Skin

Question 1

List 3 layers of skin and the tiss. in each

Answer 1

• Epidermis: Epithelial tiss.
• Dermis: Connective tiss.
• Hypodermis: Loose CT: adipose tiss.

Question 2

List 5 layers in epidural strata:

Answer 2

• Stratum corneum (SC): Flat, non-nucleated, keratinised cells
• S… lucidum (SL): very flat cells *only found in THICK skin
• S… granulosum (SG): nucleus & organelles degenerate (stains dark with Heaemat.)
• S… spinosum (SS): Thick cuboidal/lil flattened cell w/ spinous processes
• S… tratum basale (SB): Simple cuboidal/columnar

Question 3

Diff. b/w thick and thin skin

Answer 3

Thick: palms & feet; hairless; thick SC, SL present;

Question 4

2 layers of dermis

Answer 4

• Papillary: Loose CT w/ elastic, fine collagen fibres. Fingerprints
• Reticular: Dense irregular CT w/ thin elastic fibres, thick collagen bundle

Question 5

Diff and smilarity b/w histology of eccrine and apocrine sweat gland

Answer 5

Ecc: narrow lumen
Apo: wide lumen (in axilla- arm pit-, genital)
Both: Found in clusters

Question 6

3 types of skin cancer

Answer 6

Basal cell carcinoma: slow growing tumour in stratum basale
Squamous cell carcinoma: basement membrane disrupted & tumour cels spread into lypmh
Malignant melanoma: metastatic

Question 7

When a wound heals describe what happens in the epidermis

Answer 7

1. cells migrate to surface
2. Proliferation of stratum basale in surrounding damaged tissue
3. As cells repair & keratinise the scab lifts

Question 8

When a wound heals describe what happens in the dermis

Answer 8

1. Blood clot formation
2. Removal of damaged CT fibres
3. Re-epithelisation
4. Deposition & remodelling of CT & Ct matrix

Question 9

4 epidermal cells

Answer 9

• keratinocytes
• melanocytes
• Langerhan’s cells: antigen-presenting (immunity)
• Merkel cells: in thick skin. > detect light touches & superficial pressure

Question 10

Which cell makes collagen, reticulin and elastic fibres?

Answer 10

Fibroblast & fibrocytes

Question 11

function of skin

Answer 11

Barrier, immunity, homeostasis, sensory information, endocrine function, excretory

Question 12

What’s desquamation & keratinization?

Answer 12

• Desquamation: as mitosis ongoing = cells pushed upwards & top layer exfoliated
• Keratinisation: as cells move upwards they fill w/ keratin

Question 13

What factors influence skin colour? What happens in skin in persons w light or dark skin?

Answer 13

A) pigments, blood circulation, thickness of stratum corneum
B) - white: melonocytes @ SB & lysozyme in keratinocytes degrade melanin quickly
- dark: melanocytes around epiderm. except in SC and melanin degrades slowly