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MSK Week 1 > Skin and Glands > Flashcards

Flashcards in Skin and Glands Deck (69):
1

Layers of the epidermis

Basale
Spinosum
Granulosum
Lucidum
Corneum

Epidermis is of ectodermal origin

2

Stratum Basale

Mitotically active cells that attach directly to the basement membrane by hemidesmosomes. Single layer of basophilic cuboidal or columnar cells.

3

Stratum Spinosum

Still mitotically active, but cells are starting to differentiate. Keratinocytes are connected to each other by desmosomes. Largest layer of epidermis.

4

Stratum Granulosum

Bundles of Keratin aggregates bound via accessory proteins like filagrin (keratohyalin granules)

5

Stratum Lucidum

Palms and soles of feet only. No nuclei or granules

6

Stratum Corneum

Non-nucleated dead cells filled with keratin.

As you go higher, fat and desmosome linkages disappear until "squames" start to sluff off

7

Psoriasis

T Lymphocytes are overactive causing an autoimmune reaction in the skin, leading to irritation and increased keratinocytes causing thickening and scaling of the skin

8

Thin vs. Thick skin

Size of Stratum Corneum

Thick skin DOES NOT have hair follicles (palms and soles)

9

What does Keratohyalin promote?

Within the SG layer, it promotes the dehydration of cells and cross-linking of keratin fibers

10

Layers of Dermis

Papillary Layer
Reticular Layer

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Papillary Layer

Fine bundles of collagen. Loose connective tissue in this area that interdigitates with the epidermis for strong attachment. Mast cells, fibroblasts and leukocytes are present here

12

Reticular layer

Large bundles of collagen. Much thicker, dense irregular connective tissue with more fibers and fewer cells. Elastic fibers also present

13

Where are melanocytes?

Basal layer but they project to spinosum

14

Eumelanin

Brown and Black melanin

15

Pheomelanin

Melanin for redheads

16

Cytology of melanocytes

1. Many small mitochondria
2. Short cisternae of RER
3. Well developed golgi

17

Steps of melanin synthesis

1. Tyrosine synthesized in RER, processed in the golgi
2.Tyrosine accumulates in the vesicles that also have a fine matrix of other proteins (Stage I melanosomes)
3. Stage II melanosomes: Melanin synthesis begins
4. Stage III - Deposited and accumulated melanin
5. Stage IV - No tyrosinase left and melanosome is mature and full of melanin

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Activity of Tyrosinase

Converts tyrosine to DOPA which is polymerized and transformed to melanin

19

Melanosomes after they bud off

Keratinocytes cleave melanosomes off of melanocytes, they go to nearby keratinocytes in the spiney layer and basal layer and go close to the nucleus to shield against UV radiation

20

Albinism

Dysfunction in the melanocyte pathway or tyrosinase pathway causing hypopigmentation. Related to vitiligo where you lose pigmentation due to melanocyte deterioration (depigmentation)

21

Moles

Melanocytes proliferate in small areas. Can be indicative of cancer

22

Merkel Cells

Slowly adapting somatosensory cells that are found in the SB.

Allow for light touch discrimination of objects/shapes

23

Unencapsulated sensory receptors

Merkel Cells
Free nerve endings
root hair plexus

24

Where are free nerve endings

In papillary dermis and low epidermis - Good for high/low temperature, pain, itching, and also tactile

25

Root Hair plexus

Web of sensory fibers surrounding the bases of hair follicles in reticular dermis to detect hair movement

26

Encapsulated Receptors

Meissner's Corpuscles
Lamellar/Pacinian Corpuscles
Krause End Bulbs
Ruffini Corpuscles

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Meissner's Corpuscles

Also called Tactile corpuscle. Sensitive to light touch (concentrated on the fingers, foreskin, and lips)

Located just beneath the epidermis (in the dermal papillae)

Rapidly adapting Mechanoreceptor

28

Pacinian Corpuscles

Also called Lamellar Corpuscles. Detect deep pressure changes and vibrations.

Very large receptor field. Located deep in the dermis.

Rapidly Adapting Mechanoreceptor

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Krause Ends Bulbs

Thermoreceptors for sensing cold temperatures.

