Download Skin

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Basal-cell carcinoma wikipedia, lookup

Pattern hair loss wikipedia, lookup

Transcript
Integumentary System
Anatomy & Physiology
Body Membranes


Cover surfaces, line body cavities and form
protective sheets around organs
2 major groups


Connective tissue membranes
Epithelial membranes
Connective Tissue Membranes

AKA synovial membranes



Made of connective tissue, no epithelial cells
Line fibrous capsules of synovial joints, bursae
and tendons
Secrete a lubricating fluid, providing a smooth
surface
Epithelial Membranes

1. Mucous membranes





Typically stratified squamos epithelium or simple
columnar epithelium
Epithelium resting on the lamina propria
(connective tissue sheet)
Many secrete a mucous
Lines all cavities open to the exterior; very moist
Functions in absorption and secretion
Epithelial Membranes

2. Serous Membranes



Layer of simple squamos epithelium laying on layer of
areolar tissue
Lines cavities closed to exterior
Occur in pairs
 Parietal layer lines the wall of the cavity
 Visceral layer lines the organ within that cavity
 Cavities separated by serous fluid
 Fluid allows for decreased friction between mobile organs
and cavity walls
Epithelial Membranes

3. Cutaneous Membrane


Aka the skin
Exposed to air and is a dry membrane
The Integumentary System








The skin, hair, nails, sweat and oil glands
Mostly functions in protection but there are 6
separate functions of the skin
1.) Protection
2.) Body Temp. Regulation
3.) Cutaneous Sensation
4.) Metabolic Functions
5.) Blood Reservoir
6.) Excretion
Skin Functions

1. Protection: 3 types of barriers


A. Chemical barriers
 Includes skin secretions and melanin
 Acid mantle: kills bacteria on skin
B. Physical Barrier
 Provided by continuity of the skin and hardness of
keratinized cells
 Glycolipids: waterproof skin, blocking water & water soluble
substances
 Only lipid solubles can pass through

CO2, O2, oleoresins, vitamins A,D,E & K
Skin Functions

C. Biological Barrier


Langerhan’s cells and macrophages
2.) Body Temp. Regulation


Elevated: Blood vessels dilate & sweat glands
are stimulated
Lowered: Blood vessels constrict to conserve
body heat
Skin Functions

3.) Cutaneous Sensation


4.) Metabolic Functions


Sunlight reacts with cholesterol in the body to form vitamin
D which helps to metabolize calcium
5.) Blood Reservoir


Exteroreceptors respond to external stimuli
Holds large volumes of blood
6.) Excretion

Wastes eliminated through sweat
Skin Regions


Skin contains 2 major skin regions: dermis
and epidermis
1. Epidermis: thick, stratified squamos
epithelium

Contains 4 different types of cells




Keratinocytes
Melanocytes
Langerhans cells
Merkel cells
Epidermis Cell Types

1.) Keratinocytes





Makes keratin
Renews every 25-45
days
Found throughout
epidermis
Younger cells found in
deeper layers
Cells start to die as they
reach the surface

2.) Melanocytes



Makes the pigment
melanin
Accumulates on the
sunny side of the cell
Forms a pigment shield
against UV rays
Epidermis Cell Types

3.) Langerhans




From bone marrow
A type of macrophage
Activates immune
system
Can you break the word
macrophage down?

4.) Merkel Cells

Sensory receptors for
touch
Epidermal Skin Layers



Thick skin: has 5 layers of skin
Thin skin: only has 4 layers of skin
Layers:





Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Stratum Corneum
Stratum Basale

The Basal Layer




Deepest layer
Attached to dermis
Only 1 row of cells- the youngest keratinocytes
10-20% of melanocytes
Stratum Spinosum

Prickly Layer



Several layers thick
Has tension resistant filaments to toughen skin
Holds many langerhans, melanocytes and older
keratinocytes
Stratum Granulosum

The Granular Layer




3-5 cell layers thick
Contains flattened keratinocytes
Water proof glycolipids in extracellular space
Plasma membranes thicken
Stratum Lucidum

The Clear Layer


Present only in thick skin
Holds a few layers of clear, flattened, dead
keratinocytes
Stratum Corneum

The Horny Layer




Outermost layer
20-30 cell layers thick
Holds keratin and thickened plasma membranes
Glycolipids for water proofing
Remember….

The epithelium is AVASCULAR so….



Nutrients diffuse into epidermis from dermis
Layers above the granulosum too far away to
receive nutrients from diffusion
Dead cells shed from scalp and skin ~ 40-50
pounds in one lifetime
Dermis





The second major skin region
Made of flexible connective tissue
Functions to bind body together
Holds sensory receptors, blood vessels,
lymphatic vessels, hair follicles, oil & sweat
glands
Has different cell types and 2 major layers
Dermal Cell Types

Fibroblasts


Macrophages


For renewal
For protection
White Blood Cells

For protection
Dermal Skin Layers

Papillary Layer




Thin and superficial
Holds many blood vessels
Holds dermal papillae: small projections with
nerve endings, capillary loops and touch
receptors
Papillae enhance gripping ability on palms and
soles
Dermal Skin Layers

Reticular Layer





80% of dermis
Made of dense, irregular connective tissue
Bundled collagen fibers-run in many directions
Collagen gives skin strength and prevents cuts
Elastin fibers provide stretch and recoil
Hypodermis

