Download Integumentary System

Integumentary System
Anatomy A-Day 11/21/16
Bellringer
• What is the body
membrane layer that is
the outermost layer
(skin)?
• What membrane
surrounds joints and is
composed of only areolar
connective tissue?
Agenda
• Bellringer
• Skin Structure Notes
• Skin Label and Diagram
• Skin Sensory Lab
Anatomy A-Day 11/21/16
Bellringer
• What is the body
membrane layer that is
the outermost layer
(skin)?
– Cutaneous
• What membrane
surrounds joints and is
composed of only areolar
connective tissue?
– Synovial membrane
Agenda
• Bellringer
• Skin Structure Notes
• Skin Label and Diagram
• Skin Sensory Lab
Body Membranes
• Body membranes cover surfaces, line body
cavities, and form protective sheets over organs
• Two major groups:
– Epithelial membranes – cutaneous (skin), mucous,
and serous membranes
– Connective tissue membranes – synovial
membranes
Epithelial Membranes
• Epithelial membranes – covering and lining
membranes
• Contain an epithelial sheet, but it is always
combined with a connective tissue layer
• 2 tissues = These membranes are actually
simple organs
Cutaneous Membrane = Skin
• Its superficial epidermis
is composed of
keratinizing stratified
squamous epithelium.
• Underlying dermis is
mostly dense (fibrous)
connective tissue.
• Exposed to air = dry
membrane
Mucous Membrane = Mucosa
• Composed of epithelium resting on loose
connective tissue called lamina propria.
• Lines all body cavities that open to exterior
• Varied types
– Stratified squamous epithelium in mouth, esophagus
– Simple columnar epithelium in digestive tract
• Wet membranes bathed in secretions or urine
• Adapted for absorption or secretion
Serous membrane = serosa
• Layers of simple squamous epithelium resting
on a thin layer of areolar connective tissue
• Line body cavities that are closed to exterior
• Occur in pairs:
– Parietal layer lines the wall of the ventral cavity
– Visceral layer covers the outside of those organs
• Layers separated by serous fluid, which allows
organs to slide without friction (heart, stomach)
Serosa
• Serosa lining the abdominal cavity and
covering its organs = peritoneum
• Membrane surrounding lungs = pleura
• Membrane around the heart = pericardium
Synovial Membranes
• Composed of soft areolar
connective tissue and
contain no epithelial cells.
• Line the fibrous capsules
surrounding joints and
tendon sheaths
• Secrete lubricating fluid to
cushion organs during
muscle activity
Tattoos
• Tattoos are made
by using a needle
to deposit
pigment in the
dermis.
• Risk of Hepatitis C
is 15x higher in
people who have
tattoos…
Cutaneous Membrane = Skin
• Skin and its glands (sweat, oil), along with hair
and nails, make up the integumentary system
• Integument (covering):
– keeps water and other molecules in the body
– Insulates and cushions body organs
– Protects body from damage.
• Uppermost layer of skin is full of keratin and is
cornified (hardened) to help prevent H2O loss.
Regulation and Reception
• Capillary network and sweat glands in
skin regulate heat loss
• Urea, salts, and water are lost when we
sweat
• Manufactures proteins - immunity
• Synthesizes Vitamin D (sunlight
converts cholesterol in skin into vit. D).
• Cutaneous sensory receptors are
located in skin – sense pain, pressure,
temperature, touch
Skin Structure
• Two kinds of tissue in skin
• Epidermis (outer) – stratified squamous
epithelium, keratinizing (can become hard)
• Dermis (inner) – dense connective tissue
• Subcutaneous layer (hypodermis) – below
dermis, adipose tissue, anchors skin to organs.
Skin Structure
• Subcutaneous layer
– shock absorber
and insulation from
extreme T changes
• Thicker in women
than in men
(adipose tissue)
Epidermis
• Five layers / strata:
– Stratum Corneum
– Stratum Lucidum
– Stratum Granulosum
– Stratum Spinosum
– Stratum Basale
• Epidermis is avascular (no blood supply)
– Ex: shaving is cutting off cells w/ no blood (usually)
Stratum Basale
• Most cells of epidermis are keratinocytes
(keratin cells) which produce keratin
• Keratin –protein that makes epidermis tough
• Deepest layer of epidermis / closest to dermis
• Stratum basale constantly undergoing mitosis,
a.k.a. stratum germinativum
• Daughter cells pushed upward into superficial
layers
Epidermis
• New cells become
increasingly
flatter and full of
keratin
• Stratum Spinosum
– relatively thick
• Stratum
granulosum –
cells granular
Epidermis
• As new cells die they form
the stratum lucidum (no O2)
• Only present where skin is
hairless and thick (palms of
hands, soles of feet)
• Stratum corneum – ¾ of
epidermal thickness
• Cornified or horny (cornu =
horny) cells, completely
keratinized (…and dead)
Melanin
• Melanin is a pigment that ranges from yellow to
brown to black
• Produced by melanocytes, found in stratum
basale.
• Everyone has same number of melanocytes
• Complexion determined by quantity of melanin
produced
• Heredity – genes specific for melanin production;
mutant genes can cause lack of melanin
Albinism
• Albinism results when
genetic changes result
in a lack of pigment
(melanin) production
• Can have eye problems
(light scattering, optic
nerve problems)
Dermis = your hide
• Two major regions
– Papillary – upper dermal region
• Dermal papillae (papill=nipple) – house pain receptors,
send nutrients to epidermis, form fingerprints
– Reticular – deepest skin layer
• Contains blood vessels, sweat and oil glands, and
pressure receptors (Pacinian corpuscles)
• Collagen (toughness) and elastic (stretch when
growing) fibers found in dermis
• Many receptors for nervous system
Skin Appendages
• Cutaneous glands –
exocrine. Release secretions
to skin surface via ducts.
– Sebaceous (oil) glands –
often open into hair follicles.
Everywhere but palms and
soles.
• Secrete sebum – oil that keeps
skin soft and kills bacteria.
Increased amount in
adolescence
Acne = infection of sebaceous gland
• When sebaceous gland’s duct is
blocked by sebum, a whitehead
appears on skin surface
• If the material accumulates and
dries it darkens to form a
blackhead.
• Sebaceous cysts occur when
keratin blocks the sebaceous
gland and inflammation occurs.
• Sebaceous Cyst
Sweat Glands
• Sweat (Sudoriferous) Glands – more than 2.5
million per person. Two types:
– Eccrine glands – most numerous, all over body.
Produce sweat (water plus salts and vitamins)
• Sweat is acidic (pH 4-6) so inhibits growth of bacteria
– Apocrine glands – confined to armpits and genital
areas of the body. Secrete fatty acids and proteins
• Function unclear but activated during stress, pain, sex
Hair
• Millions of hairs
• Minor protection:
– Head bumps
– Eyelashes
– Nose hairs
• Early humans –
provided insulation
from cold weather
Hair
•
•
•
•
•
Produced by hair follicle
Flexible epithelial structure
Root in follicle
Shaft projects from skin
Matrix (growth zone) of
hair bulb at end of follicle
• Pigment made by
melanocytes
Nails
• Scale-like modification of
epidermis
• Free edge
• Body (visible portion)
• Mostly nonliving
keratinized cells