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HHP > Integumentary System > Flashcards

Integumentary System Flashcards

1
Q

What percentage of body mass does skin account for?

A

15-20%

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2
Q

Where is epidermis derived from?

A

Ectoderm

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3
Q

Where is dermis derived from?

A

Mesoderm

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4
Q

What is thick stratum corneum?

A

No hairs, abundant sweat glands, found in palms and soles of feet

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5
Q

Thin stratum corneum contains?

A

Hairs, sweat glands, sebaceous glands

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6
Q

Describe statum basale

A

Small cuboidal to low columnar, basophilic cells that rest on basal lamina, mitotically active stem cells, abundance of ribosomes that synthesize cytokeratin, contains cytokeratin intermediate filaments called tonofilaments

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7
Q

What are stratum basale cells attached to each other by?

A

Desmosomes

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8
Q

What are stratum basal cells attached to basal lamina by?

A

Hemidesmosomes

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9
Q

What are tonofilaments?

A

Cytokeratin intermediate filaments that strengthen hemidesmosomal attachment

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10
Q

What does basophilic cytoplasm of stratum basale cells indicate?

A

They are actively synthesizing keratin protein in form of tonofilaments

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11
Q

What are white cells that can be found in stratum basale that are not basophilc?

A

Melanocytes

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12
Q

Describe stratum spinosum

A

Prickle cell layer, cuboidal or polygonal cells, numerous short cytoplasmic processes known as spines, Nodes of Bizzozero, contains keratin filaments, and melanin granules

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13
Q

What are Nodes of Bizzozero?

A

Desmosomal attachments of spine processes in stratum spinosum

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14
Q

How are cytoplasmic processes attached to other processes in stratum spinosum?

A

Desmosomes

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15
Q

What is cytoplasm of stratum spinosum filled with?

A

Melanin granules, and tonofilaments that extend into cytoplasmic processes and attach to desmosomes

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16
Q

What happens to cells in stratum spinosum as they mature and move towards granulosum layer?

A

Polygonal shape cells at base start to flatten and become squamous shaped towards surface

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17
Q

What are the pale staining cells located in stratum spinosum that are not prickle cells?

A

Langerhans cells, come from monocytes which is part of MPS system

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18
Q

What do the tonofilamets in stratum spinosum cytoplasm attach to?

A

Extend through cytoplasmic processes and attach to desmosomes

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19
Q

Describe stratum granulosum

A

1-3 cell layers thick, basophilic cells due to active synthesis and contains many keratohyalin granules

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20
Q

What do keratohyalin granules contain in stratum granulosum?

A

Filaggrin, and Trichohyalin

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21
Q

What happens when Filaggrin and Trichohyalin are released into cytoplasm of granulosum cell?

A

Promote aggregation of keratin filaments into tonofibrils, leading to conversion of granular cells into cornified cells; called keratinization

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22
Q

Where is stratum lucidum found?

A

Only thick skin

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23
Q

Describe stratum lucidum

A

Eosinophilic cells, well advanced keratinization, nucleus and organelles become disrupted and disappear as cell fills with keratin

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24
Q

What happens to pH as cells rise from stratum granulosum to stratum corneum?

A

pH rises to more acidic range;
7.1 in granulosum
6.5 in lucidum
4.5 in corneum

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25
Q

Describe stratum corneum

A

Anucleated cells, filled with keratin filaments, thickness allows for identification of thick or thin skin

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26
Q

Describe stratum corneum

A

Anucleated cells, filled with keratin filaments, thickness allows for identification of thick or thin skin

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27
Q

What layer creates the water barrier?

A

Stratum corneum

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28
Q

What is the water barrier?

A

Cells of deeper portion are coated with an extracellular layer of lipids

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29
Q

What are dermal papillae?

A

Finger like protrusions of CT, project into undersurface of epidermis

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30
Q

What are epidermal ridges or Rete ridges?

A

Epidermal protrusions into dermis

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31
Q

What happens to rete ridges at sites of increased mechanical stress?

A

They are much deeper, and dermal papillae are longer and closely spread; increasing interface between epidermis and dermis

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32
Q

Where are dermal ridges found?

