STRUCTURE & STRUCTURE & FUNCTIONSFUNCTIONS

OF SKINOF SKIN

INTRODUCTIONINTRODUCTION

The skin covers the whole of the external surface of the body.It forms the largest and heaviest organ in the body. The skin consists of three main layers.

Epidermis (an upper protective layer)Dermis (a lower supporting layer)Hypodermis

EpidermisEpidermisThe epidermis is thick, hard and horny in regions, such as on the palms of the hand and soles of the feet.

Properties

• Primary barrier to microbial invasion• Impermeability to water and chemicals• High capacity of regeneration after damage

DermisDermisThe dermis is soft and elastic in all parts but

may be very thick.

Properties

• The dermis gives strength to the skin

• Act as reservoir of elements capable of fighting infections and repairing deep wounds

HypodermisHypodermis

The skin is supported by a layer of fatty subcutaneous tissue sometimes known as the hypodermis.

FUNCTION OF SKINFUNCTION OF SKIN

The most obvious function of the skin is to provide the body with physical protection.

It forms an outer covering, which defends the body against injury from mechanical, thermal, chemical sources and microorganisms

The skin also acts as an organ of sensation to make the body aware of its environment.

FUNCTION OF SKINFUNCTION OF SKIN(Contd…)(Contd…)

• Another important function of the skin is regulation of body temperature (37-38C).

• It plays a minor role in excretion of the body’s waste products

Bacterial StructureBacterial Structure CELL ENVELOPE:

– Protects cell’s internal structures from its external environment.

– It comprises cell wall, cell membrane

CYTOPLASM: – Watery gelatinous substance – Contains ribosomes, nucleoids & plasmids – Keeps the cell alive

Bacterial StructureBacterial Structure (Contd…) (Contd…)

RIBOSOMES: – Produces enzymes and proteins – Helps the cell to live and grow

NUCLEOIDS: – Contains cell’s genetic material. – Also called bacterial chromosome– Single circular molecule of double stranded DNA

PLASMIDS: – DNA fragments carrying genetic information

MYCOLOGYMYCOLOGY

The study of fungi is called Mycology.There are several widespread human and

animal diseases that are due to fungi.There are many beneficial fungi, some used

to make antibiotics, bread and foods or used as insecticides.

CHARACTERISTICS OF FUNGICHARACTERISTICS OF FUNGI

The fungi (sing., fungus) are a diverse group of eukaryotic microorganisms, with over 80,000 identifiable species.

Fungi were classified as plants, but laboratory studies have revealed a set of four properties that distinguish fungi from plants.

Differentiation from PlantsDifferentiation from Plants Fungi lack chlorophyll, while plants have this

pigment. The cell walls of fungal cells contain a

carbohydrate called chitin not found in plant cell walls.

Fungi are not truly multi-cellular like plants. Fungi are heterotrophic eukaryotes, while plants

are autotrophic eukaryotes.

GROWTH OF THE FUNGIGROWTH OF THE FUNGI

Fungi are aerobic organism, with the notable exception of the yeasts that multiply in the presence or absence of oxygen.

High concentration of sugar is favorable for the growth

Most fungi grow best at approximately 25 C fungi grow under acidic conditions at a pH from 5

to 6

FUNGAL INFECTIONS OF THE FUNGAL INFECTIONS OF THE SKINSKIN

Superficial Skin InfectionDeep Fungal Infection

Superficial Skin InfectionSuperficial Skin InfectionThe superficial fungi live on the dead horny

layer of the skin Secrete an enzyme that enables them to

digest keratin causing the superficial skin to scale and disintegrate the nails, and the hairs to break off.

Fungi are also capable of causing an allergic reaction.

CLINICAL CLASSIFICATIONSCLINICAL CLASSIFICATIONS

Tinea of the feet (tinea pedis) - T. mentagrophytes Tinea of the hands (tinea manus) - T. mentagrophytes Tinea of the nails (onychomycosis) T.rubrum, T. mentagrophytes Tinea of the groin (tinea cruris) - E.Floccosum Tinea of the smooth skin (tinea corporis) - T. mentagrophytes Tinea of the scalp (tinea capitis) - T.tonurans, T.verucosum Tinea of the beard (tinea barbae) Dermatophytid (Acute Eruption of Fungal Infection) Pityrosporum Tinea of Chest and Back (Tinea versicolor) Pityrosporum

DEEP FUNGAL INFECTIONDEEP FUNGAL INFECTION

Fungi that invade the skin deeply and go into living tissue

Also capable of involving other organs.

