INTEGUMENTARY SYSTEM Flashcards
What is the thickness of the skin?
Varying from 1.5 to 4mm or more
Characteristics of Epidermis?
Superficial epithelial region; Layered; Thick; Keratinized stratified squamous epithelium; Outermost protective Shield of the body
Characteristics of dermis ?
making up the bulk of the skin, is a tough, leathery layer composed mostly of dense connective tissue; vascularized
Characteristics of hypodermis?
it is superficial to the tough connective tissue wrapping (fascia) of the skeletal muscles. The subcutaneous tissue is not part of the skin, but because it shares some of the skin’s protective functions it is considered part of the integumentary system. It consists mostly of adipose tissue with some areolar connective tissue.
Keratinocytes produce _________
Keratin
Properties of Keratin ?
fibrous protein that helps give the epidermis its protective properties
Keratinocytes are tied together by _______
Desmosomes ; for strength
Keratinocytes undergo _______ __________. Are they alive or dead? Where are they found ?
continuous mitosis in response to epidermal growth factor, a peptide produced by various cells throughout the body. Newly formed keratinocytes are pushed upward by the production of new cells beneath them, all the while making the keratin that eventually fills them. By the time the keratinocytes approach the skin surface, they are dead, scale-like flat sacs completely filled with keratin.
Keratinocytes arise in the deepest part of the epidermis or closest to the dermis
Lifespan of keratinocytes?
25-45 days
Melanocytes produce _______
Melanin
Where are melanocytes found?
deepest layer of the epidermis. Melanin is made in membrane-bound granules called melanosomes and then transferred through the cell processes (the “spider legs”) to nearby keratinocytes.
Dendritic cells arise from _____ and migrate to the ________.
Bone marrow ; epidermis
What is the Dendritic cells do?
They ingest foreign substances and are key activators of our immune system
Where are Tactile Epithelial cells present?
Present at the epidermal-dermis boundary
Tactile Epithelial cells are associated with
a disc-like sensory nerve ending. The combination functions as a sensory receptor for touch.
Thick skin consist of __ layers or strata. What does thick skin cover?
5; covers areas subject to abrasion—the palms, fingertips, and soles of the feet
Thin skin consist of __ layers. What is absent? What does it cover?
4; stratum lucidum; Thin skin covers the rest of the body
Stratum corneum is the most _______ layer. It contains __ to __ cell layers of dead cells.
Superficial ; 20 to 30
Properties of stratum corneum?
Keratin and proteins that accumulate just inside the plasma membrane of cells in this stratum protect the skin against abrasion and penetration. The glycolipid between its cells helps keep this layer nearly waterproof.
Properties of lucidum?
few rows (2-3 rows) of clear, flat, dead keratinocytes
Properties of Stratum granulosum?
one to five layers of flattened layers in which keratinocyte appearance changes drastically, and the process of keratinization begins. These cells flatten, their nuclei and organelles begin to disintegrate, and they accumulate two types of granules (lamellar granules and keratohyaline granules)
Properties of Stratum spinosum?
several cell layers of keratinocytes unified by desmosomes. Cells of the stratum spinosum contain thick bundles of intermediate filaments, which consist of a tension-resisting protein, pre-keratin.
Properties of Stratum basale?
the deepest epidermal layer. The many mitotic nuclei seen in this layer reflect the rapid division of these cells. Each time one of these basal cells divides, one daughter cell is pushed into the cell layer just above to begin its specialization into a mature keratinocyte. See occasional melanocytes and tactile epithelial cells.
Dermis is made up of
strong, flexible connective tissues as well as fibroblasts, macrophages, and occasionally mast cells and WBCs
The semi fluid matrix of dermis is heavily embedded with _______
collagen, elastin and reticular fibers
The fiber in the dermis matrix bind body together. What does it produce and what is the specific word used to describe it?
It produces leather and the word used to describe it is “hide”.
Dermis also contains
Nerves, blood vessels, lymphatic vesselsepidermal air follicles, oil glands and sweat glands
Papillary Dermis is also know as
Thin superficial
Papillary dermis made up of
Areolar connective tissue in which fine interlacing
Collagen and elastic fibers with many small blood and lymphatic vessels
What is the role of connective tissue in papillary dermis?
Allows phagocytes and other defensive cells to wander freely as they patrol the area for bacteria that have penetrated the skin
Dermal papillae?
Peglike projection from its surface-indent the overlying epidermis
What does Dermal papillae contain?
Capillary loops ,others houses free nerve ending (pain receptors) and touch receptors called tactile corpuscles or meissners corpuscles
What makes up reticular layer ?
