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Chapter 4: . Skin and Body Membranes. Skin and Body Membranes. Function of body membranes: Cover body surfaces Line body cavities Form protective sheets around organs. Types of Body Membranes. Epithelial Membranes Cutaneous membrane Mucous membrane Serous membrane

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chapter 4
Chapter 4:

Skin and Body Membranes

skin and body membranes
Skin and Body Membranes
  • Function of body membranes:
    • Cover body surfaces
    • Line body cavities
    • Form protective sheets around organs
types of body membranes
Types of Body Membranes
  • Epithelial Membranes
    • Cutaneous membrane
    • Mucous membrane
    • Serous membrane
  • Connective Tissue Membranes
    • Synovial membranes
cutaneous membrane
Cutaneous Membrane




  • Cutaneous membrane = skin
    • A dry membrane
    • Outermost protective boundary
    • Two major regions:
  • Superficial epidermis
    • Consists 0f keratinized stratified squamous epithelium
  • Underlying dermis
    • Mostly dense connectivetissue

Cutaneousmembrane (the skin) covers the body surface.

Figure 4.1a

mucous membranes
Mucous Membranes
  • Surface epithelium
    • Type depends on location:
      • Stratified squamous epithelium (mouth, esophagus)
      • Simple columnar epithelium (rest of digestive tract)
  • Underlying loose connective tissue known as lamina propria
  • Lines all body cavities that open to the exteriorbody surface
  • Often adapted for absorption or secretion

Mucosa of

nasal cavity

Mucosa of




Mucosa of

lung bronchi

(b) Mucous membranes line body cavities

open to the exterior.

Figure 4.1b

serous membranes
Serous Membranes
  • Surface is a layer of simplesquamous epithelium
  • Underlying layer is a thin layer of areolarconnective tissue
  • Lines open body cavities that are closedto the exterior of the body
  • Serous membranes occur in pairs, separated by serous fluid
    • Visceral layer covers the outside of the organ
    • Parietal layer lines a portion of the wall of ventral body cavity

Outer balloon wall

(comparable to parietal serosa)

Air (comparable to serous cavity)

Inner balloon wall

(comparable to visceral serosa)

(d) A fist thrust into a flaccid balloon demonstrates

the relationship between the parietal and visceral

serous membrane layers.

Figure 4.1d

serous membranes1
Serous Membranes
  • Specific serous membranes
    • Peritoneum
      • Around the abdominal cavity
    • Pleura
      • Around the lungs
    • Pericardium
      • Around the heart

What is the meaning of “peri”?














(c) Serous membranes line body cavities

closed to the exterior.

connective tissue membrane
Connective Tissue Membrane
  • Synovial membrane
    • Found in connective tissue only
    • Lines fibrous capsules surrounding joints
    • Secretes a lubricating fluid to cushion and protect joint area

Figure 4.2


integumentary system
  • Skin (cutaneous membrane)
  • Skin derivatives
    • Sweat glands
    • Oil glands
    • Hair
    • Nails
skin functions
Skin Functions:
  • Make sure you can explain (in your own words) HOW the skin completes each of the functions listed
  • Refer to Table 4.1…
  • Checkpoint: Create an example that demonstrates each skin protection function
skin structure
Skin Structure
  • Epidermis – outer layer
    • Stratified squamous epithelium
    • Often keratinized (hardened by keratin)
  • Dermis
    • Dense connective tissue
skin structure1
Skin Structure:
  • Subcutaneous tissue (hypodermis) is deepto dermis
    • Not part of the skin!!!
    • Function: Anchors skin to underlying organs
    • Composed mostly of adipose tissue
layers of epidermis
Layers of Epidermis
  • Stratum basale (stratum germinativum)
    • Deepest layer of epidermis
    • Lies next to dermis
    • Cells undergoing mitosis
    • Daughter cells are pushed upward to become the more superficial layers
  • Stratum spinosum
  • Protects against foreign materials and produces lipids that prevent moisture loss from the skin.
  • Stratum granulosum
  • This layer helps prevent fluid loss from the body.
layers of epidermis1
Layers of Epidermis
  • Stratum lucidum
    • Formed from dead cells of the deeper stata
    • Occurs only in thick, hairless skin of the palms of hands and soles of feet
  • Stratum corneum
    • Outermost layer of epidermis
    • Shingle-like dead cells are filled with keratin (protective protein prevents water loss from skin)
  • Pigment (melanin) produced by melanocytes
  • Color is yellow to brown to black
  • Melanocytes are mostly in the stratum basale
  • Amount of melanin produced depends upon genetics and exposure to sunlight
  • Two layers
    • Papillary layer (upper dermal region)
      • Projections called dermal papillae
        • Some contain capillary loops
        • Others house pain receptors and touch receptors
    • Reticular layer (deepest skin layer)
      • Contains blood vessels
      • Sweat and oil glands
      • Deep pressure receptors