A

Thick skin, fingertips

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33
Q

What is arrangement of dermal ridges?

A

Parallel arrangement, with dermal papillae located in between

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34
Q

What do dermal ridges form?

A

Distinctive pattern that is genetically unique and forms basis of Dermatoglyphics

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35
Q

How is epidermis connected to underlying dermis?

A

Hemidesmosomes

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36
Q

Proteins of hemidesmosomes link?

A

Intermediate filaments (tonofilaments) of cytoskeleton into basal lamina

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37
Q

How are tonofilaments attached to plaque?

A

BP230

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38
Q

How is plaque attached to laminin in basal lamina?

A

BP180 or Type 17 collagen

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39
Q

What regulates the function of laminin in basal lamina?

A

BP180 or Type 17 collagen

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40
Q

What is Bullous Pemphigoid?

A

Rare autoimmune condition where high levels of antibodies are formed against BP230 and BP180, absence of BP230 causes blistering of the skin due to build up of fluid between epidermis and dermis, sores typically heal without scarring

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41
Q

What are two layers of dermis?

A

Papillary layer and reticular layer

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42
Q

What is papillary layer of dermis?

A

Most superficial layer below epidermis, consists of loose CT, includes dermal papillae and rete ridges

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43
Q

What does papillary layer of dermis contain?

A

Type 1 and 3 collagen, elastic fibers form irregular threads, blood vessels and sensory nerve endings

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44
Q

What is reticular layer of dermis?

A

Deep to papillary layer, thicker and less cellular, creates langers lines

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45
Q

What does reticular layer of dermis contain?

A

Thick irregular bundles of type 1 collagen and coarse elastic fibers

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46
Q

What are Langers Lines?

A

Collagen and elastin form regular lines of tension in skin

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47
Q

What do langers lines provide involving skin incisions?

A

Least scarring when lines are followed during incisions

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48
Q

What two vascular plexuses are present in reticular layer of dermis?

A

Subpapillary and Deep Plexus

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49
Q

Where is subpapillary reticular layer located in dermis?

A

Below papillary layer

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50
Q

Where is deep plexus reticular layer located in dermis?

A

Interphase between dermis and subcutaneous layer

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51
Q

What is found between the two vascular plexuses in reticular layer of dermis?

A

Numerous AV arterio-venous anastomoses called Glomus bodies

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52
Q

What are glomus bodies surrounded by?

A

Connective tissue capsule

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53
Q

What are glomus bodies involved in?

A

Body temperature regulation, numerous in fingers toes and lips

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54
Q

In glomus bodies, arteriolar smooth muscle cells are modified to?

A

Glomus cells, serve as sphincters

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55
Q

Deepest part of reticular layer contains smooth muscle plexuses in what sites?

A

Areola, penis, scrotum, perineum, account for puckering of skin

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56
Q

What are the three features in the hypodermis?

A

Panniculus adiposus, arrector pili muscle, and panniculus carnosus

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57
Q

What is panniculus adiposus?

A

Thick layer of adipose tissue, major energy storage site, also considered as insulation layer

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58
Q

What is arrector pili muscle?

A

Individual or bundles of smooth muscle cells that originate in hypodermis, connects base of hair follicles to superficial dermis

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59
Q

What does contraction of arrector pili muscle in hypodermis cause?

A

Erection of hair and puckering of skin (goosebumps)

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60
Q

What is panniculus carnosus?

A

Thin striated muscular layer located deep to subcutaneous fascia, well defined in human platysma of neck, facial expression muscles, and scalp

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61
Q

Keratinocytes originate in?

A

Stratum basale

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62
Q

What is function of keratinocyte?

A

Produce keratin filaments called tonofilaments, and form epidermal water barrier

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63
Q

What does EM of keratinocytes show?

A

Many secretory cells, and many free ribosomes

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64
Q

Why does keratinocytes need lots of ribosomes?

A

For synthesis of keratins which forms tonofilaments

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65
Q

What happens when synthesis of keratin filaments continues in stratum spinosum?

A

The filaments become grouped and form tonofibrils

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66
Q

Keratinocytes in UPPER part of stratum spinosum begin to produce what?

