the skin is composed of what two distinctive layers
the epidermis and the dermis
the epidermis is composed of __ cells
epithelial
the dermis is composed of __ tissues
dense connective
only the ___is vascularized
dermis
nutrients reach the dermis by __
diffusing through the tissue fluid from blood vessels in the dermis
the ___ lies just deep to the skin
subcutaneous tissue
the subcutaneous tissue is also known as the
hypodermis or superficial fascia
true or false: the subcutaneous tissue is part of the skin
false
the subcutaneous tissue consists mostly of __ with some __
adipose tissue, areolar connective tissue
the epidermis consists of what four cell types
keratinocytes, melanocytes, dendritic cells, and tactile epithelial cells
the epidermis consists of what five distinct layers (from superficial to deep)
stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale
what is the main role of keratinocytes
to produce keratin and give the epidermis its protective properties
keratinocytes are tied together by __ for strength and some layers by __ to hinder movement of water between cells
desmosomes, tight junctions
keratinocytes arise from the __ layer
stratum basale
what is the function of melanocytes
the spider shaped epithelial cells synthesize the pigment melanin
where are melanocytes found
in the deepest layer of the epidermis
where is melanin made
in the membrane bound granules called melanosomes
what is the function of dendritic cells
to ingest foreign substances and are key activators of our immune system
where do dendritic cells arise from
they arise form the bone marrow and migrate to the epidermis
dendritic cells extend among the surrounding___ forming a more or less continuous network
keratinocytes
where are tactile epithelial cells found
at the epidermal-dermal junction
what is the function of tactile epithelial cells
a sensory receptor for touch
the stratum basale is also called the
stratum germinativum
the stratum basale consists of
a single row of stem cells
stratum spinosum is also known as the
prickly layer
in what layer does keratinization occur
stratum granulosum
what is keratinization
the process by which cells fill with keratin
what two types of granules are found in the stratum granulosum
keratohyaline granules, and the lamellar granules
the stratum lucidum is found
only in thick skin
the cells of the stratum lucidum are identical to those found in
the stratum corneum
the stratum corneum is also called the
horny layer
the stratum corneum accounts for up to __ of the epidermal thickness
3/4
the dermis is made up of
strong flexible connective tissue
the dermis consists of the __ dermis and the __dermis
papillary, reticular
the thin, superficial papillary dermis consists of
areolar connective tissue
peg like projections from the papillary dermis are called
dermal papillae
what are friction ridges
ridges formed by the papillae lying atop dermal ridges
the reticular dermis accounts for about __ of the thickness fo the dermis
80%
the dermis consists of
dense irregular connective tissue
what are cleavage lines
less dense regions of collagen fibers running parallel to the skin
what are flexure lines
dermal folds that occur at or near joints
melanin is a __ made of an __called __
polymer, amino acid, tyrosine
melanin is transported from __ to the __
melanocytes, basale keratinocytes
what is carotene and what is its function in the body
a yellow to orange pigment, can be converted to vitamin A
the pinkish blue hue of fair skin reflects the crimson color of the oxygenated pigment __
hemoglobin
what is bilirubin
a waste from red cell breakdown
what are some examples of skin appendages
hard, hair follicles, nails, sweat glands, and sebaceous glands
all skin appendages derive from __ and extend into the __
epithelial cells of the epidermis, dermis
hairs can also be called
pili
what advantages do hard keratin have over soft keratin
it is tougher and more durable, it does not flake off
what are the chief regions of the hair
the shaft and the root
what are the three concentric layers of keratinized cells
medulla, cortex, and cuticle
what is the only part of the hair that contains soft keratin
the medulla
what layer surrounds the medulla
the cortex
the __ is the most keratinized part of the hair
cuticle
red hair is colored by a pigment called
pheomelanin
a hair follicle receptor or root hair plexus is
a knot of sensory nerve endings surrounding the hair bulb
definition of a hair papilla
a dermal papilla that protrudes into the hair bulb
what are the components of hair follicle from external to internal
peripheral connective tissue, glassy membrane, epithelial root sheath
true or false: hair grows because cells in the bulb of the follicle divide rapidly
true
definition of hirsutism
when women develop coarse terminal hairs in a. masculine distribution
nails contain what type of keratin
hard keratin
the ___ is responsible for nail growth
nail matrix
the cuticle is also called the
eponychium
the thickened region beneath the free edge of the nail is called the
hyponychium
sweat glands are also called
sudoriferous glands
what are the two types of sweat glands
eccrine and apocrine
sweating is regulated by by
a branch of the involuntary nervous system
eccrine sweat glands are also called
merocrine sweat glands
true or false: Apocrine sweat glands are more numerous than eccrine sweat glands
false
where are eccrine sweat glands particularly abundant
palms, soles of feet, and forehead
eccrine gland secretion (sweat) is 99% ___
water
sweat is __ with a pH between ___
acidic, 4 and 6
there are approximately ___ apocrine sweat glands in the body
2000
apocrine sweat glands are largely confined to the __ and __ regions
axillary, anogenital
apocrine glands are __ glands
merocrine
how do apocrine glands release their product
by exocytosis
two important types of modified apocrine glands are
ceruminous glands(ear wax), and mammary glands
sebaceous glands are also called
oil glands
sebaceous glands are
simple branched alveolar glands that are found all over the body except in the thick skin of the palms and soles
sebaceous glands are __ glands
holocrine, because they burst
the skin constitutes at least three types of barriers which are
chemical, physical, and biological
chemical barriers the skin include
skin secretions and melanin
what are defensins
natural antibiotics that punch holes in bacteria
what is a physical barrier of the skin
its continuity and hardness of its keratinized cells
substances that penetrate the skin in limited amounts
lipid soluble substances, oleoresins, organic solvents, salts of heavy metals, selected rugs, penetration enhancers
what are some biological barriers of the skin
dendritic cells of the epidermis and macrophages in the dermis
explain dendritic cells
they are a part of the immune system and one e they have captured the invader of the skin they leave the skin and migrate to the nearest lymph node
how do dermal macrophages work
they dispose of viruses and bacteria that manage to penetrate the dermis
cutaneous sensory receptors are part of the __ system
nervous
cutaneous receptors are classified as
exteroceptors
examples of cutaneous sensory receptors
tactile corpuscle, lamellar, hair, and free nerve endings
keratinocyte enzymes can
disarm many cancer causing chemicals and activate some steroid hormones
what are the three major forms of skin cancer
basal cell carcinoma, squamous cell carcinoma, and melanoma
basal cell carcinoma is the __ malignant and __ common
least, most
squamous cell carcinoma is the __ common skin cancer
second most
squamous cell carcinoma arises from the __ of the __
keratinocytes, stratum spinosum
true or false: squamous cell carcinoma tends to grow slowly and does not metastasize
false. squamous cell carcinoma tends to grow rapidly and will metastasize if not removed
melanoma is the __ dangerous skin cancer because
most, it is highly metastatic and resistant to chemotherapy
what doe the ABCD rule for melanoma stand for
Asymmetry, Border irregularity, Color, Diameter
definition of renal failure
kidney shutdown
in 1st degree burns the __ is damaged
epidermis
in 2nd degree burns the __ is damaged
epidermis and upper region of dermis
1st and 2nd degree burns are considered
partial thickness burns
third degree burns are considered
full thickness burns
definition of sepsis
widespread bacterial infection
definition of eschar
burned skin
definition of debrided
removed
the epidermis develops from the __
embryonic ectoderm
the dermis and subcutaneous tissue develop from the
mesoderm