Chapter 5 Integumentary Flashcards
Functions of the integumentary system
Regulate body temperature
Store blood
Protection from external environment
Detect cutaneous sensations
Excrete and absorb substances
Synthesize vitamin D
Epidermis
Composed of epithelial tissue. Superficial, thinner portion of the skin. Avascular.
Dermis
Deeper, thicker connective tissue portion of skin. Vascular.
Subcutaneous tissue
Consists of areolar and adipose tissue. Anchors fibres from the dermis.
Keratinocytes
85% of epidermal cells, which are arranged in four or five layers and produce the protein keratin. Also produce lamellar granules, which release water repellent sealant.
Melanocytes
8% of epidermal cells. Produce the pigment melanin.
Melanin
Yellow-red or brown-black pigment which contributes to skin colour and absorbs UV light. Melanin granules protect keratinocytes from UV.
Dendritic cells
Langerhans cells. Originate in red bone marrow. 5% of epidermal cells. Participate in immune response.
Tactile epithelial cells
Merkel cells. 2% of epidermal cells. Located in deepest layer of epidermis. Make contact with non encapsulated (merkel disc) corpuscle.
4 layers of thin skin epidermis
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum corneum
Thick skin epidermis layers
Stratum basale
Stratum spinosum
Stratum granulosum
Stratus lucidum
Stratus corneum
Stratum basale
Deepest layer. Single row of cuboidal or columnar keratinocytes. Some cells in this layer are epidermal stem cells.
Stratum spinosum
Superficial to stratum basale. Consists of numerous keratinocytes in 8-10 layers. Produces coarser bundles of keratin than basal layer.
Stratum granulosum
Mid epidermis. 3-5 layers of flattened keratinocytes undergoing apoptosis. Presence of keratohyalin. Lamellar granules present. Marks transition state between metabolically active strata and dead superficial strata.
Stratum lucidum
4-6 layers of flattened dead keratinocytes. Can contain large amounts of keratin and thickened plasma membranes.
Stratum corneum
25-30 (sometimes 50) layers of flattened dead keratinocytes. Cells overlap one another in a layer.
Keratinization
Cells being pushed from one epidermal layer to the next, accumulating more keratin.
Papillary dermis
Superficial. 1/5 the thickness of dermis. Contains collagen and elastic fibres. Surface area increased by dermal papillae, which contain capillary loops, free nerves, or meissner corpuscles.
Reticular dermis
Deeper part. Attached to subQ tissue. Contains collagen, fibroblasts, macrophages, some adipocytes.
Hair
Composed of columns of dead, keratinized epidermal cells.
Types of hairs
Lanugo: fine, downy hairs
Terminal: coarse, heavily pigmented
Vellus: peach fuzz
Sebaceous glands
Branched acinar glands usually connected to hair follicles. Secretes an oily protective substance called sebum.
Sudoriferous glands
Sweat glands. Divided into eccrine and apocrine based on structure and type of secretion.
Eccrine sweat glands
Simple coiled tubular. Distributed through most of the body. Main function is help regulate temperature. Also helps eliminate waste. Also release sweat in response to stress.
