RAT-1 CHAPTER FIVE

Question 1

What is the major distinguishing factor between connective tissue and other tissue types (epithelium, muscle, and nerve)

Answer 1

the major constituent of connective tissue is the extracellular matrix

Question 2

What are the major tissue types found in connective tissue proper

Answer 2

1. fibroblasts
2. plasma cells
3. lymphocytes
4. eosinophilic leukocytes
5. neutrophilic leukocytes
6. macrophages
7. mast cells and basophilic leukocytes
8. adipocytes

Question 3

List the major components of the extracellular matrix

Answer 3

protein fibers and ground substance

Question 4

Describe the function of fibroblasts

Answer 4

the major cell of connective tissue that synthesize and secrete most components of the ECM

Question 5

Describe the function of macrophages

Answer 5

they function in ECM turnover, phagocytosis of dead cells and debris, and antigen presentation to lymphocytes

Question 6

Describe the function of mast cells

Answer 6

release various vasoactive agents and other substances during inflammatory or allergic reactions

Question 7

Describe the function of plasma cells

Answer 7

abundant secretion of specific antibodies (immunoglobin)

Question 8

Describe the function of heparin

Answer 8

acts locally as an anticoagulant

Question 9

Describe the function of histamine

Answer 9

promotes vascular permeability and smooth muscle contraction

Question 10

What are the three major fiber types found within the extracellular matrix

Answer 10

1. collagen
2. reticular fibers
3. elastic fibers

Question 11

What are the three major groupings or classifications of collagen molecules

Answer 11

1. fibril-forming collagens
2. network-forming collagens
3. linking/ anchoring collagens

Question 12

Describe the general structure of type I (pro)collagen fibers

Answer 12

they assemble to form extremely strong fibrils, which are then bundled further by other collagens into larger units called collagen fibers

Question 13

Describe the cellular organelles involved in the formation of (pro)collagen molecules and the site of collagen fiber formation

Answer 13

RER: the site where initial pro-collagen alpha chains are assembled

ER: three alpha chains are selected, aligned, and stabilized by disulfide bonds at their carboxyl terminal and are folded as a triple helix

ECM: where further assembly into fibrils occurs after pro-collagen secretion

golgi: packaging of soluble pro-collagen in secretory vesicles

secretory vesicles: assisted by microtubules and microfilaments and transport soluble pro-collagen molecules to the cell surface

Question 14

State the major type of collagen molecules found in collagen

Answer 14

collagen type I

Question 15

State the major type of collagen molecules found in reticular fibers

Answer 15

collagen type III

Question 16

Which type of fibers provide greater tensile strength

Answer 16

type I collagen fibers

Question 17

Give examples of where collagen fibers are most abundant

Answer 17

cornea, blood vessels

Question 18

Give examples of where reticular fibers are most abundant

Answer 18

liver and endocrine glands, stroma of hemopoietic tissue (bone marrow), the spleen, and lymph nodes

Question 19

What is the classification of type III collagen fibers

Answer 19

network-forming

Question 20

What is the classification of type I collagen fibers

Answer 20

fibril-forming

Question 21

What is the function of elastic fibers

Answer 21

provide structural support to the extracellular space of connective tissues, they provide elasticity and resilience to connective tissue

Question 22

List the major components of ground substance

Answer 22

glycosaminoglycans (GAGs), proteoglycans, multiadhesive glycoproteins

Question 23

Describe the structure of GAGs

Answer 23

long polymers of repeating disaccharide units, some are synthesized in the ECM and others in the golgi complex

Question 24

Describe the structure of proteoglycans (PGs)

Answer 24

core protein that has various number and combinations of GAGs covalently attached, they are synthesized in the RER, mature in the golgi apparatus, and are secreted from the cell by exocytosis

Question 25

What is the significance of the water binding capacity of GAGs in tissue function

Answer 25

GAGs assume an extended confirmation and they sequester cations well in water, this provided GAGs with space-filling, cushioning, and lubricant functions

Question 26

Describe the general role of multiadhesive glycoproteins

Answer 26

they have binding sites for collagens and for integrin proteins in the cell membrane, thus allowing temporary attachments between cells and the ECM required for cell migration and positioning

Question 27

Describe the properties of loose connective tissues

Answer 27

many cells, little collagen, randomly distributed, function to support microvasculature, nerves, and immune defense cells

Question 28

Describe the properties of dense regular connective tissues

Answer 28

almost completely filled with parallel bundles of collagen, few fibroblasts, aligned with collagen, function to provide strength connections within musculoskeletal system and a strong resistance to force

Question 29

Describe the properties of dense irregular connective tissues

Answer 29

little ground substance, few cells, many fibroblasts, a lot of collagen in randomly arranged fibers, function to protect and support organs and resist tearing