Chapter 5 - Connective Tissue Flashcards
What is the function of connective tissue?
- structural and mechanical support
- EX: bone and cartilage
What two classifications of Adult CT are there?
- CT proper
- specialized CT
What are the subdivisions of CT proper?
- loose
- dense
Loose CT proper
- relatively few fibers w/ space btwn them
- underlies epithelia
- flexible, vascularized
Dense CT proper
- lots of fibers packed together tightly
- very tough, maintains integrity even when force is exerted form many directions
- forms things like tendons, ligaments, and dermis of skin
- Regular
- abundant collagen fibers, aligned in parallel structure
- extremely strong
- tendons and ligaments
- capsules of organs such as kidneys, testes, heart (pericardium)
- Irregular
- large number of collagen fibers oriented in many directions
- few cells
- skin, mesentery
What are the general properties of CT proper?
- matrix acts as glue for tissues and organs
- nutrients and waste products diffuse through it
- most organs are surrounded by a CT capsule (pericardium, pleura EX)
- strong and resilient
- capable of self renewal and repair (have stem cells)
What does CT proper consist of?
- cells
- extracellular matrix (fibers, ground substance, tissue fluid)
- contains relatively few cells and lots of EXT matrix, not tightly packed together
Specialized CT
- supporting (cartilage and bone)
- hematopoietic
- adipose storage
What are the 3 types of fiber in CT?
- collagen
- reticular
- elastic
- all secreted by fibroblasts and self assembled extracellularly
Collagen fibers
- most common type
- requires 40 genes to make collagen
- very strong, but not very stretchy
- 28 diff types
- found in dermis, tendons, ligaments
- used medically in cosmetic surgery, artificial skin/burn treatment, joint health supplement
What medical condition is associated with collagen?
Scurvy
- caused by vitamin C deficiency
- cofactor for proline hydroxylase, an enzyme needed for collagen synthesis
- tender gums/tooth loss, poor wound healing, mucous membranes bleed easily, weak bones, pallor
Reticular fibers
- forms a spiderweb/chickenwire network
- very fine/thin, requires stain to visualize (silver stain, periodic acid)
- composed of type 3 collagen
- found in lymph nodes, spleen, smooth muscle, liver, endocrine glands
Elastic fibers
- composed of elastin
- stretch, then return to original size when released
- very important in the lungs and the walls of large arteries (aorta)
What two clinical disorders are related to elastic fibers?
- marfans and ehlers danlos syndrome
Ground substance
- all fibers and cells of CT are grounded in this
- amorphous gell like substance
- active in development, movement and proliferation of tissues
What are glycosaminoglycans (GAGs)?
- part of ground substance
- long chains of repeating disaccharides’
-involved in making the proteoglycans - important in keeping the CT hydrated - attracts H2O
- contains chondroitin sulfate, dermatan sulfate, keratan sulfate and hyaluronic acid
Proteoglycans
- part of ground substance
- many GAGs on protein core/attached to it
Glycoproteins
- part of ground substance
- protein with branched sugar chains
- important for binding cells to CT fibers
What cells are present in CT?
- fibroblasts
- macrophages
- mast cells
- plasma cells
- lymphocytes
- adipocytes
Fibroblasts
- predominant cell type in CT
- elongated cells
- produce the subunits of CT fibers and ground substance (produce less with age)
- produce some growth factors (wound healing)
- can undergo mitosis
Why do fibroblasts have abundant RER?
the subunits of collagen fibers are made of proteins, and the proteins need to be released
Macrophages
- phagocytic cells that remove bacteria and debris in the CT (lysosomes)
- monocytes from bone marrow leave the circulation and enter the CT, where they are differentiated into macrophages
- liver, skin, bone, CNS
- also bind and present antigens to other cells of the immune system
Mast cells
- important in inflammatory response (immediate hypersensitivity reactions)
- prominent basophilic granules containing heparin and histamine
- most abundant in skin (dermis), digestive and respiratory tracts
Heparin and histamine
- heparin - clotting inhibitor, more blood is brought to the area
- histamine - vasodilator, bronchoconstrictor
Plasma cells
- involved in inflammations
- make antibodies
- derived from B-lymphocytes
- common in loose CT
- heterochromatin usually gives plasma cells their appearance
Lymphocytes
- small cells that have a prominent nucleus with very little cytoplasm
- involved in inflammatory response - produce antibodies
Adipocytes
Storage of fats (long-term energy storage)