This document discusses the classification and structure of the skin and other body membranes. It covers the three main types of membranes - epithelial, serous, and synovial membranes. It then describes the layers and structures of the skin in detail, including the epidermis, dermis, glands, hair follicles and nails. It discusses skin color and conditions like sun exposure, bruising and jaundice. Finally, it briefly outlines some common skin disorders and conditions.

1. Skin and Body Membranes
Human Anatomy and Physiology
Mr. McCammon

2. I. Classification of Body
Membranes
 Epithelial Membranes include the cutaneous
membrane (skin) and the mucus
membranes, and the serous membranes.
 Always combined with an underlying layer
of connective tissue.
 That’s why it is considered an organ.

3. I. Classification of Body
Membranes
 Cutaneous Membrane
– This is your skin.
– Composed of keratinizing stratified squamous
epithelium.
– Underlying dermis is dense (fibrous)
connective tissue.
– Exposed to air and is dry.

4. I. Classification of Body
Membranes
 Mucous membranes (or mucosa)
– composed of epithelium (the type varies from
site to site) resting on a loose connective tusse
membrane called a lamina propria.
– Lines all the cavities that open to the exterior
such as respiratory, digestive, urinary, and
reproductive tracts.
– Always moist because they are continually
bathed in secretions.

5. I. Classification of Body
Membranes
 Serous Membranes (serosa)
– Layer of simple squamous epithelium resting
on a thin layer of areolar connective tissue.
– Line the body cavities that are closed to the
exterior (except for the dorsal body cavities and
joint cavities)
– Occur in pairs – parietal layer lines a specific
portion of the wall of the ventral body cavity
and folds in on itself to form the viseral layer
with covers the outside of the organs in that
cavity.

6. I. Classification of Body
Membranes
 The serous layers are separated by a clear
fluid called serous fluid.
 Important to decrease friction by moving
organs (heart, stomach)
 Some serous membranes
– Peritoneum – abdominal cavity
– Pleura – around the lungs
– Pericardium – around the heart

7. I. Classification of Body
Membranes
 Synovial membranes are composed of
connective tissue and contain no epithelial
cells at all.
 Line the fibrous capsules surrounding joints
where they provide a smooth surface and
secrete a lubricating fluid.
 Contain small sacs of connective tissue
called bursae and tubelike tendon sheaths –
both cushion organs moving against each
other during muscle activity.

8. II. The Integumentary System
 The Skin
– Includes cutaneous membrane, sweat and oil
glands, hairs, and nails
– External body covering
– Keeps water and other molecules in the body.
– Keeps and other things out
– Pliable yet tough

9. II. The Integumentary System
 Study chart on page 95.
 The structure of the skin.
– Epidermis
 Stratified epithelium – becomes keratinizing
(hard and tough)
– Dermis
 Dense connective tissue
 Both connected tightly until a burn or
friction causes a blister.

10. II. The Integumentary System
 Deep down in the skin is the subcutaneous
tissue or hypodermis
– Basically adipose tissue
– Not considered part of this skin, but does
anchor the skin to the underlying organs.
– Shock absorber and protected from temperature
changes.
– Makes you ‘curvy’

11. II. The Integumentary System
 KNOW THE DIAGRAM ON PAGE 96.
 The Epidermis in Detail
– 5 zones (layers) called strata
 In order, basale, spinosum, granulosum, lucidum,
corneum.
 They are avascular
 Most cells are keratinocytes (produce fibrous
protein that makes the epidermis tough.
 Deepest layer is stratum basale lies closes to the
dermis and contains the only cells that receive
adequate nourishment via diffusion from the
dermis.

12. II. The Integumentary System
 Cells from the stratum basale are constantly
dividing and pushed up to become part of
the epidermis.
 Stratum lucidum only occurs where the skin
is hairless and extra thick (palms, feet)
 Stratum corneum makes up ¾ of our body.
 Constant replaced – New epidermis every
25-45 days.

13. II. The Integumentary System
 Melanin – yellow to brown pigment is
produced by cells called melanocytes found
in the stratum basale.
 Sunlight stimulates melanin production
causes tanning.
 Melanin forms a protective shield from
sunlight so it doesn’t affect genetic
material.
 Freckles and moles are where melanin is
concentrated in one spot.

14. II. Integumentary System
 Excessive exposure can lead to skin cancer.
 It can cause the elastic fibers to clump and
lead to leathery skin.
 Black people seldom have skin cancer
because melanin is an effective shield
against it.

15. II. The Integumentary System
 The Dermis
– Your ‘hide’ – strong, stretchy envelope
that helps to hold the body together.
Leather goods are just treated dermis of
animals.
– Two regions
 Papillary layer
 reticular layer

16. II. The Integumentary System
 The Papillary Layer is the upper dermal
region
– Uneven with finger like projections called
dermal papillae
– Contain capillary loops which nourish the
epidermis
– Pain receptors touch Meissner’s corpuscles.
– On hands and feet papillae are arranged in
patterns to enhance gripping ability.