A

Keratohyalin granules, and lamellar bodies

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67
Q

What happens to production of keratohyalin granules in stratum granulosum?

A

Keratohyalin granules production increases in stratum granulosum

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68
Q

What do keratohyalin granules contain?

A

Filaggrin and Trichohyalin

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69
Q

What happens with Filaggrin and Trichohyalin is released?

A

They convert tonofilaments into tonofibril bundles, this leads to conversion of granular cells into cornified cells called keratinization

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70
Q

What is formed keratin known as in keratinization process?

A

Soft keratin

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71
Q

What does transformation of granular cells into cornified cells during keratinization include?

A

Breakdown of nucleus and organelles, thickening of plasma membrane, decrease in pH from 7.1 in granulosum to 4.5 in corneum

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72
Q

How long does keratinization take?

A

2-6 hours

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73
Q

What is desquamation process in keratinization regulated by?

A

Proteolytic degradation of desmosomes

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74
Q

What becomes active in keratinocytes in acidic pH?

A

Kallikreins

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75
Q

What do kallikreins do?

A

Degrade desmosomes and cause keratinocyte release

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76
Q

What is epidermal water barrier established by?

A

Deposition of substances on outer and inner surfaces in terminally differentiating keratinocytes

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77
Q

What happens to outer surface in epidermal water barrier?

A

Formation of lipid layer that is attached to outer layer of plasma membrane, called LIPID ENVELOPE

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78
Q

What happens to inner surface in epidermal water barrier?

A

Deposition of insoluble proteins on inner surface of plasma membrane, called CELL ENVELOPE

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79
Q

How is lipid envelope made?

A

Keratinocyte lamellar bodies contain ceramides, cholesterol and fatty acids, lamellar bodies are discharge by cells in granular layer, when secreted out, ceramides provide a teflon like coating on underside cell surface of plasma membrane

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80
Q

As cells move towards the surface, how is barrier constantly maintained?

A

Keratinocytes reaching terminal differentiation

81
Q

How is cell envelope made?

A

Insoluble proteins deposited on inner surface of plasma membrane formed by Small proline rich proteins and large structural proteins

82
Q

What are some of the large structural proteins used in cell envelope?

A

Keratin chains, desmosomal proteins, loricrin, elafin, filaggrin, involucrin

83
Q

Melanocytes originate from where?

A

Neural crest

84
Q

What are melanocytes?

A

Pigment producing dendritic cells scattered among basal keratinocytes of stratum basale

85
Q

Where do melanocyte processes reach to?

A

Stratum spinosum layer

86
Q

One melanocyte is associated to how many keratinocytes?

A

36

87
Q

What is ratio of melanocyte to keratinocyte in stratum basale?

A

1:4 to 1:40 depending on area of body, ratio is constant to all races

88
Q

Do melanocytes form desmosomal attachments to keratinocytes?

A

NO

89
Q

What is function of melanocyte?

A

Produce and distribute melanin into keratinocytes

90
Q

How is melanin produced in melanocyte?

A

By oxidation of tyrosine to DOPA and transformation of DOPA into melanin

91
Q

Where is melanin produced in?

A

Membrane bound premelanosomes

92
Q

What is formed with increased production of melanin?

A

A mature melanin granule called Melanosome

93
Q

Where can mature melanosomes be found?

A

At the ends of melanocyte processes

94
Q

Describe pigment donation in melanocytes?

A

Keratinocytes phagocytose tips of melanocyte processes through cytocrine secretion

95
Q

Why does light skin occur?

A

Melanosomes are more concentrated in keratinocytes near basal layer, melanin is degraded faster because of lysosomal activity in keratinocytes of stratum spinosum, therefore melanin doesnt reach the upper layers of epidermis

96
Q

What are two forms of melanin that are genetically determined?

A

Eumelanin: brownish - black
Pheomelanin: red - yellow

97
Q

What is albinism?

A

Hereditary lack of pigmentation

98
Q

What is Leukoderma?

A

White patches on the skin, due to partial or total loss of skin pigmentation, many causes for this

99
Q

What are langerhans cells?

