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)

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. Review Membranes!

13. 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
Skin: Basic Functions

14. 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)

15. 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

16. 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)

17. 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 thick…soles of feet and palms

18. Skin: Structure (5) Stratum corneum
Thickest layer of 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 layer…and so it comes full circle  )

19. 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

20. Skin Structure: Dermis
1. Papillary: indented into epidermis
Have capillaries: supply nutrients to epidermis (stratum basale)
Pain receptors (free nerve endings)
Touch receptors: Meissner’s corpuscles (light touch)

21. Skin Structure: Dermis
Make finger, toe, palm, foot prints by forming looped/whorled ridges on epidermis
Prints are result of sweat begin left behind

22. 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
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

24. 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. Blood Supply to dermis

26. 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 melanin…hence, we tan
Melanin absorbs UV light and protects against DNA damage
Freckles and moles are concentrated with melanin

27. The Skin and UV Light
A small amount of UV radiation is important! It stimulates the synthesis of Vitamin D.
Melanocytes concentrate around the nuclear membrane and absorb UV
light before it can damage
the DNA.

28. Making Vitamin D3
Cells in epidermis convert a cholesterol related steroid into Vitamin D3
Vitamin D3 is absorbed, modified,
and released by the liver. It travels
to the kidney and is converted into
calcitrol (hormone essential for
the absorption of calcium by the
small intestine).

29. The Subcutaneous Layer
Not part of skin!
Binds skin to underlying
tissue.
Made of Loose CT and
Fat cells

30. Appendages of the Skin Includes: Each arises (forms in) the epidermis
1. Cutaneous glands
A. Sebaceous glands
B. Sweat glands
2. Hair
3. Hair follicles
4. Nails
Each arises (forms in) the epidermis

31. 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

32. Appendages of the Skin A. Sebaceous glands (oil glands):
Found everywhere except palms and soles
Most associated with hair
Sebum (product)
Mixture of fats,
Cholesterol, proteins,
Organic salts

33. 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)

34. Appendages of the Skin B. Sweat glands (sudoriferous)
2.5 million/person
Two types:
1. merocrine
2. apocrine

35. Appendages of the Skin Sweat glands: Merocrine 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

36. Sudoriferous Glands aka Sweat Glands
Merocrine Glands
Most sweat glands are this type
Can make 600 mL/day!!!
Found almost everywhere –palms, soles
Secretion is 99% water – cool body and lower body temp.

37. 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
Appendages of the Skin

38. Sudoriferous Glands aka Sweat Glands
Apocrine
Associated with hair follicles
Secretion is sticky, cloudy and odorous
Where does odor come from???

39. 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

40. 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

41. Nails Like hair dead Hard keratinized stratified
squamous ET found over
the dorsal surface of the
terminal portions of the
digits!
Function:
To help grasp small objects
To prevent trauma to ends of digits
To Scratch

44. Skin Structure: Dermis

45. Skin Structure: Dermis
Well supplied with blood
Ulcers
Bed sores

46. Skin: Color Emotions Jaundice Bruises
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
Skin: Color