Transcript unit 5integumentary

The Integumentary
System
The skin and its derivatives (hair, nails,
glands, ect…) which provide the
external protective covering of the
body
Functions
1.
2.
3.
4.
5.
6.
Protection: against abrasions, bacterial
invasion, UV light, dehydration
Stimulus perception: nerve endings in dermis
detect: temp, pressure and pain
Excretion: perspiration releases body waste
Regulates body Temp: via perspiration
Synthesis of vitamin D: via exposure to UV
light
Blood reservoir: dermis holds large volume of
blood until needed elsewhere
3 Layers
1.
2.
3.
Epidermis: epithelial cells ( stratified
squamous)
Dermis: dense irregular connective tissue
Hypodermis: areolar and adipose
Epidermis
►
a)
b)
c)
d)
Made up of :
stratified squamous epithelium
karatinocytes ( produce keratin)
melanocytes ( produce melanin for skin
pigment)
langerhan’s cells and gransteid cells ( for
immunity.
Sublayers of epidermis ( called
strata) Starting with deepest
1. Stratum basale: mitotic layer, 1 cell thick
► It continuously divides pushing the cells above
them toward the surface,
► they can change and slowly die before being shed
2. Stratum spinosum: 8-10 rows of irregularly
shaped cells.
► Begin producing keratine
3. Stratum granulosum: 3-4 rows of darkly stained
cells.
► cell nuclei begin to degenerate as layers receives
less nourishment
4.
5.
Stratum lucidum: 2-3 rows of clearish cells only found
in thick skin of palms and soles
Stratum corneum: 25 + rows of shingle-like cells
remnants. The protective waterproof layer layer
Epidermis:
No blood vessels
► Nourished by diffusion ( does not make it to last 2 to 3
strata
► Takes about 2 to 3 weeks to completely replace skin (
basale to corneum)
►
Dermis
Thicker connective tissue layer beneath
epidermis, contains collagen and
elastic fibers
2 Regions of Dermis
1.
Papillary region
Contains dermal papilla which are dermal
projections into epidermis
► Some papilla contain blood vessels and pain
receptors or touch receptors (meissner’s
corpuscles)
► The dermal papilla produces ridges and valleys on
the surface of epidermis ( increases friction for
grip)
► Sweat glands have glands that open at ridge
peaks (making peaks sweaty) and reason for over
fingerprints
►
2 Regions of Dermis
2.
Reticular region
►
a.
b.
c.
d.
Contains:
Dense irregular connective tissue
Adipose tissue
Hair follicles
Oil and sweat glands
►
►
This region provides strength and elasticity to the skin
With age, elasticity lessens
►
Repeated stretched areas don’t bounce back… they
wrinkle
IF overstretched (pregnancy) they tear leaving stretch
marks (scars)
►
Hypodermis
► Also
called superficial fascia
► Composed of aereolar and adipose
connective tissue (usually muscle)
► Acts as a shock absorber and insulator due
to fat and water content
► Contains Pacinian corpuscles (nerve
endings for pressure)
► Technically not part of integument
Skin color
►
1.
2.
3.
Would be clear if not for 3 pigments:
Melanin:
Carotene
Hemoglobin
Melanin:
► Range
in color from orange to brown to
dark brown,
► All people have it except albinos
► Amount produced is influenced by: genetics
and exposure to UV light
Carotene
► Yellowish
pigment
► Collects in stratum corneum and adipose
Hemoglobin
► Oxygen
carrying blood pigment
► Gives skin its pinkness
► So
skin color is a blend of 3 pigments
as influenced by genetics and
environment
Epidermal Derivatives
►
Hair: somewhat protective ( nose, eyelashes or
from sun/cold)
►
A hair (pili) consists of:
Shaft: visible portion
► consisting of 3 layers of dead cells: 1. cuticle
(outer) 2. medulla (inner) and 3. cortex (middle)
2. Root: portion of hair below surface, extends
into the dermis and possible even hypodermis.
Has the same 3 layers.
1.
► The
root is surrounded by epidermal
extensions which form the hair follicle (
sac around the hair)
► The enlarged base of the root is called the
bulb
► The indention into the bulb is called the
papilla of hair (contains blood vessels)
Epidermal Derivatives
► Arrector
pili muscle:
► smooth muscle attached to the follicle and
anchored in dermis
► pulls air up straight out from skin in
response to cold and fright
Cross section of Hiar
Nails
► Another
epidermal modification with little
remaining function
► Are hard keratinized dead cells produced by
stratum basale, but nail itself is stratum
corneum
Glands
►Sebaceous
► Exocrine
glands: oil
glands, usually associated with hair
follicle
► An oily mixture of cholesterol, lipids and cell
fragments is called sebum
► Sebum: protects hair from drying, becoming too
brittle and from bacterial growth
► A blocked sebaceous gland is a whitehead ( or a
blackhead if the melanin and sebum oxidize), if it
is infected it is a pimple
Glands
►Sudoriferous
► Sweat:
gland: (sweat)
mixture of water, salt and organic
waste ( very similar to urine)
► Functions:
► eliminate waste
► temp regulator
►
Types of sudoriferous glands
1.
