Connective Tissue And Adipose Tissue

Question 1

What are the functions of connective tissue?

Answer 1

1. Binding and storing
2. Protecting - bones protecting vital organs
3. Insulating (fat underlying skin)
4. Transporting substances (blood and interstitium
5. Storing fuel reserves and cells
6. Separation of tissues (fascia and tendons and cartilage)

Question 2

What are the different types of connective tissue?

Answer 2

1. Loose connective tissue, also known as areola tissue, areola means little space e.g. lamina propria in mucosal membrane
2. Dense connective tissue also known as fibrous collagenous tissue and it has two types

• regular - fibres running parallel to each other
  Tendons and ligaments
• irregular - fibres running in different directions
• fascia - a thin sheath that separates muscle from other tissues
• Aponeurosis - a thin sheath that connect muscle to muscle

Pg 41

Question 3

What is the function of the loose connective tissue?

Answer 3

• holds vessels that supply fluid
• permits cell migration
• involved in inflammation pathways
• acts as packaging around organs
• Cushions and stabilises organs

Question 4

What are the 4 main cells found in the loose connective tissue?

Answer 4

• fibroblast
• macrophages
• mast cells
• adipocytes

Question 5

What is the function of fibroblasts?

Answer 5

• it synthesises and secretes fibres that are found in the ground substance (extracellular matrix)
• they are important in wound healing and are the cells responsible for formation of scar tissue.

Pg 14

Question 6

What can fibroblast be converted to?

Answer 6

• Myofibroblast

- modified fibroblast that contains actin and myosin. They are responsible for wound contraction when tissues are lost.

Question 7

What is the role of macrophages in loose connective tissue?

Answer 7

• Move into loose connective tissue, especially when there is local inflammation.
• They are phagocytic and can degrade foreign organisms and debris
• They are antigen presenting cells and they can present foreign materials to B and T lymphocytes of the immune system

Pg 15

Question 8

What is found in the cytoplasm of mast cells in loose connective tissue?

Answer 8

Contains abundant granules
Histamines - increases blood vessel wall permeability
Heparin - anticoagulant
Cytokines - attracts basophils and eosinophils

Pg 16

Question 9

How does the mast cell work?

Answer 9

• The cell becomes coated with IgE molecules which specifically bind allergens
• When allergens cross-link theses surface bound IgE molecules p, the contents of the granules are rapidly released.

Pg 16

Question 10

What are the different types of adipocytes?

Answer 10

1. Unilocular adipocytes

2. Multilocular adipocytes

Question 11

Where are unilocular adipocytes (white adipose tissue) found and what are there structures and functions ?

Answer 11

• Most adipocytes in loose connective tissue is white/yellow (white adipocytes)
• normal number of mitochondria
• enormous droplet of lipid with the nucleus, cytoplasm and organelles squeezed to one side
• padding and shock absorber, insulating and energy reserve.
• in adults lipid breakdown is slow and generates heat through shivering reflex

Pg 17

Question 12

What are multilocular adipocytes (brown adipose tissue) and what is its structure and function?

Answer 12

• Multiple small lipid droplets, with the nucleus, cytoplasm and organelles squeezed into the centre of the cell
• Increased mitochondria
• insulation and energy reserve
• very few found in adults
• found in neonates and infants, lipid breakdown is accelerated and oxidative phosphorylation is uncoupled to generate heat

Question 13

What are the four different fibres?

Answer 13

• Collagen - multiple types, type 1 is the most important and common
• Elastin - made up of hydrophobic amino acids - most common in aorta, lungs and skin
• Reticulin - different type of collagen fibre, most common in lymphatic system
• Fibrillin - glycoproteins essential for the construction of elastin fibres (wherever elastin is found)

Question 14

What are the four types of collagen.

Answer 14

1. Type 1 - most widely distributed, fibrils aggregate into fibres and fibre bundles (e.g. tendons, capsule of organs and skin dermis)
2. Type ll - fibrils do not form fibres (hyaline and elastic cartilage)
3. Type lll - fibrils form fibres around muscle and nerve cells and within lymphatic tissues and lymphatic organs (e.g. spleen) and in tendons. It is called reticulin.
4. Type lV - unique form present in basement membrane ( considered part of epithelial tissues)

Question 15

What are the different roles of the fibres in connective tissue?

Answer 15

Collage - flexibility and high tensile strength

Elastin - allows tissue to recoil after stretch or distension

Reticular/rectulin - provides supporting framework/sponge ( not found in loose/areolar tissue, only found in lymphatic system).

Question 16

What is found in ground substance that allows for its structure and function?

Answer 16

• it is viscous, clear and slippery feel ( has high water content
• Composed of proteoglycans ( large macromolecule consisting of a core protein with glycosaminoglycans covalently bound to ).
• Glycosaminoglycans (GAGs) are long chain polysaccharides and attract water to form hydrated gel
• A unique GAG is hyaluronic acid which is bound to proteoglycans by link protein to form a giant hydrophilic macromolecule.

Question 17

What is important in the structure of proteoglycans

Answer 17

1. Hyaluronate is key
2. GAGs (chondroitin and keratan sulfate) are attached to the core protein
3. In turn these are attached to hyaluronate.
4. The sugar moieties attract water, but make the ground substance ‘sticky and slippery at the same time.

