Skin Structrue And Function And Dermatology

Question 1

Describe the macroscopic structure of the human skin

Answer 1

1) The epidermis, which is the superficial, epithelial, avascular layer
2) The dermis, which is deeper and provides support for the epidermis. The dermis contains connective tissue elements, part of the skin appendages and vascular and nervous structures.
3) The hypodermics, which is a layer of loose connective tissue with adipose tissue (fat) cells, sweat and sebaceous glands, and larger blood vessels.

Question 2

Describe the microscopic and molecular structure of the hypodermis

Answer 2

It is the lowest layer of skin and is also known as sub-cutaneous (superficial fascia) layer so its not considered part of the skin.
It contains mainly adipose tissue (some neurovascular bundles/lymphatics) and loose connective tissue e.g., fibroblasts/macrophages/fibres.
It’s function is to provide energy store to generate heat. It is an insulator for underlying heat generation as well as a shock absorber. It connects skin to underlying muscle and bones and makes hormone e.g., leptin

Question 3

Describe the microscopic and molecular structure of the dermis

Answer 3

The dermis is between the epidermis and hypodermis. It is also known as the cerium, (dermis + epidermis is cutis).
It contains 3 layers:
- Papillary - Upper
- Reticlar - Lower
- Dermal papillae - interdigitating
It has a variable thickness 0.6mm on the eyelid, 3mm on hands/feet.
Functions include:
- Contains hair and sweat glands - thermoregulation
- Contains sensory structures - Special senses (touch)
- Gives structure to skin and so body shape.

Question 4

Describe the microscopic and molecular structure of the epidermis

Answer 4

The epidermis is the outermost layer made of epithelial cells (keratinocytes)
It contains either 4 or 5 layers of cells. It is held together laterally by adherents junctions and held together basal-apical by desmosomes. There are some terminal nerve endings and no blood vessels.
It’s functions include preventing water loss, preventing entry to bacteria and parasites, special cells that present pathogens to immune cells, synthesis of keratin, preventing underlying tissue loss to abrasion.

Question 5

Describe the microscopic and molecular structure of the different regions of the epidermis (Statum corneum)

Answer 5

Stratum corneum (corny/horny layer)

Outermost layer made of squames (dead keratinocytes). Thick on palms and soles of feet - prone to injury. They continuously shed.

Question 6

Describe the microscopic and molecular structure of the epidermis (Statum lucidum)

Answer 6

Stratum lucidum (transparent layer)

Only on palms and soles of feet

Question 7

Describe the microscopic and molecular structure of the epidermis (Stratum granulosum)

Answer 7

Stratum granulosum (granular layer)

Statified squamous epithelium. Lamellar granules (filament-associated proteins that assemble keratin fibrils and release it). Tonofibrils (bundles of keratin filaments and keratohyalin granules) made by lamellar bodies. Golgi apparatus appears increased in this layer

Question 8

Describe the microscopic and molecular structure of the epidermis (Stratum spinous)

Answer 8

Stratum spinosum (spinous layer/prickle cell):

Cuboidal epithelium arranged in 3 layers (held together by desmosomes)
Producers of lamellar bodies (keratohyalin factories and lipid production)

Question 9

Describe the microscopic and molecular structure of the epidermis (Stranum basale)

Answer 9

Statum basale (basal cell layer)

Tall columnar epithelial cells. They constantly renew keratinocytes by cell division. As daughter cells differentiate, they move away from the epidermis-dermis junction. They make keratin filaments (tonofilaments). They are also home to the melanocytes - produce melanin

Question 10

Describe the structure and function of skin appendages

Answer 10

Skin appendages are skin-associated structures that serve a particular function and include:
- Hair: Functions as thermoregulation as hair lays flat/stands erect. Also acts as a partial barrier to UV rays. It can also be alluring. Other functions include sensation and protection.
- Arrector pili muscle: Consist of smooth muscle fibres attached to papillary region of dermis and hair bulb. Fight or flight response. May also induce sebum release from sebaceous gland.
- Sebaceous glands: Holocene glands that produce sebum. Functions include lubrication, reduce water loss, aids skin flexibility, protect skin and hair from moisture.
- Sweat glands
- Nails: Consists of solely alpha keratin. Functions include protection of distal phalanx, enhancing precise delicate movements, enhancing sensitivity of the fingertip.

