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Flashcards in Skin Deck (148):
1

What are the three components of all connective tissues?

Cells, fibers, ground substance

2

Connective tissue is derived from....

Mesoderm

3

Fibroblast function

Create and repair ECM

4

Fasciacytes function

Produce hyaluronan: space filling, lubrication, water homeostasis, creation of matrix that facilitates migration of cells through ECM

5

Myofibroblast

Special CT cell that has contractile properties

6

Fibroblast characteristics

1.) Long spindle shaped cells
2.) round or spindle shaped nuclei (round = active, spindle = inactive); 3.) pale cytoplasm
4.) contain rER and Golgi

7

Adipocytes function

Store energy as TGs and produce leptin

8

Cells that migrate into CT and stay

Macrophages, mast cells, and plasma cells

9

Transient cells

Cells that wander in and out of CT; B and T lymphocytes, eosinophils, neutrophils, monocytes

10

Macrophage characteristics

1.) Derived from monocytes found in circulating blood (leave circulation and develop into macrophages)
2.) phagocytic
3.) named differently based on location in which they're found (Kupffer, osteoclasts, microglial cells, Langerhans)

11

Mast cell characteristics

1.) derived from bone marrow
2.) inflammatory response
3.) oval/round cells with large basophilic granules in cytoplasm
4.) granules contain: heparin, histamines, chemotatic mediators

12

Plasma cell characteristics

1.) Derived from B lymphocytes
2.) produce and release antigen specific antibodies
3.) eccentric nucleus, clock face chromatin, basophilic cytoplasm (rER), Golgi

13

ECM contains...

Fibers, ground substance, and extracellular fluid

14

Type I collagen fibers...

3 collagen polypeptide alpha chains>>collagen molecules>>fibrils>>fibers (parallel fibrils)

15

Collagen precursor proteins (called _______) are created in fibroblast _______ and assembled in _______

Tropocollagen; cytoplasm; EC space

16

Collagen types

I: most common
II: cartilage
III: reticular
IV: basal lamina of epithelial cells
VII: anchors basement membrane of epithelial cells

17

Elastic fibers 1.) made by, 2.) composed of, 3.) function in

1.) fibroblasts, chondrocytes, and smooth muscle cells)
2.) elastin and fibrillin
3.) stretch and recoil

18

Fibrillin serve as _____ for longer ______ molecules

Anchors; elastin

19

How do elastic fibers provide so much elasticity?

Fibrillin and elastin molecules branch three-dimensionally and surround nearby collagen fibers to provide a greater degree of elasticity; ligaments have high density to allow them to snap back

20

Reticular fibers 1.) made by and 2.) function to

1.) fibroblasts, Schwann cells, smooth muscle cells
2.) create frame meshwork of dense organs to support functional cells within (type I collagen takes up a lot of space; reticular fibers organize cells and take up less space)

21

Matrix metalloproteinases

CT cells and some epithelial cells release these to break fibers into smaller chunks that can then be phagocytosed by macrophages, degraded by lysosomal enzymes, and removed

22

Ground substance allows diffusion of _______ but not ________

water soluble molecules; large macromolecules and bacteria

23

In ground substance, _______ release charged substances into the ______ to create a ________ environment. This promotes ______ to and from cells.

Fibroblasts; ECM; hydrophilic; diffusion

24

Glycoproteins in ground substance help to...

Anchor cells to ECM

25

Glycosaminoglycans (GAGs) in ground substance are.....

The most plentiful and are negatively charged, attracting water

26

Proteoglycans are 1.) created by... 2.) and provide

1.) arranging GAGs like bristles stemming from a core protein
2.) Stability to the extracellular space while allowing diffusion to occur

27

Stroma

Structural tissues of organs (scaffolding)

28

Parenchyma

Functional parts of an organ

29

Types of CT

1.) Embryonic (mesenchymal, mucous)
2.) CT Proper (dense reg and irreg, loose)
3.) specialized (adipose, supporting, blood, lymph)

30

Composition of mesenchymal CT

Ground substance (semi-fluid, gelatinous)>>cells (mesenchymal)>fibers (type III); allows for rapid growth without constricting the fetus

