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Flashcards in Connective Tissue - Histology Deck (39)
1

Connective Tissue is derived from...

Mesoderm

2

Special Connective Tissue

Adipose
Blood
Cartilage
Bone

3

Components of Connective Tissue

Cells - Fixed and transient

Extracellular Matrix (material between cells) - Fibers (resist tensile forces)

Ground Substance - Amorphous (reisist compressive forces)

4

Collagen

Resist Tensile Forces

Most abundant

White (tendons)

Formed by fibroblasts and non-connective tissue

28 types

DO NOT BRANCH

5

Collagen Formation

1) 3 PREPROCOLLAGEN (glycine, proline, hydroxyproline, and hydroxyglysine)
ALLIGN = PROCOLLAGEN MOLECULE = rope, soluble

2) At secretion = terminal protein removed by procollagen peptidases = TROPOCOLLAGEN

3) TROPOCOLLAGEN polymerizes in extracellular matrix = FIBRILS

4) FIBRILS polymerize = COLLAGEN FIBERS

6

Reticular Fibers

Type II Collagen

AGYROPHILLIC

BRANCHES (Lattice Network)

SILVER STAIN

Small (glycoprotein coat prevents enlargement)

Make up LCT and Reticular CT

7

Elastic Fibers

Elastin

NO HYDROXYLYSINE = stretch

4 lysine molecule with a desmosome link (elasticity)

Surrounded by microfinrils (fibrillin)

BRANCHES

Can form internal elastic membrane (DRCT) = sheath - cont around an artery

8

Elastic Fiber Formation

1) Elastin is deposited on the scaffold of microfibrils forming amorphous structures

2) initially fiber consists of fibrollin microfinrils secreted by fibroblasts and smooth muscle

3) Elastin accumulates = occupies most of electron-dense center of single elastin fiber and fibrillin microfibrils remain at the fiber surface

9

Elastin resists digestion by ---------- but is hydrolyzed by----------

Proteases

Pancreatic Elastase

10

Elastin (unlike collagen) can form...

...a sheet = ELASTIC MEMBRANE or ELASTIC LAMINA

Prominent in arteries

Formed by fibroblasts and smooth muscle cells

11

Ground Substance

Stuff in between the cells and the fibers

Hydrated gel of complex sugars (glycosaminoglycans (GAGs), proteoglycans, and multiadhesive glycoproteins)

Resists forces of compression, lubricant, and barrier to the penetration of invaders

12

Glycosaminoglycans (GAGs)

Unbranched, negatively charged long chain of disaccharides

Attracts water = hydrated gel which resists compression

Repel each other = slippery texture that resists compression

EX = HYALURONIC ACID (common)

13

Proteoglycans

Made of test-tube brush proteins with GAGs attached

Negative

Attract water and repulse each other

Form hydrated gel

Act as diffusion barrier

Aggrecan = macromoleculs that allows for gel state and barrier for diffusion

Many bact secrete hyaluronidase = gel state ot sol state = rapid spread of bact

14

Multiadhesive Glycoproteins

1) Attachment to cells in ECM

2) Mediate interaction between cells

3) Has transient regulatory substances (interleukins, growth factors, hormones, plasma proteins, etc.)

EX = LAMININ (basal lamina of stratified epithelium and external lamina of nerves and muscle fibers) and FIBRONECTIN (ECM)

15

Movement of Fluids

Water leaves capillary and goes into ECM at arterial end of capillary = Hydrostatic P

Water is pulled back in at the venous end of the capillary = Plasma Colloid Osmotic P

Mix of nutrients, etc.

16

Connective Tissue is classified by....

....amount, direction, and tyoe

17

Dense Connective Tissue

1) DENSE REGULAR CONNECTIVE TISSUE

Elastin or collagen
Tendons, ligaments, cornea
Fibers on one direction
Tensile strength
One break = whole thing is weakened

2) DENSE IRREGULAR CONNECTIVE TISSUE

Elastic or collagen
Dermis, capsules of organs, and periosteum
Protective Coating
Multiple directions

18

Loose Connective Tissue

Areolar
Superficial fascia, lamina propria of intestines
Less fibers = more cells and open space (amorphous material)
Exchange

19

Reticular Connective Tissue

Spleen and lymph nodes
Basement membranes
Agyrophilic = silver
Cellular movement and nutritional exchange

20

1st sign of decrease in collagen

Teeth falling out

21

Connective Tissue Cells

1) Fixed Cells
Fibroblast
Fibrocyte
Pericyte
Adipocyte
Mast Cell
Myofibroblasts

2) Transient Cells
Plasma Cell
Neutrophil
Eosinophil
Lymphocyte
Macrophage

22

Fibroblast

FIXED CELL IN CONNECTIVE TISSUE

Most numerous cell in connective tissue

Produces and maintains the ECM (with smooth muscle cells) = Fibers and Ground Substance

Metabolically active (open faced = euchromatin in nucleus)

Spindle shape

Cytoplasm not apparent

Tendinoctytes in tendon

23

Myofibroblasts

FIXED CELL IN CONNECTIVE TISSUE

Modified fibroblasts that demonstrate similar characteristics to fibroblasts (by creating massive amounts of ECM) and smooth muscle cells (by contracting)

