Lecture 3: Tissue and Adipose Flashcards
What are the four classes of connective tissue?
- embryonic CT
- Loose CT
- Dense CT
- Specialized CT
What class is mesenchyme, what are 4 characteristics?
EMBRYONIC
- Small spindle shaped cells
- relatively uniform appearance
- 3D cellular network
- Capable of turning into other tissue type
What class is mucous CT where is it found and what are 4 characteristics?
EMBRYONIC - umbilical cord
- fibroblast and mesenchymal cells
- more space between cells
- less reticular fibers
- Wharton’s jelly
What are 4 characteristics of Areolar (loose) CT?
- loosely arranged collagen fibers
- primarily found under epithelium
- Site of inflammatory and immune reaction
- lamina propria
What are 5 characteristics of dense irregular CT?
- mostly collagen fibers
- little ground substance and fibroblasts
- strength and stress resistance
- submucosa of hollow organs
- reticular layer of dermis
Where is dense regular CT found? (3)
tendons, aponeuroses, ligaments
What are resident cells of the CT? (4)
- Fibroblast/myofibroblast
- Macrophages
- adipocytes
- mast cells
What are the transient cells of CT? (6)
- Lymphocytes
- Neutrophils
- Eosinophils
- Basophils
- Monocytes
- Plasma cells
What are the two stem cell populations the cells of CT arise from?
Hematopoietic stem cells
undifferentiated (mast cell + plasma cell)
mesenchymal cells (fibroblast + adipocyte)
What is the function of fibroblasts?
major protein synthesizer (GAGs, collagen, elastin, collagen, proteoglycans, multiadhesive)
What is characteristic of a mast cell what do they release?
Histamine, heparin, serine proteases, leukotrienes
Basophilic
cell surface is covered in IgE
What is characteristic of plasma cells, where are they found?
CLOCKFACE nuclei
prominent in LCT
produce antibodies
What are the 6 functions of the ECM?
- Mechanical and structural support
- biochemical barrier
- metabolic regulation
- anchors CT cells
- Cell migration
- Regulates growth and maturity
What classes of molecules compose the ECM?
- proteoglycans
- Glycosaminoglycans
- Multiadhesive glycoproteins
What are the 4 types of GAGs?
- Hyaluronan - lubricant/shock absorption
- Chondroitin 4/6 sulfate- shock absorption
- Keratin sulfate- axonal guidance, cellular recognition
- Heparin sulfate- facilitates interactions with FGF
What are the 4 proteoglycans?
- Aggrecan - hydration of ECM
- Decorin - Collagen fibrogenesis
- Versican- cell-cell/ cell-ECM interactions
- Syndecan - Links cells to ECM
What are the 4 multi-adhesive glycoproteins?
Laminin- anchors cell to basal lamina
osteoportin- binds osteoclast, binds calcium
fibronectin- cell adhesion
tenascin- modulation of cell attachment to ECM
What are three types of fibers?
- Collagen fibers
- Reticular fibers
- elastic fibers
What are characteristics of collagen fibers?
Collagen fibrils (68nm banding pattern)
Describe collagen fibrils
staggered collagen molecules
stregnth by covalent bonds
every third AA –> glycine
H bonding between prolines and glycines
Type I collagen
Resistance to force, tension, and stretch (found in skin, bone, tendon, ligaments)
Type II collagen
Resistance to intermittent pressure (cartilage –> hyaline / elastic)
Type III collagen
Supportive scaffolding
LCT forms reticular fibers
Type IV Collagen
support and filtration
basal laminae of epithelia
Osteogenesis imperfecta type I
Defect in Type I collagen (normal quality, abnormal quantity) –> abnormal teeth, blue sclera, brittle bones, progressive hearing loss, repeated fractures
GENES: COL1A1
Osteogenesis imperfecta type II
Defect in Type I collagen (abnormal quality/quantity) –> severe bone deformities, respiratory complications, very short life span
GENE: COL1A1, COL1A2
Kniest Dysplasia
Defect in Type II collagen–> short stature, ocular changes, wide fingers
Stickler’s syndrome
Defect in Type XI collagen and Type II
Kniest dysplasia with craniofacial deforminites
Ehlers-Danlos Syndrome
Defect in Type III collagen –> hyperflexibility of joints, hyperextensibility of skin (vascular organ rupture)
Alport’s syndrome
Defect in IV collagen –> hematuria, progressive hearing loss, ocular lesions
Kindler’s syndrome
Defect in Type VII, absence of anchoring fibrils (blistering disease)
Generalize atrophic benign epidermolysis bullosa (GABEB)
Type XVII collagen (blistering disease with faulty hemidesmosomes)
What are the two components of elastic fibers?
elastin (core) and fibrillin microfibrils (produced by fibroblast & SM cells)
Fibrillin production depends on what gene?
FBN1
Marfan’s syndrome
Autosomal dominant, mutation on chromosome 15 –> tall and thin, high risk for aortic rupture
What does chronic sun exposure lead to? (3)
- fibrillin microfibrils –> nonfunctional elastic fibers
- decrease skin elasticity
- increased expression of MMP1 and 9, (elastase)
Characteristics of white adipose tissue (5)?
- Unilocular adipocyte
- energy storage + source of water
- insulation
- cushioning
- endocrine functions
Charateristics of brown adipose tissue?
- multilocular
- Sympathetic nerve innervation (norepinephrine)
- Highly vascular
- Thermogenesis
- Many mitochondria
What are 2 short term weight regulating hormones?
- Ghrelin - appetite stimulant
2. PYY- Appetite suppressant
What are 2 long term weight regulating hormones?
- Leptin- foot intake inhibitor
- insulin - regulation of blood glucose
**act on brain centers
Prader- Willi
Deletion or silencing of q11-13 of chromosome 15 –> Hyperghrelinemia
(low muscle tone, short stature, incomplete sexual development, chronic hunger)
What are 6 Endocrine molecules that come from adipose?
- leptin
- adiponectin
- resistin (insulin inhibit)
- apelin
- IL-6
- TNF a and B
* * Obesity= increase in leption = increase all of these (except adiponectin)
Lipoma, Fibrolipoma, Angiolipoma, Liposarcoma
Lipoma- benign adipocyte tumor
fibrolipoma- adipocytes surrounded by fibrous tissue
angiolipoma- adipocytes surrounded by vascular channels
liposarcoma- malignant adipocyte tumor
