Dermatology 1 > Physiology > Flashcards

Physiology Flashcards

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1
Q

3 ways the integumentary system protects the body

A
  1. chemical barrier
  2. mechanical barrier
  3. biological barrier
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2
Q

How is integument a chemical barrier

A
  • low pH

- antibacterial secretions (defensin) destroy bacterial cells

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3
Q

How is integument a mechanical barrier

A

keratinized surface and glycolipids waterproof skin

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4
Q

How is integument a biological barrier

A

immune cells such as Langerhan’s cells (phagocytes stationed in epidermis)

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5
Q

What else is a part of the integumentary system that helps provide protection

A

normal flora - 1000 species of resident bacteria

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6
Q

How does integument system provide body temp regulation

A
  • endotherms: body temp regulated internally
  • Sweat allows for evaporative cooling, heat release
  • Arrector pili muscles generate heat at skin surface
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7
Q

Overview of integument role in cutaneous sensation

A
  • skin receptors sense the environment
  • Meissner’s corpuscles and Merkel discs sense light touch
  • Pacinian corpuscles in dermis and hypodermic sense pressure
  • hair movement senses wind
  • raw nerve endings sense cold, heat, pain
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8
Q

Integument role in Vitamins

A
  • modified cholesterol molecules circulate through dermal blood vessels
  • converted via solar energy into vitamin D precursor
  • liver and kidneys finish activation
  • Vitamin D aids in ca absorption
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9
Q

How is the integument system related to CVS?

A

blood reservoir

  • dermal blood holds about 5% of total body volume
  • blood vessels can constrict to shunt blood flow as needed (will cool skin surface)
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10
Q

What is the role the integument system plays in excretion

A
  • small amt nitrogen-containing waste from protein metab are eliminated via the skin
  • eliminate electrolytes in sweat
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11
Q

Keratinocytes

  • location
  • function
A
  • outer layer of stratified squamous epithelium
  • most abundant epidermal cell
  • produce keratin, a fibrous protein
  • cell differentiation occurs as progress from deep to outer layers of epidermis “keratinization”
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12
Q

List the four layers of keratinocytes in the epidermis that are always present

A

deepest to outermost

  1. Stratum basale
  2. Stratum spinousum
  3. Stratum granulosum
  4. Stratum corneum
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13
Q

Stratum Basale

A
  • deepest layer
  • single row of cuboidal/columnar cells
  • epidermal stem cells that become stem cells or keratinocytes
  • keratinocytes start to express keratin which form intermediate filaments
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14
Q

What are two types of cell connections found in stratum basale

A
  • hemidesmosomes attach cells to basal lamina

- desmosomes attach cells to each other

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15
Q

Stratum spinosum

A
  • several cell layers thick
  • active keratin production
  • full of weblike keratin filaments: provides strength in many directions
  • tonofibrils give spiky appearance (protein filaments that lock keratin fibers together, esp around desmosome connections)
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16
Q

Stratum granulosum

A
  • 2-5 layers of cells
  • cells in terminal differentiation
  • Keratin granules: dehydration of the cell and cross-linking of keratin fibers
  • laminated granules: layers of membrane (from golgi), spaces filled with lipids and glycolipids. Exocytosis creates a lipid-rich waterproof layer around keratinocytes
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17
Q

Stratum corneum

A
  • horny layer (tough)
  • 20-30 cells thick, outermost layer
  • keratinized: masses of keratin fibrils and protein aggregates
  • keratinocytes have lost nuclei and organelles, are dead, dry, flat
  • waterproof outer surface
  • desmosomes degrade, cells slough off
    (keratinocyte processes take 15-30 days)
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18
Q

Thick skin

  • location
  • what is special about the epidermis
A
  • palms and soles

- additional layer: Stratum lucidum

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19
Q

Stratum lucidum

A
  • under stratum corneum
  • flattened, differentiated layers of keratinocytes
  • held together by desmosomes
  • appears clear
  • 2-3 layers of cells
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20
Q

Melanocytes

A
  • specialized epidermal cell
  • in stratum basale and hair follicles
  • attached to basal lamina by hemidesmosomes, not attached to neighboring cells
  • cytoplasmic extensions reach through basal and spiny layers
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21
Q

What does sun exposure of skin do to melanocytes

A
  • darkens existing melanin
  • stimulates keratinocyte paracrines
  • stimulates melanin production in melanocytes
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22
Q