A

Antigen presenting cells in epidermis, part of MPS system

100
Q

What happens to antigens caught by langerhans cells?

A

After antigen processing in the skin, the cells go to regional lymph nodes and interact with T lymphocytes

101
Q

Does langerhans cells form desmosomal attachments with keratinocytes?

A

NO

102
Q

What do langerhans cells closely resemble?

A

Dendritic antigen presenting cells in lymph node, spleen and thymus

103
Q

What does langerhans cells look like in TEM?

A

Nucleus is indented in many places, show characteristic granules called BIRBECK GRANULES

104
Q

What does rod shaped Birbeck granules indicate?

A

Active cell against pathogens or antigens

105
Q

How are Birbeck granules formed?

A

Proteins langerin and CD1a are present as receptors on plasma membrane, takes in antigens through langerhans cell, when cell is activated then Birbeck granules are formed

106
Q

Where are merkel cells found?

A

Stratum basale

107
Q

What is function of merkel cell?

A

Cutaneous sensation, tachtile sensation or 2 point discrimination

108
Q

Where are merkel cells abundant?

A

Where sensory perception is acute; fingertips

109
Q

How are merkel cells bound to adjacent keratinocytes?

A

Desmosomes

110
Q

What filaments do merkel cells have in the cytoplasm?

A

Keratin filaments

111
Q

Why does merkel cell bulge into dermis?

A

Merkels disc: myelinated afferent nerve looses its myelin when reaches merkel cell, cell puts out process and takes up merkel disc into cytoplasm

112
Q

What is considered the merkel corpuscle?

A

Combination of afferent nerve terminal and merkel cell

113
Q

What does cytoplasm of merkel cell consist of?

A

Dense cytoplasm, may contain some melanosomes, but best characterized by presence of dense cored neurosecretory granules

114
Q

What is merkel cell considered to be?

A

Sensitive mechanoreceptor, found in relation to hair follicles

115
Q

What are the most numerous nerve supply receptors in the skin?

A

Free nerve endings

116
Q

Where do free nerve endings terminate?

A

Stratum granulosum

117
Q

What do free nerve endings lack?

A

CT cover or schwann cell sheath

118
Q

What do free nerve endings function in?

A

Fine touch, heat, cold, pain

119
Q

Where are free nerve endings usually found?

A

Papillary layer of dermis

120
Q

What is the hair root plexus?

A

Network of free nerve endings surrounding hair follicles, sensitive to hair movement and serve as mechanoreceptors

121
Q

Encapsulated nerve endings are enclosed by what?

A

CT capsule

122
Q

What are the four types of encapsulated nerve endings?

A

Pacinian corpuscle
Meissners corpuscle
Ruffinis corpuscle
Krauses end bulbs

123
Q

Pacinian corpuscles are what kind of pressure receptors?

A

Deep pressure receptors for vibratory and mechanical pressure

124
Q

Where are pacinian corpuscles located in epithelium?

A

Deep dermis, hypodermis

125
Q

Where can pacinian corpuscles be found?

A

CT, joints, periosteum, internal organs

126
Q

How is pacinian corpuscle composed?

A

Composed of myelinated nerve ending surrounded by capsule, nerve enters capsule at one end with myelin intact, then myelin is lost and unmyelinated portion extends to opposite end

127
Q

What is considered the inner core of pacinian corpuscle?

A

Unmyelinated portion of nerve surrounded by a series of tightly packed flattened schwann cell lamellae

128
Q

What is considered the outer core of pacinian corpuscle?

A

The bulk of the capsule, formed of a series of concentric lamellae, composed of flattened cells that correspond to perinerial cells

129
Q

What are the lamellae separated by in the pacinian corpuscle?

A

Filled with lymph like fluid, collagen fibrils, occasional capillaries

130
Q

What are meissners corpuscles considered to be?

A

Fine touch receptors, senses very little pressure

131
Q

Where are meissners corpuscle located in epithelium?

A

Dermal papilla just beneath epidermal basal lamina

132
Q

Where are meissners corpuscles abundant in?

