Integumentary System Flashcards
What are the two main layers of the skin?
Epidermis and Dermis
What is the deepest layer of the integumentary system?
Hypodermis
What is the epidermis composed of?
keratinzed, stratified squamous epithelium
How many layers are in the epidermis?
4 or 5 depending on location in the body
What are the layers of the epidermis?
Stratum corneum
Stratum lucidum (only in thick skin)
Stratum granulosum
Stratum basale
(melanocytes)
What is the Stratum Basale (stratum germinativum)?
Lowest layer of the epidermis; is a single layer if cuboidal mitotic stem cells that give rise to keratinocytes.
10-25% are melanocytes
some tactile and epidermal dendritic cells
What layer of the epidermis forms the patterns for fingerprints?
Stratum Basale
What is the Stratum Spinosum?
The prickly layer of the skin above the stratum basale.
Has 8-10 layers of keratinocytes
Melanin granules and dendritic cells are most abundant here
What is the Stratum Granulosum?
Also known as the Granular layer, this is the third deepest layer of the epidermis.
Only has 3-5 rows of flattened cells
Cells undergo keratinization in this layer due to its distance from the dermis.
What is keratinization?
Flattening of cells and disinegration of nuclei and organelles.
What do keratohyaline granules aid in?
Cell dehydration, crosslinking keratin (intermediate) filaments, and kertanization.
What do keratohyaline granules aid in?
Cell dehydration, crosslinking keratin (intermediate) filaments, and kertanization.
What is the Stratum Lucidum?
Thin, transparent band above the stratum granulosum.
Consists of 2-3 rows of dead keratoncytes.
Clear appearance due to eledin.
What is the Stratum Corneum?
AKA the horny layer; has 20-30 cell layers of horny scales made up of dead keratinocytes.
Offers biological, chemical, and physical protection
Why is the Stratum Corneum water resistant?
Glyco protiens
What are the cells of the epidermis?
Keratinocytes
Merkel Cells
Langerhans Cells
Melanocytes
What are Melanocytes?
Produce brown pigment (melanin) in response to UVB light.
Located b/w cells of stratum basale
What is albinism?
Lack of melanin, leaving individuals defenseless against sun cancer.
Can be caused by defect in enzyme used to make melanin.
What is vitiligo?
When Melanocytes die or unable to function
Often caused by autoimmune reasons
Can be treated by transplanting melanocytes.
What is bronze diabetes?
When there is too much iron in the body associated with hemochromatosis
What are the layers of the dermis?
Papillary and Reticular
What is the papillary layer of the dermis?
Superior surface contains peg like projections called dermal papillae
What are Merkel Cells?
touch receptors, membranes intact with free nerve endings.
What are Langerhans Cells
dendritic cells, epidermal macrophages.
What are Cleavage (tension) lines?
Important skin patterns to how the body heals.
A parallel cut remains shut and heals well, a cut across pulls open and scars
How are cleavage (tension) lines formed?
by the collagen and elastic fibers in the dermis that are arranged in parallel bundles and resist force in a specific direction.
What composes the reticular layer of the dermis?
Dense connective tissue
Collagen fibers add strength and resiliency to skin
Elastin fibers provide stretch and recoil properties.
What is the Hypodermis?
Mainly adipose tissue; its a shock absorber, insulator, and stores energy.
It is a subcutaneous layer that is deep in the skin (superficial fascia)
Areolar tissue connects skin to underlying structures (muscle)
How does the integumentary system provide protection?
Chemically - low pH secretions retard bacterial activity (sebum and sweat), melanin provides UV protection.
Physically - keratin and glycolipids prevent entry and loss of fluids.
Biological - immune cells attack foreign substances (dendritic cells)
How does the skin sense temperature?
Thermoreceptors aka ruffini
How does skin sense touch?
Merkel discs
Meissners corpiuscles (light touch)
hair follicules.
How does skin detect pressure?
Pacinian Corpuscles (deep pressure and adapts quickly)
How does skin detect pain?
Free nerve endings
What is the metabolic function of the skin?
Produces vitamin D precursor
Activates steroid hormones
