Exam #2: Connective Tissue

Question 1

Migratory Cells in Connective Tissue

Answer 1

• Plasma Cells

- Leukocytes (Neutrophils & Monocytes)

Question 2

Fixed Cells in Connective Tissue

Answer 2

• Fibroblasts
• Myofibroblasts
• Adipocytes
• Mast Cells
• Macrophages

Question 3

What are the four functions of connective tissue?

Answer 3

1) Structure
2) Defense/ Protection
3) Nutrition
4) Cushion & Insulation

Question 4

What is the most undifferentiated type of a connective tissue cell? What are they derived from?

Answer 4

• Undifferentiated mesenchymal cell

- Mesoderm & neural crest cells

Question 5

What cell types can an undifferentiated mesenchymal cell become?

Answer 5

• Chondroblast = cartilage
• Adipocyte= Fat
• Fibroblast= Collagen/ ECM
• Osteoblast= Bone

Question 6

Characteristics of an Active Fibroblast

Answer 6

• Euchromatic nucleus
• rER= very intense basophilic cytoplasm
• Golgi Apparatus
• Mitochondria
• Many processes that increase SA

Question 7

Characteristics of an Inactive Fibroblast

Answer 7

• Decreased volume
• Less rER
• Less robust Golgi
• Heterochromatic nucleus

Question 8

What is the effect of cortisol on fibroblasts?

Answer 8

• Cortisol decreases the activity of fibroblasts & decreased synthesis of connective tissue elements
• Degradation of connective tissue elements including bone (osteoporosis)

Question 9

How do the nuclei of inactive fibroblasts differ from active fibroblasts?

Answer 9

Inactive fibroblasts have a very prominent basophilic nucleus because they are heterochromatic

Question 10

How do fibroblasts change in wound healing?

Answer 10

1) Much more active
2) Greater tendency to divide
3) Light (euchromatic) & more spherical nucleus
4) Multinucleated
5) More robust cytoplasm

Question 11

What important steps of collagen formation occur in the rER?

Answer 11

1) Formation of triple helix

2) Vitamin C dependent hydroxylation of prolyl & lysyl residues (Scurvy)

Question 12

What is the function of collagen pro-peptides?

Answer 12

Maintain the solubility of the structure

Question 13

What contains the procollagen peptidases that cleave pro-collagen into collagen?

Answer 13

ECM

Question 14

Myofibroblast

Answer 14

• Possess characteristics of fibroblast & smooth muscle
• Contains actin & myosin for contractile activity
• Become more numerous in wound healing

Question 15

Dupuytren’s Contracture

Answer 15

• Microvascular ischemia of the palmar aponeurosis leads to increased activity of fibroblasts & myofibroblasts
• Increased type III collagen synthesis occurs
• Type III collagen cross links with myofibroblasts
• Type III collagen/ myofibroblast cross-links lead to contracture of digits 4 &5

Question 16

How do white adipocytes appear in a micrograph?

Answer 16

• As signet rings (the large space is where the lipid droplet was)
• Nucleus is located in the periphery
• Stippling seen is vimentin

Question 17

What is vimentin?

Answer 17

Intermediate filament of adipocytes

Question 18

Leptin

Answer 18

• Hormone synthesized by adipocytes that indicates satiety

- Mutation in leptin leads to morbid obesity

Question 19

Lipodystrophy

Answer 19

• Disorders that affect the distribution of fat on the body

- Can be caused by a defect in Lamin (intermediate filament associated with the nucleus)

Question 20

How do brown adipocytes differ from white adipocytes?

Answer 20

• Multilocular (multiple fat droplets per cell) vs. Unilocular
• Nucleus is centrally located vs. peripheral
• Acidophilic b/c of a large volume of mitochondria

Question 21

What is the function of brown fat cells?

Answer 21

Production of heat, especially in newborns

Question 22

What is the signature feature of mast cells?

Answer 22

Metachromatic granules

Question 23

Characteristics of Mast Cells

Answer 23

• Metachromatic granules
• Large centrally located nucleus
• Packed with secretory granules (histamine, heparin, chemotaxic factors)

Question 24

Histamine

Answer 24

Vasodilation

Question 25

Leukotryenes

Answer 25

Produce bronchoconstriction & incude vaso-permability that is typical of anaphylaxis

Question 26

What induces mast cell to release their contents?

