Integumentary System Overview Flashcards
What are the two main components of the integumentary system?
Skin and epidermal derivatives
What are four examples of epidermal derivatives>
- hair follicles and hair
- sweat (sudoriferous) glands
- sebaceous (oil) glands
- nails
What are the major functions of the integumentary system? (6)
Protective, immunologic, homeostasis, sensory, endocrine, and exocrine
What are the two principle layers of the skin?
Epidermis and the dermis
What kind of epithelium is the epidermis?
Keratinized stratified squamous epithelium
Is the epithelium vascular or avascular?
Avascular
The epidermis is derived from what embryonic tissue?
Ectoderm
Generally what kind of tissue is the dermis?
Connective tissue
What embryonic tissue is the dermis derived from?
Mesoderm
Is the dermis vascular or avascular?
Highly vascularized
What is the layer of tissue deep to the skin?
Hypodermis (subcutaneous layer/subcutaneous fascia), consists of adipose tissue and is vascularized
What are the 4 cells of the epidermis?
Keratinocytes (85%), melanocytes (5%), Langerhans’ cells (2-5%), and Merkel’s cells (6-10%)
What do keratinocytes do?
Produce keratins, and participate in formation of water barrier
What do melanocytes do?
Produce pigment
What are Langerhans’ cells of the epidermis?
Antigen presenting cells of the immune system
What are Merkel’s cells?
Mechanoreceptor cells associated with sensory nerve endings
What is the major structural protein of the epidermis?
Keratins
Keratins are classified as what kind of filaments?
Intermediate filaments, more commonly referred to as tonofilaments
Describe the stratum basale layer of the epidermis.
- Single layer of basophilic cells,
- cells are small and cuboidal/low columnar
- mitotically active layer; contains stem cells tha tgive rise to keratinocytes
- production of intermediate (keratin) filaments begins
What two things begin production in the stratum spinosum layer?
Keratohyalin granules and lamellar bodies
Stratum granulosum layer stains what?
Intensely basophilic
Granular cells in the stratum granulosum layer turn into what?
Cornified cells (keratinization)
Describe the histologic appearance of stratum lucidum.
Thin, translucent layer of eosinophilic cells. Nucleus and cytoplasmic organelles become disrupted and disappear
Describe what is found in the cells of the stratum corneum.
Cells lose nuclei and cytoplasmic organelles. They are filled almost entirely with keratin (85%)
Melanin is synthesized and stored in what?
Melanosomes
Melanocytes are what kind of cells?
Dendridic cells
Why does melanin accumulate over the nuclei of cells?
To protect DNA from UV radiation
Describe a histologic appearance of a melanocyte.
Elongated nuclei surrounded by clear cytoplasm
Antigen presenting cells are typically found in what epidermal layer?
Stratum spinosum
What tissue are antigen presenting cells derived from?
Bone-marrow
What do the antigen presenting cells do?
Present processed antigen to T lymphocytes within nearby lymph node
What epidermal layer are mechanoreceptor cells found?
Within the stratum basale
What is merkel’s corpuscle?
This structure is the base of merkel’s cells that associate with expanded plate-like terminal of afferent nerve fibers
What are the three types of skin cancer?
Basal cell carcinoma, squamous cell carcinoma, and malignant melanoma
What are three characteristics of basal cell carcinoma?
- Most common
- Resembles cells of stratum basale
- Slow-growing tumor
What are two characteristics of squamous cell carcinoma?
- Second most common
- Characterized by highly atypical cells at all levels of epidermis
What are three characteristics of malignant melanoma?
- Most serious form
- Originates from melanocytes
- Presents as irregularly pigmented, multicolor lesion
What are the two layers of the dermis?
Papillary layer and the reticular layer
The papillary layer is consisted of what connective tissue?
Loose (areolar) connective tissue
Describe the histologic appearance of the papillary layer of the dermis.
Dermal papillae: finger-like connective tissue protrusions that project into the epidermis at the epidermal-dermal junction
The reticular layer of the dermis is what kind of connective tissue?
Dense irregular connective tissue
Is the papillary layer or the reticular layer of the dermis thicker?
Reticular layer is considerably thicker
Does the papillary layer or the reticular layer have more cells?
Papillary layer
Where would one find pacinian corpuscles?
These structures are found in the dermis and hypodermis
Describe the structure of pacinian corpuscles?
Large ovoid structures that are myelinated nerve ending surrounded by a capsule consisting of concentric lamellae. The inner core is a series of tightly packed, flattened Schwann cell lamellae surrounding unmyelinated axon
What do pacinian corpuscles do?
Detect pressure and vibration
Where are meissner’s corpuscles found?
Within dermal papillae of hairless skin
What kind of flattened cells form the lamellae of meissner’s corpuscles?
Schwann cells
What do meissner’s corpuscles do?
Detect light touch
Define hair.
Elongated filamentous, keratinized structures that project from hair follicles
What is the hair follicle responsible for?
The production and growth of a hair
Where is hair and hair follicles found?
Along the surface of almost the entire body, but definitely NOT associated with thick skin
What is the smooth muscle that extends from connective tissue sheath surrounding the hair follicle to the papillary layer of dermis?
Arrector pili muscle
What kind of innervation do arrector pili muscle receive?
Sympathetic
What role do arrector pili muscles serve?
Insulation
What leads to body odor?
Bacterial breakdown of sweat
Sebaceous (oil) glands are found where?
Everywhere in the skin except thick skin
What type of gland are sebaceous glands?
Branched acinar glands
Define sebum.
Lipid-containing substance produced and secreted by gland
Where do sebaceous glands secrete their product?
Into hair follicle
What kind of secretion comes from sebaceous glands?
Holocrine
What gland is involved in acne development?
Sebaceous (oil) glands
Define finger nails and toe nails.
Plates of keratinized cells that rest on nail beds
