Connective Tissue Flashcards
1
Q
connective tissue
A
- tissue that forms a continuum with the other 3 major tissues to maintain a functionally integrated body
- second basic tissue
2
Q
function of CT
A
mostly structural
characterized on the base of its ECM
3
Q
examples of CT
A
- organ capsules
- tendons and ligaments
- areolar tissue filling spaces
- fat
- cartilage
- bone
4
Q
classification of CT
A
- resident/fixed
- immigrant/wandering
5
Q
development of CT
A
from embryonic mesenchyme
- mesenchyme comes from mesoderm or NCC
- mesenchymal cells have an oval nucleus with prominent nucleoli and a small amt of cytoplasm
- mesenchymal cells function as stem cells in adult tissue
6
Q
CT ECM
A
- ground substance
- protein fibers-elastin, collagen, reticular
- tissue fluid
7
Q
CT cells
A
-resident or immigrant
8
Q
Resident CT cells
A
- mesenchymal cells
- fibroblasts
- fibrocytes
- reticular cells
- adipocytes
9
Q
Immigrant CT cells
A
- macrophages
- mast cells
- plasma cells
- leukocytes
10
Q
Fibroblasts
A
most numerous and ubiquitous of all CT cells
- synthesize and secrete the ECM including CT fibers.
- synthetically and mitotically active
- fibroblast has oval, euchromatic nucleus with several prominent nucleoli and a basophilic cytoplasm due to RER
11
Q
fibrocyte
A
- inactive/resting
- fibrocyte is shorter and more spindle-shaped with a more heterochromatic nucleus and acidophilic cytoplasm.
- can revert to fibroblast during tissue repair
12
Q
myofibroblast
A
appears in adult wound healing
-shares features of a fibroblast and smooth muscle cell
13
Q
Reticular cells
A
- fibroblast-like cells that produce reticular fibers in hematopoietic, lymphoid, and adipose tissue
- stellate-shaped cells with oval euchromatic nucleus that has a prominent nucleolus (idaho potato)
14
Q
white adipose cells
A
- adipocytes
- specialized for lipid storage
- called signet ring cells because a single drop of lipid displaces the nucleus and cytoplasm to the edge of the cell
- fixed by osmium tetroxide
15
Q
Macrophages
A
- monocytes (from bone marrow precursors) travel in the blood and migrate into CT to form macrophages
- the fixed macrophage is also called a histiocyte
- smaller than fibroblasts with a heterochromatic kidney shaped nucleus and cytoplasm filled with vacuoles and granules
- identified by injecting live animals with trypan blue (colloidal dye)
- mono-nuclear phagocyte system
- host defense as antigen presenting cells
- secrete enzymes and cytokines
- langerhans in skin, kupffer in liver
16
Q
Mast cells
A
- largest of the CT cells (20-30 microns in diameter)
- cytoplasm filled with membrane-bounded basophilic granules that contain heparin, histamine, chondroitin sulfate, and ECF-A
- involved in allergic reactions
- frequently found around blood vessels
- granules not fixed
- cell surface receptors for IgE trigger degranulation by exocytosis and initiates local inflammation of allergic reactions
17
Q
Plasma cells
A
- differentiate from antigen-stimulated B cells
- primary producers of immunoglobulins
- large ovid cells
- eccentric nucleus, abundant RER, “clock face” nucleus, clear zone near nucleus contains Golgi.
- medulla of lymph nodes and lamina propria of the stomach and intestines
18
Q
Ground substance
A
- viscous mixture that binds cells to CT fibers
- consists of GAGs, proteoglycans, and multiadhesive glycoproteins (laminin and fibronectin)
- functions are both structural and physiological
- hormones and growth factors have reservoirs in the ground substance
19
Q
CT fibers
A
collagen, reticular, elastic
20
Q
Collagen fibers
A
- large
- greater than 50 nm diameter fibrils make 1-20 micron fibers
- made of type I collagen
- in dense regular CT-parallel and appear white in fresh tissue and stain pink
21
Q
Tropocollagen
A
- 280nm by 1.5 nm 200kd rod composed of three peptide chains
- Rods produce 64 nm periodicity in electron micrographs of collagen fibrils
- fibrils associate with one another to produce fibers and bundles
22
Q
fibril forming collagens
A
- aggregate to form fibrils visible by EM
- Types I, II, III.
- Type I is most widespread and abundant and resists tension and stretch
- Type II-forms fibrils and resists pressure in hyaline cartilage
- Type III- reticular fibers in meshworks that provide support
23
Q
Type I collagen
A
- fibril forming
- resists tension and stretch
- most widespread and abundant
24
Q
Type II collagen
A
- fibril forming
- resists pressure in hyaline cartilage
25
Q
Type III collagen
A
fibril forming
-reticular fibers in meshworks that provide support
26
Q
Reticular Fibers
A
- small
- less than 50 nm fibrils make 0.5-2 micron diameter fibers
- collagen type III
- not visible in H and E
- stain black with silver salts due to heavy glycosylation
- create flexible network in lymph nodes, liver, red bone marrow and spleen
- synthesized by fibroblasts, reticular cells, Schwann cells and smooth muscle cells
27
Q
Ehlers-Danlos Type IV
A
- type III collagen faultly
- can lead to aortic and intestinal rupture
28
Q
Type XII Collagen
A
binds type II, fibril associated
29
Q
Type IV collagen
A
form networks, BM meshwork (basal lamina)
30
Q
Type VII collagen
A
anchoring, anchors BM to collagen fibers
31
Q
Elastic fibers
A
- elastin and fibrillin make 0.1-10 micron diameter fibers
- rubber band properties through cross linking of amino acids
- special stains: Picro-Orcein
- occur in arterial walls, lung tissue, vocal ligaments, ligamenta flava in spinal column
- no axial periodicity and abundant in elastic ligaments and arteries
32
Q
Fibers of Elastic fibers
A
oxytalan- first stage, composed partly of fibrillin
elaunin- formed as elastin is deposited between oxytalan
elastin becomes a core surrounded by microfibrils
33
Q
Marfan Syndrome
A
mutation in elastin can lead to aortic rupture and hypermobile joints
34
Q
Loose Connective Tissue
A
- intervening spaces
- more cellular than dense CT
- lots of resident cells
- found in lamina propria, mesentary, and papillary layer of the dermis
- positioned between tissues and allows movement
35
Q
Dense Irregular CT
A
- more fibers than cells
- interwoven fibers
- found in organ capsules, reticular layer of dermis and periosteum
- fabric like arrangement
- fibroblast (cyte) is predominant cell
36
Q
Dense Regular CT
A
- more fibers than cells
- fibers arranged in parallel bundles or sheets
- found in tendons, ligaments, and trachea
- ropelike arrangement
- fibroblast (cyte) is predominant cell
37
Q
Reticular CT
A
- previously called hematopoietic tissue with special properties
- reticular cells and reticular fibers
- creates specialized microenvironments for cells in bone marrow, lymph nodes and spleen
38
Q
Adipose tissue
A
- CT with special properties
- two types- unilocular and multilocular
39
Q
Unilocular fat
A
- common, yellow, white
- single large droplet of fat
- abundant
- beneath skin except in eyelids, penis, scrotum, ears
- in and around most organs
- store FA in triglycerides and are the largest repository energy source in the body
- thermal insulation
- fills spaces to position organs
- from mesenchymal lipoblasts
40
Q
Multilocular fat
A
- brown
- primarily in fetus
- transforms chemical energy into heat
- brown due to large number of capillaries and mitochondria with cytochrome c
- also develops from lipoblasts
- protects newborn from cold
