1. Skin and Body Membranes
Chapter 4
Skin and Body Membranes

2. Objective Checklist Classification of Body Membranes
General functions of each membrane type and its location in the body
Compare the structure of the major membrane types
The Integumentary System
Important functions of the integumentary system and how these functions are accomplished
On a model or diagram recognize and name skin structures
Name and describe the characteristics of the layers of the epidermis
Describe the distribution and function of the epidermal derivatives
Name the factors that determine skin color and describe the function of melanin
Developmental Aspects of Skin and Body Membranes
List several examples of integumentary system aging

3. Body Membranes Cover surfaces Line body cavities
Form protective and lubricating sheets around organs

4. Classification of Body Membranes
Epithelial Membranes
All contain an epithelial sheet that is always combined an underlying layer of connective tissue making them simple organs
Types
Cutaneous
Mucous
Serous
Connective Tissue Membranes
Synovial

5. Cutaneous Membranes The skin
Superficial epidermis composed of a keratinizing stratified squamous epithelium
Underlying dermis is mostly dense fibrous connective tissue
Exposed the air and thus is a dry membrane

6. Cutaneous & Mucous Membranes

7. Mucous Membranes
Composed of epithelium resting on a loose connective tissue membrane called the lamina propria
Lines all body cavities that open to the exterior
Hollow organs of the respiratory, digestive, urinary, and reproductive tracts
Most contain either stratified squamous or simple columnar epithelia
Often adapted for absorption or secretion
Many secrete mucus
The are wet membranes that are continuously bathed in secretions

8. Serous Membranes
Layer of simple squamous epithelium resting on a thin layer of areolar connective tissue
Line body cavities that are closed to the exterior
Occurs in pairs
Parietal layer lines the wall of the ventral body cavity
Visceral layer covers the outside of the organs in that cavity
Serous layer are separated by a scanty amount of thin clear fluid (serous fluid)
Allows organs to slide easily across the cavity walls and one another without friction

9. Serous Membranes

10. Peritoneum

11. Pleura

12. Pericardium

13. Connective Tissue Membranes
Soft areolar connective tissue with no epithelial cells
Line the fibrous capsules surrounding joints, bursae, and tendon sheaths
Provide a smooth surface and secrete a lubricating fluid
Cushion organs moving against each other

14. Synovial Joint

15. The Integumentary System
Skin
Skin derivatives
Sweat glands
Oil glands
Hair
Nails

16. Functions of the Integument
Protects deeper tissue
Mechanical damage
Keratin toughens cells
Fat cells cushions blows
Pressure receptors alert the nervous system to possible damage
Chemical damage
Impermeable keratinized cells
Pain receptors alert the nervous system to possible damage
Bacterial damage
Unbroken surface prevents penetration
Continuous shedding removes pathogens
Phagocytes ingest pathogens
Ultraviolet radiation
Melanin shields cells from UV damage
Thermal damage
Contains heat/cold/pain receptors
Desiccation
Waterproofing glycolipid and keratin

17. Functions of the Integument cont.
Temperature control
Sweat glands allow for evaporative cooling
Flushing blood to capillary beds allows for radiative cooling
Flushing blood away from capillary beds prevents radiative cooling
Excretion
Perspiration produced by sweat glands contains urea and uric acid
Synthesizes vitamin D
Modified cholesterol molecules are converted to vitamin D by sunlight

18. Structure of the Skin Two main layers Subcutaneous tissue (hypodermis)
Epidermis
Dermis
Firmly connected
Burn or friction may cause them to separate
Allows interstitial fluid to accumulate in the cavity between causing a blister
Subcutaneous tissue (hypodermis)
Adipose tissue
Anchors the skin to underlying organs
Serves as a shock absorber and insulates from temperature extremes

19. Epidermis Avascular Composed of up to five layers of cells
Keratinocytes
Produce keratin
Melanocytes
Found in the stratum basale
Produce melanin
Pigment that ranges from yellow to brown to black
Produced in larger amounts when exposed to sunlight
Melanin is taken up by keratinocytes and they use it to shield their nucleus from sunlight

20. Strata of the Epidermis

21. Melanocytes

22. Dermis Two major regions Papillary layer Reticular layer
Upper dermal region
Dermal papillae
Contain capillary loops, pain and touch (Meissner’s corpuscles) receptors
Form the fingerprints
Reticular layer
Deepest layer
Contains blood vessels, sweat and oil glands, and deep pressure receptors (Pacinian corpuscles), and phagocytes

23. Dermis cont. Fibers Abundant blood supply Rich nerve supply Collagen
Toughness
Attract and bind water
Elastic fibers
Give elasticity
Abundant blood supply
Maintain body temperature
Rich nerve supply

24. Dermis

25. Appendages of the Skin
Cutaneous glands
Hair
Hair follicles

26. Cutaneous Glands Exocrine glands Two groups
Release their secretions to the skin surface via ducts
Two groups
Sebaceous (oil) glands
Sudoriferous (sweat) glands

27. Sebaceous (oil) Glands
Found all over the skin except the palms of the hands and soles of the feet
Ducts usually empty into a hair follicle
Secrete sebum
Mixture of oily substances and fragmented cells
Lubricant that keeps the skin soft and moist and prevents the hair from becoming brittle
Contains chemicals that kill bacteria

28. Sebaceous Glands

29. Sudoriferous (sweat) Glands
Eccrine
More numerous
Found all over the body
Empty onto the surface of the skin
Produce sweat
Clear secretion that is mainly water plus some salts, vitamin C, traces of metabolic wastes, and lactic acid
Acidic
Inhibits bacterial growth
Important part of temperature regulation
Apocrine
Confined to the axillary and genital areas
Empty into hair follicles
Begin functioning during puberty
Activated by pain, stress, and during sexual foreplay
Secretion contains fatty acids and proteins as well as normal sweat
When bacteria use the fatty acids it creates a musky smell
Function not clearly known

30. Sudoriferous Glands

31. Hair and Hair Follicles
Primarily dead keratinized cells
Serves to protect and insulate the body but has mostly become non-functional in humans
Hair on the head protects the scalp from bumps and abrasion
Eyelashes keep dirt out of the eyes
Nose hairs filter dirt and bacteria out of inhaled air
Hair on axillary and genital area is involved in the function of the apocrine glands
Arrector pili
Smooth muscle cells that raise hair upright on the skin (goose bumps)
Helps keep animals warm by adding an insulating layer of air against the skin

32. Hair & Hair Follicle

33. Nails Scalelike modification of the epidermis
Primarily dead keratinized cells
Protects the distal parts of the fingers and toes
Nail matrix
Responsible for nail growth

34. Nails