Transcript Integumentary System - Dayton Independent Schools

Schedule
Tissue Drawings Due
- Integ Notes; Lab activity
- Finish Integ Notes, Finish Lab
- Integ. Lab Due,
- Review for Test
- Tissue/Integumentary Test
- Intro to Bones, Bones Lab
- Intro to Bones (contd), Bones Lab
- Vocab 4 & 5 Quiz
Integumentary System
Chapter 5 in your textbook
Skin Physiology
A. Protection: from microorganisms, chemicals, physical injury,
dehydration, UV light
B. Sensation: receptors
C. Excretion: sweat contains uric acid, ammonia, urea, salt,
water
D. Metabolism: Vitamin D production by absorbing UV light
E. Immunity: T cells, Langerhans cells, and macrophages found
in the skin to fight microorganisms
F. Temperature Regulation: varies from 37.6oC to 36.2oC; heat
produced comes from metabolism in muscles and glands; heat
is lost if blood vessels widen (vasodilation); heat is saved if
blood vessels constrict (vasoconstriction); regulated by
hypothalamus
The Skin
•Waterproof, stretchable,
washable, repairs small rips,
cuts and burns
•The skin and the associated
organs of sweat and oil glands,
hairs, and nails make up the
Integumentary system
Fun Facts
• Consists of Skin,
Hair, Nails, and
Glands
• Avg. makes up
about 9-11 lbs. or
7% of your
weight
• Regenerates
every 25-45 days
Structure
• Epidermis: Stratified squamous
epithelium that is keratinized
• Dermis: Dense fibrous connective tissue
• A burn or friction causes a separation of
the layers : blister
• Hypodermis or superficial facia:
subcutaneous tissue; adipose tissue:
anchors skin to underlying organs. Shock
absorber, insulator
Skin Anatomy AKA Cutaneous
Membrane consists of:
epidermis (epithelial) dermis
(fibrous) subcutaneous layer (fat)
 hypodermis
Epidermis
• (keratinocytes & melanocytes); avascular; “tissue layer above
skin”; stratified squamous epithelium; BARRIER LAYER
Five layers:
• Stratum corneum: “horny” layer; dead stratified squamous; look
rough; keratin present (water-repellent protein); can become
thick from irritation (callus)
• Stratum lucidum: “clear” layer; dead cells
• Stratum granulosum: “granular” layer; thin; cells dying; begin
keratinization (cells move up)
• Stratum spinosum: “spiny” layer; protein synthesis with RNA to
generate keratin; living cells
• Stratum basale: “base” layer; AKA stratum germinativum; rapid
mitosis; youngest cells; melanin (pigment protects from UV
light);
NOTE:
• Thick skin- covers palms, fingertips, soles of
feet
• Thin skin – covers rest of body
– missing stratum lucidum and sometimes stratum
granulosum
Cells of the Epidermis
• Keratinocytes, melanocytes, Merkel cells and
Langerhan’s cells
• Majority of the cells are keratinocytes
– Produce keratin, a fibrous protein: protective
– Connected by desmosomes and arise in the
stratum basale layer until they rich the outer
surface where the dominate the cells content.
Here they are dead, scale-like structures
– We shed our skin every 25-45 days
Epidermis
• Stratum basale:deepest
layer; contains the only
epidermal layer that
receive adequate
nourishment via
diffusion from the
dermis
• Cells constantly
undergoing mitosis:
stratum germinativum
Dermis: True Skin
Contains sensory receptors for pain, pressure, touch, and
temperature; vascular; forms basement membrane
•
•
Papillary Layer- thin; projections of collagen and
elastin into basement membrane; areolar tissue;
elastic fibers ex. fingerprints
Reticular Layer- “skin network”; thick; dense fibrous
connective tissue; elastic fibers (stretchable);
arrector pili muscles (attach to hair follicle & contract
when cold); stretch marks (tears of elastic fibers)
Papillary Layer
 Thin superficial areolar
connective tissue with collagen
and elastin fibers
 Superior surface appears as peg
like projections called dermal
papillae that indent the epidermis
 House Meissner’s corpuscles
(touch receptors); pain receptors
and capillary loops
Reticular Layer
80 % of the dermal
thickness is dense
irregular tissue
 Contains blood vessels,
sweat and oil glands
Deep pressure receptors
(Pacinian corpuscles)
Phagocytes: prevent
bacteria from penetrating
to deeper body layers
II. SKIN COLOR
• GENETICS is the key factor
• Quantity of melanin
– (yellow to reddish- brown to black)
– protects skin from UV radiation
• In melanocytes, use enzyme tyrosinase to convert
tyrosine into dark brown melanin pigment, albinos lack
DNA code to make tyrosinase
• sunlight increases melanin production by affecting
release of hormones
• freckles or moles are accumulations of melanin
• other pigments such as carotene or hemoglobin
contribute to skin color
Three pigments :
1.The amount and kind of
melanin (yellow, reddish
brown or black)
2.The amount of carotene
deposited in the stratum
corneum and subcutaneous
tissue
3. The amount of oxygen
bound to hemoglobin
SKIN Color
Freckles and pigmented moles
are large accumulations of
melanin
Melanoctyes are stimulated
when the skin is exposed to
sunlight
Prolonged exposure causes
substantial melanin buildup
which helps protect the DNA
of viable skin cells from UV
radiation by absorbing the light
and dissipating the energy as
heat
SKIN Color
Hair: aka pili
covers all of humans
EXCEPT palms of
hands, soles of feet, lips,
nipples some genitalia
1. Hair follicle- shaft, root,
medulla (inner), cortex
(outer), cuticle (cover)
2. Growth- 4 in./year or 2
mm/week; male-pattern
baldness- genetic, sexinfluenced, hormones
(testosterone)
Nails
• Consists of:
–
–
–
–
–
–
free edge
Body
Root
Cuticle
Lunula
keratin
• growth- 0.5 mm/week
• fingernails faster than
toe nails – blood flow?
Skin Glands
1. Sweat Glands- AKA sudoriferous;
found in palms, feet, forehead
(perspiration/ sweat – 99% water) or
found in axillary and anogenital regions
– milky color
2. Sebaceous Glands- in dermis; secrete
sebum oil for hair and skin; 2/hair;
antifungal; antibacterial
3. Ceruminous Glands- cerumen or
earwax; can block ear from insects
Sebaceous (Oil) Glands
• Found all over except on the soles and palms
• Holocrine glands; ducts usually empty into a hair
follicle
• Sebum: mixture of oily substances and fragmented
cells; acts as a lubricant that keeps skin soft and
prevents the hair from becoming brittle; contains
chemicals that kill bacteria
Sweat (Sudoriferous) Glands
•
Two types: eccrine and apocrine
1. Eccrine/merocrine glands: sweat: clear secretion primarily
water, salts
2. Apocrine: axillary and genital areas; Secretion contains
fatty acids and proteins, as well as the eccrine substances;
can appear milky-white or yellow