31

Location of mesenchymal CT

Embryo and fetus

32

Location of mucous CT

Umbilical cord (Wharton Jelly), subdermal CT of fetus, dental pulp of developing teeth

33

Composition of mucous CT

Ground substance (semi-fluid, gelatinous)>>cells (stellate fibroblasts)>fibers (few type I)

34

Location of dense regular CT

Collagenous: tendons, ligaments, and aponeuroses
Elastic: some vertebral ligaments and suspensory ligaments of penis

35

Composition of dense regular connective tissue

Fibers (mostly type I or elastic - fibers in one direction)>>>cells (fibroblasts)>ground substance (very little)

36

Locations of dense irregular CT

Dermis, submucosa of organs, scars, and organ capsules

37

Composition of dense irregular CT

Fibers (mostly type I with some elastic and reticular)>>cells (mostly fibroblasts with some macrophages and mast cells)>ground substance (very little)

38

Location of reticular tissue

Dense organs (liver, kidney, spleen, bone marrow, lymph nodes)

39

Composition of reticular tissue

Fibers (type III)>cells (reticulocytes, fibroblasts)>ground substance (very little)

40

Location of oose (areolar) CT

Lamina propria: GI and Resp
Superficial fascia and invests in neurovascular bundles and around glands

41

Composition of loose CT

Ground substance (watery tissue)>>cells (fibroblasts with many transient immune cells)>fibers (very few)

42

Composition of loose CT allows for _______ __________ of nutrients and other substances. Because these regions are in close contact with _________ environment, there are many ________ cells that move into the area to interact with _______ ________.

Rapid diffusion; external; transient; invading pathogens

43

Unilocular (white) adipose

Distributed throughout body but mostly around neurovascular bundles, mesenteries, and hypodermis

44

Adipose function

Storage of fat, thermal insulation, shock absoption

45

Composition of adipose

cells>fibers>ground substance (very very little)

46

Multilocular (brown) adipose

Found in neonate (and upper back of adults who endure low temps over prolonged periods); many droplets of TGs in cell cytoplasm vs single droplet in white fat; heat-generating (high content of mitochondria that release ATP)

47

Function of epithelial tissue

Absorption
Secretion
Movement of material along surface
Protection from mechanical abrasion, chemicals, and pathogens
Reception of sensory signals
Reduction of friction
Secreting enzymes, hormones, lubricants, and other products
Synthesis of proteins, enzymes, mucins, hormones, and other substances

48

What characteristics make epithelium different from other tissues?

Polarity, cell arrangement, avascular, and basement membrane

49

Basement membrane is a thin ______ on the basal surface that binds ________ ______ to underlying tissues. It does not contain ______ or ______.

ECM; epithelial cells; cells; blood supply

50

Layers of basement membrane from top to bottom...

Lamina lucida>>lamina densa>>lamina reticularis

51

Basal lamina is made up of what 2 layers? What produces the basal lamina? What type of collagen is it?

Lamina lucida and lamina densa; epithelial cells; type IV

52

Lamina reticularis is type ____ collagen and comes from ______ cells

III; CT

53

Anchoring fibrils within the lamina reticularis are type ______ collagen

VII

54

Metaplasia is a response to ________ ________ or _______.

chronic irritation; damage

55

Microvilli function

Increase surface area for absorption and secretion

56

Stereocilia function

Facilitate absorption in male genital ducts, sensory mechanoreceptors in ear

57

Motile cilia function

Transport substances along epithelial surface

58

Primary cilia function

Generate and transmit signals from outside to inside the cell

59

Nodal cilia function

Development of left and right asymmetry or internal organs

60

Pseudostratified columnar epithelium located in....

Respiratory tract

61

Transitional epithelium located in....

Bladder and ureters

62

Keratinization is a process by which ________ _____ produce the protein _______. It provides ________ and _______. It is found in _______, _______, and ______.

epithelial cells; keratin; waterproofing; protection; skin; hair; nails

63

Goblet cells are ________ glands that produce ______.