A

Lips, palm and sole of foot, particularly in fingertips and toes

133
Q

Describe structure of meissners corpuscle

A

CT capsule, cylindrical structure, perpendicular to skin surface, consists of 1 to 2 unmyelinated endings of myelinated nerves, unmyelinated endings take a spiral path; surrounded by flattened schwann cells that form irregular lamellae

134
Q

What is function of ruffinis corpuscles?

A

Respond to mechanical displacement of adjacent collagen fibers during stretch and torque

135
Q

Describe structure of ruffinis coupuscle

A

Thin CT capsule encloses fluid filled space, afferent myelinated nerve enters capsule, loses its myelin and forms an arborization of axonal endings each ending in a bulb

136
Q

What is function of Krauses end bulbs?

A

Sense cold temperatures

137
Q

Describe structure of Krauses end bulbs

A

Oval bodies, capsule, contain soft semifluid core in which nerve terminates in a bulbous extremity or in a coiled up plexiform mass

138
Q

What is a hair follicle?

A

Invagination of epidermis in which a hair is formed

139
Q

What are 4 regions in growing hair follicle?

A

Infundibulum, Isthmus, Follicular Bulge, Inferior Segment

140
Q

What is the follicular bulge contain?

A

Epidermal stem cells

141
Q

What does inferior segment of hair follicle contain?

A

Bulb which holds matrix cells, and dermal papilla which is tuft of vascularized loose CT

142
Q

What are matrix cells in hair follicle?

A

Stem cells from follicular bulge collected in inferior segment and populate hair bulb

143
Q

What do matrix cells differentiate into?

A

Keratin producing cells of hair and form internal root sheath

144
Q

Division and proliferation of matrix cells account for what?

A

Hair growth

145
Q

External root sheath is formed by?

A

Epidermal downgrowth

146
Q

What is basal lamina of hair follicle epidermis called?

A

Glassy membrane

147
Q

What happens when matrix cells divide?

A

Produce a set of cells that move upwards towards surface, form internal root sheath and then modify themselves to form hair shaft, then undergo keratinization with soft keratin being formed, hair follicle has hard keratin

148
Q

What do epithelial cells covering apex of dermal papilla give rise to?

A

Medulla of the hair

149
Q

What do epithelial cells of lateral dermal papilla give rise to?

A

Hair cortex

150
Q

What do epithelial cells at the margin of dermal papilla give rise to?

A

Follicular cuticle

151
Q

What is the keratogenous zone in a hair follicle?

A

Where maturing cells of hair follicle accumulate hard keratin through keratinization

152
Q

What does matrix cells contain that produce melanin in hair?

A

Melanocytes

153
Q

What does the hair shaft consist of?

A

Medulla, cortex, and cuticle

154
Q

What is Griscelli syndrome?

A

Mutation in Myosin Va gene involved in the transport of melanin containing melanosomes and causes silvery hair

155
Q

Keratin on hair shaft is ?

A

Hard Keratin

156
Q

Keratin on internal root sheath is?

A

Soft keratin

157
Q

What do sebaceous glands secrete?

A

Sebum that coats the hair and skin

158
Q

How do sebaceous glands develop?

A

Develop as outgrowth of external root sheath of hair follicle

159
Q

Basal lamina of sebaceous gland is ______ with epidermis and hair follicle

A

Continuous

160
Q

Sebaceous gland cells are attached by what?

A

Desmosomes

161
Q

Cells at the periphery of sebaceous glands are known as?

A

Basal cells, produce new cells by mitosis

162
Q

Why are basal cells in sebaceous gland darkly staining?

A

Have many sER and rER

163
Q

What do the basal cells in sebaceous glands produce as they move away from basal layer?

A

Produce lipids and sER content increases

164
Q

Where is sebum secreted in sebaceous gland?

A

Secreted into the infundibulum of hair follicle by holocrine secretion

165
Q

Eccrine sweat glands consists of 2 segments?

A

Secretory segment, and duct segment

166
Q

Where is secretory segment of eccrine sweat gland located?

A

Deep dermis or upper part of hypodermis

167
Q

Where is duct segment of eccrine sweat gland located?

