Skin Structure

 

Introduction

Learn all about the human skin structure. 

There are 2 learning objectives, each learning objective contains information and questions to help prepare you for the upcoming lesson.

 

 

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1. Describe the functions and structure of the skin.

Which of the following is not a function of the skin?

8 Functions of Skin

The skin is the largest organ in the human body

  • Secretion of Sebum / Absorption of Drugs or Essential oil / Keeps out bacteria and creates barrier against rays of the sun
  • Elimination of waste products / Some toxins are eliminated from the body through the skin via the sweat glands
  • Sensation/  pain, cold, heat, pressure and touch

Vitamin D and Melanin production

  • Vitamin D is essential for the formation and maintenance of bone 
  • The melanocytes in the basal layer of the epidermis to produce melanin, a substance which produces a darkening of the skin to protect the underlying structures. The pigment protects the body from harmful effects of the sun’s rays since dark colours absorb radiation.

  • Protection
  • Temperature regulation
  • Transportation
  • Excretion

Structure of the Skin

The skin is a part of the integumentary system

The integumentary system comprises of the skin and its associated components such as the hair and nails

There are two main layers of the skin:

  • the epidermis, which is the outer, thinner layer
  • the dermis, which is the inner, thicker layer.

 

Below the dermis is the subcutaneous layer, which attaches to underlying organs and tissues.

Although the skin is technically a single organ, the two main layers do have different structures and functions

Which of the following is responsible for making the skin pigmentation darker?

Epidermis

The epidermis is composed of 4 types of cells and has 5 layers.
This complex cellular structure allows new cells to be continually produced to replace those that get worn away and facilitates the healing of damaged skin.

  1. Horny layer - hardened, flattened dead cells, constantly being shed-desquamation
  2. Clear layer (stratum lucidum) - This layer consists of transparent cells which permit light to pass through. The cells in the clear layer are filled with a substance called eleidin, which is produced from keratohyalin and is involved in the keratinisation process.
  3. Granular layer (stratum granulosum) - This layer consists of distinctly shaped cells that resemble granules, which are filled with keratin and produce intercellular lipids (the substances that fill the spaces between the upper epidermal cells) from structures called lamellar bodies.
  4. Prickle cell layer (stratum spinosum) - the thickest layer of the epidermis
  5. Basal layer - contains pigment known as melanin which gives the skin natural color. Melanin is produced by melanocytes. This layer of the epidermis is concerned with cell regeneration

  • keratin
  • sebum
  • carotene
  • melanin

Which specialized cells are responsible for production of areolar tissue, collagen, elastin?

Dermis

The dermis is thicker than the epidermis, tough and elastic. It is composed of connective tissue, collagen (a protein) and elastic fibres. Demis is also called true skin.

Dermis is composed of connective tissue, collagen (a protein) and elastic fibres

  • Papilla: small conical projections at the base of the hair containing blood vessels and nerves which supply the hair with nutrients
  • Fibro: responsible for production of areolar tissue, collagen, elastin
  • Mast: produce histamine as a allergic response
  • Histiocytes: produce histamine
  • Leucocytes: white blood cells helping to fight infection

  • Fibroblast cells
  • Mast cells
  • Histiocytes
  • Leucocytes

In which layer of the skin would you find collagen fibres?

Layers of Dermis

The key function of the papillary layer of the dermis is to provide vital nourishment to the living layers of the epidermis above.

Papillary Region (Upper)

The upper portion of the dermis The papillary region is characterized by small, finger-like projections called dermal papillae that indent the epidermis. Dermal papillae can contain loops of capillaries and nerve endings.

Reticular Region (Lower)

It contains connective tissue and a network of collagen fibres and coarse elastic fibres. These fibres provide the skin with strength, extensibility and elasticity. The reticular region contains the hair follicles, nerves, sebaceous (oil) glands and ducts, and sweat glands

  • Papillary layer
  • Reticular layer
  • Subcutaneous layer
  • Basal cell layer

Which part of the dermis contains a network of collagen and elastic fibres that give the skin its strength, extensibility and elasticity?

Sebaceous (oil) glands & Hair Follicles

Sebum and sweat combine together then form the acid mantle which helps to control bacteria levels and prevents infections and disease and also acts as a natural moisturiser

* Past Exam Question

Sebaceous glands is connected with what?
Answer: hair follicles

Fill in the blanks

Sebaceous gland is connected with .

They produce , a fatty acid which keeps the skin moist.

What type of sweat glands that are widely distributed throughout the body?

Sweat Glands

Sweat glands play an important role in temperature control. They release sweat which removes heat from the body. Sweat, containing a mixture of water, salts, urea, uric acid, amino acids, ammonia, sugar, lactic acid and ascorbic acid, is secreted from the coiled glands and travels up the sweat duct.

When the duct reaches the surface of the epidermis it forms a pore from which the sweat is released. 

* Knowledge of Ikeda treatment *

Ganbanyoku detox treatment will stimulate eccrine gland which can help to reduce the accumilation of organic matter in sweat, therefore effectively reducing body odor.

