Connective And Adipose Tissue

Question 1

What are five functions of connective tissue?

Answer 1

Connects cells to form tissues
Provides a medium for transportation of nutrients/wastes
Protection between tissues and organs and insulation (adipose)
Storage (adipose)
Defence against infection - loose connective tissue (blood, lymph, fixed and wandering cells)
Wound healing - macrophages, fibroblasts

Question 2

What is ground substance?

Answer 2

Clear, viscous substance with high water content. Composed of proteoglycans

Question 3

What are proteoglycans?

Answer 3

Macromolecules consisting of core protein covalently bound to glycosaminoglcans (GAGs)

Question 4

What are the function of GAGs?

Answer 4

Attract water to form a hydrated gel which resists compression and permits rapid diffusion

Question 5

What is hyaluronic acid? And where is it present?

Answer 5

A unique GAG - binds to core protein by a link protein

Present in cartilage

Question 6

What is extracellular matrix?

Answer 6

Ground substance + fibres

Question 7

Where is loose connective tissue found?

Answer 7

Mainly located beneath epithelia (facilitate diffusion), associated with gland epithelium and around small blood vessels

Question 8

What are the features of loose connective tissue? (4)

Answer 8

Many cells
Viscous, gel-like consistency
Sparse collagen fibres
Abundant ground substance

Question 9

What are the feature of dense connective tissue? (3)

Answer 9

Few cells - mostly fibroblasts
Many collagen fibres
Little ground substance

Question 10

Where is regular dense connective tissue found?

Answer 10

Tendons (connect muscle to bone)
Ligaments (connect bone to bone)
Aponeuroses

Question 11

What is regular dense connective tissue?

Answer 11

Collagen fibres arranged in densely packed, parallel bundles (with fibroblast in between).
Designed to withstand stress in a single direction

Question 12

Where is irregular dense connective tissue found?

Answer 12

The submucosa of the intestine and deep layer of dermis

Question 13

What is irregular dense connective tissue?

Answer 13

Collagen arranged in bundles orientated in various directions (fibroblasts between bundles).
Designed to withstand pressure in multiple directions.

Question 14

What is a fascicles?

Answer 14

Bundle of parallel collagen fibres

Question 15

What are wandering cells?

Answer 15

Blood cells

Question 16

What cells are present in connective tissue?

Answer 16

Fibroblasts
Mast cells
Macrophages 
Adipocytes
Mesenchymal stem cells

Question 17

What do fibroblasts do?

Answer 17

Synthesise and secrete ground substance and fibres (procollagen).

Question 18

What are myofibroblasts?

Answer 18

Modified fibroblasts - contain actin - responsible for wound contraction when tissue loss has occurred

Question 19

What are macrophages?

Answer 19

Derived from monocytes
Phagocytic - degrade foreign organisms/cell debris
Also act as APC for T lymphocytes

Question 20

What are mast cells?

Answer 20

Abundant in granules containing histamine (increase blood vessel permeability), heparin (anticoagulant) and substances that attract neutrophils.
Mast cells are coated with IgE - binds allergens - causes release if granules - result in immediate hypersensitivity reactions

Question 21

Elastic fibres consist of what?

Answer 21

Elastin, surrounded by microfibrils called fibrillin

Question 22

Where are elastic fibres important in connective tissue?

Answer 22

Dermis, artery walls, lungs and sites bearing elastic cartilage

Question 23

What is marfans syndrome?

Answer 23

An autosomal dominant disorder where there is abnormal expression of fibrillin - abnormal elastic tissue.
Sufferers are abnormally tall, exhibit arachnodactyly, frequent joint dislocation

Question 24

What type of fat cells are more common?

Answer 24

White

Question 25

What are white fat cells?

Answer 25

Cells filled almost completely with one lipid droplet - cytoplasm and nucleus displaced to the side of the cell.
Act as a fuel reserve, role in thermal insulation and shock absorption

Question 26

What are brown fat cells?

Answer 26

Multilocular adipose cells - contain multiple lipid droplets and a central nucleus.
Brown colour due to rich vascular supply and abundant mitochondria.
High respiratory capacity for heat generation

Question 27

Where are brown fat cells found?

Answer 27

Found close to the scapula, sternum and axillae (especially in newborns).
Also present in the upper chest and neck of adults

Question 28

How is regular dense connective tissue arranged in ligaments?

Answer 28

Parallel collagen fibres densely packed but undulate and are arranged in fascicles which are separated by loose connective tissue

Question 29

What are aponeuroses?

Answer 29

A flat sheet of regular dense connective tissue with bundles of collagen fibres in one layer arranged at 90degree angles to those in adjacent layers

Question 30

What vitamin is needed for intracellular procollagen production?

Answer 30

Vitamin C

Question 31

What disease can be caused by vitamin C deficiency?

Answer 31

Scurvy - vitamin c acts as a cofactor for hydroxylation of proline and lysine (use in collagen) results in poor wound healing and impaired bone formation

Question 32

What type of collagen is present in reticular fibres? And where are these fibres seen?

Answer 32

Type 3 collagen

Present in lymph nodes - form irregular structure throughout node with lymphocytes densely packed in spaces between fibres (spongy)

Question 33

pH is logarithmic, so 1 unit change equates to what?

Answer 33

A tenfold change in hydrogen ion concentration

Question 34

What is the pH limit of survival?

Answer 34

6.8-7.8

Question 35

At pH 7, what is the hydrogen ion concentration?

Answer 35

100 nM/L