Skin and Body Membranes

What is the function of body membranes?



What is the function of the skin?



What are body membranes?










How are body membranes classified?








































What is the Integumentary System?




What are basic skin functions?













What makes up the structure of the skin?






























What causes the color of skin?











What are the appendages of the skin?














What are some homeostatic imbalances of the skin?

††††††††††††††††††††††††††††† Infections and Allergies


















††††††††††††††††††††††††††††††† ††††††††††††††††Burns




























††††††††††††††††††††††††††††††††††††††††††††††††† Skin cancer


























†††††††††††††††††††††††††††††††††††††††† Porphyriaand epidermolysis bullosa

To line, cover, protect and lubricate body surfaces


Protect against a variety of potential injuries


Cover surfaces, line body cavities, form protective sheets around organs

†††† 1. Epithelial membranes:

††††††††††††† a. cutaneous

††††††††††††† b. mucous

†††††††††† †††c. serous

†††† 2. Connective Tissue:

††††††††††††† a. synovial membranes†††††††††††††



in part to tissue makeup

1. Epithelial membranes

††††† contain an ET sheet, combines with CT††††††† underlayer


2. Cutaneous membranes


Superficial epidermis: stratified squamous full of keratin

Dermis: dense fibrous connective tissue

Exposed to air and is dry


3. Mucous membranes

ET resting on lamina propria (LCT)

Lines all cavities that are open to exterior

Respiratory, digestive, urinary and reproductive tract

Mucosa refers to location of ET

Most contain stratified squamous(mouth,eso)

Or Simple columnar

Et is adapted for absorption /secretion


4. Serous membranes

a layer of simple squamous ET on aerolar CT

lines cavities that are closed to the exterior

occur in pairs: parietal layer and visceral layer

fused to cavity wall

serous fluid separates the layers and is secreted by layers: allows little friction to occur between organs

†††††† a. peritoneum : lines abdominal cavity

†††††† b. pleura: lines lungs

††††† c. pericardium: lines the heart


5. Synovial membranes (CT)

no ET at all

lines fibrous capsules around joints

secrete lubrication line small sacs of CT: bursae and tendon sheaths


Cutaneous membrane: skin, derivatives (sweat and oil glands, hair and nails) serve for primary protection


Integument means covering

Keeps items in and out

Insulates and cushions

Protects from mechanical damage

Chemical damage

Thermal damage

UV radiation

Cornified: hardened with keratin=waterproof

Mini-excretory system: urea, salts and water

Synthesizes Vit D from cholesterol

Cutaneous sensory receptors: touch, pressure, temp and pain

Composed of 2 tissue types

1. outer epidermis: stratified squamous ET

capable of keratinizing

2.dermis: dense fibrous tissue

blister results when these two layers are separated

3. Subcutaneous tissue (not part of the skin)

: aerolar tissue contains fat and anchors skin to organs

shock absorber and insulator

responsible for shape




A. Deepest layer: stratum germinativum or basale

1 row of cuboidal /columnar, makes keratinocytes and melanocytes, contains Merkel cells

B. Stratum spinosum: lots of keratinocytes with Langerhans cells

††††† Daughter cells are pushed up and away from nourishment becoming

C. stratum granulosum contains granules

D. stratum lucidum (clear) full of keratin and die

E. Stratum corneum: outermost layer: shingle like dead cells full of keratin


Melanocytes make the pigment melanin which is found in stratum germinativum which eats melanin forming an umbrella over the nuclei


UV: causes elastic fibers to clump

Depresses immune system

Alter DNA


DERMIS: dense fibrous tissue

†††† 1. papillary region: dermal papillae

†††††††† areolar loose connective tissure

†††††††† house capillaries and some pain nerves

†††††††(Free end) and touch receptors

†††††††† (Meissnerís corpuscles)Merkel discs

†††† 2. reticular region : deepest skin layer

†††††††† dense irregular connective tissue

†††††††† blood vessel, sweat and oil glands

†††††††† Pacinian corpuscles: deep pressure

†††††††† Phagocytes are abundant

†††††††† Collagen : toughness, bind water

†††††††† Elastic fibers

†††††††† Age: lose fibers and fat

†††††††† Thermal regulation

†††††††† Decubitus ulcers: occur when blood

†††††††† supply is restricted to the skin

†† ††††††Epidermis projects downwards

†††††††† To form glands etc


A combination of melanin in epidermis, carotenein stratum corneum and subcutaneous and amount of oxygen carried by hemoglobin


Cyanosis: occurs when hemoglobin is poorly oxygenated and skin appears blue


Color can be influenced by emotion or disease:

1. Redness, erythema : blush, fever, hypertension,inflammation or allergy

2. Pallor, blanching: anemia, low blood pressure, restricted blood flow

3. Jaundice: yellow tint can be due to high amounts of bile in the blood.

4. Bruises or hematomas

can be due to lack of Vit C or hemophilia


1. Cutaneous glands:

exocrine glands: ducts

a. sebaceous : can empty into hair follicle or directly to skin

sebum keeps moist, kills bacteria

if blocked by sebum=whitehead and if oxidizes=blackhead

b. sweat (sudoriferous)

formed by stratum germinativum which pushes into the dermis

2 types;

1. eccrine: more numerous and secrete sweat: water, salt, urea, Vit C and ph4-6. duct ends at a pore

*thermal regulation

2. Apocrine glands: axillary and genital areas, larger and empty into hair follicles, secrete fatty acids and proteins in addition to sweat (bacteria can breed and create odor)

function not known


2. Hair and hair follicles

serves as protector from invaders mostly no longer really an insulator


hair follicle produces the hair at the root

hair grows from germinal ET cells known as the matrix as they move away they become keratinized and die


central core=medulla

surrounded by a cortex layer

surrounded by cuticle: shingle like layer heavily keratinized

cuticle wears away when leaving shaft causing friz


shape and texture caused by shape of follicle


follicle: inner sheath: ET that forms the hair

outer sheath is dermal tissue arrecotorpilli


free edge



nail folds: thick one makes the cuticle

stratum germinativum makes the nail bed with a thickened matrix responsible for nail growth



Athleteís foot: itchy red, peeling between toes caused by fungus


Boils & carbuncles: inflammation of hair follicles an sebaceous glands caused by bacteria


Cold sores: fever blisters caused by herpes


Contact dermatitis: itch, red, swelling to blisters due to allergies like poison ivy


Impetigo: pink water filled lesions around mouth develop yellow crust and rupture caused by Staph.


Psoriasis: reddened ET lesion with dry scales cause unknown


Tissue damage and death caused by chemicals, heat, electricity and UV


2 Life threats:

1. loss of fluids with proteins and electrolytes (circulatory shock: low blood pressure)

Infections: open wounds and suppressed immune system


Classified to severity:

1st degree: only epidermis heal in 2 to 3 days


2nd: epidermis and upper dermis are damaged, blisters appear

1st and 2nd: partial thickness burns


3rd: entire thickness of skin: full thickness burns. Appears white or black, not painful

no regeneration but grafting


Critical :

1. >25% of body has 2nd

2. >10% 3rd

3. 3rd on face, hands or feet


most tumors are benign (do not spread or metastasize) ex. Wart

tumors can be malignant or cancerous


1. Basal Cell Carcinoma: least malignant

stratum germinativum cannot form keratin proliferate into the derms and subcutaneous tissue


2. Squamous cell carcinoma: also germinativum but not near basement membrane


3. Malignant melanoma: cancer of melanocytes, metastatizes rapidly to lymph nodes and blood vessels


ABCD Rule:

A: Asymmetry

B: Border irregularity

C: Color

D: Diameter > 6mm