Transcript The Integumentary System Human Anatomy and Physiology

The Integumentary System
Human Anatomy and Physiology
Types of Membranes
Membranes
Synovial
lines joints;
made of CT
Serous
lines body cavities that lack openings
to the outside; reduce friction
Mucous
lines cavities and tubes that
open to the outside of the body
Cutaneous
organ of the integumentary
system; aka skin
Functions of the
Integumentary System
Protective covering
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Prevents harmful
substances and
organisms from
entering the body
Reduces water loss
from deeper tissues
Regulation of body
temperature
Houses sensory
receptors
Contains immune
system cells
Synthesizes vitamin
D
Excretes small
quantities of waste
Absorption of drugs
and other agents
Components of the
Integumentary System
Skin
Hair
Nails
Sebaceous glands
Sweat glands
Layers of the Skin
Epidermis
Dermis
Subcutaneous layer
(hypodermis)
Thick versus Thin Skin
Thick Skin
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Palms of hands and
soles of feet
Hairless
Subject to much
abrasion
Thicker epidermis
(has an extra layer)
Thin Skin
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Found everywhere else
on the body
Has hair
Lacks one layer of the
epidermis
“Thick” and “thin” are
not describing actual
depth of tissue!!!
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Thickest skin = upper
back
Thinnest skin = eyelids
Epidermis
Stratified squamous
epithelium
Lacks blood vessels
Grows from the
bottom layer
(stratum basale)
Keratinization
Layers of Epidermis
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
Basement
membrane
Epidermal Layers
Stratum corneum – flattened cells,
desicated, anucleate cells, keratinized
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Water barrier
Varies in thickness
Thickens with unusual amounts of friction
 calluses
Stratum lucidum – in thick skin only,
cells in process of keratinization
Epidermal Layers continued…
Stratum granulosum – only a few cells thick,
appears granular
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Cells contain numerous keratin granules
Stratum spinosum – several cells thick,
numerous cytoplasmic processes called
spines, nuclei elongated
Stratum basale – single layer of cells on
bottom, contains skin stem cells
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Cells appear cuboidal or low columnar
Dermis
Epidermal ridges and dermal
papillae
Irregular dense connective
tissue
Thicker than epidermis
Muscle and nerve fibers, blood
vessels, hair follicles,
sebaceous glands, and sweat
glands
2 layers: papillary and
reticular
Layers of Dermis
Papillary layer
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Thinner, superficial
layer
Loose CT
Contains blood
vessels that serve
the epidermis
Contains nerve
processes
Reticular layer
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Varies in thickness,
but generally thicker
than papillary layer
Contains thicker
collagen and elastic
fibers
May contain smooth
muscle cells
Subcutaneous
Layer/Hypodermis
Loose connective
tissue and adipose
tissue
Connective tissue
fibers are continuous
with dermis
Panniculus adiposus –
layer of adipose tissue
that insulates and
stores energy
Arrector pili muscles
originate here
Cells of the Epidermis
Keratinocytes
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Main cell type
Produce keratin
Melanocytes
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In stratum basale
Contain melanin granules
Langerhans cells
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Involved in contact
dermatitis reactions
Merkel cells
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In stratum basale
Most abundant in fingertips
Sense light touch
Skin Color
There are 3 pigments involved in skin color:
melanin, carotene, and hemoglobin.
Melanin is the only pigment made by the skin
(from tyrosine) and ranges in color from
yellow  red-brown  black.
Skin color differences result from the kind
and amount of melanin made and retained by
the skin cells.
All humans have relatively the same number
of melanocytes.
Skin Color continued…
Freckles and moles are local accumulations of
melanin.
A tan is darkening of the skin as a result of
increased melanin production, usually in
response to prolonged exposure to UV
radiation.
Carotene is a yelloworange pigment found
in certain plant products. It tends to
accumulate in the stratum corneum and in
the fat of the hypodermis, and it is more
obvious when large amounts of carotene-rich
foods are eaten.
Skin Color continued…
Hemoglobin gives a pinkish hue to fair skin
which is most noticeable in Caucasian skin. A
more crimson pigment results when the
hemoglobin is highly oxygenated.
Hemoglobin is found in the RBCs of the
dermal capillaries.
Hair color is genetically determined and
results from the amount and type of pigment
secreted by melanocytes near hair follicles.
Dark hair has more melanin than light hair.
Red hair contains an iron pigment called
trichosiderin, and gray hair is a mixture of
pigmented and unpigmented hair.
Nerve Supply to the Skin
Free nerve endings found in the
epidermis and papillary dermis sense
temperature, vibration, pain, etc.
Encapsulated nerve endings:
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Pacinian corpuscles – deep dermis and
hypodermis; sense deep pressure
Meissner’s corpuscles – in papillary region
of dermis; sense light touch
Hair
Present on all surfaces
except for palms, soles,
lips, nipples, and parts of
external reproductive
organs
Made of keratinized cells
Hair follicle
Hair papilla
Hair shaft
Hair color
Arrector pili
Nails
Protective coverings
on the ends of
fingers and toes
Nail plate
Nail bed
Lunula
Sebaceous Glands
Sebaceous glands
are associated with
hair follicles
Sebum
Found everywhere
except palms and
soles
Acne
Sweat Glands
In dermis or superficial
subcutaneous layer
Eccrine glands
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Most numerous
Produce sweat on hot days and
during exercise
Apocrine glands
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Become active at puberty
Secretions smell because of
bacterial activity
Active during emotional upset,
fright, pain, sexual arousal
Ceruminous glands and
mammary glands
Healing of Wounds
Inflammation =
normal response to
injury or stress
Epidermal cuts
Deep cuts
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Blood clots
Scabs
Scars
Healing of Burns
First degree burns
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Superficial partialthickness burn
Second degree
burns
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Deep partialthickness burn
Third degree burns
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Full-thickness burn
Rule of 9s
Aging and Skin
Epidermal cells reproduce slower
 larger and more irregular shape
Age spots – sites of oxidation of
fats in secretory cells of apocrine
and eccrine glands
Dermis reduces  wrinkling and
sagging
Drier skin because of less oil from
sebaceous glands
Gray or white hair from decreased
melanin production
Aging – continued…
Slower hair growth and fewer hair follicles 
thinner hair and/or hair loss
Less blood supply to nail beds  impaired
growth
Diminished sensitivity to pain and pressure
because of fewer receptors
Fewer sweat glands, fewer dermal blood
vessels, and declined ability to shiver 
decreased ability to control temperature
Diminished ability to activate vitamin D 
reduced skeletal health