17. II. The Integumentary System
 Reticular layer
– Deepest layer
– Contains seat, blood vessels, sweat and oil
glands, deep pressure sensors called Pacinian
corpuscles
– Collagen and elastic fibers make it tough
– Restrictions of blood in the dermis results in
cell death and causes Decubitus ulcers
(bedsores)

18. II. The Integumentary System
 Skin Color
– The amount and kind of melanin in the dermis
– The amount of carotene deposited in the
stratum corneum (carotene is an orange yellow
pigment
– The amount of oxygen bound to hemoglobin
(pigment in red blood cells)

19. II. The Integumentary System
 People with lots of melanin have brown-
toned skin.
 Light skinned people (caucasian) people
have less melanin and have a crimson color
due to oxygen-rich blood.
 Then hemoglobin is poorly oxygenated the
skin can become blue (cyanosis) – common
during heart failure and breathing disorders

20. II. The Integumentary System
 Skin color
– Redness or erythema – may indicate
embarrassment (blushing), fever, hypertension,
inflammation, or allergy.
– Pallor or blanching – becoming pale – fear,
anger, stress, anemia, low blood pressure,
impaired blood flow
– Jaundice or yellow cast – liver problems
– Bruises or black-and-blue marks – sites where
blood has escaped from circulation and has
clotted in the tissue spaces – called hematomas

21. III. The Appendages of the
Skin
 Cutaneous glands – all exocrine glands that
release their secretions to the skin surface
via ducts.
 Two groups
– Sebaceous glands
– Sweat glands
 Form in Stratum basale but push lower into
the dermis

22. III. Appendages of the Skin
 Sebaceous (oil) glands – found all over the
body except palms of hands and feet.
 Most open onto a hair follicle, but some
open directly onto the skin.
 Sebum is the name of the oil – mixture of
oil and fragmented cells that keep the hair
and skin moist. Kills bacteria
 Increase in male hormones increase sebum
during adolescence.

23. III. Appendages of the Skin
 If a sebaceous gland’s duct becomes
blocked by sebum a whitehead forms. If
the whitehead dries it becomes a blackhead.
 Acne is an active infection of the sebaceous
glands
 Severe acne results in scarring of the skin.

24. III. Appendages of the Skin
 Sweat Glands – Sudoriferous glands
 Can be as many as 2.5 million per person
 Two types
– Eccrine
– Apocrine

25. III. Appendages of the Skin
 Eccrine glands
– More numerous
– Produce seat
 Water, salt, vitamin C, ammonia, urea, uric acid,
and lactic acid (which attracts mosquitoes)
 Sweat is acidic (ph 4-6) which kills bacteria
 Reaches the skin by a funnel-shaped pore.
 They secrete sweat when the external or body
temperature is high.

26. III. Appendages of the Skin
 When the sweat evaporates, it carries heat
with it, cooling the body.
 On a hot day the body can lose 7 liters of
water per day.
 A few degrees change in body temperature
can radically alter body chemistry.
Maintaining body temp. is very important to
homeostasis.

27. III. Appendages of the Skin
 Apocrine sweat glands are confined to the
axillary and genital areas
 Larger than eccrine glands
 Ducts empty into hair follicles
 Secretions contain fatty acids, proteins, as
well as all the other stuff secreted by the
eccrine glands.

28. III. Appendages of the Skin
 The secretions can have a milky or
yellowish color.
 Odorless until bacterial that live on the skin
use the proteins and fats as nutrients. Then
it produces a musky unpleasant odor.
 Begin to function during puberty.
 A lot is unknown about these. They have
almost no thermoregulatory function.
 Become more active during stress or sexual
foreplay.

29. III. Appendages of the Skin
 There are millions of hairs scatterd all over
the body.
 Only a few serve an important function
 Hair on head to protect brain from bumps.
 Eyelashes shielding the eyes
 Nose hairs keep particles from the
respiratory tract.

30. III. Appendages of the Skin
 Hairs original purpose was to keep the body
warm.
 Hair is produced by a hair follicle
 Root hair is enclosed in the follicle.
 The hair shaft extends out of the follicle.
 Hair is formed by a division of the stratum
basale called hair bulb matrix.

31. III. Appendages of the Skin
 KNOW THE DIAGRAM OF A HAIR ON
PAGE 100
 Arrector pili muscles are part of the hair
follicle that make the hair stand up and
makes “goose bumps”

32. III. Appendages of the Skin
 Nails are scalelike modifications of the
epidermis that corresponds to the hoof or
claw of other animals.
 Each nail has a free edge, a body (visible
portion), and a root (embedded in the skin)
 Each nail has overlapping edges called nail
folds.
 Proximal nail fold is called the cuticle.

33. III. Appendages of the Skin
 Stratum basale of the epidermis extends beneath
the nail as the nail bed.
 Nail matrix is responsible for nail growth.
 The white cresent is called the lunula.
 Nail is normally clear. Pink color is due to blood
supply to the stratum basale.
 When blood supply is low, nail becomes cyanotic.
 KNOW THE DIAGRAM ON PAGE 102.

34. IV. Homeostasis
 The skin has more than 1000 different
ailments.
 Athlete’s foot – itchy, red, peeling condition
of the skin between the toes resulting from a
fungal infection; tinea pedis
 Boils and carbuncles – inflamation of the
hair follicles and sebaceous glands,
common on the dorsal neck. Carbuncles
are caused by bacterial infection (usually
Staphlococcus aureus)

35. IV. Homeostatis
 Cold Sores – fever blisters – small fluid-filled
blisters that itch and sting, caused by a herpes
simplex infection. Localized in a cutaneous nerve,
where it remains inactive until emotional upset –
usually around the lips and oral mucosa
 Contact dermatitis – itching, redness, and swelling
of the skin, progressing to blistering. Exposure of
the skin to chemicals the provokes an allergic
response.

36. IV. Homeostatis
 Impetigo – pink, water-filled, raised lesions
of the mouth and nose that develops a
yellow crust and eventually rupture. Very
contagious – common in elementary school
children.
 Psoriasis – chronic condition, characterized
by reddened epidermal lesions, covered
with dry, silvery scales. Can be disfiguring.
Cause is unknown .