Types of Deep Fungal InfectionTypes of Deep Fungal Infection

Candidiasis Sporotrichosis

Deep Fungal InfectionDeep Fungal Infection

Candidiasis:

Candidiasis is a fungal infection caused by Candida albicans that produces lesions in the mouth, the vagina, the nails, the lungs, or the gastrointestinal tract or occasionally a septicemia.

Deep Fungal InfectionDeep Fungal Infection

Sporotrichosis:

Sporotrichosis is a fungal infection of the skin and the subcutaneous tissues that forms a chain of tumors that develop into ulcers

DermatomycosisDermatomycosis

Fungal infection of the skin ,especially of moist parts covered by clothing.

EczemaEczemaEczema is pruritic condition associated with

erythema and edema in acute phaseIt is dominated by thickening and scaling

when it becomes chronic The term eczema is broadly applied to a

range of skin conditions. Eczema is defined as allergic, pruritic

dermatitis

InflammationInflammation

A protective reaction of tissue to irritation, injury, or infection.

Two types of Inflammation: Localized Inflammation Systemic Inflammation Symptoms includes pain, redness, swelling and

heat.

Localized InflammationLocalized Inflammation

Inflammation is a process in which the body's white blood cells and chemicals can protect us from infection and foreign substances (bacteria and viruses)

Symptoms includes pain, redness, swelling and heat.

Systemic InflammationSystemic Inflammation

Inflammation may also be associated with general "flu"-like symptoms including: • Fever • Chills • Fatigue/loss of energy • Headaches • Muscle stiffness & myalgia• Anorexia (Loss of appetite)

ANTIFUNGAL AGENTSANTIFUNGAL AGENTS

CLOTRIMAZOLE Clotrimazole is an imidazole antifungal agent. Clotrimazole is applied topically two or three

times daily for 2 to 4 weeks as a 1% cream. Local reactions including irritation and burning

may occur in patients treated topically; contact allergic dermatitis has been reported.

KETOCONAZOLE Ketoconazole is an imidazole antifungal agent,

which interferes with ergosterol synthesis and therefore alters the permeability of the cell membrane of sensitive fungi. It is reported to be fungistatic.

After topical administration of Ketoconazole, irritation, dermatitis or a burning sensation has occurred

MICONAZOLE

Miconazole is an imidazole antifungal agent with similar antimicrobial activity to Ketoconazole.

Local irritation and sensitivity reaction may occur with Miconazole nitrate

CorticosteroidsCorticosteroidsCorticosteroids are a class of steroid

hormones that are produced in the adrenal cortex.

Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation

Effects of CorticosteroidsEffects of Corticosteroids

Corticosteroids exerts their effects by suppressing:

The inflammatory responseThe immune response

Mechanism of Corticosteroids Mechanism of Corticosteroids

Corticosteroids suppress inflammation by a number of mechanisms:

Inhibition of production of prostaglandins, leukotrienes and other inflammatory mediators

Inhibition of migration of neutrophils to areas of inflammation

Inhibition of accumulation of macrophages in areas of inflammation

Hydrocortisone Hydrocortisone is a corticosteroid hormone

produced by the adrenal gland. It is usually referred to as the "stress hormone" as

it is involved in response to stress. It increases blood pressure and blood sugar, and

reduces immune responses. When first introduced as a treatment for

rheumatoid arthritis, hydrocortisone was referred to as Compound E

Diflucortolone Diflucortolone is a synthetic corticosteroid and is

used to decrease inflammation in skin. It works by preventing the release of certain

chemicals from the cells. These chemicals are important in the immune system, and are released as a result of allergy or irritation.

By decreasing the release of these chemicals in the skin, diflucortolone reduces inflammation and relieves itch.

Diflucortolone is classed as a very potent corticosteroid.

BetamethasoneBetamethasone is a moderately potent

corticosteroid with anti-inflammatory and immunosuppressive properties.