Answer 26

Fc Receptor binding to antigen/antibody complex

Question 27

What cell type are macrophages derived from?

Answer 27

- Monocytes | - Monocytes migrate into the connective tissue and morph into macrophages

Question 28

What are the different types of marcophages?

Answer 28

- Microglia (CNS) - Kupffer Cells (Liver) - Alevolar Macrophages (Lung) - Osteoclasts (bone)

Question 29

Characteristics of Macrophages

Answer 29

- Centrally located nucleus with indentation - Well developed Golgi - Lysosomes

Question 30

Giant Cell

Answer 30

- Fusion of macrophages in response to chronic inflammation | - Horseshoe nuclei appearance in some

Question 31

What are conditions that would cause chronic inflammation?

Answer 31

- IBS - TB - Arthritis - Autoimmune Disorders

Question 32

What cell type do plasma cells originate from?

Answer 32

B-lymphocytes

Question 33

What is the function of plasma cells?

Answer 33

Secretion of antibodies

Question 34

Characteristics of Plasma Cells

Answer 34

- Basophilic cytoplasm (rER synthesizing antibodies) - Clock Face Nucleus (Euchromatin central, Heterchromatin peripheral) - Large Negative Golgi (packaging antibodies) - NO SECRETORY VESICLES (constitutive release of antibodies)

Question 35

Describe the leukocyte response to inflammation of heart tissue.

Answer 35

1st wave= neutrophils in the first day | 2nd wave= monocytes that become macrophages on second day

Question 36

What are the two types of embryonic connective tissue?

Answer 36

1) Mesenchyme | 2) Mucous

Question 37

What are the types of proper connective tissue?

Answer 37

1) Loose (areolar) | 2) Dense, which can be regular or irregular

Question 38

What are the different types of specialized connective tissue?

Answer 38

1) Adipose 2) Reticular 3) Cartilage 4) Bone 5) Blood

Question 39

Mesenchymal Connective Tissue

Answer 39

Least differentiated form of connective tissue Contains: - Fibroblasts - Type III Collagen (Reticular Fibers) - Ground Substance

Question 40

How does mucous connective tissue differ from mesenchymal connective tissue?

Answer 40

- More differentiated | - Contains Type I & Type III Collagen vs. Type III only

Question 41

Where is loose/ areolar connective tissue found?

Answer 41

Immediately deep to the epithelium & surrounding blood vessels

Question 42

Structure of Loose CT

Answer 42

- Loose array of Type I Collagen - Reticular Fibers/ Type III Collagen - Elastic Fibers - Many cell types seen

Question 43

Where is dense regular collagenous connective tissue found?

Answer 43

Tendons & Ligaments

Question 44

Structure of Dense Regular Collagenous CT

Answer 44

- Type I Collagen arranged parallel (densely) - Elongated nuclei of fibroblasts seen occasionally - Don't see many cell types b/c of tight collagen packing

Question 45

What is the hallmark feature of mucoid degeneration of the ACL on MRI?

Answer 45

"Celery Stalk" Appearance

Question 46

Where is dense regular elastic connective tissue found?

Answer 46

- Ligamentum flava - Suspensory Ligament of the Penis - Vocal Ligament

Question 47

Structure of Dense Regular Elastic CT

Answer 47

- Elastin forms sheets of membranes - Few collagen fibers are found - Fibroblasts are trapped between

Question 48

Where is dense irregular connective tissue found?

Answer 48

- Organ capsulses - Dermis of skin - Around sleeves of nerves

Question 49

Structure of Dense Irregular CT

Answer 49

- Type I Collagen packed along different axes - Elastic fibers interspersed - Scattered Fibroblasts

Question 50

Ehler's Danlos Syndrome

Answer 50

Defect in Type I Collagen

Question 51

Where is reticular tissue found?

Answer 51

- Red bone marrow - Liver - Lymphatic Tissues/ Organs

Question 52

Xanthoma

Answer 52

Accumulation of lipid in tissue

Question 53

How would a xanthoma appear histologically?

Answer 53

- Foam cells | - Macrophages that attempt to rid the body of cholesterol take on a foam-like appearance