Skin and Body Membranes

1
Skin and Body Membranes

• Cover surfaces, line body cavities, form
  protective sheets around organs (and mucous)
• Two types
• 1. Connective tissue
• Synovial membranes
• 2. Epithelial
• Cutaneous (skin), mucous, serous

2
1. Connective Synovial membranes

• Soft areolar tissue
• No epithelial cells
• Line fibrous capsules surrounding joints (joint
  is where bones align next to each other)
• Line bursae (purse) and tendon sheaths (both
  cushion organs that move against each other
  during muscle contractions)

3
(No Transcript)
4
2. Epithelial Membranes

• Coverings and linings
• Types
• A. Mucous
• B. Serous
• C. Cutaneous (skin)
• All have epithelial tissue on a layer of
  connective tissue

5
Epithelial a. Mucous Membranes (mucosa)

• Tissues Epithelial tissue resting on loose
  connective tissue called lamina propria (areolar)
• Lines all body cavities that open to the exterior
  (lungs, nasal, mouth, esophogus, anus/rectum,
  reproductive openings, urethra)

6
Epithelial a. Mucous Membranes

• Different types of epithelial tissues
• Ex lungs have simple squamous, intestines have
  simple columnar and mouth has stratified
  squamous.
• All mucosa membranes are WET (continuously bathed
  in mucous or with urine)

7
Epithelial b. Serous Membranes (serosa)

• Line body cavities that are closed to the
  exterior
• Not the dorsal cavity or joint cavities (so
  basically ventral cavities)
• Tissues simple squamous on a thin layer of
  areolar connective tissue

8

• Serous membranes come in layered pairs
• Parietal lines the wall of the ventral body
  cavity
• Visceral lines the outside of the organ
• Both layers secrete serous fluid thin, clear
  fluid that separates the layers
• Function of serous fluid allows organs to slide
  past each other (ex digestion, heart pumping)

9
Epithelial b. Serous Membranes (serosa)

• Membranes named according to where they are
  located
• Three names
• Peritoneum abdominal cavity
• Pleura lungs
• Pericardium heart

10
Epithelial c. Cutaneous Membrane (skin)

• Tissues Stratified squamous on a layer of dense
  connective tissue
• Squamous is keratinizing produces keratin which
  makes skin
• Unlike other epithelial membranes, cutaneous is
  exposed to air and is dry!

11
Epithelial c. Cutaneous Membrane (skin)

• The skin and its appendages (hair, nails, oil and
  sweat glands) make up the Integumentary System

12
Skin Basic Functions

• Integument means covering
• 1. Protective covering
• 2. Keeps water and other substances out of the
  body (dirt, gases, microbes)
• 3. Insulates and protects deeper body organs
• 4. Protects body from mechanical damage,
  chemical damage, thermal damage, UV damage
• 5. Keeps water in

13
Skin Basic Functions

• 6. Regulates heat loss (capillaries and sweat
  glands)
• 7. Mini-excretion system sweat contains water,
  salt and urea
• 8. Manufactures vitamin D
• 9. Sensory receptors allow us to understand our
  environment (pain, temperature, pressure,
  tissue-damaging factors)

14
Skin Structure

• Two layers
• Epidermis epithelial tissue
• Stratified squamous that produces keratin allows
  the skin to be hard and tough
• Dermis dense connective tissue
• Epidermis and dermis are tightly connected.
• Friction can lead to blister
• Underlying subcutaneous layer adipose tissue
• Cushions
• Insulates

15
Skin Structure

• Epidermis contains up to five layers called
  strata
• Avascular
• Most cells are keratinocytes produce keratin
  (allows skin to be tough and waterproof)
• Deepest layer (1) Stratum basale
• Closest to dermis, most nourished
• Constantly undergoing mitosis (millions of new
  cells daily)

16
Skin Structure

• (2) Stratum spinosum and (3) Stratum granulosum
• Become flatter, increasingly full of keratin
  (allows skin to be tough and waterproof) and
  finally die forming
• (4) Stratum lucidum
• Not seen in all skin region
• Only where skin is hairless and extra thicksoles
  of feet and palms

17
Skin Structure

• (5) Stratum corneum
• Thickest layer of 20-30 cells in thickness
• Dead cells are like shingles on a roof
• Completely filled with keratin (allows skin to be
  tough and waterproof)
• Slough off steadily and is replaced by the
  Stratum basale (the deepest layerand so it comes
  full circle ? )

