Connective Tissue Flashcards
(52 cards)
Function of Connective Tissue
- Structure
- Defense and protection
- Nutrition
- Fat deposit for cushioning, insulation, and energy reserves
Where does connective tissue derive from
mesoderm and neural crest from ectoderm
Chondroblasts
responsible for synthesis and elaboration of the ECM’s associated cartilage
Osteoblast
synthesis and elaboration of bone
Where do undifferentiated mesenchymal cells come from
mesoderm and in some ares of the body can also come from neural crest cells from ectoderm
Function of active fibroblasts
synthesize and elaborate components of ECM
Organelles of active fibroblasts
- euchromatic nucleus
- large column of rER and thus also a basophilic cytoplasm
- Well-developed golgi apparatus seen proximate to the nucleus
- Mitochondria to supply fuel for protein synthesis
Inactive fibroblasts are also called
quiescent or fibrocyte
Organelles of inactive fibroblasts
- decreased rER
- less elaborate golgi
- slender nucleus and condensed chromatin
- more eosinophilic cytoplasm
Cortisol
has putative antifibrotic activities including inhibition of fibroblast growth and deposition of collagen
-Prolonged administration can lead to decrease in bone
Why do active fibroblasts have increased activity
due to need to synthesize extracellular material for wound healing. Greater capacity to divide during wound healing
What happens if you are defienct in vitamin C
hydroxylation step is compromised, get decreased collagen synthesis - scurvy
Procollagen peptidases
Will enzymatically cleave the propeptides to make the molecules less soluble so they can assemble.
Extensions of helix
propeptides on each end, which maintain the solubility of this structure and can be processed internally by fibroblast
Myofibroblasts
- Possess characteristics of fibroblasts and smooth muscle cells
- Has actin and myosin (so they have contracile activity)
- become more numerous in wound healing
Dupuytren’s contracture
- Palmar aponeurosis, a triangular shaped collagenous structure in palm of hand
- Repair of microvascular ischemia in tissue leads to active myofibroblast and fibroblasts
- Increased elaboration of type III collagen, which forms cross links with myofibroblasts, leading to contractions of 4th and 5th digits
White adipocytes
- look like empty spaces, tissue processing removes the lipid droplet, leaving a signet ring appearance
- Nucleus pushed out to periphery
Apidocytes
synthesize leptin, thus have endocrine function
Leptin
works to suppress appetite by signaling decrease in caloric intake
-mutation leads to morbid obesity
Lipdystrophies
- can be acquired or due to genetic defect
- loss of body fat may be general or confined to specific body regions
Brown adipocytes
- multilocular
- nucleus is centrally located
- peripherally located cytoplasm, which is acidophilic due to large column of mitochondria
- cancer of brown adipose tissue is rare but possible
Functions of brown adipose tissue
produce heat, especially in newborns to regulate body temperature
Why do infants need brown fat
- they can’t shiver
- ATP synthesis capability is uncoupled so we use mitochondrial steps to produce heat rather than to synthesize ATP
Do adults have brown fat?
Yes, some. Can be seen by putting them in a cold environment then imaging
