1. Integumentary System Body Membranes
Human Anatomy
Integumentary System
Body Membranes

2. Introduction Largest organ of the body
21 square feet, square meters
4 kilograms, 9 pounds, 7% - 15% of total body weight
One square inch contains
20 blood vessels
65 hairs and hair muscles
78 nerves
78 sensors for heat
13 sensors for cold
160 sensors for pressure
100 sebaceous/oil glands
650 sudoriferous/sweat glands
1300 nerve endings
19,500,000 cells
0.5 million cells dying and being replaced

3. Classification of Body Membranes
Epithelial membranes – composed of epithelial tissue and underlying connective tissue
Connective tissue membranes – composed of various types of connective tissue

4. Classification of Body Membranes
Cutaneous membrane: The skin
Accounts for approximately 16% of body weight
The largest, most visible organ

5. Epithelial Membranes (cont’d.)
Serous membrane: Two layers: simple squamous epithelium lies on basement membrane
Types
Parietal: Lines walls of body cavities
Visceral: Covers organs found in body cavities
The serous membrane that lines body cavities and covers the surfaces of organs is a single, continuous sheet of tissue.
The name of the serous membrane is determined by its location.
What are some examples of serous membranes? (parietal and visceral pleura and the peritoneum)
What are their functions? (cover and protect internal organs)

6. Epithelial Membranes (cont’d.)
Serous membrane
Diseases
Pleurisy: inflammation of the serous membranes that line the chest cavity and cover the lungs
Peritonitis: inflammation of the serous membranes that line the walls of the abdominal cavity and cover the abdominal organs
Serous membranes secrete a thin, watery fluid that helps to reduce friction and serves as a lubricant when organs rub against one another and against the walls of the cavities that contain them.
Pleurisy is also known as pleuritis.
Why might peritonitis sometimes be a serious complication of an infected appendix? (If the appendix ruptures, the contents spill into the abdominal cavity onto the peritoneum, which then becomes infected.)

7. Epithelial Membranes (cont’d.)
Mucous membranes
Line body surfaces that open directly to the exterior
Produce mucus, a thick secretion that keeps the membranes soft and moist
What are some examples of mucous membranes in the body? (those lining the respiratory, urinary, reproductive, and intestinal tracts)
What is the mucocutaneous junction? (where skin and mucous membranes meet)
The epithelial component of a mucous membrane varies depending on location and function.
The esophagus has a tough, abrasion-resistant stratified squamous epithelium.
The lower segment of the digestive tract has simple columnar epithelium.

8. Connective Tissue No epithelial components
Produce a lubricant called synovial fluid
Synovial membranes between joints
Lining of the bursal sacs

9. Function
Protection: barrier against microbes, dirt, chemicals; shock bsorber
Water balance: prevents loss of water and absorption
Temperature regulation: blood vessels near surface vasoconstriction / vasodilation
Waste disposal: excretion of oil, water, Na+, CO2, etc.
Receptor organs: sensations of touch, pain, heat, cold, pressure
Vitamin D production

10. Layers of the Skin
Epidermis
Dermis
Subcutaneous (hypodermis)

11. Epidermis Outermost layer of skin Composed of 5 layers
Avascular – no blood
supply
Complete regeneration in
approximately 35 days
Some regions are thicker
than others (thinner on
scalp and armpit than on
sole of foot)

12. Dermis Called ‘corium’ or the true skin
Framework of elastic connective tissue and blood vessels
Contains
Blood vessels and capillaries
Lymphatic vessels
Nerves
Involuntary muscles
Sweat and oil glands
Hair shafts and hair follicles
Sensory receptors

13. Subcutaneous – Hypodermis
Innermost layer
Composed of:
elastic and fibrous connective tissue
Adipose (fatty) tissue
Connects skin to underlying muscles

14. Microscopic View of the Skin
This figure shows the layers of the skin and its various structures.
What are the functions performed by the parts of the skin shown in the figure? (Protection, storage, secretion)

15. Accessory Organs of the Skin
Hair
Hair growth requires an epidermal tubelike structure called a hair follicle
Hair growth begins from hair papillae located at the base of the follicle
Hair root lies hidden in the follicle
The visible part of the hair is called the shaft
Are there any parts of the body that are hairless? If so, which? (yes, palms of the hands and the soles of the feet)
What is lanugo? (fine hairs present on body in a fetus/newborn)
What is the arrector pili? (a tiny, smooth muscle present in the dermal skin layer) What function does it perform and why? (These muscles contract when one is frightened or cold.)

16. Accessory Organs of the Skin (cont’d.)
Hair Follicle
This figure illustrates the relationship of a hair follicle and related structures to the epidermal and dermal layers of the skin.
What parts of the hair are in the dermis? (hair papilla, root, and follicle)
What part/parts is/are in the epidermis? (The visible portion of the hair shaft is in the epidermis.)

17. Accessory Organs of the Skin (cont’d.)
Receptors
Specialized nerve endings that make it possible for skin to act as a sense organ
Relays messages to the brain of touch, pain, temperature, and pressure
What are the names and functions of receptors located in the skin? (The names indicate their functions; touch, pain, temperature, and pressure.)
Receptors are widely distributed in the skin.