Common in healing wounds = speed healing by contracting edge of wounds

24

Pericytes

FIXED CELL IN CONNECTIVE TISSUE

Immature mesenchymal cell

Wall of capillaries and venules

Cytoplasm with actin and myosin

Can differentiate into other cell types (myofibroblasts, smooth muscle cels, or endothelial cells)

FUNCTIONS:
Blood brain barrier
Blood flow regulator

Damage to = diabetic retinopathy

Too many in brain = Alzheimer's Disease

Tumors cannot recruit = weakness and disorganization of tumor vasculature

When they die, they constrict

25

Adipocyte

FIXED CELL IN CONNECTIVE TISSUE

1) Unilocular/ White - single large lipid droplet
Energy storage
Prominent in SER
Lipid metabolism
Endocrine tissue
Nucelus is pushed to the side

2) Multilocular/Brown
Multiple lipid droplets
Heat Production = non-shivering thermogenesis
Abundant MITOCHONDRIA
Neonatal/ hibernating animals

Lipid only present in vivo (removed due to processing)

26

Mast Cell

FIXED CELL IN CONNECTIVE TISSUE

W/in connective tissue of organs with orifices, skin, and serous membranes

Also prominent in LCT of blood vessels

Primary Mediators:
Chondrotin sulfate
HISTAMINE
Eosinophil chemotactic factor (ECF) = limit inflammatory response
Neutrophil chemotactic factor (NCF) = limit inflammatory response

Secondary Mediators
D2
leukotrienes C4 and D4

Basophilic granules can obscure nucleus BUT cytoplasm is easily identified

27

Mast Cell Tumors

Most common cutaneous tumor found in dogs

Affects heart rate, BP, etc.

Develop in dermis and subcutaneous

Found commonly on trunks

28

Leukocytes

TRANSIENT CELL IN CONNECTIVE TISSUE

WBC

1) Granulocyte - sp. granules; segmented/lobed nucleus

Neutrophil (PMN)
Eosinophil
Basophil

2) Agranulocyte:- NO sp. granules BUT contain primary granules; round nuclei and minimal cytoplasm

Common in CT of mucous membranes, spleen, thymus, lymph nodes, tonsils, etc.

Lymphocytes
Monocyte (can only ident. in a blood smear)

29

Macrophage

TRANSIENT CELL IN CONNECTIVE TISSUE

Agranuloctyes = from Monocyte (stays in blood; out of blood = macrophage)

Kidney bean shaped nucleus = open- faced

FUNCTIONS:
Ingest and destroy
Secretion of cytokines (messages)
Antigen Presentation

Cell shape is ueven due to filopodia projections

30

Eosinophil

TRANSIENT CELL IN CONNECTIVE TISSUE

Granulocyte

Elongated nuclei

Acidophilic cytoplasmic granules

FUNCTIONS:
Phagocytosis
PARASITES
Limit inflammation from mast cells

Specific or secondary granules are eosinophilic

Granules contain major basic protein, eosinophilic peroxidase, neurotoxins, and eosinphilic cationic portein

Azuric sp ganules

31

Neutrophil

TRANSIENT CELL IN CONNECTIVE TISSUE

Granulocyte

Most common leukocyte

Cytoplasmic granule present BUT not visible

FUNCTIONS:
Phagocytosis of BACTERIA
Limit inflammation by mast cells

Stained mildly by basophilic and eosinophilic dye = neutrophil

stores of glycogen

can survive in an anaerobic env = can fight bact in necrotic tissue

when die, neutrophils and bact become white/yellow pus

the more lobes of the nucleus = the older the neutrophil

32

Basophil

TRANSIENT CELL IN CONNECTIVE TISSUE

Granulocyte

Large cytoplasmic granules= obscure nucleus (bilobed)


Store and release histamine = SIMILAR TO MAST CELLS

33

Pasma Cell

TRANSIENT CELL IN CONNECTIVE TISSUE

Immunoglobulin

Abundant RER = basophilic cytoplasm

Clock-face nucleus (round with heterchromatin)

Lack of staining around nucleus = negative golgi

Derived from B lymphocyte

34

Exuberant Granulation Tissue = ?

Proud Flesh

35

Tendon

DRCT

Tendinocytes (fibroblasts)

Boxcar Effect - fibroblasts pushed together in a row

Basophilic Streaming - active fibroblast

36

What molecule stains evenly with eosin?

Plasma Protein

37

Granules of Neutrophils

Azurophillic primary granules contain:

1) Myeloperoxidase (MPO) - gnerates reactive oxygen sp. = superoxide, hydroxide

2) Lysozymes = degrades bact wall and structure

3) Defensins = small proteins which are inserted into bact wall = bact cannot control ion gradient = explode



Sp. or Secondary Granules

1) Do not stain
2) Contain chemokines to attract more WBCs
3) Lactoferrin = binds iron which bact need to live

38

Macrophages and mast cells attract -------- and -----

Eosiniphils and neutrophils

39

Jejunum

1) Epithelial layer

2) Basment Membrane


Lamina lucida = adhesion molecules (integrin, laminin)

Lamina Densa = type IV collagen and fibronectin

Lamina Reticularis = type I and III Collagen, types IV and VII collagen anchoring plaques and fibrils; made by fibroblasts