Unicellular; mucin

64

Endothelium are classified as _______ ________ epithelium. They are found lining the inside or _________ and _________.

simple squamous; blood vessels; heart

65

Mesothelium is classified as ______ _______ epithelium. It is found lining ______ ________.

simple squamous; body cavities

66

Glandular epithelium characteristics

Secretory cells that arise as ingrowths of the epithelium; typically in single layers or clusters; cuboid or columnar

67

Function and location of simple squamous epithelium

Diffusion, filtration; capillaries, alveoli, glomerulus

68

Function and location of simple cuboidal

Secretion, absorption; ovaries, nephrons, renal tubules

69

Function and location of simple columnar

Secretion, absorption; GI, repro, resp

70

Function and location of stratified squamous

Protection; tongue, hard palate, esophagus, anus

71

Function and location of stratified cuboidal

Secretion, absorption; glands

72

Function and location of stratified columnar

Protection; conjuctiva, resp

73

Function and location of pseudostratified columnar

Movement; trachea and upper resp

74

Function and location of transitional epithelium

Stretch; bladder and ureters

75

Microfilaments...
1.) Structural function?
2.) Motility?
3.) Energy for polymerization
4.) Polarity
5.) Components

1.) Yes
2.) Yes
3.) ATP
4.) Yes
5.) actin, myosin

76

Microtubules...
1.) Structural function?
2.) Motility?
3.) Energy for polymerization
4.) Polarity
5.) Components

1.) Yes
2.) Yes
3.) GTP
4.) Yes
5.) tubulin

77

Intermediate filaments...
1.) Structural function?
2.) Motility?
3.) Energy for polymerization
4.) Polarity
5.) Components

1.) Yes
2.) No
3.) None
4.) No
5.) Keratins, nuclear lamins, etc

78

Cytoskeletal classes have both ________ and _______ function. __________ _________ do not have ________ function.

Structural; motile; intermediate filaments; motile

79

Crosslinking proteins

Bind filaments together

80

Networks

Filaments cross-linked into 3D, criss-crossed meshworks (resist stretching and compression)

81

Bundles

Filaments cross-linked in parallel to form fibers that resist stretching

82

Anchoring by junctions serve to anchor the __________, attach cells to the ________ ________ or to _____ _______, or allow cells to interact with _________.

cytoskeleton; basal lamina; each other; ECM

83

Motility mechanisms include the use of _______ ______ an example of which is ________ _______ in muscle contraction and ____________________ an example of which is segregation of chromatids during anaphase.

motor proteins; sliding filaments (microfilaments); polymerization-depolymerization (microtubules)

84

G actin subunits polymerizing into F actin filaments is driven by __________.

ATP hydrolysis

85

Actin is ________ because the plus sides of G actin subunits point to one end and the minus to the other end of the F actin filaments

Polarized

86

___________ and _______ bind F actin and interact with ______ heads to mediate _______ _________ _________.

Troponin; tropomyosin; myosin; sliding filament contraction

87

Spectrin

Actin cross-linking protein that forms networks in erythrocytes

88

Dystrophin

Cross-linking protein that forms striated muscle network

89

Duchenne muscular dystrophy is a mutation of the X linked _________ gene

Dystrophin

90

________ are finger-like projections of the plasma membrane that increase surface area for _________ and are supported by internal ______ bundles. They are present in ____ cells but most abundant on the brush border of ________ epithelium.

Microvilli; absorption; actin; all; intestinal

91

These microfilaments serve as motor proteins for actin and some serve a structural role

Myosin

92

Myosin heavy chains are composed of two _______ and two globular ________. The _____ coil around each other to form dimers which requires ___ __________.

tails; heads; tails; ATP hydrolysis

93

Myosin light chains bind the _______ of each head. They serve as regulatory factors controlling __________ of the globular heads.

Neck; contraction

94

The myosin tetramers associate with the ______ extending into the periphery, and the ______ pointing inward making the myosin microfilament _______. The heads provide the _______ force.

heads; tails; polar; motor

95

Sliding filament model

ATP hydrolysis activates a conformational change of the myosin heads. These contractions cause myosin to crawl along actin. Hence, microfilaments slide past each other to induce contraction.

