Integumentary Flashcards
1
Q
What does the integumentary system consist of?
A
- Skin, skin derivatives (hair follicles, nails, glands)
2
Q
What are the overall functions of the integument?
A
- Provide protection
- Participates in homeostasis
- Perceives sensory stimuli
- Performs endocrine and exocrine function
3
Q
Describe how the integument provides protection
A
IIts a physical barrier and immunologic barrier
4
Q
Describe how the integument participates in homeostasis
A
- Regulates temp by conserving or dissipating heat
- Regulates water loss to prevent dehydration
5
Q
Describe how the integument perceives sensory stimuli
A
Sensory receptors are abundant in skin
6
Q
Describe how the integument performs endocrine and exocrine functions
A
- Synthesizes vit D
- Secretes hormones, cytokines and growth factors
- Secretes sweat and sebum
7
Q
What are the 3 basic layers of the skin?
A
- Epidermis
- Dermis
- Hypodermis
8
Q
What is the epidermis?
A
Protective outer layer of stratified squamous keratinized epi
9
Q
What is the dermis?
A
Supportive middle layer of CT that is highly vascularized and extensively innervated
10
Q
What is the hypodermis?
A
Deep layer of loose CT and fat that links skin to underlying muscle, stores energy and provides insulation
11
Q
Where is thin skin?
A
On most of boddy, thinnest is on eyelids
12
Q
Where is thick skin?
A
Soles of feet, palms of hand
13
Q
What is thin skin?
A
Thinner epidermis, has hair follicles and their associated sebaceous glands
14
Q
What is thick skin?
A
Thicker epidermis, can have an extra layer and is more keratinized, no hair follicles or sebaceous glands
15
Q
Characteristics of epidermis
A
Tough and flexible
16
Q
Why is the epidermis tough?
A
KEratin proteins and desmosomes
17
Q
Why is epidermis flexible?
A
Underlying elastic fibers
18
Q
How often does the epidermis renew?
A
every 45 days
19
Q
How many layers does the epidermis have?
A
4-5
20
Q
What are the layers of the epidermis?
A
- S. corneum
- S. Lucidum
- S. granulosum
- S. spinosum
- S. basale
21
Q
What is the predominant cell of the epidermis?
A
Keratinocyte
22
Q
Cells in the S. basale are ____________, they constantly produce new keratinocytes, causing older ones to be pushed upwards
A
Mitotically active
23
Q
As cells in the epidermis ascend, they undergo terminal differentiation. During this process, they:
A
- Rapidly increase keratin synthesis
- Lose their nuclei and cytoplasmic organelles
24
Q
Is epidermis avascular or vascular?
A
Avascular- it gets nutrition by vessels in dermis
25
Desmosomes
Attach cells laterally to each other in the same layer and attach each layer to the next
26
Hemidesmosomes
Attach bottom layer of cells to the basement membrane
27
What are the main proteins linking desmsomes?
Desmocollins and desmogleins
28
Desmoglein 1 expression is greatest in what layers?
Superficial layers
29
Desmoglein 3 expression is greatest in what layers?
Deeper layers
30
Antibodies targeting proteins within desmosomes cause a group of disorders called
Pemphigus
31
What is pemphigus foliaceus?
Less severe-
Antibodies target Dsg1 causing superficial seperation of epidermal layers. Space fills with fluid causing a blister
32
What is pemphigus vulgaris?
More severe
Antibodies target Dsg3 causing deeper seperation of epidermal layers (lesions can also appear in mouth or genitals)
33
What do hemidesmosomes do?
link cells to the basement membrane
34
Bullous pemphigoid antigen proteins help attach the
intermediate filaments of the cytoskeleton the hemidesmosome
35
Antibodies directed against BPAGs can cause
seperation of the epidermis and dermis
36
Which layer of epidermis is closest to dermis?
S. basale
37
Describe the S. basale
single row of cuboidal cells sitting on a basement membrane. Structure identical in both thin and thick skin
38
S. basale contains mitotically active _________ resposnsible for producing keratinocytes
stem cells
39
What type of cells are in the S. basale?
Keratinocytes, melanocytes and Merkel cells
40
Melanocytes synthesize melanin which protects keratinocytes from
UV radiation
41
How do melanocyte nuclei appear in an H&E?
Shrunken with a clear cytoplasm
42
How do melanin granules appear in an H&E?
Dark brown dots in the cytoplasm of nearby cells
43
What is albinism?
Congenital disorder producing skin hypopigmentation. Normal # of melanocytes, but defect in melanin production. Decrease in tyrosinase activity
44
What is vitiligo?
Patches of skin depigmentation due to loss of melanocytes. Oxidative stress to melanocytes causes cell degeneration
45
What are moles?
Proliferation of melanocytes that cause benign clusters of cells
46
What types of moles should be tested for melanoma?
Asymmetric, large, evolving or multi colored moles
47
What does histology of melanoma show?
Abundant, out of place melanocytes that sometimes cluster into nests. They can also infiltrate into the dermis
48
What is merkel disk?
Cell is S> basale associated with afferent nerve fibers
49
What does merkel disk detect?
Skin indentation, which transmits information about the shape, texture of an object. Abundant in fingertips
50
What are free nerve endings?
Unmyelinated branched endings of axons of sensory neurons. Freely located or found wrapped around the base of hair follicles
51
What do free nerve endings respond to?
Pain, temp, touch, hair movement
52
What is the largest epidermal layer?
S. spinosum
53
How does the S. spinosum characteristically look?
