2 - Dermis and SubQ Tissue

Question 1

What is the dermis? What is its function?

Answer 1

Derived from mesoderm and contains adnexal structures. Two parts: papillary dermis and reticular dermis.

Functions:

• structure and flexibility
• vascular support
• immunologic protection
• nerve sensation.

Question 2

What is the function of the ECM? What are the components?

Answer 2

Supports cells of the dermis and regulates cell functions.

Components: collagen, elastic fibers, extrafibrillar matrix.

Question 3

What is collagen? What makes it?

Answer 3

Main component of the dermis: 20% of overall skin volume, 75% of dry weight of skin.

Produced by dermal fibroblasts. Very strong, stretches very little.

12 of 28 collagen types are in skin.

Question 4

What are the different types of collagen?

Answer 4

Type 1: most abundant (80-90%)

Type 2: second most abundant; increased levels during embryogenesis, infancy, and wound healing.

Types IV, VII, and XVII are in the basement membrane.

Question 5

What is the function of elastic fibers? What is their structure?

Answer 5

Give skin elasticity

Structure: _microfibrils (_mainly fibrillin) and elastin.

Question 6

What is the composition of the extrafibrillar matrix (ground substance)?

Answer 6

Water, electrolytes, plasma proteins, and proteoglycans.

Question 7

What is the structure and function of proteoglycans?

Answer 7

Structure: protein core, glycosaminoglycans with long-chain polysaccharides (ie dermatan sulfate)

Function: bind large amounts of water

Question 8

What are fibroblasts? What is their function?

Answer 8

Cells derived from mesoderm.

Synthesize ECM components such as collagen, elastic fibers, and ground substance. (have a lot of ER to make proteins).

Question 9

Describe the production of collagen fibrils?

Answer 9

1. Proteins made in the RER
2. Modified in the ER and golgi
3. Intracellular assembly of procollagen
4. Extracellular cleavage of N and C terminals via protease
5. Assembly of collagen fibril

Question 10

Describe the blood supply to the dermis?

Answer 10

Deep plexus sits in Subcutaneous fat and communicates exteriorly (outwards) towards a superficial plexus that feeds the epidermis.

Question 11

Describe the touch and pressure receptors of the epidermis and dermis?

Answer 11

Epidermis: free nerve endings may reach the epidermis (but they are mainly in the dermis)

Dermis: free nerve endings, meissner’s corpuscles, pacinian corpuscles, sensory nerve fibers.

Question 12

What is marfan syndrome?

Answer 12

Autosomal dominant disease caused by a mutation in fibrillin (variable expression).

Question 13

What is Ehler’s Danlos Syndrome? How is it inherited?

Answer 13

Group of inherited connective tissue disorders.

Abnormalities of collagen structure, production, processing, or assembly.

Variable inheritance and clinical features based on mutation.

Question 14

What is morphea?

Answer 14

An autoimmune disease; the body attacks its own collagen causing sclerosis (thickening of collagen).

Skin loses its ability to stetch at all; results in limb and join complications and may have neurologic involvement.

Question 15

What are characteristics of morphea?

Answer 15

Startsas plaques that are usually asymptomatic and then they scar down and cause sclerotic plaques that are shiney and tight.

More common in women than men. Equally occur in children and adults.

Question 16

What is systemic sclerosis? Who does it occur in?

Answer 16

Autoimmune disease causing widespread sclerosis most commonly in middle-aged women.

Question 17

What are clinical features of systemic sclerosis?

Answer 17

Sclerosis of the skin, microstomia (small mouth), and sclerodactyly (tightening of the skin on the fingers)

Raynaud’s

Telangiectasia

Arthritis

Internal organ involvement: pulmonary fibrosis, renal crisis, esophageal dysmotility

Question 18

What are the three steps of hemostasis?

Answer 18

Reflexive vasoconstriction

Coagulation through platelet activation

Formation of fibrin plug

Question 19

Describe the inflammation phase of wound healing? When does it occur?

Answer 19

Hours to 3 days.

Vasodilation (causing redness), increased vascular permeability, and leukocyte recruitment.

Question 20

Describe the proliferation phase of wound healing? When does it occur?

Answer 20

4-12 days.

• Angiogenesis by endothelial cells.
• Collagen, elastin, and matrix synthesis by fibroblasts.
• Re-epithelialization through keritinocyte migration from edges (fomr outside in).

Question 21

Describe the maturation phase of wound healing? When does this occur?

Answer 21

12 days to 2 years.

Inflammatory cells cleared, fibroblast apoptosis, blood vessel maturation, and collagen maturation.

Question 22

What is subcutaneous fat derived from? What is its function?

Answer 22

Below the dermis, derived from mesoderm.

Functions:

• Energy storage
• Insulation
• Shock absorption

Question 23

What is Erythema Nodosum? What can cause it and who gets it?

Answer 23

A disease of subcutaneous fat causing tender red nodules on the shins.

Reactive panniculitus (inflammation of subQ fat) can be from:

• strep pharyngits
• oral contraceptives
• inflammatory bowel disease
• malignancy

Young women