96

Examples of microfilament mediated motility

Intracellular membrane trafficking (directed along actomyosin or microtubule filaments), muscle (actomyosin organized into sarcomeres), contractile ring of cytokinesis (actomyosin ring that pinches the cell in two), amoeboid motion (pseudopodia), stress fibers (long bundles of microfilaments that lie along the basal surface of fibroblast that provide tension across a surface

97

Chemicals that interfere with __________ assembly preferentially attack ________ cells because these rapidly dividing cells require microtubules for cell cycle progression. This occurs drugs during ___________ treatment.

microtubular; tumor; chemotherapy

98

MAPs

microtubular associated protein (crosslinking protein that forms networks)

99

__________ is a motor protein that moves ________, cilia, ________, and mitotic chromosomes associating with the mitotic ______. It also moves ______, ________, and ________ ______ up and down an axon.

Dynein; flagella; cytosolic vesicles; spindle; vesicles; organelles; cytoskeletal fragments

100

______ is a motor protein that moves _______ _______ and ______ _______ associating with the mitotic spindle.

Kinesin; cytosolic vesicles; mitotic chromosomes

101

Examples of microtubular mediated motility

Intracellular membrane trafficking, mitotic apparatus, and axonal transport (factors depleted by signal transduction have to be replenished)

102

Intermediate filament _______ are used to identify the origin of tumor cells. Antibodies target the _______ and ______ of IFs due to their uniqueness. If the ______ were tagged, every IF would be bound to antibody.

Antibodies; heads; tails; core

103

Ankyrin

Speicific IFAP that anchors desmin to the plasma membrane as well as spectrin to the band 3 anion transporter of erythrocytes

104

Nuclear lamins

Meshwork of intermediate filaments on the nucleoplasmic face of the nuclear envelope

105

Lamin B

Anchored to the inner membrane of the nucleus by an isoprenyl side group

106

All 3 forms of lamins consist of _______ ________ and alpha helical ______ and _____.

globular heads; cores; tails

107

During prophase, nuclear lamins are _________ by MPF. This causes them to _______, inducing nuclear membrane _______. During ________ the nucleus reforms because the lamins are _______, allowing their crisscrossed network to associate.

phosphorylated; depolymerize; breakdown; telophase; dephosphorylated

108

Lamins A and C are released into the _______, while Lamin B remains bound to _____.

Cytosol; vesicles

109

_________ force collagen alpha chains into left-handed helices due to ________ of the backbone, while _______ residues (every third amino acid) allows the helix to be left-handed due to its small _____ ______ (larger side chains would produce _____ _______).

Prolines; contortion; glycine; side chains; stearic hindrance

110

_______ groups are bound to numerous prolines and lysines. They increase the ___-________ ________ of the collagen helices.

Hydroxyl; non-covalent stability

111

Why does dietary deficiency of vitamin C result in scurvy?

The enzyme that produces hydroxyproline requires vitamin C as a cofactor

112

Enzyme that drives cross-linking between lysines near tropocollagen termini

Lysyl oxidase

113

Collagen synthesis

Procollagen spontaneously assembles into triple helices>>post-translational modification in ER>>exocytosis and cleaving of terminal regions (now tropocollagen)>>crosslinkage of tropocollagen to form fibrils>>aggregation into collagen fibers

114

Excessive collagen production

Fibrosis

115

Scurvy

Lack of hydroxyproline residues due to dietary deficiency of vitamin C. Symptoms include weak and malformed bones, teeth, skin, blood vessel walls, and dermal hemorrhaging.

116

Ehlers-Danlos

Mutations resulting in underproduction or incomplete processing of different collagens. Symptoms range from loose skin and joints, to neonatal death. Contortionists often have this disorder.

117

Osteogenesis imperfecta

Mutations of type I collagen, which interfere with triple helix assembly (e.g. substitution of glycines residues with bulkier amino acids). The most severe mutations result in lethality in utero or soon after birth. Less severe mutations produce brittle bones. Note, due to the numerous fractures observed in children with this disorder, it can easily be misdiagnosed as child abuse.