Overall dermis structure

    • Collagen and elastic fibers located throughout the dermis
      • Collagen fibers give skin its toughness
      • Elastic fibers give skin elasticity
      • Blood vessels play a role in body temperature regulation
normal skin color determinants
Normal Skin Color Determinants
  • Melanin
    • Yellow, brown or black pigments
  • Carotene
    • Orange-yellow pigment from some vegetables
  • Hemoglobin
    • Red coloring from blood cells in dermalcapillaries
    • Oxygen content determines the extent of red coloring
skin appendges
Skin Appendges
  • Cutaneous glands are all exocrine glands:
  • Sebaceous glands
    • Produce oil to lubricate skin
      • Prevents brittle hair
      • Kills bacteria
    • Most have ducts that empty into hair follicles; others open directly onto skin surface
    • Glands are activated at puberty
appendages of the skin
Appendages of the Skin
  • Sweat glands
  • Release sweat to surface of skin to regulate body temperature
  • Widely distributed in skin
  • Two types:
    • Eccrine
      • Open via duct to pore on skin surface
    • Apocrine
      • Ducts empty into hair follicles
sweat and its function
Sweat and Its Function
  • Composition
    • Mostly water
    • Salts and vitamin C
    • Some metabolic waste
    • Fatty acids and proteins (apocrine only)
  • Function
    • Helps dissipate excess heat
    • Excretes waste products
    • Acidic nature inhibits bacteria growth
  • Odor is from associated bacteria
appendages of the skin1
Appendages of the Skin
  • Hair
    • Produced by hair bulb
    • Consists of hard keratinized epithelial cells
    • Melanocytesprovidepigment for hair color
hair anatomy
Hair Anatomy
  • Central medulla
  • Cortex surrounds medulla
  • Cuticle on outside of cortex
    • Most heavily keratinized

Trivia: Hair conditioner helps the cuticle lie flat, which makes your hair shiny…

Figure 4.7b


associated hair structures
Associated Hair Structures
  • Hair follicle
    • Dermal and epidermal sheath surround hair root
  • Arrectorpilli
    • Smooth muscle
    • Pulls hairs upright when cold or frightened
  • Sebaceous gland
  • Sweat gland
appendages of the skin2
Appendages of the Skin
  • Nails
    • Scale-like modifications of the epidermis
      • Heavily keratinized
    • Stratum basale extends beneath the nail bed
      • Responsible for growth
    • Lack of pigment makes them colorless
nail structures
Nail Structures
  • Free edge
  • Body is the visible attached portion
  • Root of nail embedded in skin
  • Cuticle is the proximal nail fold that projects onto the nail body

Figure 4.9


skin homeostatic imbalances
Skin Homeostatic Imbalances
  • Infections
    • Athletes foot (tineapedis)
      • Caused by fungal infection
      • Spread in warm moist areas, such as showers, gyms, pools
    • Boils and Carbuncles
    • Common in skin areas of sweat, abrasions or at of the nape of the neck
      • Caused by bacterial infection
      • Carbuncle involves 3+ hair follicles
    • Cold Sores
      • Caused by Herpes Simplex virus
      • Spread by sharing eating utensils/cups, razors, kissing, saliva
skin homeostatic imbalances1
Skin Homeostatic Imbalances
  • Infections
    • Contact dermatitis
      • Can be caused by an allergic reaction or a skin irritant
      • Example: Poison Ivy, Soaps & Detergents
    • Impetigo
      • Caused by Staphylococcus or Streptococcus bacteria
      • MRSA can also lead to impetigo
      • Spread by physical contact, sharing clothes, towels, etc.
    • Psoriasis
      • Cause is unknown, but develops due to an overactive immune system
      • Flares are triggered by trauma, infection, stress
      • NOT contagious!!



