Chapter 5 - Connective Tissue

Question 1

What is the function of connective tissue?

Answer 1

• structural and mechanical support
• EX: bone and cartilage

Question 2

What two classifications of Adult CT are there?

Answer 2

• CT proper
• specialized CT

Question 3

What are the subdivisions of CT proper?

Answer 3

• loose
• dense

Question 4

Loose CT proper

Answer 4

• relatively few fibers w/ space btwn them
• underlies epithelia
• flexible, vascularized

Question 5

Dense CT proper

Answer 5

• 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

Question 6

What are the general properties of CT proper?

Answer 6

• 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)

Question 7

What does CT proper consist of?

Answer 7

• cells
• extracellular matrix (fibers, ground substance, tissue fluid)
• contains relatively few cells and lots of EXT matrix, not tightly packed together

Question 8

Specialized CT

Answer 8

• supporting (cartilage and bone)
• hematopoietic
• adipose storage

Question 9

What are the 3 types of fiber in CT?

Answer 9

• collagen
• reticular
• elastic
• all secreted by fibroblasts and self assembled extracellularly

Question 10

Collagen fibers

Answer 10

• 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

Question 11

What medical condition is associated with collagen?

Answer 11

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

Question 12

Reticular fibers

Answer 12

• 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

Question 13

Elastic fibers

Answer 13

• composed of elastin
• stretch, then return to original size when released
• very important in the lungs and the walls of large arteries (aorta)

Question 14

What two clinical disorders are related to elastic fibers?

Answer 14

• marfans and ehlers danlos syndrome

Question 15

Ground substance

Answer 15

• all fibers and cells of CT are grounded in this
• amorphous gell like substance
• active in development, movement and proliferation of tissues

Question 16

What are glycosaminoglycans (GAGs)?

Answer 16

• 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

Question 17

Proteoglycans

Answer 17

• part of ground substance
• many GAGs on protein core/attached to it

Question 18

Glycoproteins

Answer 18

• part of ground substance
• protein with branched sugar chains
• important for binding cells to CT fibers

Question 19

What cells are present in CT?

Answer 19

• fibroblasts
• macrophages
• mast cells
• plasma cells
• lymphocytes
• adipocytes

Question 20

Fibroblasts

Answer 20

• 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

Question 21

Why do fibroblasts have abundant RER?

Answer 21

the subunits of collagen fibers are made of proteins, and the proteins need to be released

Question 22

Macrophages

Answer 22

• 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

Question 23

Mast cells

Answer 23

• important in inflammatory response (immediate hypersensitivity reactions)
• prominent basophilic granules containing heparin and histamine
• most abundant in skin (dermis), digestive and respiratory tracts

Question 24

Heparin and histamine

Answer 24

• heparin - clotting inhibitor, more blood is brought to the area
• histamine - vasodilator, bronchoconstrictor

Question 25

Plasma cells

Answer 25

- involved in inflammations - make antibodies - derived from B-lymphocytes - common in loose CT - heterochromatin usually gives plasma cells their appearance

Question 26

Lymphocytes

Answer 26

- small cells that have a prominent nucleus with very little cytoplasm - involved in inflammatory response - produce antibodies

Question 27

Adipocytes

Answer 27

Storage of fats (long-term energy storage)