the integumentary system Flashcards
(76 cards)
what are the functions of the skin?
-protection
-regulation of body temp
-sensory perceptions
-synthesis of vitamin D
-excretion and absorption
-serves as an important reservoir of blood
how does the skin help with the regulation of body temperature?
by liberating sweat and adjusting blood flow to the demis
what is the structure of the skin?
-it has 2 major layers
-the outer, thinner layer is the epidermis and consists of the epithelial tissue and is vascular
-the inner, thicker layer is the dermis and conostst pf C.T and is vascularised
what is the subQ layer?
-the subcutaneous layer, it is underneath but not part if the skin and is a loose areolar/dispose C.T that attaches the skin to the underlying tissues and organs
what is the epidermis composed of?
-keratinized stratified squamous epithelium that contains 4 major types of cells
what are the 4 major types of cells the keratinised stratified squamous epithelium consists of?
-keratinocytes
-melanocytes
-langerhans cells
-merkel cells
what do keratinocytes do?
-produce keratin which provides protection
what do melanocytes do?
-produces melanin which helps protect against damage by UV
what do langerhan cells do?
-they are macrophages which are involved in immune responses
what do merkel cells do?
-they are tactile receptors that have a function in the sensation of touch along with other adjacent tactile discs
how many layers in thin and thick skin is the epidermis composed of?
-4 layers in thin skin
-5 layers in thick skin
what is the stratum corneum?
-it is composed of 25 layers of flathead keratinocytes that are like bags of turtle wax with no cellular organelles filled with only keratin protein
what is the stratum lucidum?
-it has 4-6 layers of dead keratinocytes
-it is the 4th layer but is only present in thick skin (skin of the fingertips, pals and soles)
what is the stratum granulosum?
-it is 3-5 layers of flattened keratinocytes undergoing apoptosis and they are filled with granules of keratin
-they release lamellar granules which are lipid rich secretion that acts as a water repellant sealant
what does the stratum spinosum consist of?
-a layer of 8-10 keratinocytes
what does the stratum basal consist of?
-cuboidal or columnar keratinocytes
-it is always the bottom, deepest layer
-stem cell division produces new keratinocytes
what happens to newly formed cells in the stratum basale?
-they are pushed to the surface and accumulate more and more keratin (this is the process of keratinisation)
-they can also undergo apoptosis and slough off and be replaced by underlying cells
what are the different types of skin?
-thin hairy skin (4 layers) which covers all body regions except the palms, palmar surfaces of digits and soles
-thick hairless skin (5 layers inc the stratum lucidium) covers the palms, palmar surfaces of digits and soles
what is melanin produced by?
-melanocytes in the stratum basale and it dictates skin colour
-it can accumulate in patches, freckles or liver spots
-it can either be eumelanin (brown/black polymer) or pheomelanin (yellow/red polymer)
what is nevi?
-nevi is birthmarks/moles and they are chronic benign lesions of the skin caused by an overgrowth of melanocytes
what is malignant melanoma?
-a cancer of melanocytes
what is albinism?
-a congenital disorder characterised by an inability to produce melanin nd is missing from the skin, hair and eyes
what is vitiligo?
-a chronic depigmentation disorder,there is a partial or complete loss of melanocytes from patches of skin produces irregular white spots
what does the dermis do?
-it provides temperature stability and provides dehydration
-it is composed of dense irregular connective tissue containing collagen and elastic fibres
-it contains two regions