Fou 8 - Extracellular Environment

Question 1

What is the most abundant structural protein in the body?

Answer 1

Collagen.

Question 2

Where is Type I Collagen found?

Answer 2

The strong type. Found in skin, bone, dentin.

Question 3

Where is Type II Collagen found?

Answer 3

Found in slippery tissue: cartilage, vitreous body, nucleus pulposus.

Question 4

Where is Type III Collagen found?

Answer 4

The bloody one. Found in blood vessels, skin, uterus, fetal tissue, granulation tissue.

Question 5

Where is Type IV Collagen found?

Answer 5

Basement membrane.

Question 6

What are the six main steps of post translational modification of collagen?

Answer 6

1.Basic peptide(preprocollagen Alpha chains) synthesized in rough ER of fibroblasts. 2. Hydroxylation of lysine and proline residues (requires Vit C). 3. Glycosylation of hydroxylated lysine (turns it into procollagen). 4. Exocytosis of procollagen outside the fibroblast. 5. Cleave terminal regions of procollagen, turning it into tropocollagen. 6. Crosslink (covalent bond) tropocollagen molecules to make collagen fibrils.

Question 7

What is the most common type of Osteogenesis Imperfecta?

Answer 7

OI type I.

Question 8

What is Osteogenesis imperfecta type I?

Answer 8

AD; normal type I collagen but not enough. Causes multiple fractures from low force trauma. Blue sclerae. Hearing loss. Dental abnormalities.

Question 9

What is Osteogenesis Imperfecta II?

Answer 9

AR; so severe the die in utero or first few days of life. AKA perinatal lethal OI.

Question 10

What is Classical Ehlers-Danlos syndrome (EDS)?

Answer 10

Collagen type V is affected (a little of type I collagen as well). Causes hyperextensible skin and joint hypermobility.

Question 11

What is Vascular EDS?

Answer 11

Affects type III collagen. Causes arterial rupture, hemorrhages, easy bruising, Berry aneurysms.

Question 12

What is Alport syndrome?

Answer 12

Genetic defect of collagen type IV. Causes kidney disease, hearing loss, and eye problems (cataracts and lenticonus).

Question 13

Where do we find elastin?

Answer 13

Blood vessels. Alveoli. Larynx. Ligamenta flava in the spine.

Question 14

What is the structural unit of Elastin?

Answer 14

Tropoelastin which are held together by a matrix of fibrillin.

Question 15

What disease is caused by defect in fibrillin?

Answer 15

Marfan syndrome.

Question 16

What is Marfan syndrome?

Answer 16

Caused by defect in fibrillin. It causes hyperelastic joints, problems w/ heart valves, aorta. They are very tall w/ long arms and legs and archnodactyly. Positive Steinberg sing (thumb sticks out when making a fist). Can have pectus carinatum (protrudes like a bird).

Question 17

What does alpha1-antitrypsin do?

Answer 17

It inhibits elastase, which is an enzyme that breaks down elastin.

Question 18

What are the symptoms of alpha1-antitrypsin deficiency?

Answer 18

Destruction of elastin in the alveoli, causing emphysema (young people). Liver problems (the defective alpha1-antitrypsin accumulating in the liver).

Question 19

What are two ways for angiogenesis to occur?

Answer 19

Existing vessels can grow new branches with VEGF to areas where it is neede. Or VEGF can recruit endothelial precursor cells that are in the bone marrow to the area that needs it, and from there connect to existing blood vessels.

Question 20

Which aminoacids are found in large concentrations in collagen? In elastin?

Answer 20

Collagen: Glycine, Proline, hydroxyproline. Elastin: Glycine, Proline.

Question 21

What is the role of vitamin C in collagen production?

Answer 21

Hydroxylation of lysine and proline.

Question 22

RFF: Hyperflexible joints, arachnodactyly, aortic dissection, lens dislocation.

Answer 22

Marfan syndrome.

Question 23

RFF: Hereditary nephritis, cataracts, sensorial hearing loss.

Answer 23

Alport syndrome.