Question 11

Describe the contents and function of the hypodermis and immediate subcutaneous fat

Question 12

Describe the main functions of the skin

Answer 12

Protection and repair -
Temperature regulation and excretion of waste products - Sweat glands: urea, sodium chloride
Lubrication - Sebaceous glands release oil
Storage - White adipose cells provide lipids
Vitamin D synthesis
Absorption - Absorbs small amounts of water
Aesthetics - Skin as a mode of communication
Sensation - Specialised structures call mechanoreceptors

Question 13

Differentiate between thick and thin skin from photomicrographs

Question 14

Describe the structure and function of hairy skin

Question 15

Describe the structure and function of non-hairy skin

Question 16

Describe the sensory receptors of skin and how they cause sensation (mechanoreceptors)

Answer 16

Krause End bulbs - thermoreceptor that registers temperature (cold temperature).
Free nerve endings have nociceptors - registers pain, fine touch, heat, cold
Tactile discs - Vertical dimpling of skin - attaches to basal layer keratinocyte. Senses touch, pressure and texture
Meissen corpuscle - tapping and flicker movements detected (light touch vibration)
Pacinian corpuscle - Vibration/pressure
Ruffin is corpuscle - joint movement and tissue stretch (stretch and torque thermoreceptor)
Root hair plexus - Vibration in the hair shaft

Question 17

What is the correct terminology for:
the size of a lump/bump
Colour changes
Superficial changes
Hair changes

Answer 17

Small lump (<5mm) - Pauple
Larger lump (5-10mm) - Nodule
Small water blister - Vesicle
Larger water blister - Bulla
Pus-filled vesicle - Pustule
Redness - Erythema
Non palpable area of discolouration - Macule
Macule > 2cm - Patch
Palpable, flat topped area >2cm - Plaque
Scratch - Exoriations
Stretch - Striae
Itch - Pruritus
Thinning - Atrophy
Thread vein - Telangiectasia
Scaling - Ichthyosis
Loss of epidermis (superficial) - Erosion
Loss of epidermis and dermis (deep) - Ulcer
Thickening of skin (exaggerated markings) - Lichenification
Too much hair - Hirsutism
Too little/no/thinning hair - Alopecia

Question 18

Recognise and describe the various forms and clinical signs of skin inflammation

Answer 18

The process of inflammation results from 3 majors events:
- Vasodialtion
- Increased micro vascular permeability resulting in production of a protein rich exudate
- Influx of leukocytes
The cardinal signs include:
- Rubor
- Tumour
- Calor
- Dolor (symptom not sign)
- Functio laesa

Question 19

Describe Psoriasis, how its caused, how it can affect quality of life and create a psychological burden

Answer 19

It is the most common and important inflammatory disease. It is an autoimmune disease affecting T-cells ad keratinocytes. It can be inherited. Triggers include injury to skin, excessive drinking etc.
Features include reduced epidermal transit time, Acanthosis, and increased vascularity of the upper dermis
Topical treatments are Emollients, Salicylic acid, Topical steroids and Vitamin D analogues.
Systemic treatments include Psoralen and PUVA, cytotoxic drugs, Retinoids and Monoclonal antibodies

Question 20

Describe Eczema, how its caused, how it can affect quality of life and create a psychological burden

Answer 20

Eczema is dermatitis, a chronic skin disease. It can be internal (Atopic Dermatitis) or External (Occupation related)
Topical treatments include Emollients, Topical steroids and Topical immunosuppressants.
Systemic treatments include anti-histamines, and immunosuppressants.

Question 21

Describe Malignant melanoma, how its caused, how it can affect quality of life and create a psychological burden

Answer 21

It is a skin Describe Malignant melanoma, how its caused, how it can affect quality of life and create a psychological burden cancer (5th most common in the UK). Some families have a genetic predisposition to melanoma. Non-inherited mutations can also occur.
Most melanoma skin cancers occur in the trunk or legs
Treatment include wide local excision, radiotherapy and chemotherapy

Question 22

Describe Vitilgo, how its caused, how it can affect quality of life and create a psychological burden

Answer 22

It is when the skin become depigmented. Causes are autoimmune condition, tigger event and it can be Hereditary.
Symptoms include pale white patches on the skin. There are 2 types : segmental and non-segmental. Most common areas affected are: Skin around mouth and eyes, fingers and wrist, armpits, groin, genitals, inside of the mouth.
Treatments include Topical steroids, Calcineurin inhibitors, Cosmetic Camouflage, Sunscreen

Question 23

Describe Alopecia areata, how its caused, how it can affect quality of life and create a psychological burden

Answer 23

It is spot baldness, and has autoimmune causes. Treatment includes Topical and intralesional steroids. Calcineurin inhibitors (tactolimus) and Cosmetic methods

Question 24

Describe Acne, how its caused, how it can affect quality of life and create a psychological burden

Answer 24

Acne is a skin condition that affects the sebaceous glands. The causes depends on the type.
Treatments depends on the type. Topical agents are first, them mixed topical with oral, then surgical/intralesional injections/more potent oral treatments.