Skin Flashcards
What type of cells make up the majority of the epidermis of the skin?
Keratinocytes
What are the four layers of the epidermis?
Horny(stratum corneum) granular(stratum granulosm) prickle(stratum spinosum) basal(stratum basale)
What is the name of the layer below the epidermis? And what tissue type is this?
Dermis. Dense irregular connective tissue.
Where in the epidermis does keratinocytes mitosis occur?
Basal layer
What is the function of keratinocytes in the prickle layer?
In the prickle layer terminal cell differentiation means that these cells have lost their ability to divide. They therefore synthesise keratin and contribute to strength.
What cell differentiation occurs in the granular layer of the epidermis?
In the granular layer, keratinocytes loose their plasma membrane and they differentiate to become corneocytes.
What is a keratinhyalin granule and where is it found?
These are aggregations of keratins, fibrous proteins. They are found in the granular layer of the epidermis.
What is the structure of the stratum corneum?
The stratum corneum contains rows of corneocyte cells - major role in skin barrier.
Where in the skin are melanocytes found, and what is their function.
Melanocytes are found at regular intervals along the basal layer of the epidermis. They produce melanin which gives our skin its colour. Mature melanosomes are transferred to keratinocytes by pigment donation.
What is a Langerhan’s cell?
These are cells found in the prickle layer of the epidermis which present antigens to T cells and therefore mediate an immune response.
Describe psoriasis.
Psoriasis is excessive proliferation of keratinocytes in the basal layer of the epidermis. This leads to a thickened prickle layer and excess stratum corneum. It can occur anywhere on the body.
What is allergic contact dermititis?
This is mediated by Langerhan’s cells found in the granular layer. It leads to redness of the skin and sometimes pussy wounds.
What is Malignant melanoma?
Malignant melanoma is an aggressive malignant tumour of melanocytes. Prognosis is good if this remains above the basement membrane. Moles are benign growths of melanocytes.
Describe vitiligo
Vitiligo is autoimmune destruction of melanocytes which leads to decrease pigmentation. It is unknown why, but this normally occurs symmetrically across the body.
What cell types and structures are found in the dermis of the skin?
The dermis is a dense irregular connective tissue. It is made up of Extracellular matrix and so contains collagen, elastic fibres and other components. This is synthesised by fibroblasts. The dermis has lymphatic and blood vessels and nerve. It also contains mast cells.
