Lecture 3: Skin and Appendages

Question 1

What is the Integument made up of ?

Answer 1

Stratified Squamous Epithelium (epidermis), which is keratinized and dermis, which is made up of connective tissue in 2 layers.

Question 2

Hypodermis

Answer 2

is a layer of the skin and others consider it a superficial fascia overlying muscles that is mainly adipose tissue and connective tissue

Question 3

What are the functions of the skin?

Answer 3

Barrier, Homeostasis, Immunologic, Sensory, Endocrine, and Excretion

Question 4

What are the differences between the thin and thick skin?

Answer 4

Thick skin is mainly palms and sole of the feet. No hair follicles. While the thin skin is the rest of the body.

Question 5

What layer does the thick skin have that the thin does not ?

Answer 5

Stratum Lucidum

Question 6

What is apart of the thin skin that is not apart of the thick skin ?

Answer 6

Sebaceous Gland

Question 7

What are the two layers ?

Answer 7

Epidermis and Dermis

Question 8

Epidermis

Answer 8

is stratified squamous, keratinized epithelium and has 5 identifiable layers in thick skin

Question 9

Dermis

Answer 9

connective tissue and has two identifiable layers

Question 10

What are the 5 layers of the epidermis ?

Answer 10

1. Stratum Germinativum
2. Stratum Spinosum
3. Stratum Granulosum
4. Stratum Lucidum (only thick skin)
5. Stratum Corneum

Question 11

Stratum Germinativum

Answer 11

This is a mitotically active area.

- cubodial or columnar cells that rest on the basal lamina.

Question 12

What are the stratum germinativum attached to ?

Answer 12

They are attached to the basal lamina by the hemidesmosomes

Question 13

What are the adjacent cells of the stratum germinativum attached by ?

Answer 13

Desmosomes

Question 14

Stratum Spinosum

Answer 14

Made up of polygonal cells that have spiny projections that form “intercellular bridges”
- Mitoses seen in this layer also

Question 15

What are the intercellular bridges are now known to be locations of ?

Answer 15

Desmosomes

Question 16

What are the contributions of the intercellular bridges ?

Answer 16

Cohesiveness of the epidermis .

Question 17

What type of desmosomes are present in stratum spinosum?

Answer 17

Cytokeratin Type III

Question 18

Malphigian Layer

Answer 18

• is the stratum germinativum and stratum spinosum

- region of keratinocyte proliferation

Question 19

Stratum Granulosum

Answer 19

characterized by basophilic granules, keratohyaline granules, and membrane coating granules

Question 20

Keratohyaline granules

Answer 20

which are not membrane bound

Question 21

Membrane Coating Granules

Answer 21

Membrane Bound Granules

Question 22

What do these granules contain?

Answer 22

glycosaminoglycans and phospholipids that are extruded out into the extracellular space

Question 23

What does is the role of having these granules ?

Answer 23

• form a barrier to micro-organisms, foreign substances and most importantly water

Question 24

What is the water barrier in the epidermis is partially formed by ?

Answer 24

lamellar bodies, secretion is high in lipids

Question 25

What happens when the keratinocytes mature and differentiate ?

Answer 25

they produce keratin hyaline granules and lamellar bodies

Question 26

What is the function of the keratin hyaline ?

Answer 26

- increase in number and release their contents into the cytoplasm as the cell dies

Question 27

Stratum Lucidum

Answer 27

most prominent in thick skin | - it is a translucent layer that is very acidophilic cells that do not have nuclei and organelles

Question 28

Stratum Corneum

Answer 28

- Flattened Keratin- filled cells | - Devoid of any organelles and nucleus

Question 29

What is another name for stratum Corneum ?

Answer 29

horny cells or squams

Question 30

1st Degree Burns

Answer 30

Damage to superficial epidermis

Question 31

2nd Degree Burns

Answer 31

Epidermis completely destroyed

Question 32

3rd Degree Burn

Answer 32

Full-thickness burn - Destroys epidermis and dermis - Skin grafts are necessary

Question 33

What are the cells found in the Epidermis ?

Answer 33

1. Keratinocytes 2. Melanocytes 3. Langerhans Cells 4. Merkel Cells

Question 34

Keratinocytes

Answer 34

- predominant cell type in the epidermis | - go through a very specialized differentiation to give rise to the protective dead cell layer ( stratum corneum)

Question 35

What is the origin of the Keratinocytes ?

Answer 35

Ectodermal Origin

Question 36

What is the origin of the Melanocytes ?

Answer 36

Neural Crest Origin

Question 37

Why are the Langerhans cells not attached ?