Thick dense irregular CT (thick bundles of collagen fibers running in different direction but mostly parallel to the skin surface
Why are cleavage lines important?
Collagen fibers in our body run in various planes but most run in parallel to the skin surface. When incision lines are made parallel to these lines, the skin gapes less and heals more readily.
What are friction ridge?
Dermal papillae lie on top of dermal ridges can be seen on the palms of hands, soles of feet.
Functions of frictions ridges.
Enhance gripping ability
Contribute to sense of touch
Sweat pores in ridges leave unique fingerprint pattern Friction Ridges
What are stretch mark?
Stretch marks or striae are extreme stretching of the skin, such as during pregnancy, can tear the dermis
Blisters?
Short-team but acute trauma can cause a blister a fluid- filled pocket that separate the epidermal and dermal layer
Flexure lines ?
Dermal fold that occur at near joint, where the dermis is tightly secured to deeper structure. Since the skin cannot slide easily to accommodate joint movement in such regions, the dermis told and deep skin creases forme.eg: fingers, soles, toes
What is the structure of melanin? What are the colour range?
Melanin is a polymer made of an amino acid called tyrosine. The colour ranges from reddish yellow to brownish black.
Why does people have different skin colour?
All humans have the same relative number of melanocytes, differences in skin coloring reflect the kind and amount of melanin made and retained. Melanocytes of black- and brown-skinned people produce many more and darker melanosomes than those of light-skinned individuals, and their keratinocytes retain it longer.
What damage does sun do to the skin & where does melanin figure into this?
-Elastic fibers clump, causing skin to become leathery
-Temporarily depresses immune system
-Cause alterations in DNA that may lead to skin cancer
-UV light destroys folic acid
What is carotene?
a yellow to orange pigment found in certain plant products such as carrots. It tends to accumulate in the stratum corneum and in the fat of the subcutaneous tissue (Hypodermis). Most obvious in palms and soles
What is hemoglobin?
The pinkish hue of light skin reflects the crimson color of the oxygenated pigment hemoglobin in the red blood cells circulating through the dermal capillaries. Because light-skinned people have only small amounts of melanin in their skin, the epidermis is nearly transparent and allows hemoglobin’s color to show through.
What is cyanosis?
When hemoglobin is poorly oxygenated, the skin may take on a bluish-gray tint. This is especially obvious in the oral mucous membranes and nail beds, particularly in darker-skinned individuals. Cyanosis can be a sign of respiratory or cardiovascular problems.
What is hair?
They are hair follicle, and largely composed of dead keratinized cells
What is hair pigment made of?
made by melanocytes at the base of the hair follicle and transferred to the cortical cells. Different concentrations of melanin produce hair color from blond to brown to black. Red hair is colored by a related pigment called pheomelanin.
3 Functions of hair
1) main function in humans is to sense insects on the skin before they bite or sting us.
2) Hair on the scalp guards the head against physical trauma, heat loss, and sunlight.
3) Eyelashes shield the eyes, and nose hairs filter large particles like lint and insects from the air we inhale.
what kind of keratin is hair?
Hard keratin
Advantages of keratin
(1) It is tougher and more durable, and (2) its individual cells do not flake off.
more cysteine-cysteine bonds that gives it less flexibility, more strength
Shaft
part that projects from skin (keratinization complete) - has 3 layers
Root
part embedded in skin (contained within hair follicle)
Bulb
expanded deep end of follicle - has papilla & root hair plexus
follicle
outer CT root sheath & inner epithelial root sheath; hair matrix
Arrector pili muscle
1/3 follicle; contract to pull hair up & dimple skin
Sebaceous gland
holocrine gland that secretes sebum (oily - lubrication & waterproofing; bactericidal)
Medulla
its central core, consists of large cells and air spaces. The medulla, the only part of the hair that contains soft keratin, is absent in fine hairs.
Cortex
a bulky layer surrounding the medulla, consists of several layers of flattened cells.
Cuticle
formed from a single layer of cells overlapping one another like shingles on a roof. This arrangement helps separate neighboring hairs so the hair does not mat.
Follicle shape determines _____
Texture
Follicle size determines ______
Thickness
What are split ends?
cuticle is the most heavily keratinized part of the hair. Because it is subjected to the most abrasion, the cuticle tends to wear away at the tip of the hair shaft. This allows keratin fibrils in the cortex and medulla to frizz, creating “split ends.”
What happens when hair is turning gray or white?
When melanin production decreases and air bubbles replace melanin in the hair shaft, as commonly occurs with aging, the hair turns gray or white.