Melanin production from tyrosine

A
  • melanin is aggregated to structural proteins
  • accumulates in melanosomes
  • melanosomes are transported to termini of cellular extensions
  • keratinocytes phagocytize tips of extensions
  • granules are transported to keratinocyte nuclei
  • shields nucleus from UV radiation
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23
Q

Langerhans cells

A
  • monocytes derived from cells in epidermis
  • most abundant in spiny layer
  • phagocytize foreign particles, enter circulation, present antigen to lymphocytes in lymph nodes
  • immune defense and surveillance role
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24
Q

Describe the dermis

A
  • CT layer deep to epidermis
  • cells and matrix (ECF embedded with fibers)
  • rich with nerve fibers, blood vessels, lymphatic vessels (NOT in the epidermis)
  • contains most hair follicles and glands
  • form dermal papillae
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25
Dermal papillae
- extensions or interdigitations of dermis into epidermis | - fingerprints!
26
What are the two dermis layers
1. Papillary layer | 2. Reticular layer
27
Papillary layer of dermis
- thin - dermal papillae - fibroblasts - collagen fibrils: insert into basal lamina, binding dermis to epidermis
28
What two cells are found in the dermis
1. Mast cells - skin and mucous membrane CT granulocytes (phagocytes) - secrete inflammatory mediators histamine, leukotriene, and prostaglandings 2. Dendritic cells - derived from monocytes - in skin, resp. tract, GI tract - antigen presenting cells
29
Reticular layer of the dermis
- deep to papillary layer - thick, dense irregular CT - more fiber, fewer cells - lots of collagen - rich in elastic fibers - elastin: produced by fibroblasts, stretch and recoil
30
Vasculature of dermis
- Subpapillary plexus - Deep dermal plexus - AV anastomoses
31
Subpapillary plexus in dermis
- btwn papillary and reticular dermal layers - extensive capillary network - extends to dermal papillae and subepithelaial basal lamina - provides nutrients and support to epidermal tissue
32
Deep dermal plexus in dermis
layer of vessels near interface of dermis and subcutaneous layers
33
AV anastomoses in dermis
- shunts blood between subpapillary and deep dermal plexi - increased flow to papillary layer to vent heat - decreased flow to papillary layer to conserve heat
34
Subcutaneous layer
- hypodermis - deep to dermis - loosely anchors skin to underlying muscle - loose CT - adipocytes make it fatty - vascular
35
Sensory receptors List (6)
1. Merkel cells 2. Free sensory nerve endings 3. Root hair plexus 4. Meissner corpuscle 5. Lamellated (Pacinian corpuscle) 6. Ruffini corpuscle
36
Merkel cells
- oval epidermal cells - stratum basal - associated with somatosensory nerve fiber - fn as sensory receptor for light sustained touch and texture
37
Free sensory nerve endings
- papillary and lower dermal layers | - sense pain, temp, itch
38
Root hair plexus
- sensory web at hair follicle base | - detects hair movement
39
Meissner Corpuscle
- disks perpendicular to epidermis in dermal papilla - stacks of flattened Schwann cells - single afferent nerve attached - highly sensitive to light touch - determines two point touch - abundant on fingertips and lips - rapidly adapting/phasic: action potential generated and decreased quickly, habituation
40
Laminated (Pacinian) corpuscles
- among adipose cells in deep dermis and subcutaneous layer - also in walls of bladder and rectum - singel afferent nerve at the core of 20-60 concentric lamellae of Schwann cells - sense vibration and sudden pressure
41
Ruffini corpuscles
- anchored firmly to CT | - sense torque and twist
42
List the () types of skin gland
1. Sebaceous glands 2. Specialized sebaceous glands 3. Sweat glands 4. Specialized apocrine sweat glands
43
Sebaceous glands
- acinus gland structure (lots of cells around a duct) - sebocytes produce sebum - cells die and disintegrate, sebum is released into duct - Duct leads to hair or skin surface - Holocrine secretion
44
Sebum composition
- TG - wax esters - squalene - FFA (odorless, bacteria produce odor)
45
two types of specialized sebaceous glands
1. Meibomian glands: tear ducts, sebum mixes with tears | 2. Areolar glands: lubrication and protection of nipple
46
Sweat glands
- aka sudoriferous glands - epidermal invagination into dermis - SNS innervation
47
List the two types of sweat gland
1. Eccrine | 2. Apocrine
48
Eccrine sweat glands