Eccrine: small coiled tubular glands release
►
Sweat is about 99% water
“sweat”
► Found everywhere except lips, nipples and genital
2.
Apocrine: largely still tubular, but ducts open
into hair follicles
► Found only in axillary and pelvic regions and do
not begin to function until stimulated by
hormones at puberty
► Produce thicker sweat with more organic wastes
( likely to have an odor due to bacteria living on it)
3.
►
►
Ceruminous gland: modified apocrine
sudoriferous glands
Found in external auditory meatus ear
canal)
Secrete a fluid which reacts with sebum to
produce cerumen ( a waxy protective
substance)
Injury and Tissue Repair
►Contact inhibition:
► Cells will migrate and continue to divide
until they come in contact with other cells of
the same tissue type
► A wound which only penetrates as far as
stratum basale ( epidermis)
► Heals with no scar tissue
Deep wound healing:
► Inflammation:
first response to damage
► The damage cells release histamine (cause
vascular dilation (bigger) and increase cell
membrane permeability)
► This causes more blood to enter wound (
swelling, heat and redness)
► The increased blood delivered increase
nutrition, and blood clotting factors and
macrophages (WBC)
►A
blood clot forms scaling wound from both
external world and surrounding healthy cells
► The surviving cells next to the wound divide
beneath the necrotic (dead) tissue
repairing the wound
► Since this new tissue does not match the
original, it is called granulation tissue
(scar tissue)
►Regeneration:
replacement of
destroyed tissue by same kind of cells
►Fibrosis: process of fibrous connective
tissue repair ( scar)
►Scab: blood clot and dead tissue
which are sealed from healthy cells
So tissue repair depends on type of
tissue damaged
► Epithelial
tissue: heals rapidly and nearly
perfect
► Connective tissue: repairs fairly rapid, but
is imperfect (scars)
► Muscles and nervous tissue: hardly
replace the destroyed cell at all, just work
around them
Burns
►
►
1.
2.
3.
Tissue damage by heat, electricity,
radioactivity or chemical causes
Burns destroy protective epidermis
allowing:
Microbial infection
Extensive fluid, electrolyte, protein loss
Loss of temperature
Burns
► Immediate
danger of burns is the loss of
fluid and electrolytes ( reduces volume of
blood, renal shutdown and shock)
► After fluid replacement the first 24 hrs, the
major damage is infection
► Burns are classified by depth and
percentage of surface area affected:
Burn Classification
► 1st
degree: surface epidermis only ( no
scarring) ex sunburn
► 2nd degree: epidermis and some dermis,
blistering and pain, mild scarring
► 3rd degree: integumentary system or more
is destroyed, no pain, charred dry
appearance extensive scarring slow healing,
skin graft or death
Cancer
► Tumor
or neoplasm: excessive growth of tissue
uncontrolled cell division
► Benign tumor: harmless, cells don’t spread (stay
in one clump)
► Malignant: cells keep dividing, spreading and
invading other body areas
► Metastasis: migration of cancer cells and other
body parts. They produce 2ndary tumors and
usually the cause of death in cancer
Check your risk for skin cancer
► Sarcoma:
general term for cancer of
connective tissue
► Adeosarcoma: cancer in a gland
► Myeloma: cancer in bone marrow
► Osteogenic sarcoma: bone cancer
Melanoma
► Melanoma
can grow very quickly.
► It can become life-threatening in as little as six
weeks and if untreated, it can spread to other
parts of the body.
► It can appear on skin not normally exposed to the
sun.
► It is usually flat with an uneven smudgy outline.
► It may be blotchy and more than one color –
brown, black, blue, red or grey.
Melanoma
►
Basal cell carcinoma
► This
is the most common but least
dangerous form of skin cancer.
► It grows slowly, usually on the head, neck
and upper torso.
► It may appear as a lump or dry, scaly area.
► It maybe red, pale or pearly in color.
► As it grows, it may ulcerate or appear like a
sore that fails to completely heal or one that
does heal but then breaks down again.
Basal cell carcinoma
Squamous cell carcinoma
► This
type of skin cancer is not as dangerous
as melanoma but may spread to other parts
of the body if not treated.
► It grows over some months and appears on
skin most often exposed to the sun.
► It can be a thickened, red, scaly spot that
may bleed easily, curst or ulcerate.
Squamous cell carcinoma
Warning signs of sun damaged skin
and skin cancer risk
► Spots,
blemishes, freckles and moles, similar
to those pictured , are signs of sundamaged skin. They are usually harmless,
but if you notice them changing, see a
doctor.