When you sweat on the Ganbanyoku bed, sebum and sweat combine together then form the acid mantle which helps to control bacteria levels and prevents infections and disease and also acts as a natural moisturiser.

* Past Exam Question

In which homeostatic process do the sweat glands perform a major role?
Answer: Temperature control

  • apocrine
  • eccrine
  • adipose
  • sebaceous

Which type of sweat gland releases sweat directly onto the surface of the skin?

  • Eccrine
  • Apocrine

Which type of sweat gland begins to function at puberty?

  • Apocrine
  • Eccrine

Subcutaneous layer

* Past Exam question

What name is given to the connective tissue containing fat that makes up the majority of the subcutaneous layer?
Answer: Adipose tissue

Video of Skin Structure

2. Describe diseases and disorders of the skin.

What is urticaria?

General Disorders of the Skin​

  • UV damage: UV rays stimulate rapid production of basal cells. This causes the stratum corneum to thicken. Over-exposure to UV rays may cause premature ageing whereas over-exposure to UVB may cause skin cancer.
  • Urticaria: hives, nettle rash: often an allergic reaction. Characterised by weals or welts of pinkish colour produced by extreme dilation of capillaries. Very itchy
  • Allergic reaction: when irritated, the body produces histamine(part of the defence mechanism) in the skin. This can cause red, blotchy patches on skin, watery, stinging eyes, swellings and runny nose. Can be slight or intense, depending on each body’s reaction.

* Menard product *

MENARD Fairlucent Day Cream White SPF 40

SPF refers to the ability of a sunscreen to block ultraviolet B (UVB) rays, which cause sunburns, but not UVA rays.

PA stands for “Protection Grade of UV-A”. PA+ signifies the product as having “protection efficacy” with PA ++ and PA+++ indicating strong protection efficacies

  • Itchy, highly contagious skin disease caused by an infestation
  • Normally caused by hormonal imbalances which increase sebum production leading to blocked glands and infection
  • Adult form of chicken pox. Usually affects spinal nerves and one side of the thorax
  • Characterised by weals or welts of pinkish colour produced by extreme dilation of capillaries

Infestations of the Skin

Direct skin-to-skin contact is the mode of transmission.

  • Scabies is an itchy, highly contagious skin disease caused by an infestation /skin rash composed of small red bumps and blisters
  • Pediculosis is an infestation with lice.

* Past Exam question

Itchy, highly contagious skin disease caused by an infestation is known as what?
Answer: Scabies

What is psoriasis?

Congenital Disorders of the Skin

Congenital is a disorder that exist at birth

  • Eczema: the skin becomes extremely dry and ichy

  • Dermatitis: an allergic inflammation of the skin characterised by erythema – redness of the skin, itching and various skin lesions

  • Psoriasis: chronic inflammatory skin disease characterised by red patches covered with silvery scales that are constantly shed.

  • Erythema covered with silvery scales
  • An allergy marked by eruption of weals
  • A fungal infection of the skin
  • Inflammation od skin caused by a virus

Identify the disorder

Hypopigmentation Disorders

Vitiligo部分的: a complete loss of colour in well-defined areas of the face and limbs. A form of leucoderma (an abnormal whiteness of the skin due to absence of pigmentation); begins in patches but may converge to form fairly large areas; most obvious in darker skins.

Albinism全体: complete lack of melanocytes resulting in lack of pigmentation in skin, hair and eyes. Sufferers have poor eyesight and extreme ultraviolet sensitivity. This is an inherited condition.

* Past Exam question

A complete loss of colour in well-defined areas of the face and limbs. A form of leucoderma is known as what?
Answer: Vitiligo

  • Vitiligo
  • Albinism

Hyperpigmentation Disorders

Hyperpigmentation is a common, usually harmless condition in which patches of skin become darker in color than the normal surrounding skin. This darkening occurs when an excess of melanin,

Dermatosis Papulosa Nigra: Is a condition of many small, benign skin lesions, characterized by dark-brown papular lesions on the face and upper body, mainly found on a black skin.

Chloasma: brown patches on the skin /butterfly mask often caused by pregnancy and the contraceptive pill; a hyper pigmentation condition involving the upper cheeks, nose and occasionally forehead. Discolouration usually disappears spontaneously at the end of pregnancy.

Ephelides: freckles; small pigmented areas of skin which become more evident on exposure to sunlight and are found in greatest abundance on the face, arms and legs; fair-skinned individuals suffer most from the condition.

Lentigo: known as liver spots; dark patches of pigmentation which appear more distinct than freckles and have a slightly raised appearance and more scattered distribution.

Port wine stain; a kind of large, deep red birthmark, a persistent hemangioma or nevus, typically on the face.

Naevae; birth mark may occur on any part of the body.

Papillima: a small wart-like growth on the skin or on a mucous membrane, derived from the epidermis and usually benign. varying in size and colour.

