Connective Tissue

Question 1

What are the types of connective tissue?

Answer 1

Blood
Adipose
Cartilage
Bone
Loose connective
Dense

Question 2

What is the definition of connective tissue?

Answer 2

A tissue that binds, separates or supports other tissues/organs. Typically having few cells embedded in an amorphous matrix often with collagen or other fibres

Question 3

What 3 components make up the structure of connective tissue?

Answer 3

Cells
Fibres
Ground substance

Question 4

What are the types of cells found in connective tissue?

Answer 4

Fibroblasts
Fibrocytes
Adipocytes
Mast cells
Macrophages

Question 5

What are fibroblasts? What are their features? What do they secrete?

Answer 5

Responsible for producing fibres and extra cellular matrix
Large nuclei
Secrete collagen and elastin
MAIN connective tissue cells in body

Question 6

What are fibrocytes? What is their function?

Answer 6

Less active/dormant fibroblasts (smaller nucleus)
Involved in tissue maintaining

Question 7

What is the function of adipocytes?

Answer 7

Store energy in the form of fat
Provide insulation and cushioning to organs/tissues

Question 8

What is the function of mast cells in connective tissue?

Answer 8

Involved in immune response (typically allergic reactions) by releasing histamine and orbed inflammatory mediators

Question 9

Where are mast cells found?

Answer 9

Near blood vessels in areolar connective tissue
Not in the brain as dangerous to swell there

Question 10

What is the function of fixed macrophages in connective tissue?

Answer 10

Immune cells responsible for phagocytosing pathogens, dead cells and debris
They also aid in tissue repair
Become APCs to T lymphocytes

Question 11

Where are fixed macrophages found?

Answer 11

Residing permanently in connective tissues
Particularly in organs such as the liver (Kupffer cells), lungs and spleen

Question 12

What is the ground substance?

Answer 12

Extra cellular matrix

Question 13

What are fibroblasts important for?

Answer 13

Wound healing process
Primary cells responsible for formation of scar tissue

Question 14

What are myofibroblasts?

Answer 14

Modified fibroblast that contain actin and myosin
They are responsible for wound contraction when tissue loss has occurred

Question 15

What are unilocular adipocytes?

Answer 15

Most of the other sites a loose connective tissue are white adipocytes
A single large lipid droplet with the organelles all squeezed to one side of the cell

Question 16

What is the functions of unilocular adipocytes?

Answer 16

Padding and shock absorber, insulation and energy reserve

Question 17

What are multilocular adipocytes?

Answer 17

Brown adipocytes
Very few in adults
Multiple small lipid droplets with the organelles squeeze to the centre of the cell

Question 18

What is the function of multilocular adipocytes?

Answer 18

Provides insulation and energy reserve
In neonates main method of generating heat (non-shivering thermogenesis)

Question 19

What do mast cell cytoplasm contain in their granules?

Answer 19

Histamine - increases blood vessel wall permeability
Heparin - anticoagulant
Cytokines that attract eosinophils and neutrophils

Question 20

How do mast cells get activated?

Answer 20

They become coated with IgE, molecules which specifically bind allergens
When an allergen crosslinks these surface bound IgE molecules, the contents of the granules are all rapidly released from cell

Question 21

Where do macrophages move into?

Answer 21

Loose connective tissue, especially where there is local inflammation

Question 22

What are the types of fibres in connective tissue?

Answer 22

Collagen fibres
Elastic fibres

Question 23

What is the purpose of collagen fibres?

Answer 23

Provide strength and resistance to tension

Question 24

What are reticular fibres? What is their purpose?

Answer 24

Made of type 3 collagen
Scaffold lymph tissue (eg spleen)
Provide a delicate framework for soft tissues and organs

Question 25

What is type 1 collagen? How is it made? Where is it found?

Answer 25

Most widely distributed type (90%) Fibrils aggregate into fibres and fibre bundles Found in tendons, capsules of organs and skin dermis

Question 26

What is type 2 collagen? Where is it found?

Answer 26

Fibrils don’t form fibres Present in hyaline and elastic cartilage

Question 27

What is type 3 collagen? How is it made? Where is it found?

Answer 27

Fibrils form fibres around muscle, nerve cells and adipocytes and within lymphatic tissues and lymphatic organs Found in spleen and tendons Called reticulin

Question 28

Where is type 4 collagen found?

Answer 28

Unique form present in basement membrane (considered part of epithelial tissues)

Question 29

What are the identifying points of dense regular, dense irregular and loose collagen fibres?

Answer 29

Dense regular contains fibres arranged in the same direction & squashed cells and nuclei Dense irregular contains fibres arranged in multiple directions Loose contains glycoproteins (white) & thin collagen strands

Question 30

What are the three types of collagen fibres?

Answer 30

Dense regular Dense irregular Loose

Question 31

What are elastic fibres made of? What are they surrounded by?

Answer 31

Elastin is their major component Surrounded by microfibrils called fibrillin (a glycoprotein)

Question 32

Where are elastic fibres importantly found?

Answer 32

Dermis Artery walls Lungs Sites of elastic cartilage

Question 33

What happens when elastin fibres stretch?

Answer 33

Elastin fibres uncoil Cross links form between elastin strands

Question 34

What is desmosine and isodesmosine?

Answer 34

Unique amino acids only found in elastin fibres Found in urine = disease

Question 35

What are reticular fibres? What is their function?

Answer 35

Thin, delicate fibres made of type 3 collagen Form a mesh-like network providing structural support in soft tissues

Question 36

Where are reticular fibres found?

Answer 36

In organs like the liver, spleen, lymph nodes & bone marrow

Question 37

What is ground substance?

Answer 37

Key component of the extracellular matrix Substance that fills the space between cells and fibres

Question 38

What is the function of ground substance?

Answer 38

Provides a medium through which nutrients, gases & waste products can diffuse between cells and blood vessels Along w fibres forms the ECM which supports & connects tissues

Question 39

What are the 3 components of ground substance?

Answer 39

Glycosaminoglycans (GAGs) - polysaccharides that attract water & give the ground subs its gel-like consistency Proteoglycans - proteins attached to GAG chains. Help trap water, contributing to the viscosity & resilience of the ground substance Glycoproteins - adhesive molecules that help cells adhere to the ECM which supports