18
Skin Structure Dermis

• Your hide!
• Tissue dense connective
• Varies in thickness
• Palms of hands and soles of feet, very thick
• Eyelids, quite thin
• Two layers
• 1. Papillary called dermal papillae
• 2. Reticular

19
Skin Structure Dermis

• 1. Papillary indented into epidermis
• Have capillaries supply nutrients to epidermis
  (stratum basale)
• Pain receptors (free nerve endings)
• Touch receptors Meissners corpuscles (light
  touch)

20
Skin Structure Dermis

• Make finger, toe, palm, foot prints by forming
  looped/whorled ridges on epidermis
• Prints are result of sweat begin left behind

21
Skin Structure Dermis

• 2. Reticular Layer
• Deepest layer
• Contains blood vessels, sweat and oil glands
• Deep pressure receptors Pacinian corpuscles
• Phagocytes eat bacteria that has managed to break
  into skin

22
Skin Structure Dermis
23
Skin Structure Dermis

• Reticular layer has many collagen and elastic
  fibers
• Collagen toughness, bind water to keep skin
  hydrated
• Elastic stretch
• Age number of fibers decreases
• (ulcers coming next)

24
Skin Structure Dermis

• Well supplied with blood
• Ulcers
• Bed sores

25
Skin Color

• Based on three factors
• 1. Amount and kind of melanin (yellow, reddish
  brown, black)
• 2. Amount of carotene (orange-yellow pigment) in
  the corneum layer and subcutaneous tissue
• 3. Amount of oxygen-rich hemoglobin (pigment in
  RBC)

26
(No Transcript)
27
Skin Color

• Stratum basale contains melanocytes cells that
  produce melanin
• Roughly same concentration of melanocytes
  regardless of skin color.
• Amount of melanin determined genetically and
  environmentally.
• Sunlight stimulates melanocytes to produce more
  melaninhence, we tan
• Melanin absorbs UV light and protects against DNA
  damage
• Freckles and moles are concentrated with melanin

28
Skin Color

• Emotions
• Redness/erythema embarrassment, fever, allergy,
  inflammation, hypertension
• Pallor/blanching emotional stress (anger, fear),
  anemia, low blood pressure, impaired blood flow
• Jaundice
• Yellow tone from excess bile pigments in blood
• Indicates liver damage
• Bruises
• Hematomas blood clots

29
Appendages of the Skin

• Includes
• 1. Cutaneous glands
• A. Sebaceous glands
• B. Sweat glands
• 2. Hair
• 3. Hair follicles
• 4. Nails
• Each arises (forms in) the epidermis

30
Appendages of the Skin

• 1. Cutaneous glands
• A. Sebaceous
• B. Sweat (sudoriferous)
• Exocrine glands (have ducts)
• Release secretions on the skin
• Made in epidermis but reside in dermis

31
Appendages of the Skin

• A. Sebaceous glands (oil glands)
• Found everywhere except palms and soles
• Most associated with hair
• Sebum (product)
• Mixture of oily substances and fragmented cells

32
Appendages of the Skin

• Sebum functions
• Lubricant
• Skin stays moist and soft
• Hair not brittle
• Chemicals that kill bacteria
• During adolescence, very active
• Male sex hormones trigger increased production
• Whiteheads can lead to blackheads
• Acne
• Cradle cap in babies (seborrhea)

33
Appendages of the Skin

• B. Sweat glands (sudoriferous)
• 2.5 million/person
• Two types
• 1. eccrine
• 2. apocrine

34
Appendages of the Skin

• Sweat glands Eccrine
• Found all over body
• Produce sweat clear secretion mostly water,
  salts, vit C, lactic acid and urea
• Sweat is acidic pH 4-6
• Inhibits bacterial growth on skin
• pores on face are not sweat pores but hair
  follices
• Huge role in cooling body

35
Appendages of the Skin

• Sweat glands Apocrine
• Found in axillary and genital regions
• Secretions contains fatty acids and proteins in
  addition to water, salt, lactic acid, urea, vit C
• Bacteria live on this and cause body odor
• Start functioning during puberty when androgens
  are released in body
• Not a huge role in cooling body

36
Appendages of the Skin

• Hair
• Parts root, follicle and shaft
• Formed from epithelial tissue in skin (epidermis)
  and extend into dermis/hypodermis
• Dead cells filled with keratin and melanin
• Arrector pilli muscle causes hair to stand
  straight from skin

37
Appendages of the Skin

• Nails
• Parts Nail root, nail bed and free nail
• Formed from epithelial tissue (epidermis)
• Dead cells filled with keratin
• Modified scale or hoof