Histology

Question 1

Name the 5 layers of the epidermis from superficial to deep.

Answer 1

Stratum Corneum Stratum Lucidum Stratum Granulosum Stratum Spinosum Stratum Basale

Question 2

Which epidermal layer is only present in thick skin?

Answer 2

Stratum Lucidum

Question 3

Cell type that makes up the stratum basale.

Answer 3

Simple Columnar: this layer undergoes mitosis to replenish the skin cell population

Question 4

How are cells in the stratum spinosum connected?

Answer 4

Desmosomes

Question 5

Most superficial epidermal layer that is not keratinized, however, contains granules of keratohyalin

Answer 5

Stratum Granulosum

Question 6

In which epidermal layer do cells lose their nucleus?

Answer 6

Stratum Lucidum in thick skin

Stratum Corneum in thin skin

Question 7

Name and describe the two layers of the dermis.

Answer 7

1. Papillary Layer: superficial dermal layer, forms dermal papilla into the epidermis, forms dermal ridges in thick skin (forms fingerprints), contains sensory nerve endings, Thin type I and Type II collagen fibers
2. Reticular Layer: deep dermal layer containing smooth muscle units, Type 1 collagen/ elastic fibers

Question 8

Major components of the Hypodermis.

Answer 8

Adipose tissue

Hair follicles

Glands, blood vessels

Arrector pili muscles

Question 9

Name the Function of the two structures labeled in this picture.

The ones labeled KG and the “tail-less” arrows

Answer 9

KG: keratohyalin granule, found in the stratum granulosum keratinocytes to induce aggregation of filaggrin and trichohyalin filments and induce keratinization

The arrows are pointing to lamellar bodies that are exocystosed into intercellular spaces to act as a water barrer.

Question 10

Where are melanocytes located and how do they function?

Answer 10

Located in the stratum basale.

The melanocytes respond to UV radiation and produce melanin. The melanin is sent up the dendritic processes and the tips of these processes are phagocytosed by the keratinocytes.

Question 11

Location and function of Langerhans Cells.

Answer 11

Antigen Presenting Cells in the epidermis. They are mainly located in the stratum spinosum.

Question 12

Function of this structure and its location.

Answer 12

Pacinian Nerve Ending: detects mechanical or vibratory pressure. Located in the Reticular layer of the dermis and hypodermis.

Question 13

Location and function of the meissner corpuscle.

Answer 13

Found in the papilla of the dermal papillary layer. Touch, pressure, and temperature sensation.

Question 14

Apocrine gland associated with the hair follicle.

Answer 14

Sweat Gland

Question 15

Holocrine Gland associated with the hair follicle.

Answer 15

Sebaceous Glands: the nuclei gradually get smaller as the cell undergoes apoptosis to become sebum (oil) secretion

Question 16

Layer of the hair follicle that contains melanocytes to give hair its color.

Answer 16

Matrix cells that surround the dermal papilla

Question 17

What makes up the external root sheath of the hair follicle?

Answer 17

It’s just a continuation of the epidermis.

Question 18

Name the 3 layers of the inner root sheath

Answer 18

1. Henle’s Layer: outermost, cuboidal cells
2. Huxley’s Layer: middle layer, squamous cells
3. Cuticle of the hair follicle: inner layer, squamous cells

Question 19

What is the:

Nail Matrix

Eponychium

Hyponychium

Lunula

Answer 19

Nail Matrix: germinative layer forming hard keratin

Eponychium: edge of skin covering the nail root

Hyponychium: skin nail junction

Lunula: cresent shaped white area at the end of the nail