The “other” skin layer





Not a major skin region
Subcutaneous tissue deep to skin
Made of areolar and adipose tissues
Stores fat, anchors skin to muscles
Shock absorption & insulation
Skin Markings

Dermal Tearings



Extreme stretching of
skin
Appear as silvery, white
scars
AKA Striae: stretch
marks

Blister


Separation of epidermal
& dermal layers by a fluid
filled pocket
Flexure Lines


Dermal modifications
Skin attached to deeper
structures to allow joint
movements
Skin Color

1.) Melanin: only pigment made in skin




Ranges from yellowish-red to brown to black
Amount and shade varies
The number of melanocytes relatively the same among
people
2.) Carotene



Yellow to orange pigment
Found in plant products
Accumulates in stratum corneum and hypodermis
Skin Color

Hemoglobin




Pinkish hue of fair skin
Oxygen carrying protein
in skin
Red in oxygenated blood
Cyanosis

Bluish tint due to low
oxygen levels

Redness/Erythema


Embarrassment, fever,
inflammation or allergy
Jaundice


Yellow cast
Signifies liver problems
Skin Color

Black and Blue Marks


Contusions or bruises
Broken capillaries
causes blood to leak




Pale skin
Emotional stress
Low blood pressure
Impaired blood flow
Skin Appendages
1.
2.
3.
4.
Sweat glands
Sebaceous glands
Hair
Nails
Sweat Glands

AKA Sudoriferous Glands



Located everywhere except nipples & external
genitalia
Over 25 million glands/person
4 types




Eccrine
Apocrine
Ceruminous
Mammary
Eccrine Glands





Most abundant gland, especially palms, soles
& forehead
Pores connect ducts to skin surface
Releases sweat: 99% water, salt, vitamin C,
antibodies, wastes (urea), lactic acid
Unable to control
Assists thermoregulation
Eccrine Glands

Heat induced sweat


Starts on forehead and spreads inferiorly
Emotionally induced sweat

Begins on palms, soles and armpits, then spreads
Apocrine Glands





Larger glands and ducts
Empty into hair follicles
Same composition as eccrine sweat +
proteins and fatty substances
Viscous, milky/yellow color
Odorless, but bacteria decomposes it on skin
creating B.O.
Apocrine Glands



Starts functioning @ puberty
Activated during pain and stress
Analogous to pheromones in animals
Sweat Glands Continued

Ceruminous


In the ear
Releases wax to deter
insects & block entry of
foreign materials

Mammary glands


Specialized sweat glands
Secretes milk
Sebaceous Glands






Oil Glands
Located everywhere EXCEPT palms and
soles
Secretes SEBUM via hair follicles or skin
pores
Softens, lubricates hair and skin
Stimulated by hormones activated @ puberty
Glands involved in acne
Hair and Hair Follicles

Function:




Detects stinging insects
Guards head from physical trauma, heat loss &
sunlight
Eyelashes shield eyes
Filters particles & insects from air inhaled through
nose
Hair and Hair Follicles

Structure



Made of hard keratin
Stronger, more durable
Doesn’t flake like soft
keratin of skin

Regions:



Root: embedded in the
skin
Shaft: projects from skin
Shape of shaft
determines hair type
 Flat, ribbon-like
 Oval
 Round
Hair Layers




Hair made of keratinized cells
1. Medulla: central core of hair; large cells
separated by air spaces
2. Cortex: bulky layer; surrounds medulla
with several layers of flattened cells
3. Cuticle: single layer of overlapping cells;
most heavily keratinized
Hair Structure
Hair Parts

Hair Follicle



Extends from epidermal
surface into the dermis
Root Hair Plexus

Hair Bulb

Expanded part of deep
end of follicle

Knot of sensory nerve
endings wrapped around
hair bulb
Hair Matrix

Actively dividing area of
new hair cells; older cells
have more keratin
Hair Parts

Arrector Pili Muscle



Small muscle cells
Contraction pulls hair follicle to upright position &
dimples skin surface
In response to fear and cold
Hair Extras


Split Ends: an
abrasion causing
cuticle to wear away,
allowing cortex and
medulla to “frizz out”
Hair color: pigment
made by melanocytes

Gray and white hairs due
to decreased melanin
production


Vellus hair: body hair
of kids and adult
females; pale and fine
Terminal hair: coarser
and longer; darker;
grows in response to
hormones
Hair Extras


Rate of growth:
varies, but on average
2mm/week
Growth cycles: has
active and resting
stages

Hair life span:



Scalp: active for ~4
years; inactive for ~2
months
Lose ~ 90 scalp
hairs/day
Eyebrows active for 3-5
months
Nails

Structure:



Scale-like modifications of the epidermis
Contains hard keratin
Functions:


Used as tools
Same growth pattern as hair and skin
Skin Development



Lanugo: downy hair “cloak” covering fetus
body, shed at birth
Vernix caseosa: white substance made by
sebaceaous glands to protect skin in womb
Baby’s skin: thin and transparent, thickens
and moistens with age
Skin Development





Adolescence: oily, acne
Prime time for skin in 20’s-30’s
Visual changes occur due to abrasion,
chemicals, wind and sun, air pollutants and
bacteria
Old age: skin thins; decreases elasticity
Prevention: good diet, fluids, cleanliness,
sun avoidance