Pg 29

Question 18

Where can dense irregular connective tissue be found?

Answer 18

• The superficial layer of the dermis
• the skin can resist forces in multiple directions, preventing tearing
• the elastic fibres allow for a degree of stretch and restoration to original shape after skin is bent and folded.

Pg 31-32

Question 19

What is an example of dense regular connective tissue and what is its function?

Answer 19

• Tendons - connect muscle to bone
• the collagen bundles lie parallel, densely packed formation in line with the tensile force exerted by the muscle
• rows of elongated flattens fibroblast lie between the collagen bundles

Question 20

What is the myotendious junction?

Answer 20

Pg 34

Question 21

What is key in the tendon anatomy?

Answer 21

• forces can be transmitted along collagen bundles because they glide over each other
• mainly made up of water

The collagen is
70% collagen l
30% collage lll

Question 22

What is another example of dense regular connective tissue?

Answer 22

• Ligaments
• Connects bone to bone
• Parallel collagen fibres
• Not straight but undulated (wavy)
• Wrapped in loose connective tissues - fascicles

Pg 37-38

Question 23

What is the three types of Fascia?

Answer 23

Fascia is a connective tissue

• Superficial (on the surface)
• Deep (underneath something else)
• Visceral or parietal (right next to an organ or next to the skin)

Question 24

What is the fascia made up of?

Answer 24

• Fascia is made up of fibrous connective tissue containing closely packed bundles of collagen fibres oriented in wavy pattern parallel to the direction of pull.
• Flexible
• Able to resist great unidirectional tension forces

Question 25

What is the Aponeuroses?

Answer 25

- Pearly white fibrous tissue - Attaches: - flat muscles to muscles - tendon to tendon - tendon to ligament Examples - Head - Abdomen - Foot - Hand

Question 26

What is the need for vitamin C?

Answer 26

1. It is required for the intracellular production of pro collagen, it is involved as a co-factor for the enzyme that hydroxylates proline and lysine. ( which helps to form procollagen which is packaged, released and modified into collagen outside of the cell) 2. Fibroblast secretes procollagen that is converted to collagen molecules outside the cell and the collagen molecules aggregate to form final collagen fibrils.

Question 27

What happens when there is no vitamin C?

Answer 27

- Collagen formation is disrupted - Vitamin C deficiency leads to scurvy, a condition that includes - poor wound healing - impaired bone formation (strong collagen fibres is needed to make good bones - it is the hydroxylation process that is damaged, lysine hydroxylase requires vitamin C as its co-factor. Pg45

Question 28

What occurs to the collagen is Scurvy?

Answer 28

- The thin collagen fibrils aggregate in some areas to form thick collagen fibrils. - The majority don’t aggregate and they remain as fibrils, it doesn’t come together and had no strength. - The collagen triple helix cannot be formed.

Question 29

What are the symptoms and signs of scurvy?

Answer 29

- Gum disease (weak gums that bleed) - Bruising of the skin - Bleeding - Poor wound healing

Question 30

What is marfan’s syndrome ?

Answer 30

- Autosomal dominant disorder in which expression of fibrillin 1 gene is affected such that elastic tissue is abnormal

Question 31

What are the signs and symptoms of marfan’s syndrome?

Answer 31

- Individual is abnormally tall - Exhibits arachnodactyly - fingers and toes are very long and spider like, long limbs (legs and arms) and normal sized aorta. - Frequent joint dislocations - Risk of catastrophic aortic rupture - haven’t got enough elastin in the aorta

Question 32

What are the key concepts about elastic fibres?

Answer 32

1. Elastin is a primary component of elastic fibres, but it enfolds and is surrounded by micro fibrils called fibrillin. - fibrillin is layed out first and then elastin grows in and around it Sites at which elastic fibres have an important role - dermis - artery walls - lungs - sites bearing elastic cartilage

Question 33

What happens when you pull elastic fibres?

Answer 33

- They straighten out and the have cross links between them and the cross links hold them in that position until the force is take away - When the force is taken away the elastin fibres spring back. - If the fibres are degraded or broken down by an enzyme, it will destroy the link and the rebound capacity - if you find amino acids desmosimes and isodesmosime in the urine that means the elastic fibres are broken down

Question 34

What are the three layers of blood vessels?

Answer 34

- Tunica intima (in distinct endothelial cells) : epithelial layer next to the blood. - Tunic media (elastin lamellae): have elastic fibres so when the blood comes through they expand to take your extra volume of the blood. - Tunica adventitia (collagen): has a lot of smooth muscle and collagen on the outside and the collagen stops the vessel from getting too big and so it doesn’t burst - it is the smooth muscle in the aorta that produces elastin, collagen and matrix not fibroblast Pg 50-53

Question 35

What is osteogenesis imperfecta?

Answer 35

- Encompasses a number of different genetic aetiologies. - Mild to serve disease - Due to mutated collagen, fibres that do not knot together or insufficient collagen produced or both

Question 36

What are the signs and symptoms of osteogenesis imperfecta?

Answer 36

- Weakened bones - short stature - blue sclera - Hearing loss - poor teeth development