A

Leading to epidermal surface

168
Q

What is function of eccrine sweat glands?

A

Regulation of body temperature

169
Q

Describe structure of secretory component of eccrine sweat gland

A

Double layer of cuboidal epithelial cells, and within the basal lamina, is a layer of myoepithelial cells

170
Q

Describe structure of duct component of eccrine sweat gland

A

Narrowed outside diameter, consists of double layer of small cuboidal cells without myoepithelial cells

171
Q

What 3 cell types does the secretory component of eccrine sweat gland contain?

A

Clear cells, Dark cells, and myoepithelial contractile cells

172
Q

What do clear cells in eccrine sweat gland have abundantly?

A

Glycogen, mitochondria, plasma membrane folds laterally and apically

173
Q

How do clear cells in eccrine sweat gland secrete since they dont reach the lumen?

A

Secrete water and electrolytes through lateral folds of cell into intercellular canaliculi

174
Q

What do clear cells of eccrine sweat gland produce?

A

Watery component of sweat

175
Q

What are abundant in dark cells of eccrine sweat gland?

A

Abundant in rER and granules, apical cytoplasm has mature secretory granules and occupies most of luminal surface

176
Q

How do dark cells of eccrine sweat gland secrete?

A

Secrete glycoproteins through lumen of cell by exocytosis (merocrine secretion), mixes with clear cell secretion in lumen

177
Q

Where are myoepithelial cells located in eccrine sweat glands?

A

Basal aspect of secretory segment and lies between secretory cells

178
Q

What does cytoplasm of myoepithelial cells in eccrine sweat gland contain?

A

Numerous actin filaments

179
Q

What does contraction of myoepithelial cells in eccrine sweat gland cause?

A

Causes expression of sweat from the gland

180
Q

What are apocrine sweat glands associated with?

A

Hair follicles

181
Q

Where is secretory portion of apocrine sweat gland located?

A

Dermis or hypodermis

182
Q

Where does duct of apocrine sweat gland open into?

A

Into the hair follicle just above where sebaceous gland duct enters

183
Q

Where are apocrine sweat glands located?

A

Axilla, areola, circumanal glands, external genitalia, ceruminous glands of external ear, glands of Moll of eyelid, mammary glands are modified apocrine sweat glands

184
Q

How do apocrine sweat glands differ from eccrine sweat glands?

A

Wider lumen, stores secretions in lumen, secretory portion composed of simple epithelium, only one cell type is present, eosinophilic cytoplasm

185
Q

When does secretory activity of apocrine sweat gland start?

A

At puberty

186
Q

Describe structure of apocrine sweat gland

A

Apical surface has bleb like protrusion, apical granules are discharged by exocytosis, therefore secretory mode is merocrine secretion (not apocrine)

187
Q

What cells are present in secretory portion of apocrine sweat gland that facilitate expulsion of secretion?

A

Myoepithelial cells

188
Q

What is duct of apocrine sweat gland lined with?

A

Stratified cuboidal epithelium with no myoepithelial cells

189
Q

Where are circumanal apocrine sweat glands located?

A

Lower part of ano-rectal junction, at the anal verge where there is stratified squamous epithelial cover with hair follicles

190
Q

What are nails classified as?

A

Plates of keratinized cells containing hard keratin

191
Q

What do nail plates rest on?

A

Nail bed consisting of epithelial cells

192
Q

What is proximal part of nail called?

A

Nail root, buried in a fold of epidermis

193
Q

What is the edge of the epidermal fold in nails called?

A

Eponychium or cuticle

194
Q

What does the epidermal fold in nails cover?

A

Cells of the germinative zone or matrix

195
Q

The cuticle is composed of what kind of keratin?

A

Hard keratin, therefore does not desquamate

196
Q

The free edge of the nail is secured by thickened epidermal layer called?

A

Hyponychium

197
Q

What does nail matrix contain?

A

Stem cells that regularly divide

198
Q

Where do stem cells in nail matrix migrate to?

A

Towards the nail root, differentiate to produce hard keratin of nail

199
Q

What does constant addition of new cells at root and their keratinization account for?

A

Nail growth

HHP (17 decks)

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