Lecture 21-Skin

Question 1

Epidermis arrangement

Answer 1

Laterally connected by adherence proteins

To adjacent cells- desmosomes

Question 2

Keratinocyte differentiation

Answer 2

1) Basal cell-Begin to synthesise intermediate keratin filaments. Grouped into bundles
2)Spinous layer-Synthesis continues and the upper part begin to produce keratohyolin granules- contain lamellar bodies+ intermediate filament associated proteins
3) Granulosom- cell discharges lamellar bodies
Remainder of cytoplasms contains numerous Keratohyalin granules which form the cells envelope along with the tonofilaments
4) Corneum- surface cells are keratinized- contain a thick cell envelope+ bundles of tonofilaments in a specialised matrix

Question 3

What does the KLK/ LEKTI desmosomes do?

Answer 3

Regulates the desquamation of keratinized cells, dependant on pH.
Near the granulusom layer, neutral ph, maintain desmosomal interactions
As you go above the corneum, pH decreases, active KLK molecules digest desmosomal proteins, leading to the degradation of desmosinal junctions and detachment of the superficial layer of keratinocytes

Question 4

Psoriasis

Answer 4

• Transit time is reduced.
• From 28-40 days it goes to 2-3 days
• Very low pH

Question 5

Hyperkeratosis

Answer 5

Too much keratin is produced.

Can lead to keratin horns

Question 6

Epidermis cells

Answer 6

Melanocytes- Stratum basale layer with dendritic projections,
Melanin is transferred to neighbouring keratinocytes by pigment donation.
Langerhans cells- antigen presenting cells
Merkel cells-Sensory nerve cells- mechanoreceptors

Question 7

Skin appendages

Answer 7

Hair
Arrecotor Pilli muscle
Mechanoreceptors
Nails
Sebaceous glands
Sweat glands

Question 8

Hair types

Answer 8

3 types: Lanugo(fetal)
Vellus- not connected to sebaceous gland
Terminal- connected to the sebaceous gland

Question 9

Hair function

Answer 9

1) Thermoregulation
2) Sensitivity
3) Water regulation
4) Sexual attraction
5) Protection

Question 10

Mechanoreceptors- Excessive farting triggers more people rapidly running

Answer 10

End bulb
Free nerve ending
Tactile discs
Meissen corpuscle
Pacinian corpuscle
Root hair plexus

Question 11

End bulbs

Answer 11

Thermoreceptor- register temperature

Question 12

Free nerve ending

Answer 12

Register pain- nociceptors

Question 13

Tactile discs

Answer 13

• Sense touch+ pressure attached to the basale layer

Question 14

Meissner corpuscle

Answer 14

-register flicking+ minor movements

Question 15

Pacinian corpuscle

Answer 15

Vibration+ pressure

Question 16

Ruffini’s corpuscle

Answer 16

Joint movements and tissue stretch

Question 17

Root hair plexus

Answer 17

Vibrations in the hair shaft

Question 18

Nails

Answer 18

1) Protection of the distant phalanx
2) Mainly composed of alpha keratin
3) Used as a tool
4) Growth of nails is correlated with length of phalanx

Question 19

Arrector pilli muscle

Answer 19

Contract- cause hair to stand up, consists of smooth muscle

Fight or flight

Question 20

Main function of skin

Answer 20

1) Vitamin D synthesis
2) lubrication
3) Thermoregulation
4) Protection and repair
5) adipose storage
6) Absorption
7) Sensation