structures of the skin hct i. layers of the skin two primary layers epidemis dermis subcutaneous...
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STRUCTURES OF THE SKINHCT I
Layers of The Skin
Two primary layers
Epidemis
Dermis
Subcutaneous Tissue- A layer of loose connective tissue and fat that supports the epidermis and dermis.
Insulates the body
Stored source of energy
Shock absorbing pad
Epidermis
The outermost and thinnest primary layer of skin. Cells are arranged in distinct layers Thickness varies on the body.
Thinnest on the eyelids
Thickest on the palms and soles of the feet.
Stratum Germinativum- innermost layer where cells divide and push already formed cells to the surface. WHY IS CELL REGENERATION IMPORTANT?
Maintaining the skin barrier helps to defend against infection even with injuries.
Epidermis
Keratin- a tough waterproof protein that replaces a cells cytoplasm as they approach the surfaceProvides the outmost layer of skin with
abrasion-resistance and protective qualities.
Stratum Corneum- Outmost layer of keratin filled cells, made up of dead flat skin cells that shed every couple of weeks.
DO YOU KNOW WHAT MOST DUST IS MADE OF?
EPIDERMISPIGMENT CONTAINING LAYER- epidermal
layer that contains pigments called:MELANOCYTES ,(a specialized epidermal
cell) which produces a brown pigment called melaninAmount of melanin depends on
geneticsIncreased melanin= increased skin
colorSunlight can increase the amount of
melanin produced.
EPIDERMISDermal Epidermal
Junction-the area between the epidermis and dermis.
Break down of this junction can lead to blisters. Burns
Friction
Exposure to irritants (poison ivy)
Dermis Deeper and thicker layer of primary skin
layers
Composed largely of connective tissue
Dermal papillae-(upper layer)
Important part of the dermal epidermal junction helping to keep the skin layers together
Form groves and ridges unique to each individual.
Do you know what the ridges and groves are called?
FINGERPRINTS
Dermis
Deeper areas contain a network of collagen and elastic fibers
These elastic fibers decrease with age contributing to wrinkles
Dermis also contains Nerve endings
Sweat and sebaceous glands
Blood vessels
Muscle fibers
Hair follicles
Appendages of the skin HAIR
Born with hair all over our bodies. Newborn hair is called lanugo
Hair follicle- an epidermal tube-like structure required for hair growth
Shaft- visible part of the hair
Root= lies hidden in the follicle
Hair papilla- where hair growth begins
Hair bulb- at the base of the follicle (hair papilla is located here)
Arrector pili- specialized muscle that produces goose pimples
Receptors
Specialized nerve endings – makes it possible for skin to act as a sense organ
Meissner’s corpuscle- detects light tough
Pacinian corpuscle- capable of detecting pressure
SKIN GLANDS
TWO TYPESSweat (sudoriferous)
Sebaceous
Sweat or Sudoriferous Glands
Eccrine sweat glands-most numerous, important and wide spread.
Produce perspiration, which flows out through pores on the surface of the skin
Assist with body temperature regulation
Sweat or sudoriferous glands
Apocrine sweat glands
Found primarily in the axilla and genitalia
Secrete a thicker milky secretion
Breakdown of secretion by skin bacteria produces odor
WHEN DO APOCRINE SWEAT GLANDS ENLARGE AND START FUNCTION?
PUBERTY
Sebaceous glands Secrete oil or sebum for
hair and skin
Level of secretion increases during adolescence
Amount of secretion regulated by sex hormones
Sebum in sebaceous gland ducts may darken to form a blackhead
Acne vulgaris-inflammation of sebaceous gland ducts
Structure of the skin