Prickly, intercellular proteins of desmosomes are esposed as cells shrink
54
In S. spinosum, keratinocytes have more abundant
Tonofilaments, which assemble into bundles called tonofibrils
55
Cells in S. spinosum synthesize granules rich in lipids called
membrane coating granules
56
In S. granulosum, cells are beginning to lose
Cytoplasmic organelles
57
Intense basophilic stain of S. granulosum is due to granules within th ecells, which include
- Membrane coating granules
- Keratohyaline granules (contains filaggrin, protein that promotes tonofibril aggregation
58
How can the S. lucidum look?
Layer of flat cells
- Shiny, transparent
- Cells lack nuclei and most organelles
59
What is the outermost layer of epidermis?
S. corneum
60
Describe cells of the S. corneum
Cells are terminally differentiated.
- Have lost nuclei and remaining organelles
- Flattened, filled with tightly packed tonofibrils
- Have compund cell envelope
61
Superficial layers of skin are more
acidic (proteass that degrade desmosomes are more active)
62
What fibers does the dermis contain?
many collagen and elastic fibers
63
Dermis is extensively innervated by
sensory fibers
64
What other structures can be observed in dermis?
Ducts of sweat glands, hair follicles, lymphatics
65
Dermis can be divided into what 2 major sublayers?
- Papilalry layer
- Reticular layer
66
What is the papillary layer of dermis?
Loose, areolar CT. More cells, fewer fibers. Many BVs and sensory structures
67
What is the reticular layer of the dermis?
Thicker layer of dense irregular CT, more fibers, fewer cells. Lends strength
68
Papillary layers contains dermal papillae thathouse
many blood vessels and sensory receptors
69
In the papillary layer, capillary beds provide nutrition for the epidermis and are important for
temperature regulation
70
Sensory receptors in the papillary layer include
- Afferent nerves that synapse with Merkel cells
- Meissners corpuscles
71
What are Meissner's corpuscles?
Sensory receptors that respond to light touch and dynamic pressure (detect motion over skin)
72
How do Meissner's corpuscles appear?
As ovular structures in the dermal papillae. Modified free nerve ending, axons wind between associated schwann celsl
73
Describe the reticular layer of dermis?
Dense, irregular CT with characteristic thick, pink bundles of collagen. Provides tensile strength
74
What are accessory structures in the reticular layer of dermis?
- Sebaceous glands
- Secretory portion of sweat glands and the base of hair follicles
75
What structures are in the hypodermis?
- Pacinian corpuscles
- Hair follicles and their connected sebaceous glands
- Sweat glands
76
What are pacinian corpuscles?
Large, bulbous, lamellar structures that sense vibration and pressure
77
What are sweat glands?
Coiled, tubular structures that extednd from the hypodermis to the epidermis to release sweat to the surface of skin
78
What are the most common sweat glands that are found everywhere except lips and external genitalia?
Eccrine
79
What sweat glands are only found in axillary and anogenital region?
Apocrine
80
Apocrine sweat glands produce what type of substance?
Protein rich that contains pheromones
81
Eccrine sweat glands receive signals from where ?
The hypothalamus
82
Sweat is composed of
- Water and NaCl
- IgA, proteolytic enzymes, antimicrobial peptides
- Urea, uric acid and ammonia
83
What causes salty sweat in patients with cystic fibrosis?
Defect in the cystic fibrosis transmembrane conductance regulator
84
Myoepithelial cells are
contractile cells that push sweat out to the ducts. They are nect to the basement and look like pointy teeth
85
What do clear cells do?
Generate water and electrolyes
86
What do dark cells do?
Generate antimicrobial glycoproteins
87
What are the fucntions of hair?
- Protect from external irritants
- Heat retention
- Sensation
- Source of stem cells
88
How is hair a source of stem cells?
Cells in the hair follicle can assist in wound healing if S. basale cells of the epidermis are damaged
89
How does hair contribute to sensation?
Free nerve endings wrapped around the base of the follicle detect hair bending and thus recognixe wind, insects landing on the skin
90
What glands are associated with hair follicles?
Sebaceous glands
91
What do sebaceous glands do?
secrete sebum, a lipid rich substance which coats and protects hair, helps retain moisture
92
What does the arrector pili muscle do?
Raises hair to vertical position to squeeze out sebum and help retain heat
93
Hair follicle consists of
- Hair papilla
- Hair matrix
- Free nerve endings
94
Hair papilla
Small, highly vascularized nodule of dermis
95
Hair matrix
Layer of stem cells that enable continuous hair growth. Also contains melanocytes that determine hair color
96
What is the secretory portion of the sebaceous gland?
Solid mass of cells with no lumen. Lipid content makes secretory cells appear bubbly
97
Secretory cells spill their contents into the duct via
holocrine secretion
98
Arrecotr pili is smooth muscle innervated by
sympathetic fibers
99
Nail plate
heavy cross linked keratinocytes
100
nail bed
modified epidermis that the nail plate rests upon
101
Nail matrix
proliferating cells that enable contiuous nail growth. New cells get added to the anil root and begin keratinization
102
Eponychium
proximal edge of nail plate that contributes to formation fot he cuticle
103
Hyponchium
area underneath the distal edge of the nail where the nail and fingertip are attached
104
What are the 4 general phases of wound healing?
- Hemostasis (stop bleed)
- Inflammation (fight infection)
- Proliferation (fill in wound with new cells and BVs)
- Remodeling (form scar, finish process)
