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MEDICINE > MTM WK4 - DERMIS/EPIDERMIS > Flashcards

MTM WK4 - DERMIS/EPIDERMIS Flashcards

1
Q

LAYERS OF SKIN

A
  • epidermis (apendages are nails, hair, sweat glands)
  • dermis (angulations (bends) in bottom of epidermis stick to dermis to anchor it (Dermal-epidermal junction)
    (papillary layer on top then reticular)
  • hypodermis (has adipose tissue & larger vessels which supply & drain dermal blood vasculature)
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2
Q

JOBS OF SKIN (3 jobs)

A
  • thermoregulation (sweat)
  • protect against external threats (mechanical, water loss, biological, UV light)
  • resist bacteria/fungal invasion as have langerhan cells (antigen-presenting) to do immune response
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3
Q

INNERVATION OF SKIN (efferent & afferent)

A

EFFERENT NERVE SUPPLY - non-myelinated fibres from sympathetic part of autonomic nervous system
AFFERENT NERVE SUPPLY - transmits impulses from sensory nerve endings to CNS (free nerve endings needed for pain sensation & detecting temp)

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4
Q

BLISTER

A

friction leads to epidermis & dermis separating so fluid accumulates & blister forms

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5
Q

KERATINOCYTES

A
  • synthesise keratin (used to strengthen epidermis)
  • start in basal layer then move up to form prickle cell layer & do terminal differentiation & lose nucleus & die to form dead, protective, waterproofing keratin layer (become corneocytes as we get to top & die)
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6
Q

LAYERS OF EPIDERMIS (superficial to deep)

A
  1. STRATUM CORNEUM (dead keratinocytes/corneocytes)(horny layer)
  2. STRATUM LUCIDUM (only exists in thick skin layers)
  3. GRANULAR LAYER (stratum granulosum)(keratohyalin granules (strength) & enzymes which degrade bi-layer)
  4. PRICKLE CELL LAYER (stratum spinosum)(has langerhans cells)
  5. STRATUM BASALE (has melanocytes) (has merkel cells) (cells here change)
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7
Q

PRICKLE CELL LAYER (spinosum) keratin doings

A

keratin (from keratinocytes) accumulates within each spinous cell (keratin passed between adjacent cells upwards (as spinous cells full) at desmosome junctions)

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8
Q

HOW MELANOCYTES WORK

A

produce melanin & have dendrites throughout layer which are phagocytosed to spew out melanin

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9
Q

MERKEL CELLS

A

mechanoreceptors for touch sensation in dermal/epidermal junction (basal layer)

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10
Q

PSORIASIS

A
  • abnormal growth & differentiation of keratinocytes

- appears as excessive scaling of skin

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11
Q

ALLERGIC CONTACT DERMATITIS

A

due to epidermal Langerhans cells & T-lymphocytes

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12
Q

MALIGNANT MELANOMA

A
  • malignant tumour of melanocytes

- if tumour cells above basal membrane it is good but otherwise is worrying

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13
Q

VITILIGO

A

autoimmune disease on melanocytes

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14
Q

PILOSEBACEOUS UNIT

A
  • has hair sheath (outskirt) & hair shaft & sebaceous gland (secretes oils of skin into hair shaft) & arrector pilli muscle to keep up hair
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15
Q

ECCRINE SWEAT GLANDS

A

release sweat directly into skin surface (is mostly water w some nutrients)

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16
Q

APOCRINE SWEAT GLANDS

A

release sweat into hair follicles (apocrine secretion which is digested by microbes to form body odour)

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17
Q

VASCULATION OF SKIN

A

smaller blood vessels (e.g. capillary) in epidermis lniked to larger blood vessels in dermis by interconnecting vessels

18
Q

FIRST DEGREE BURN

A

epidermal damage only (red but no blister)

19
Q

SECOND DEGREE BURN

A
  • SUPERIOR PARTIAL THICKNESS (all the way through epidermis & touches top of dermis (papillary layer))(red blistered)
  • DEEP PARTIAL THICKNESS (into upper dermis (reticular layer))(yellow/white)
20
Q