Located in the penis and clittoris (genital corpuscles) and in the eye, lips, tongue, and trunk.

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Ruffini Corpuscles

Slowly adapting Mechanoreceptor

Sensitive to the stretch and torque of skin

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Types of receptors

Mechanoreceptors
Thermoreceptors
Nociceptors
Electromagnetic Receptors
Chemoreceptors

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Temperature control in the skin

1. Constrict arterioles = constrict blood = retain heat in cold situations
2. Evaporative cooling using eccrine glands
3. Dilate arterioles to give off heat

33

Cuticle

Outermost area of the shaft. Heavily keratinized squamous cells

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Medulla

Most interior of the hair shaft. Moderately keratinized

35

Cortex

Between the root sheath and the medulla. Heavily keratinized and densely packed

36

Dermal papilla

Cells produce signals that drive the growth of hair follicles (projects into the cortex)

37

Stages of hair growth

Anagen - Long period of mitotic division

Catagen - Brief period of arrested growth and regression of the hair bulb

Telogen - Final long period of inactivity, hair shedding

38

Types of glands

Exocrine Glands
Endocrine Glands
Paracrine Glands

39

Exocrine Glands

Dump into ducts

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Types of exocrine glands

Merocrine (Eccrine)
Apocrine
Holocrine

41

Merocrine

Sometimes called Eccrine glands (major sweat glands of the human body). Makes granules and release chemicals

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Apocrine

Granules "buds off," taking part of the cell's cytoplasm

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Holocrine

Whole cell breaks down

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Endocrine Glands

Sit on the basement membrane and dumps into the blood

NOT EXOCRINE

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Paracrine Glands

Secrete signals that act on nearby cells

NOT EXOCRINE

46

Duct cells

Reabsorb sodium from the sweat to reduce loss of sodium

47

What are melanocytes derived from?

From neural crest cells (and they are found in the SB)

48

In the skin, what is the most superficial layer in which nuclei are present?

Stratum Granulosum

49

Where does lamellar body secretion occur and for what purpose?

In the Stratum Granulosum

Forms a waterproofing boundary for the skin (secretes lipids)

50

What purpose to desmosomes serve?

Because the epidermis is avascular, desmosomes create channels that permit the flow of nutrients and the movement of cells

51

What type of proteins are prevalent in the SG?

Cysteine and histidine rich proteins that bind keratin filaments together

52

How do basal cells, as the become keratinocytes, change to toughen the epithelium?

Cross-linking of the cytoplasmic proteins

53

Langerhan's cells

Dendritic cells (APCs that endocytose antigens and transport them to the lymph nodes, initiating the immune response)

54

What staining would reveal Langerhan's cells?

Antibody staining (CD1)

In a normal H&E stain, it is too hard to differentiate b/w these cells and keratinocytes

55

Where is the highest concentration of melanosomes in the skin?

SS for darker skin

SB for lighter skin

56

Degradation of melanosomes occurs faster in dark-skin or light-skin people?

Light-skin

57

Function of melanocytes

Melanocytes make melanin that is packages into melanosomes

58

Myoepithelial cells

Squeeze and force sweat through ducts (ducts reabsorb various ionic components of sweat)

59

Sebaceous gland

Holocrine secretion of oily material to allow for waterproofing

60

What makes your hair turn white?

Loss of melanocytes

61

Goblet cell

Unicellular, merocrine gland that secretes mucus

62

What type of gland is the thyroid?

Endocrine (b/c it does not have any ducts)

63

Which organs have both exocrine and endocrine components

Liver and pancreas

64

What cell types are prevalent in keratinocytes

Keratinocytes consists mainly have keratinized stratified squamous epithelium

65

Is the number of melanocytes b/w sexes equal?

Yes, however, the distribution of melanin IS NOT

66

What stimulates melanin production?

-Sun exposure
-MSH
-ACTH
-Estrogen
-Progesterone

67

Arrector pili

Small muscles attached to hair follicles that cause hair to stand on end (goose bumps)

68

Sebum

The oily/waxy matter produced by sebaceous glands to lubricate and waterproof the skin

69

Arteriovenous anastomoses

Connection b/w and artery and a vein