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MSK I > Lecture 1 + 2 > Flashcards

Lecture 1 + 2 Flashcards

(46 cards)

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1
Q

Describe the epidermis?

A

keratinized stratified squamous epithelium

derived from the ectoderm

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2
Q

Describe the dermis?

A

dense connective tissue

derived from the mesoderm

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3
Q

Describe the hypodermis?

A

deep compared to the dermis

can also be called the subcutaneous fascia

contains variable amounts of adipose tissue arranged in lobules and separated by connective tissue

can find hair follicles, glands, and mechanoreceptors

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4
Q

What are the associated appendages of the skin?

A
  1. hair follicles and hair
  2. sweat glands
  3. sebaceous glands
  4. nails
  5. mammary glands
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5
Q

Functions of the skin?

A
  1. barrier
  2. immunological role
  3. homeostasis
  4. sensory info
  5. endocrine function
  6. excretion
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6
Q

What are the functions of keratinocytes?

A
  1. produce keratin- mainly in the stratum basale
  2. produce keratohyalin granules - spinosum and granulosum layers
  3. contributes to the formation of the epidermal water barrier
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7
Q

What do keratinocytes look like under a microscope?

A 
Has a basophilic appearance
has organelles (lots of free ribosomes)  
keratin filaments (cytoskeletal)
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8
Q

melanocytes under a microscope?

A

found in the basal layer

appear clear with large elongated nuclei

cytoplasmic processes extend between keratinocytes

no desmosomal connections but are attached to the basal lamina via hemidesmosome like structures

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9
Q

Functions of the melanocytes?

A

produce melanin that is transferred to surrounding keratinocytes for UV protection

skin color is the amount and ratio of melanin types present

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10
Q

How is melanin produced?

A

oxidation of tyrosine to DOPA to melanin

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11
Q

What are the two forms of melanin?

A
  1. Eumelanin - brownish

2. pheomelanin - reddish

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12
Q

Describe the function of eumelanin?

A

protects against UVR damage

degrades faster in light-skinned individuals

scatter and absorb UV rays and eliminate free-radicals

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13
Q

Describe the function of pheomelanin

A

allows more light to pass, thus increasing Vit. D production

found more common in atypical nevi and melanomas

increased oxidative damage

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14
Q

Function of langerhan’s cells?

A

Encounters, processes and expresses antigens (APC)

migrates to lymph node to present antigen to T-cell

involved in hypersensitivity reactions

expresses both MCH I and MCH II and receptors for IgG

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15
Q

langerhan’s cell structure?

A

the nucleus is indented making the nuclear profile uneven

have tennis racquet shaped granules- function is unclear

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16
Q

Merkel’s cell structure?

A

Have desmosomes and contain keratin filaments

nucleus is lobed

cytoplasm contains neurosecretory granules

possess antigenic markers of both epidermal and neural

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17
Q

What is the function of the Merkel cell?

A

Detect touch sensation

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18
Q

What is thick skin?

A

Found only in the soles and palms

usually hairless and has a much thicker epidermis

carries a stratum lucidum

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19
Q

What is thin skin?

Study These Flashcards
A

found most places

thinner epidermis compared to thick skin

hair follicles are widespread

20
Q

What are the 5 layers of the epidermis?

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A
  1. stratum basale - differentiating cells
  2. stratum spinosum - maturing and slowly dying cells
  3. stratum granulosum - cells that are about to die
  4. stratum lucidum - only found in thick skin
  5. stratum corneum- dead keratinized cells
21
Q

describe the stratum basale?

Study These Flashcards
A

single layer of cuboidal or columnar cells (mitotically active)

has merkel cells, melanocytes, and keratinocyte stem cells

rests on the basal lamina (attached by hemidesmosomes)

extensive cell junctions (desmosomes)

22
Q

Describe the stratum spinosum?

Study These Flashcards
A

several cell layers thick

keratinocytes are larger than those seen in the basale

make cytokeratins/ keratin filaments

exhibit many cytoplasmic processes or spines

gradually change appearance as they move closer to the surface

cells connected to each other by desmosomes

langerhan’s cells are found in this layer

23
Q

Describe the stratum granulosum?

Study These Flashcards
A

most superficial of the nonkeratinized cells

one to three layers thick

contains conspicuous granules which give the cells a granulated look

keratinization begins (soft keratin): loss of organelles, thickened cell membrane, and decreased pH

lamellar bodies: epidermal water barrier

24
Q

Describe the stratum lucidum?

Study These Flashcards
A

only well seen in thick skin

in a microscopic view, it appears as a light highly refractile eosinophilic band

keratinization process is well advanced

25
Describe the stratum corneum?
several layers of dead keratinocytes keratinocytes are filled with keratin aggregated into tonofibrils abrupt transition from granulosum
26
What forms the epithelial water barrier?
the cell envelope and the lipid envelope
27
how does keratinization occur?
1. keratin is accumulated in the cell cytoplasm 2. cells lose organelles, cytoplasm, and nuclei 3. more tonofilaments are formed; fibrils are arranged by filaggrin 4. well cells reach the upper layers the desmosomes are broken apart 5. cells are sloughed off (takes about 47 days)
28
What are characteristics of the dermis?
1. gives strength and elasticity to the skin 2. contains many appendances such as nerve corpuscles and glands 3. contain smooth muscle that movie hair
29
What are the two layers of the dermis?
the papillary layer and the reticular layer
30
Explain the papillary layer of the dermis?
It is the superficial layer and is composed of mainly loose connective tissue (more cells) contains blood vessels mainly type I and III collagen fibers the elastic fibers are thin and irregular contains Meissner corpuscles
31
Explain the reticular layer of the dermis?
thicker and deeper than the papillary layer dense irregular connective tissue (less cells) has thick irregular bundles of type I collagen and thicker elastic fibers
32
What three parts of the dermis are responsible for fingerprints and allow for more mechanical stress?
epidermal ridge, dermal ridge, and dermal papillae
33
What are the functions of nails? what are they?
help with grip and gives protection they are hard plates of epidermal keratinized cells
34
What are the three parts of the hair follicle?
1. Infundibulum 2. isthmus 3. inferior segment
35
What makes up the pilosebaceous organ?
the hair follicle, sebaceous gland, and smooth muscle
36
What are the three phases of hair growth?
1. long phase of active growth (anagen) 2. short phase of involution (catagen) 3. short inactive phase (telogen)
37
Characterize the sabaceous glands?
simple branched acinar gland the secretory portion is located deeper in the dermis opens into hair follicle the secretion is holocrine product is sebum these glands prevent hair from becoming dry and brittle
38
Explain eccrine sweat glands?
they are present in both thick and thin skin simple coiled tubular glands the merocrine secretion contains clear cells, dark cells, and myoepithelial cells
39
What part of the PNS innervates the eccrine sweat glands?
sympathetic via cholinergic neurotransmitters
40
What kind of epithelium is the eccrine sweat gland ducts.
stratified cuboidal epithelium
41
explain the apocrine glands?
found only in the armpit and perineum coiled tubular glands secretes pheromones by merocrine pathway
42
what type of epithelium lines the apocrine gland ducts?
stratified cuboidal opens into hair follicle
43
What part of the PNS innervates the apocrine gland?
sympathetic via catecholamine neurotransmitters
44
characteristics of the pacinian corpuscle?
Large ovoid deep dermis/hypodermis senses deep pressure and vibration
45
What is a meissner corpuscle function?
light touch
46
What is the function of ruffini's corpuscle
stretch and torque

MSK I (23 decks)

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