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Flashcards in Skin Deck (24)
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1
Q

Describe the layers of the epidermis

A
  1. Germinative (basal) - single layer
  2. Spinous(prickle) - thickest, spinous become desosomes have mucin, also contains langerhan’s cells (immune system)
  3. Granular - narrow with keratohyaline, granules in cytoplasm
  4. dead layer - anucleate cells, dead keratinised squames, thickness depends on location and abrasion

The epidermis has no vasculature supply to relies on nutrients from the dermis

2
Q

Describe the layers of the dermis

A
  1. Rich in collagen (close to surface)
  2. Deep fatty layer

RETE ridge separates the layers

-develops from the mesoderm, contains elastic fibres (stretch) and collagen fibres (strength)

3
Q

What are the functions of the skin

A
Sensory organ
Immune system
Temp regulation
Mechanical layer
water proof
UV protection
Vit D
4
Q

How does keratinised epithelium form?

A

The germinative layer contains keratinocytes - from stem cells

  • these cells mature and move up the epithelial layer when new cells are made
  • the most superficial layer of the epidermis is made up of flattened keratinising dead cells
  • abrasion flakes these cells off of the skin
  • the rate of cell division and thicks of this layer depends on area of the body and the amount of abrasion it experiences
5
Q

What are melanocytes

A

Melanocytes secrete melanin, this is transferred to keratinocytes of the basal and prickle cell layers, the amount of melanin present is proportional to skin colour

6
Q

What is in the spinous layer?

A
  • Also known as the prickle layer
  • Joined by desmosomes so that the skin can stretch, preventing it from splitting
  • If the skin shrinks the desmosomes become obvious and the cells appear spiny
  • Contains Langerhan’s cells (these have a pale cytoplasm and irregular shaped nucleus)
  • Basal layer contains Merkel’s cells - these are difficult t resolve and synapse with nerve fibres at the dermis to transmit fine touch
7
Q

Describe the structure of hair roots

A

In hairy skin the hair root originates in the epidermis and project to the dermis, the downgrowth terminates in an expanded end that becomes invaginated by a mesodermal papilla. The central cells of the downgrowth become keratinized to form a hair, which then grows outward to reach the surface

(melanocytes result in hair colour)

8
Q

What do sebaceous glands produce?

A

Lubricating oily matter
In hairy skin is flows from hair to the skin surface oiling the hair and keratinising the skin = waterproof and stops cracking/dehydration

9
Q

Describe the structure of nails

A

Compacted keratin

  • arise from nail matrix cell under a fold of skin called the eponychium/cuticle
  • The nail lengthens across the nail bed
10
Q

Describe the structure of sweat glands

A

Eccrine sweat glands are lined by glycogen rich cells

  • MOST COMMON SWEAT GLAND
  • tightly coiled knot of fluid secreting cells and straight duct with simple cuboidal epithelium
  • contain a duct to the surface of the skin
  • the coiled section is surrounded by myoepithelium cells, this contain actin to secrete sweat

(apocrine sweat glands are found at armpits and anus) and ear wax!

11
Q

What are Merkel’s cells?

A
  • Basal layer contains Merkel’s cells - these are difficult t resolve and synapse with nerve fibres at the dermis to transmit fine touch
  • Merkel cells are slowly adapting touch receptors in the basal epidermis
12
Q

What do fibroblasts do?

A

Produce and secrete collagen - growth/repair

13
Q

What do mast cells do?

A

Granules packed with histamine and other chemicals - these are released when the cell is disturbed (inflammation)

14
Q

What do apocrine glands produce?

A

They accompany hair follicles in the armpits and groins

  • they secrete apocrine secretions eg pheromones ( territorial marker, and warning signal)
  • sensitive to adrenaline
15
Q

Describe the junctions and adhesion molecules of the dermis and epidermis

A
Dermis = anchoring fibrils
Epidermis = anchoring filaments of hermidesmosomes link cells together
16
Q

What cells anchor cells together

A

Desomsomes and conea desmosomes

  • this means that the skin is impervious to pathogens
  • lipid lamellae protects the cells lower down
17
Q

Difference between adult and baby’s skin

A

Adult’s is much thicker - so irritants pass through baby’s skin easier - eyelids and cheeks

18
Q

What are filagrins

A

Filagrins are proteins that bind to keratin fibres in epidermal cells
This increases the structure of the cells
When there is a loss of filagrin there is an increase in adhesion as more foreign material can pass through

19
Q

How does pH affect skin?

A

An increase in pH encourages serine protease activity, this means that the proteins that hold the cell together in the epidermis can be digested = breaks in the skin and irritation

20
Q

What is the function of serine proteases?

A

Digest proteins at surface of skin so they don’t get too thick

21
Q

What causes red skin

A

Red skin is caused by inflammation and the dilation of blood vessels

22
Q

What causes itchy skin

A

-Rash, hypersensitive skin, decreased sweating, allegens
-due to neural pathway
-itching can damage skin
(NERVE STIMULATION)

23
Q

What causes dry skin

A
  • Lack of moisture in the stratum corneum - leads to cracks due to reduction of lipids in barrier/proliferation of keratinocytes
  • retention of corneocytes and reduced water holding capacity (LEAKAGE)
24
Q

What causes acne

A
  • narrowing of hair follicle
  • increase in sebum production from sebaceous gland
  • more sebum gets blocked and starts to stagnate since no oxygen
  • causes ‘propioni bacterium acnes’ to multiply in the sebum
  • this ‘propioni bacterium acnes’ causes the breakdown of triglycerides to free fatty acids
  • these cause irritation, inflammation, and attracts neutrophils
  • leads to pus development