Lecture 3 - Histology of the skin

Question 1

3 layers of the skin and what are they derived from

Answer 1

epidermis - derived from the ectoderm
dermis – derived from mesoderm)
hypodermis (subcutaneous layer

Question 2

Deepest layer of the skin (1st layer)

• is a single layer of cuboidal to low columnar cells resting on a basement membrane.
• These cells have mitotic capabilities. Also contains melanocytes and Merkel cells. (mechanoreceptor)

Answer 2

Stratum basale (or germinativum)

Question 3

2nd Layer of the skin composed of many layers of polyhedral cells ( prickle cells) that have desmosomal bridges with other cells . It contains Langherhans cells and processes of Melanocytes.

Answer 3

Stratum Spinosum

Question 4

1st and 2nd layer of skin and is responsible for cell renewal.

Answer 4

Stratum Malpighi

Question 5

3rd layer of the skin has flat cells and contains keratohyaline granules.
(This layer is absent in thin skin.)

Answer 5

Stratum Granulosum

Question 6

4th layer of the skin is a thin trans-parent layer whose cells contain eleidin which is a transformation product of
keratohyalin .The cells lack nuclei
(this layer is also absent in thin skin.)

Answer 6

Stratum Lucidum

Question 7

5th layer of skin, (most superficial) composed of
Squames which are densely packed
with keratin.

Answer 7

Stratum Corneum

Question 8

Is the most predominant cell type , found in all 5 layers, produces Keratin, an intermediate filament protein

Answer 8

Keratinocytes

Question 9

Cells that are derived from neural crest cells and responsible for melanin production .Increased pigmentation can occur in Addison’s disease, hypopigmentation is a feature of Albinism.

Answer 9

Melanocytes

Question 10

Cells that act as antigen trapping cells interacting with T cells

Answer 10

Langerhans cells

Question 11

Cells derived from the neural crest cells and are involved in tactile sensations.

Answer 11

Merkel cells

Question 12

Major keratin monomers of epidermis

Answer 12

K5 & K14 basal keratinocytes

K1 & K10 replaces K5 & K14 in str. spinosum

Question 13

Disease where
↑ # proliferating cells
↓ mitotic cycle time
Result:
↑ epidermal thickness
↑ renewal rate (7 days)
Thick, scaly skin

Answer 13

Psoriasis

Question 14

When melanocytes become malignant , the condition is called what? what layer is it stemmed from

Answer 14

Melanoma

Basal layer

Question 15

Cancer of dermal invasion by abnormal cells of the epidermis

Answer 15

Squamous cell carcinoma

Question 16

2 layers of the dermis

Answer 16

Papillary (superficial)

Reticular (deep)

Question 17

Dermal layer of loose irregular CT
Dermal ridges
Dermal papillae
Capillary loops
Meissner’s corpuscles
Free nerve endings (assoc w/ Merkel cells)

Answer 17

Papillary layer

Question 18

Dermal layer of denser CT
Thicker layer
Pacinian corpuscles
Ruffini’s corpuscles

Answer 18

Reticular layer

Question 19

Plexus of arteries and veins that is found at dermo- hypodermal junction

Answer 19

Cutaneous plexus

Question 20

Plexus located in the papillary layer of dermis Capillary loops extend into each dermal papilla and result in convective heat loss , and also supply nutrients to epidermis.

Answer 20

Sub papillary plexus

Question 21

In between 1&2. Are supplied by sympathetic nerves so restrict flow through superficial plexus to reduce heat loss as in extreme cold

Answer 21

AV shunts