18. Accessory Organs of the Skin (cont’d.)
Skin Receptors
This figure illustrates the Meissner’s corpuscle and the Pacinian corpuscle.
What stimuli do these corpuscles respond to? (light touch [meissner] and pressure [pacinian])

19. Accessory Organs of the Skin (cont’d.)
Nails
Produced by epidermal cells over terminal ends of fingers and toes
Visible part is called nail body
Root lies in a groove and is hidden by the cuticle
Crescent-shaped area nearest root is called lunula
Nail bed may change color with change in blood flow
How are nails formed? (by action of the epidermal cells; nails are filled with keratin, making them hard)
What purposes might the nails serve? (protection, assessment of circulation)

20. Accessory Organs of the Skin (cont’d.)
Structure of Nails
These two illustrations view the fingernail from above and in sagittal section (divided into right and left portions).
What might cause the nail bed to change color? (impaired blood flow)

21. Accessory Organs of the Skin (cont’d.)
Skin glands
Sweat (sudoriferous) glands
Eccrine
Most numerous, important, and widespread of the sweat glands
Produce perspiration (sweat), which flows out through pores on skin surface
Function throughout life and assist in body heat regulation
A single square inch of skin on the palms contains about 3,000 eccrine sweat glands.
What is the difference between Eccrine and apocrine glands? (eccrine secrete sweat and are found throughout the body. Apocrine secret sweat, are larger, present in axilla and genital area, and secrete a thicker substance.)

22. Accessory Organs of the Skin (cont’d.)
Skin glands
Sweat (sudoriferous) glands
Apocrine
Found primarily in axilla (armpit) and around genitalia
Larger than eccrine glands
Secrete a thicker secretion quite different from eccrine perspiration
Apocrine glands enlarge and begin to function at puberty.
What causes the odor sometimes associated with secretions of the apocrine glands? (skin bacteria)

23. Accessory Organs of the Skin (cont’d.)
Skin glands
Sebaceous glands
Secrete oil, or sebum, for hair and skin
Level of secretion increases during adolescence
Amount of secretion is regulated by sex hormones
Sebum in sebaceous gland ducts may darken to form a blackhead
Sebum secretion decreases in late adulthood, contributing to increased wrinkling and cracking of the skin.
Why would sebum be referred to as “nature’s skin cream”? (prevents drying and cracking of skin)
Think of the skin changes that occur from infancy to old age.

24. Functions of the Skin Protection First line of defense against
Infection by microbes
Ultraviolet rays from the sun
Harmful chemicals
Cuts and tears
How does the skin protect the body against the potential hazards listed in this slide? (Skin acts a barrier to microbes entering underlying surfaces, melanin prevents damage from UV rays, keratin-filled cells of the stratum corneum resist chemicals and protect from cuts and tears.)
What are the defensive properties of keratin? (Keratin is waterproof.)
What are the defensive properties of melanin? Melanin is a pigment that prevents UV rays from penetrating the body.

25. Functions of the Skin (cont’d.)
Temperature regulation
The skin can release almost 3,000 calories of body heat per day
Mechanisms of temperature regulation
Regulation of sweat secretion
Regulation of flow of blood close to the body surface
How is heat lost through the skin? (Through evaporation and radiation)
Blood supply to the skin far exceeds the amount needed by the skin.

26. Functions of the Skin (cont’d.)
Sense organ activity
Skin functions as an enormous sense organ
Receptors serve as receivers for the body, keeping it informed of changes in its environment
Meissner’s corpuscles detect light touch
Pacinian corpuscles detect pressure
Other receptors detect pain, heat, and cold
How do receptors respond to environmental changes? (Receptors act as antennae, keeping body informed. The body can then react to the change.)
What does SPF mean? Is it important? Why? (SPF means sun protection factor. It is important to protect one from damaging UV rays. Excess exposure to UV rays has been associated with skin cancer.)

27. Skin Color Melanin Carotene Only pigment made in the skin
Yellow to reddish-brown to black
Racial differences due to kind and amount of melanin made
Local accumulations .. freckles and pigmented moles
Exposure to sunlight increase manufacture of melanin .. protects DNA from UV damage and results in a tan
Carotene
Yellow to orange
Accumulates in the stratum corneum and fatty tissue of hypodermis
Color obvious in palms and soles

28. Skin Cancer
Squamous Cell
Basel Cell
Malignant Melanoma
Kaposi Sarcoma

29. Causes of Skin Cancer Genetic predisposition
Sun’s ultraviolet rays - causes mistakes in mitosis
More prone to blondes, red heads
Most common skin cancer is squamous cell

30. Burns
Burns are one of the most serious and frequent problems affecting the skin
Treatment and recovery or survival depend on total area involved and severity or depth of burn
Body surface area is estimated using the “rule of nines” in adults
Body is divided into 11 areas of 9% each
In what ways can the skin be burned? (fire, contact with hot surfaces, UV light, chemicals, and electrical currents)
What are the 11 body areas defined by the Rule of Nines? (Head—front and back; torso— front and back; arms—right and left; front and back; legs—right and left, front and back; genitalia: see textbook, Figure 5-8, p. 113)

31. Burns (cont’d.) The Rule of Nines
This figure illustrates the division of the body into 11 areas of 9% each to estimate the amount of skin surface burned in an adult.
What percentage of the body is covered if a person suffers burns to the face and both arms? (22.5%)

32. Burns (cont’d.) Classification of burns
First-degree (partial-thickness) burns: Only the surface layers of epidermis are involved
Second-degree (partial-thickness) burns: Involve the deep epidermal layers
Third-degree (full-thickness) burns: Characterized by complete destruction of the epidermis and dermis
The classification system used to describe the severity of burns is based on the number of tissue layers involved.
The terms partial-thickness and full-thickness are now more readily used to describe burns.
The most severe burns destroy not only layers of skin and subcutaneous tissue but underlying tissues as well.
What are some examples of how one might receive first-, second-, and third-degree burns? What are the symptoms and what tissues are damaged?
First degree can result from a typical sunburn. Symptoms of a first degree burn are minor discomfort and some reddening. The epidermis is injured.
Second degree from scalding. Second degree burns blister. They involve injury to the epidermis as well as the dermis.
Third degree from a fire. Third degree burns may show blackened skin and the damage is extended into the subcutaneous tissues.