Lecture 8 - Connective Tissue

Question 1

Connective Tissue made of

Answer 1

ECM (ground substance, fibers, structural glycoproteins) and and cells

Question 2

Functions

Answer 2

Structural Support; Site of Exchange of nutrients/waste between tissues; defense/protection from foreign bodies; storage of fat

Question 3

Ground substance

Answer 3

glycosaminoglycans (GAG, long carb chains), proteoglycans (many gag chains attached to protein core, mostly carbohydrate in composition). V. negative so retains lots of salt and water

Question 4

Types of GAGs

Answer 4

Hyaluronic acid –> not sulfated or bound to protein, so not negative so proteoglycans bound to them. The other gags fill the space between the proteoglycan bound; keratin sulfate (skin); heparan sulfate (basement membrane, stain positive PAS); dermatan sulfate (skin); chondroitin sulfate (cartilage)

Question 5

Three types of connective tissue

Answer 5

Collagen fiber, reticular fiber, elastic fiber

Question 6

Type I collagen

Answer 6

tendon, ligaments, bone, fibrous cartilage, dermis of skin; forms fibrils

Question 7

Type II collagen

Answer 7

Hyaline cartilage, elastic cartilage; forms fibrils

Question 8

Type III collagen

Answer 8

Also called reticular fibers, thinner than type I/II; lymphoid organs, muscle cells, blood vessels, liver, endocrine glands, lung, kidney; forms fibrils

Question 9

Type IV collagen

Answer 9

Basement membrane (found around epithelium, endothelium, muscle, nerve axons); forms mesh like structure

Question 10

Properties shared by Types I-III

Answer 10

Mechanical support, gives tensile strength to tissue, resistance to stretching when pulled

Question 11

Fibril under EM

Answer 11

Can see alternating dark and white bands at 64 nm periodicity, specific to collagen

Question 12

fibril vs. fiber

Answer 12

Many fibrils make up one fiber

Question 13

Silver stain

Answer 13

Stains Type III collagen black

Question 14

Type IV collagen

Answer 14

basement membrane (heparan sulfate), mesh like structure, so do not see banding. PAS positive

Question 15

Elastic fiber components

Answer 15

Elastin (desmosine and isodesmosine) and microfibrils (fibrillin)

Question 16

Structure of elastic fibers

Answer 16

Thin branched forming irregular networks in connective tissue

Question 17

Properties of elastic fibers

Answer 17

Stretchable as rubber bc of desmoseine and isodesmoseine; elastic recoil

Question 18

Cells that make elastic fibers

Answer 18

Fibroblasts in CT, smooth muscle cells, chondroblasts and chondrocytes found in elastic cartilage

Question 19

Classification of connective tissue

Answer 19

1. Loose connective

2. Dense connective tissue –> two types, regular and irregular

Question 20

specialized types of CT

Answer 20

Reticular Tissue; Elastic Tissue; Adipose Tissue

Question 21

Embryonic CT

Answer 21

Mesenchyme; Mucous

Question 22

Loose CT, what and where

Answer 22

More Cells than collagen fibers, seen in most tissues and organs,
Largely type III collagen/lining of mucous membranes called lamina propria

Question 23

Dense Irregular CT

Answer 23

More collagen fibers than cells, irregularly arranged.
Largely types I and III, some elastic fibers
Dermis

Question 24

Dense regular CT

Answer 24

Parallel bundles of collagen fibers, separated by linear rows of fibroblasts
Type I collagen
Tendon and ligaments

Question 25

Reticular Tissue

Answer 25

Loose network Type III

Forms suportive tissue for tissue/organs, seen in lymphatic tissue

Question 26

Elastic Tissue

Answer 26

Seen in wall of aorta, elastic ligaments

Stained by resorcin fuschin stain

Question 27

Types of adipose tissue and functions

Answer 27

White –> All over body; for thermal insulation, storage of energy, visceral fats correlated to obesity
Yellow –> Bone marrow

Question 28

Mesenchyme CT

Answer 28

Embryonic
Stellate/spindle shaped, delicate branching of mesenchymal cells, surrounded by ground substance
Unspecialized, can differentiate into all CT types

Question 29

Mucous CT

Answer 29

Umbilical cord, also called whatron’s jelly

Question 30

Cell Types of CT

Answer 30

Fibroblasts, mast cells, macrophages, plasma cells, lymphocytes, neutrophils, eosinophils, adipocytes

Question 31

Fibroblasts

Answer 31

Splindle shaped, nuclei and cytoplasm elongated
Cytoplasm slightly basophilic --> RER
Produces ECM (collagens, elastic fibers, ground substance)

Question 32

Mast Cells

Answer 32

Single round dark purple nucleus, strongly acidophilic cytoplasm
Finely granular (seen in EM) 
Have IfE receptors that bind antibodies, trigger allergic rxns

Question 33

Where are Macrophages found

Answer 33

Found in CT, lungs, lymphoid organs and bone marrow. Some types are tissue specific (ex. microglia in CNS)

Question 34

Monocytes

Answer 34

pre-cursor to macrophages, develop in bone marrow, circulate in the blood. After leaving blood for CT, diff. into macrophages

Question 35

Macrophages unique properties

Answer 35

Lysosomes, which contain acid phosphotase (stain red under azo dye)
Phagocytosis
secrete cytokines which are signals to other immune cells
present antigens on cell surface to T-cells

Question 36

Where are lymphocytes found

Answer 36

Develop in bone marrow; two types (T & B); leave circulation for CT, live 2-3 years

Question 37

Plasma Bodies/Cells

Answer 37

Created from B lymphocytes; Make antibodies; live in loose CT; nucleus off center; depends on RER (protein synthesis) –> slightly basophilic cytoplasm;

Question 38

Neutrophils

Answer 38

Multilobed nucleus (3-5 lobes); slightly pink cytoplasm; usually in circulation, found in CT in cases of acute infection for 2-3 days. Defunct neutrophils are pus cells

Question 39

Eosinophil

Answer 39

Bilobed nucleus, strongly pink cytoplasm, seen in parisitic infection and allergic rxn; seen in loose CT in chronic inflammation