Membranes found all throughout body Functions of body membranes:

Line or cover body surfaces – separate in/out

Protect body surfaces Lubricate body surfaces

Classified into two types: Epithelial membranes

o Cutaneous membraneo Mucous membraneo Serous membrane

Connective tissue membraneso Synovial membrane

o Cutaneous membrane = skin Function: protect deeper body tissues dry membrane Outermost protective boundary consisting of:

Superficial epidermis Contains keratin in areas of high friction

Underlying dermis Mostly dense connective tissue - protection

Figure 4.1a

o Mucous membranes Function: protect from drying out, lubrication Lines all body cavities that open to the exterior body

surface Often adapted for absorption (i.e. large intestine) or

secretion (i.e. nasal cavity)

o Serous membranes Function: lubrication for cushion, friction Surface simple squamous epithelium Underlying areolar connective tissue Lines open body cavities that are closed to

the exterior of the body Serous layers separated by serous fluid

Specific serous membranes Peritoneum

• Abdominal cavity Pleura

• Around the lungs Inside = visceral Outside = parietal

Pericardium• Around the heart

Inside = visceral Outside = parietal

o Synovial membrane Function: lubrication for

friction Connective tissue only Lines fibrous capsules

surrounding joints

Figure 4.2

Four major functions 1. Protects deeper tissues from:

o Mechanical damageo Chemical damageo Bacterial damageo Thermal damageo Ultraviolet radiationo Desiccation (drying out)

2. Aids in heat regulationo Maintain 98.6°F body temperature

3. Aids in excretion of urea and uric acido Both nitrogen-based toxins

4. Synthesizes vitamin Do Needed to help body absorb calcium for bones

Comprised of two things: Skin (cutaneous membrane) Skin appendages/derivatives (objects coming

from skin)o Sweat glands o Oil glands (sebaceous glands)o Hairso Nails

o Epidermis – outer layer Stratified squamous

epithelium (many flat layers)

Often keratinized (hardened by keratin)

o Dermis Dense connective tissue

Figure 4.3

o Under dermis is the hypodermis Not part of the skin Anchors skin to

underlying organs Composed mostly of

adipose (connective) tissue

Where blood vessels are located

Stratum corneum Shingle-like dead cells; 25-

30 layers Stratum lucidum

Occurs only in thickened skin (calluses, corns)

Stratum granulosum Stratum spinosum Stratum basale

Cells undergoing mitosis Lies next to dermis

Pigment melanin produced by melanocytes is present in epidermis Color varies from yellows to browns to blacks Melanocytes are mostly in the stratum basale Amount of melanin produced depends upon

genetics and exposure to sunlight

Papillary layer Finger-like projections just under epidermis called

dermal papillae (form fingerprints) Pain receptors (nociceptors) at ends of nerves Capillary beds/loops (blood vessels) where veins &

arteries meet Reticular layer

Blood vessels Glands Sensory receptors (Pacinian corpuscle [pressure]

and Meissner’s corpuscle [light touch])

Figure 4.4

Three things actually determine skin color: Melanin

o Yellow, brown or black pigments Carotene

o Orange-yellow pigment found in some vegetables that deposits itself in our skin

Eating too many carrots WILL turn skin orange

During the filming of the show, teenager Susan developed anorexia.

She only ate carrots for weeks at a time.

Eventually, directors had to stop filming because her skin was orange.

Hemoglobino Red coloring from blood cells in dermis capillarieso Oxygen content determines the extent of red

coloring Light red = oxygenated (arteries) Dark red = deoxygenated (veins)

Emotional stimuli and/or disease may cause alterations in skin color: Erythema: redness due to blood vessel dilation

o Blushing, hypertension, inflammation, allergy Pallor: blanching (loss of color) of skin

o Emotional stress, low blood pressure, low hemoglobin

Jaundice: yellowingo Excess bile due to liver disorder

Hematomas: bruises

Many appendages/derivatives of skin. Four major ones:

1. Sebaceous glands 2. Sweat (sudoriferous) glands 3. hair 4. nails

1. Sebaceous glands Produce oil called sebum

o Lubricant for skino Kills bacteria

Most with ducts that empty into hair follicles Glands are activated at puberty

2. Sweat glands Widely distributed in

skin Two types

o Eccrine (merocrine) Open via duct to

pore on skin surface

o Apocrine Ducts empty into

hair follicles

Composition of sweat:o Mostly watero Some metabolic waste (i.e. garlic)o Fatty acids and proteins (apocrine

only) Function of sweat:

o Helps dissipate excess heat as evaporation occurs

o Excretes waste productso Acidic nature inhibits bacteria

growth Odor is from associated bacteria

3. Hair Produced by hair

bulb Nourished at papilla

due to blood vessels Consists of hard

keratinized epithelial cells

Melanocytes provide pigment for hair color

Figure 4.7c

Anatomy:o Central medulla

Innermost segment only present with thick hairs

o Cortex Middle segment – 90% of hair shaft strength, color, texture

o Cuticleo Outermost section o thin, colorless, protection for cortex

o Most heavily keratinized structure of body

Figure 4.7b

Structures associated with hair:o Hair follicle

Dermal and epidermal sheath surround hair root

o Arrector pilli Tiny smooth muscle causes

hair to stand upo Sebaceous glando Sweat gland

o Apocrine only

Figure 4.7a

4. Nails Scale-like modifications

of the epidermiso Heavily keratinized

Stratum basale extends beneath the nail bed in matrixo Responsible for

growth Lack of pigment makes

them colorlessLee Redmond

Guinness World Record Holder – until February 2009 when a car

accident broke her nails

Nail structure:o Free edge – what we cuto Body – main nail lying on bedo Root of nailo Eponychium – proximal nail fold that

projects onto the nail body (cuticle)o Matrix – stratum basale

Figure 4.9

Infections or allergies Athletes foot

o Caused by fungal infection Boils and carbuncles

o Caused by bacterial infection of hair follicle

Cold soreso Caused by viral infection

Herpes simplex I

Contact dermatitiso Exposures cause allergic reaction

Eczema (atopic dermatitis)o Hypersensitivity reaction (allergy)o Most common in infants & many

outgrow it Impetigo

o Caused by bacterial infection usually a result of eczema

Psoriasiso Cause is unknowno Triggered by trauma, infection, stress

Onycholysis o Separation of nail from

nail bedo Symptom of trauma or

infection Cyanosis

o Bluish (cyan) coloringo Symptom of inadequate

oxygen in the bloodo Common in newborns

Pressure ulcers (bedsore)o Lack of unrelieved pressure,

friction, humidity, temperature, age, continence and medication

o Disrupts blood flow & oxygen to cells, killing them

Burnso Tissue damage and cell death caused by heat,

electricity, UV radiation, or chemicalso Associated dangers

Infection Dehydration Electrolyte imbalance Circulatory shock

o Way to immediately determine the extent of burns is with the “Rule of Nines” Body is divided into 11

areas for quick estimation

Each area represents about 9%

One side of leg = 9% One whole arm = 9%

Figure 4.11a

Burns are categorized by severity in degreeso First-degree burns

Only epidermis is damaged Skin is red and swollen

o Second-degree burns Epidermis and upper dermis are damaged Skin is red with blisters

o Third-degree burns Destroys entire skin layer Burn is gray-white or black

Epidermis

Dermis

1°2°3°

Burns are considered critical if:o Over 25% of body has second degree burnso Over 10% of body has third degree burnso Third degree burns on face, hands, or feet

Skin cancer – abnormal cell mass (tumor) of epidermiso Two types of tumors

Benign Does not spread

(encapsulated) Slow-growing

Malignant Can metastasize

(moves) to other parts of the body

Fast-growing (starve other cells)

Epidermis

Dermis

o Three types of skin cancer: Basal cell carcinoma

Least malignant Most common type Arises from stratum basale

Squamous cell carcinoma Arises from stratum

spinosum Metastasizes to lymph nodes Early removal allows a good

chance of cure

Malignant melanoma Cancer of

melanocytes Most deadly of

skin cancers Metastasizes

rapidly to lymph and blood vessels

o Detection of skin cancer uses ABCDE rule A = Asymmetry

Two sides of pigmented mole do not match B = Border irregularity

Borders of mole are not smooth C = Color

Different colors in pigmented area D = Diameter

Spot is larger than 6 mm in diameter E = Evolving

Changing over time in size, color, texture

Chemotherapy affects integumentary system more than any other systemo Drugs target rapidly dividing cells (cancer)o Integument has rapidly dividing cells (stratum basale)

in matrix area Loss of hair – destroys matrix Dry skin – destroys stratum basale Dry brittle nails – destroys matrix Dry mouth & throat – destroys mucus membranes Nausea – destroys mucus membranes in stomach

Many changes in integumentary system occur from conception to death Hair changes Skin changes

Hair changeso Fetus has downy hair called lanugoo Oilier hair during adolescenceo Loses luster (shininess) with ageo Male pattern baldness common

Hair still produced but degenerated follicles produce fine, colorless hair (that may not emerge from hair follicle)

o Graying hair Decrease in melanin

Skin changeso Newborn baby’s skin covered

with vernix caseosa White cheesy-like

substance produced by sebaceous glands to protect it from amniotic fluid

o Newborn also has milia or “baby acne,” accumulations in sebaceous glands which disappear in few days

o Newborn skin will thicken over time with added subcutaneous fat

o Elderly people lose subcutaneous fatty tissue resulting in “thin skin” Tendency to become colder

faster Blood vessels get damaged

easily (bruise easily)