INTEGUMENTARY SYSTEM

  • Skin is the largest organ and is responsible for insulation and protection

  • Includes Hair + Nails

  • Nails have keratinised dead cells that make them hard and not easily subjected to wear and tear

  • Hair helps regulate body temperature and protect the skin from the sunlight

Hair Shaft

  • Top visible part of the hair

  • Has 3 layers:

    Outer Cuticle: outermost layer that is clear and protective

    Medulla Cortex: has the structure for keratin

    Inner medulla: Inner core

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  • Hair follicle is connected to a muscle called the arrector pili muscle

  • Arrector pili muscles contract thus pulling hair upright and leading to goosebumps

Types of Exocrine Glands

  1. SEBACEOUS GLANDS

  • Produce sebum (oily substance ) that helps to lubricate and waterproof the skin and hair.

  • Overproduction of sebum by the sebaceous glands results in acne

  • Androgen Hormones: trigger or stimulate the sebaceous glands during puberty to produce more sebum.

  1. SUDORIFEROUS GLANDS

  • Secrete sweat in order to regulate body temperature

  • The sweat released, evaporates thus cooling the body

    2 Types of Sudoriferous glands

  • Merocrine(Eccrine Glands ) :

    located all over the body especially on the forehead, palms & soles of the feet.

    Responsible for thermoregulation, cool the body by releasing sweat which evaporates

  • Apocrine Glands:

    Located in the axilla, groin & areolar (nipples)

    Responsible for emotional sweating

    Become active during puberty & are associated with a strong odour/ scent

    1. CERUMINOUS GLANDS

  • Secrete cerumen (earwax)

  • Cerumen traps dust and bacteria & lubricates ( prevents dryness) the ear canal

    4. MAMMARY GLANDS

  • Part of the female reproductive system

  • Secrete milk which provides nutrients to the baby

HYPODERMIS

  • Also known as the subcutaneous layer

  • It is the deepest layer beneath the skin & it connects the skin to the muscles & bones below

  • It keeps everything in place

    Composed of 2 tissues:

  • adipose tissue which is responsible for insulation & support

  • Areolar Connective Tissue which has passageways for blood vessels which carry food & water to the skin to keep it healthy

EPIDERMIS

  • Has 4 cell types namely:

    Keratinocytes

    Melanocytes

    Langerhan Cells

    Merkel Cells

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Keratinocytes:

  • produce keratin for protection

  • Located through out the epidermis

  • Make up 90% of the epidermal cells

Melanocytes

  • Produce melanin for protection against harmful radiation

  • Located in the Basal Layer

  • Use an enzyme called tyrosinase to convert tyrosine to melanin

    2 Types Of Melanin

  • Eumelanin: dark brown/ black

  • Pheomelanin: red/ yellow

Langerhan Cells

  • Also known as epidermal dendritic cells

  • Responsible for immune response (locate any foreign substance then alert the immune system which produces a response)

  • Located in the Stratum Spinosum

Merkel Cells

  • Responsible for touch sensation

  • Located in the Basal Layer

THIN SKIN

  • Has 4 layers

    Stratum Basale

    Stratum Spinosum

    Stratum Granulosum

    Stratum Corneum

Located in most parts of the body and is subject to wear & abrasion

STRATUM GRANUNOLOSUM

  • Keratinocytes undergo apoptosis

  • Apoptosis ensures that skin remains fresh & healthy

NB: The degree of thickness of the skin is determined by the amount of friction and pressure an area experiences. Increased friction results in rapid & increased cell division resulting in more keratin production and therefore forming thick skin

TONOFILAMENTS

  • Help skin cells stay strong & provide shape

  • Connect skin cells to one another

  • Contain keratin

SKIN GRAFTS

  • When the basal area is damaged beyond repair, cell division for new skin to form cannot occur and therefore skin grafts will be required

    Types Of Skin Grafts

  • Autografts: removing skin from one area of an individuals body and putting it in another area. There is decreased rejection since the skin is from the same individual

  • Isograft: graft from an identical twin, involves 2 people

  • Autologous Graft: An individual’s skin samples are taken & grown in the lab until a large sheet of skin has been formed to transplant on the area of damage.

EPIDERMAL RIDGES

  • Protrude downward into the epidermis

  • Interlock with the dermal papillae thus anchoring the epidermis to the dermis

  • Connection between epidermal ridges & dermal papillae results in skin being intact & reduces sliding

DERMIS

  • Located below the epidermis

  • Has 2 regions:

    Papillary region: loose connective tissue, has dermal papillae

    Reticular Region: Irregular Dense connective tissue, highly vascularised

  • Both the papillary and reticular region have Free Nerve Endings which are pain receptors