- widely distributed (esp on forehead, palms, plantar foot) - coiled, tubular gland opens to sweat pore - secretes sweat which is conducted by myoepithelial cells to skin surface - purpose: evaporative cooling
49
Sweat formation and composition
- filtrate from blood - hypotonic - 99% water with: - NaCl - bicarb - K+ - glucose - cytokines - IgA - dermicidin
50
Apocrine sweat glands
- coiled gland in dermis with sweat released to hair follicle - sweat, FA, proteins - odor dt bacteria - mostly axillary and anogenital region - sex hormone control - granules exocytose (Merocrine release)
51
List 2 types of specialized apocrine sweat gland
- ceruminous glands | - Mammary gland
52
ceruminous glands
- subcutaneous layer in outer 1/3 of EAC - drain into larger ducts, drain into guard hairs in EAC - produce cerumen (earwax) by mixing with sebum and dead epidermal cells - keeps eardrum pliable, lubricates, waterproofs - coats guard hairs, making them sticky
53
Mammary glands
- milk-secreting cuboidal cells - surrounded by myoepithelial cells - join into lobules, ea has lactiferous duct that drains to openings in nipple - myoepithelial cells contract under oxytocin, excrete the milk - one complex mammary gland in each breast, each contains 10-20 simple glands
54
Hair | - describe
- elongated keratin structure | - color is pigment from melanocytes at base of follicle
55
3 layers of keratin in hair
1. cuticle: thin outer scales 2. Cortex: inner, thickest layer 3. Medulla: core, only in thick scalp hair
56
What is the hair follicle
the hair producing gland
57
Describe the anatomy of the hair follicle
- Papilla: base of follicle, CT with capillary tuft - Hair bulb - Rooth sheath
58
Hair bulb
- dilated terminus of follicle during hair growth - houses the matrix (where hair follicle is produced) - keratinocytes: mitotic growth through terminal differentiation - melanocytes: produce melanin which is uptake by keratinocytes
59
Root sheath | - two layers
(part of follicle extending through dermis and epidermis) - internal root sheath - external root sheath
60
Internal hair root sheath
- epithelial tissue surrounding root to sebaceous gland | - two layers
61
External hair root sheath
- CT sheath covers internal sheath | - extends all the way through the epidermis
62
Three stages of hair growth
1. Anagen 2. Catagen 3. Telogen
63
Anagen phase of hair growth
- 90% of active growth - 3-4 years on scalp - 30-4 days on appendages, eyelashes, eyebrows - begins as progenitor cells form new bulb and matrix
64
Catagen phase of hair growth
- growth slows | - outer sheath shrinks, attaches to hair shaft forming club hair
65
Telogen phase of hair growth
- hair bulb shrinks | - club hair is shed
66
Arrector pili
- controlled by SNS - smooth muscle fibers at base of hair follicle - contraction pulls hair vertical, goose bumps - heat production
67
Nails - describe composition - function - anatomy
- hard keratin plate from nail bed - fn: scratching, dexterity, defense - nail root is beneath epidermal folds - nail body: visible plate - free edge: part hangs off finger - Lunula: moon shape at proximal body - distal extent of germinal matrix of nail bed - dense nucleated keratinocytes (opaque)
68
Nail folds
- lateral - hyponychium: below free edge - Eponychium: cuticle, proximal fold over nail body
69
List four types of lesion
abrasion laceration puncture surgical
70
Clotting phase of wound healing
- bleeding into wound - platelets form platelet plug - clotting factors form cross-linked fibrin mesh - thrombus (scab)
71
Inflammatory phase of wound healing
- plasma and leukocytes move from blood to injured tissue | - heat, pain, redness, edema
72
Proliferative phase of wound healing
- mitotic activity - granulation: fibroblasts secrete collagen foundation, vascularization creates nutrient supply and waste removal - epithelialization: epidermal growth from all directions to cover site
73
Maturation phase of wound healing
- collage reorganization - granulation tissue dies - debris removal - excessive collage remains as scar
74
Three wound healing categories
1. Primary or first intention 2. Second intention 3. Tertiary intention
75
Primary intention wound healing
- clean wound, no tissue lost - closure of wound - heals from outside in - can open easily - infection, abscess formation
76
Second intention wound healing
- wound heals without closure - natural process of healing from inside out - less chance of abscess forming
77
Tertiary intention wound healing
close wound after all evidence of inflammation has passed
Dermatology 1
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