dense irregular ct:
- collagen bundles are randomly arranged
- skin and stomach

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dense regular CT locations

tendons and ligaments

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Extracellular matrix composition

Fibers
Proteoglycans
Multi-adhesive glycoproteins

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Three main types of fibers

Collagen fibers — collagen 1

Reticular fibers — collagen 3

Elastic fibers — elastin

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What is the most abundant protein in the body?

Collagen

30% of dry weight
20+ types produced (mostly by fibroblasts)

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General role of collagen

Resist tension and shear forces

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Assembly of collagen

Peptide chains
Pro collagen
Tropocollagen
Collagen fibrils
Collagen fibers

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Osteogenesis imperfecta

A genetic disorder that causes collagen formation to be incorrect or not enough (collagen I)

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Collagen I fiber

Most abundant
Resist stretch
Provide tensile strength
Found in dermis, organ capsules, bone, tendons, fibrocartilage, scar tissue

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Keloid scar

Excess collagen in wound healing
Collagen I fibers
Causes large scars

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collagen types (locations/synthesis/function)

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Reticular fibers

Collagen III
Smaller than type 1 collagen, no bundles
Provide structural framework and stability

Found in: Extensible organs (stretching)
Artery walls
Intestines
Uterus
Endocrine glands
Liver endometrium
Stroma of smooth muscle and hematopoietic organs

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Collagen synthesis

Occurs in RER

proline hydroxylated to hydroxyproline
- requires Vitamin C

Collagenases or matrix metalloproteases (MMR) chew up collagen and remodel the ECM

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Elastic fibers

ELASTIN core surrounded by fibrilin

Add resiliency to CT

Maintain extensible organs (expand)

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Ground substance composition

Glycoconjugates (polysaccharides)
- glycosaminoglycans GAGs
- proteoglycans
- structural/adhesive glycoproteins
Tissue Fluid

Ground substance function

Store electrolytes and water
shock absorption
lubrication (form viscous barrier)
attachment and movement of cells in EMC

Glycosaminoglycans

GAGs Keratin sulfate & heparin sulfate Linear chain of repeating disaccharides Negatively charged (hydrophilic)

Proteoglycans

GAGs + protein backbone “Bottle brush” Hydration Viscous, resists compression

Proteoglycans aggregate

Aggrecan : Proteoglycans attached to a hyaluronic acid polymer Holds water Lubricates joints and organs

Structural/Adhesive Glycoproteins

Attach to ECM vie INTEGRIN receptors - fibronectin & laminin

Permanent/resident cells

Fibroblasts Macrophages Mast cells Adipocytes

Fibroblasts

Permanent/resident cell Most abundant Secret ground substance and fibers

Macrophages

Permanent/resident cells Wound repair Sensing damage (histocytes) Phagocytosis Secrete cytokines/enzymes Phagocytic cell derived from monocytes and yolk sac progenitors CT resident macrophages: histocytes

Mast cells

Permanent/resident cells Inflammatory response HISTAMINE/HEPRIN/LEUKOTRIENES Found in dermis, respiratory tract, digestive tract Long lived Derived from precursor in bone marrow

Adipocytes

Permanent/resident cells Whole body metabolism Store lipids Insulate Make hormones Single lipid droplet, flattened nucleus

Transient cells

Lymphocytes Plasma cells Neutrophils Eosinophils

Lymphocytes

Transient cells T lymphocytes: produce plasma cells B lymphocytes: helper and cytotoxic cells Few in CT

Plasma cells

Transient cells Short-lived "clock-face" derived from B-lymphocytes Produce ANTIBODIES

Neutrophils

Transient cells Respond to tissue damage and infection Lobed nucleus and granules

Eosinophils

Transient cells Inflammatory/infection Reddish orange granules

What cells release histamine?

Mast cells

anterior cruciate ligament *parallel collagen fibers and few fibroblasts

A patient was seen in the ER after she fell while biking. The doctor determined that she had torn a structure in her lower leg. a biopsy of this structure shows numerous collagen bundles arranged in parallel and few visible cells. What structure is this? -crural fascia -peroneal tendon -skin epidermis -tibialis anterior muscle -tibial nerve

peroneal tendon dense regular connective tissue (tendons): arranged in parallel and few cells

An 8-year-old female presents in the ED with hives, itching, dizziness, and shortness of breath following an insect bite. What connective tissue cell is most likely responsible for her symptoms? adipocytes eosinophils fibroblasts macrophages mast cells

mast cells mast cells: resident cells of CT that contain many granules rich in histamine and heparin. inflammatory process. allergic reactions = mast cells eosinophils= inflammation and asthma macrophages/fibroblasts= secrete ECM adiocytes= store energy

a 50-year-old woman presents with multiple oral blisters and a few blisters on her back. Blood tests reveal antibodies to a set of protein antigens and immunostaining of an oral mucosal biopsy shows the antigen throughout the epithelial layers. What structure is the defect? a. aquaporin water channels b. desmosomes c. gap junctions d. hemidesmosomes e. tight junctions

b. desmosomes

which CT component is located in the ECM but not in the ground substance? a. collagen bundles b. fibronectin c. glycosaminoglycans d. hyaluronic acid e. proteoglycans

a. collagen bundles ECM = ground substance + fibers *ground substance fills the space between fibers ground substance = water, GAGs, proteoglycans, glycoproteins, fibronectin, laminin

What cell produces hormones that are important for metabolism and stores energy?

adipocytes

research scientists are attempting to create methods to prevent the movement (metastasis) of malignant tumors. a new drug is marked that triggers the apoptosis (cell death) pathway by disrupting a cell's ability to adhere to the basement membrane. what is the target of this drug? cadherins demoplakin fibrilin integrins occludens

integrins integrins are receptors that help cell-to-cell and cell-to-ECM adhesion. the ligands that bind these integrins are fibronectin and laminin. desmoplakin: desmosomes - cell-to-cell attachment fibrillin: elastic fibers occludens: tight junctions

a child is seen in the clinic for "fragile skin". Skin breaks and blisters easily. Pt has a mutation in the gene coding for keratin 5, an intermediate filament that is expressed in basal cells of the epidermis. the oral cavity is NOT sensitive to stress. the reason for this difference is most likely that epithelial cells in the child's oral cavity: a. are ciliated b. do not attach to a basal lamina c. express different keratin genes d. lack desmosomes e. produce mucous

c. express different keratin gens oral cavity epithelial do not express high levels of keratins

is skin and oral epithelia ciliated?

which of the following cells produce the major protein component found in high abundance if scars? a. adipocytes b. fibroblasts c. macrophages d. mast cells e. plasma cells

b. fibroblasts fibroblasts produce Collagen I, found in scar tissue

what feature of epithelial cells contributes to their role in selective permeability and surface specialization?

polarity with distinct apical and basal surfaces

what best describes a unique characteristic of epithelial cells that aids in their protective function?

tight junctions between cells that create a continuous barrier

Individuals with Marfan's syndrome have a genetic mutation that impairs fibrillin synthesis in CT, resulting in abnormalities of the ocular, musculoskeletal, and CV systems. Which cell type would this mutation lead to abnormalities?

fibroblasts fibroblasts secrete fibrillin (ECM)

mast cells MAST CELLS = ALLERGIC REACTIONS