118

Marfan syndrome

Mutation of fibrillin gene

119

Functions of skin

Protection (barrier and immunologic)
Homeostasis (waterproof and temp regulation)
Sensory
Metabolic (endocrine and excretion)

120

Keratinocytes

Most abundant cell in epidermis; functions: produce keratins (structural protein), form epidermal water barrier; stem cells on basement membrane; differentiate as they migrate to surface

121

Langerhans

Dendritic cells of the epidermis (originate in bone marrow and travel to CT in dermis and migrate up); Birbeck granules; phagocytize foreign structures in epidermis and present T lymphocytes in regional lymph nodes; not readily visible with H&E (clear cells)

122

Melanocytes

Derived from neural crest; location: basale; produce melanosomes (transferred into keratinocytes)

123

What mechanisms are involved with natural skin color variation?

Rate at which melanin granules are produced and degraded (impacted by both intrinsic and extrinsic factors)

124

One melanocyte and its associated keratinocytes

Epidermal-melanin unit

125

Processes involved with tanning of the skin?

UV light darkens existing melanin AND increases the rate of melanin synthesis

126

Merkel cells

Location: basale
Function as mechanoreceptors; most abundant in areas of high tactile sensitivity

127

Thick vs thin skin

Thick: palms, soles; 5 layers; lacks hair follicles
Thin: everywhere else; 3 well-defined layers

128

Epidermal layers

Stratum corneum
Stratum lucidum*
Stratum granulosum*
Stratum spinosum
Stratum basale

129

Basale

Single layer of cuboidal/columnar cells; new cells (keratinocytes) undergoing mitosis

130

Spinosum

Keratinocytes appear prickly (desmosomes); keratins being synthesized by free ribosomes (more superficial gets stained darker due to increased assembly of intermediate filaments)

131

Tonofilaments

Intermediate filaments composed of keratin and most visible in spinosum; converge at desmosomes; provide support for areas under constant friction and pressure (thicker spinosum)

132

Granulosum

1-3 layers of keratinocytes with granular appearance; cytoplasm being filled with dark keratohyalin granules; initiates promotion of keratin filaments into tonofibrils, converting granular cells into cornified cells (keratinization); cells in superficial layers undergoing apoptosis

133

Lucidum

only present in thick; translucent layer of keratinocytes; nuclei and organelles lost and replaced by densely packed keratin filaments

134

Corneum

dead, keratinized cells; protection against abrasion

135

Lamellar granules

Keratinocytes produce these lipid-rich membrane coated granules; secreted by exocytosis into spece between granulosum and corneum for water barrier

136

Cells in dermis

Fibroblasts, macrophages, mast cells, B lymphocytes (skin homeostasis and immunosurveillance)

137

Layers of dermis

Papillary (loose CT)
Reticular (into hypodermis - dense irregular CT)

138

Structures in dermis

Meissner (papillae - light touch), Pacinian (reticular and hypodermis; onion; transmit vibration and pressure

139

Merocrine

Secrete product via exocytosis (form and packaged into Golgi>>plasma membrane fusion)

140

Apocrine

Products are pinched off, along with apical portion

141

Holocrine

Products accumulate in cell, which undergoes programmed cell death and discharges material

142

Eccrine sweat gland

Merocrine secretion; throughout body; watery; clear cells - produce sweat, dark cells - filled with granules with antibacterial properties, myoepithelial cells - contractile located near basal lamina of secretory portion of gland; duct extends to skin surface; thermoregulation

143

Apocrine sweat gland

Merocrine secretion; axillary, areola, anal; development dependent on sex hormones; ducts open to follicles; lumens much larger than eccrine glands

144

Sebaceous gland

Produce and excrete sebum (released via holocrine secretion)

145

Pilosebaceous unit

Arrector pili muscle, hair follicle, sebaceous gland

146

Vasculature

Capillary loops in dermal papillae; superficial plexus right underneath (allows blood to come up if you're hot); communicating vessels connecting the plexi; deep plexus (allows blood to move down if you need to warm up)

147

Innervation

Merkel - mechanoreceptors in basale
Free nerve endings - terminate in granulosum; most abundant; sense touch and temp
Pacinian - pressure and vibration in dermis and hypodermis
Meissner's - light touch in dermis

148

Hypodermis

Subcutaneous; not part of skin; DICT and adipose; sometimes Pacinian; highly vascularized