ImpetigoCaused by one of two bacteria: Staphylococcus aureusor Streptococcus pyogenes.Methicillin-resistant Staphylococcus aureus (MRSA) is also becoming an important cause of impetigo.

skin homeostatic imbalances2
Skin Homeostatic Imbalances
  • Burns
    • Tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals
    • Associated dangers:
      • Dehydration
      • Electrolyte imbalance
      • Circulatory shock
rule of nines
Rule of Nines
  • Method to determine the extent of burns
  • Body is divided into 11 areas for quick estimation
  • Each area represents about 9% of total body surface area
severity of burns
Severity of Burns
  • First-degree burns
    • Only epidermis is damaged
    • Skin is red and swollen
  • Second degree burns
    • Epidermis and upper dermis are damaged
    • Skin is red with blisters
  • Third-degree burns
    • Destroys entire skin layer
    • Affected area is gray-white or black
critical burns
Critical Burns
  • Burns are considered critical if:
    • Over 25% of body has second degree burns
    • Over 10% of the body has third degree burns
    • There are third degree burns of the face, hands, or feet
skin cancer
Skin Cancer
  • Cancer – uncontrolled division of abnormal cells
  • Two types:
    • Benign
      • Does not spread (encapsulated)
    • Malignant
      • Metastasizes (moves) to other parts of the body
  • Skin cancer is the most common type of cancer!!
types of skin cancer
Types of Skin Cancer
  • Basal Cell Carcinoma
    • Most common type
    • Least malignant
    • Arises from statumbasale
skin cancer types
Skin Cancer Types
  • Squamous Cell Carcinoma
    • Metastasizes to lymph nodes if not removed
    • Early removal allows a good chance of cure
    • Believed to be sun-induced
    • Arises from stratum spinosum
skin cancer types1
Skin Cancer Types
  • Malignant melanoma
    • Most deadly of skin cancers
    • Cancer of melanocytes
    • Metastasizes rapidly to lymph and blood vessels
    • Detection uses ABCD rule
abcd rule
ABCD 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 then 6 mm in diameter
still want to go tanning mom alert
Still want to go tanning? (Mom alert!  )
  • A study done by the Mayo Clinic, published in 2012, found that over the past 40 years, rates of this potentially deadly skin cancer grew by 800 percent among young women and 400 percent among young men!!
  • The same study found that indoor ultraviolet (UV) tanners are 74 percent more likely to develop melanoma than those who have never tanned indoors; those who tan indoors just four times a year increase their risk of developing melanoma by 11 percent. Indoor tanners are also 2.5 times more likely to develop squamous cell carcinoma and 1.5 times more likely to develop basal cell carcinoma.
developmental aspects of skin
Developmental Aspects of Skin
  • Fetal life
    • Lanugo- downy hair develops at 5th month of gestation; shed by birth
    • Vernixcaseosa- white, cheesy-looking substance, from sebaceous glands, protects baby’s skin in amniotic sac
    • Milia- oil buildup in sebaceous glands on baby’s nose and forehead; generally gone by 3rd week after birth
  • Skin and hair become oily
  • Acne- generally subsides in early adulthood
senior years
Senior Years
  • Subcutaneous tissue decreases, which leads to:
  • Decreased cold tolerance
  • Drier; itchy skin
  • Thinner skin; bruising tends to increase
  • More sagging due to decreased elasticity
hair loss
Hair Loss
  • By age 50, loose 1/3 of hair follicles
  • Involutional Alopecia- hair thinning
  • Androgenic Alopecia:
  • --Male pattern baldness- can in early 20 s, affects crown & frontal scalp
  • --Female pattern baldness—tends to begin in 40 s, affects whole scalp
    • Vellus- hair follicles degenerate, hairs are colorless and tiny
    • Graying- result of delayed-action gene--

decreased melanin causes lack of color