Answer 37

because they need to be able to wonder in and out

Question 38

What are the Langerhans Cells responsible for ?

Answer 38

- engulfing invading microorganisms in the epidermis and presenting antigens to lymphoid cells in the dermis

Question 39

In AIDS and HIV positive patients, the Langerhans cell cytoplasm contain what ?

Answer 39

- HIV-1 in their cytoplasm, and may serve as reservoir for the virus

Question 40

What technique must be used for the Langerhans cells ?

Answer 40

- cells cannot be distinguished easily in H and E stained tissue

Question 41

Melanocytes are located ?

Answer 41

Stratum Germinativum

Question 42

How do the melanocytes maintain their epidermal-melanin units ?

Answer 42

- can replicate slowly throughout life

Question 43

What are the melanocytes attached to ?

Answer 43

- Hemidesmosomes

Question 44

What are the melanocytes not connected to ?

Answer 44

- Keratinocytes by Desmosomes

Question 45

What is Cytocrine secretion ?

Answer 45

- melanin granules are injected into keratinocytes

Question 46

Where is melanin predominantly in the skin?

Answer 46

Keratinocytes

Question 47

What is the position that melanin granules take ?

Answer 47

- above the nuclei of keratinocytes in the strata germinativum and spinosum

Question 48

Where are merkel cells predominantly found ?

Answer 48

thick skin where touch is acute

Question 49

What are the two distinct layers of the Dermis ?

Answer 49

- Papillary and Reticular

Question 50

What does the papillary contain ?

Answer 50

- loose connective tissue containing fibroblasts, mast cells, and macrophages

Question 51

What does the reticular layer of the dermis include ?

Answer 51

- Dense irregular CT composed of collagen fibers, type 1

Question 52

What are the appendages of the skin ?

Answer 52

- Hair Follicles - Sweat Glands - Sebaceous Glands - Mammary Glands - Nails

Question 53

What are the two sweat glands ?

Answer 53

- Eccrine Sweat-Glands | - Apocrine Sweat Glands

Question 54

How are the sweat glands developed ?

Answer 54

- as invaginations of epidermis into the underlying connective tissue

Question 55

Eccrine Sweat Glands

Answer 55

- simple, coiled tubular glands , secrete a non-viscous fluid. - Evaporation of the fluids cools skin

Question 56

What do sweat glands contain ?

Answer 56

Catabolites

Question 57

What are myoepithelial cells ?

Answer 57

- are specialized cells that squeeze the secretions from the sweat acini

Question 58

Why are the eccrine sweat glands considered acidophilic ?

Answer 58

- because they contain actin filaments

Question 59

What are apocrine sweat glands ?

Answer 59

- specialized glands located in the axillary areolar and anal region

Question 60

What do the ducts in the apocrine sweat glands secrete ?

Answer 60

- secrete viscous, odorless fluid | - the secretion attains a distinctive odor by the action of bacteria that reside on the skin

Question 61

The Sebaceous Glands are found where ?

Answer 61

- skin of the lips, the glans penis and the clitoris where they are not associated with hair follicles

Question 62

What do the sebaceous glands secrete ?

Answer 62

- secrete sebum by the holocrine secretion

Question 63

When do the sebaceous glands become more active ?

Answer 63

- puberty

Question 64

What does the sebaceous glands respond to ?

Answer 64

- hormones

Question 65

Sebaceous glands are an ideal spot for ?

Answer 65

Bacterial growth when they are clogged

Question 66

What type of cells are at the base of the gland ?

Answer 66

germinal cells

Question 67

What happens when the sebaceous glands fill with sebum ?

Answer 67

- their nuclei become pyknotic and are eventually lost

Question 68

Nails

Answer 68

are plates of keratinized epithelial cells | - they are able to assess the oxygenation of blood

Question 69

nail root

Answer 69

germinal root

Question 70

nail bed

Answer 70

- consists of stratum germinativum and stratum spinosum only ( the malpighain layer)

Question 71

Where does the epithelium of the nail bed arises from ?

Answer 71

- nail matrix

Question 72

Nail matrix extends ?

Answer 72

deep to the root

Question 73

How does the nail grow ?

Answer 73

- proximal end and slides over the nail bed, nail bed does not contribute to the nail plate

Question 74

Free Nerve Endings

Answer 74

unmyelinated axons that penetrate the basal lamina of the epidermis to enter the stratum germinativum and spinosum

Question 75

Meissner Corpuscles are abundant

Answer 75

in thick skin as well as in the skin of the lips and nipples

Question 76

Pacinian Corpuscle

Answer 76

found in the dermis and often, hypodermis, of both thick and thin skin