* Past Exam question

What is dark patches of pigmentation which appear more distinct than freckles and also known as liver spots
Answer: Lentigo

The most lethal type of skin cancer is?

Skin Cancer

  • Basal cell carcinoma: Occurs on exposed parts of the skin, especially face, nose, eyelid, cheek.
  • Malignant melanoma: A malignant tumour of melanocytes. It usually develops in a previously benign mole. The mole has become larger and darker, ulcerated and the tumour eventually spreads.
  • Squamous cell carcinoma: Squamous cells are those found on the surface of the body, on the top layer of the skin. Squamous cell carcinoma is said to be caused by sunlight, chemicals or physical irritants. It starts very small but grows rapidly, becoming raised.

  • squamous cell carcinoma
  • basal cell carcinoma
  • rodent ulcer
  • malignant melanoma

3 Types of infections

Viral infection

* Past Exam question

Herpes simplex is a viral infection commonly known as?
Answer: Cold sore

Which of the following is a bacterial infection?

Bacterial Infection

Acne Vulgaris: normally caused by hormonal imbalances which increase sebum production leading to blocked glands and infection.

Acne Rosacea: A chronic inflammatory disease of the face in which the skin appears abnormally red. A red flushed appearance on the centre of the face with pustules and papules The condition usually occurs in adults after the age of 40, but can begin as early as age 20.gives a flushed, reddened appearance. Occurs on the face, this condition can be aggravated by anything causing vasodilation. 

Folliculitis: bacterial infection of the pilosebaceous duct (sebaceous gland and hair follicle) causing inflammation. . 

Impetigo: a bacterial infection causing thin-roofed blisters which weep and leave a thick, yellow or honey colored crust. Highly contagious.

Boils: a bacterial infection of the skin, causing inflammation around a hair follicle.

 

  • Warts
  • Herpes simplex
  • Tinea corporis
  • Impetigo

What is the bacterial infection of the skin, causing inflammation around a hair follicle known as?

  • Warts
  • Boils
  • Herpes simplex
  • Chloasma

Which of the following is a fungal infection of the skin?

Fungal Infection

Tinea corporis, pedis: infections which attach themselves to keratinised structures like the skin. Tinea corporis is commonly
known as ringworm and can be found anywhere on the body.

Tinea pedis is commonly known as athlete’s foot. Highly infectious. Soft soggy skin which flakes between the toes

  • herpes simplex
  • ringworm
  • herpes zoster
  • impetigo

True or False

  • Warts are caused by a fungus
  • Herpes Zoster is caused by a virus
  • AIDS is caused by bacteria
  • Impetigo is caused by a insect infestation

Which of the following skin disorders would NOT contra-indicate manual massage?

  • Urticaria
  • Impetigo
  • Vitiligo
  • Tinea Corporis

Match the description

  • Impetigo
    Weeping vesicles which dries to form a honey coloured crust
  • Herpes Simplex
    Begins with an ich followed by erythema and vesicles
  • Rosacea
    A red flushed appearance on the centre of the face with pustules and papules

Revision

Fill in the blanks

Basal Layer contains pigment known as  which is produced by .

Desquamation occurs in which layer of the epidermis?

  • basal cell layer
  • prickle cell layer
  • clear layer
  • horny layer

Which of the following is not a function of the skin?

  • Protection
  • Temperature regulation
  • Transportation
  • Excretion

Which of the following is responsible for making the skin pigmentation darker?

  • keratin
  • carotene
  • melanin
  • sebum

Which specialized cells are responsible for production of areolar tissue, collagen, elastin?

  • Mast cells
  • Leucocytes
  • Fibroblast cells
  • Histiocytes

In which layer of the skin would you find collagen fibres?

  • Reticular layer
  • Basal cell layer
  • Papillary layer
  • Subcutaneous layer

What type of sweat glands that are widely distributed throughout the body?

  • sebaceous
  • adipose
  • eccrine
  • apocrine

What is urticaria?

  • Itchy, highly contagious skin disease caused by an infestation
  • Normally caused by hormonal imbalances which increase sebum production leading to blocked glands and infection
  • Characterised by weals or welts of pinkish colour produced by extreme dilation of capillaries
  • Adult form of chicken pox. Usually affects spinal nerves and one side of the thorax

What is psoriasis?

  • Inflammation od skin caused by a virus
  • Erythema covered with silvery scales
  • A fungal infection of the skin
  • An allergy marked by eruption of weals

Which of the following is a fungal infection of the skin?

  • shingles
  • ringworm
  • boils
  • impetigo

Which of the following skin disorders would NOT contra-indicate manual massage?

  • Urticaria
  • Vitiligo
  • Tinea Corporis
  • Impetigo

How does exposure to sun and sunbeds affect the skin?

  • Makes it look younger
  • Causes premature aging
  • Aids the application of make-up
  • Decrease cell renewal

Identify the parts

  • Epidermis
  • Dermis
  • Fatty Tissue
  • Blood Vessels
  • Follicle
  • Oil Gland
  • Sweat Gland