THIRD DEGREE BURN

A

all the way through dermis (white/brown but painless as all way through dermis)

21
Q

REVERSE TRANSCRIPTASE

A

converts RNA to DNA

22
Q

WHY RNA LESS STABLE THAN DNA

A

RNA has -OH group at carbon 1 but DNA only has H (de-oxy) & the RNA can be attacked by water due to having that -OH)

23
Q

DNA REPLICATION style

A

semi conservative (each daughter has one old & one new strand)

24
Q

DNA polarity

A

enzymes bind from 5-prime to 3-prime (uni-directional)

25
Q

dNTP’s

A

building blocks for DN synthesis (if adenine = dATP, cytosine = dCTP)

26
Q

DNA SYNTHESIS

A
  • 5-prime to 3-prime
  • complementary base binds to first base & DNA polymerase binds next complementary dNTP but loses 2 phosphates doing it
27
Q

REPLICATION FORK

A

DNA polymerase bonds from 3-prime to 5-prime in the 5-prime strand (leading) BUT in lagging strand, there would be a gap behind where DNA polymerase starts so DNA polymerase enzymes bind in multiple sites to form okazaki fragments (joined by DNA ligase)

28
Q

HOW DNA POLYMERASE PROOF READS

A

DNA polymerase adds a base (dNTP), moves back to check it & removes it if it is wrong then moves on

29
Q

DNA TRANSLATION

A

ribosome comes in on mRNA & has 2 binding sites (P-site & A-site). First brings tRNA molecule (held in P-site) complementary to first codon & then tRNA complementary to next codon (tRNA in A-site)

30
Q

TRANSCRIPTOME

A

complete set of RNA transcripts (varies from cell to cell)

31
Q

TELOMERES

A
  • PROS - allow replication all the way to tip of chromosome
  • CONS - long tracts of repeats can be unstable which leads to deletions immediately below telomeres
  • side of chromosome & there are repeat sequences here to protect chromosome)
32
Q

CENTROMERES

A

used for segregation during cell division

33
Q

MINI SATELLITES

A

no purpose but can cause mispairing in cell division to give duplication/deletion between homologous chromosomes

34
Q

CHROMATIN

A

used in DNA packaging (DNA wraps around chromatin & chromatin fibres packed into nucleosome)

  • HETEROCHROMATIN (inaccessible as in nucleus)
  • EUCHROMATIN (accessible and can be activated or inactivated for transcription)
35
Q

MITOSIS

A
  1. P - chromosomes condense & spindle fibres are formed
  2. M - nuclear membrane broken down, spindle fibres to equator, tension on kinetochores at centromere facing opp. directions
  3. A - kinetochore microtubules disappear & chromosomes go to opp. poles
  4. T - nuclear membrane reforms around chromosomes & RNA synthesis begins
  5. C - cytoplasm divides to 2 daughter cells
36
Q

INDEPENDENT ASSORTMENT

A

mix of maternal & paternal chromosomes = genetic variation

37
Q

CROSSING OVER

A
  • homologous pair of paternal chromosomes duplicate & cross over (recombine) to give mix of chromosomes (genetic variation)
  • cross over at chiasmata
38
Q

CHIASMATA

A

hold chromosomes together & is when DNA exchanged between homologous chromosomes

39
Q

EGG

A

each month, one egg ovulated & meiosis 1 forms polar body (useless) & another cell that is cytoplasm which divides in meiosis 2 to form zygote (whole cytoplasm) & 2nd polar body

40
Q

MEIOSIS USES

A

used for reduction division (23 not 46) and to get re-assortment of genes (independent segregation & crossing over)

41
Q

MEIOSIS STEPS

A
  1. MEIOTIC METAPHASE 1 (each of 2 copies of chromosome has kinetochore joined to it so goes to centre)
  2. MEIOTIC ANAPHASE 1 - arms of sister chromatids unglued & leads to mix of maternal & paternal & go to side
  3. MEIOTIC META/ANA 2 - diploid to haploid

MEDICINE (27 decks)

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