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Hole’s Essentials of Human Anatomy & Physiology David Shier Jackie Butler Ricki Lewis
Created by Dr. Melissa Eisenhauer
Head Athletic Trainer/Assistant Professor
Trevecca Nazarene University
Chapter 6
Lecture Outlines*
*See PowerPoint image slides for all figures and tables
pre-inserted into PowerPoint without notes.

2. Skin and the Integumentary System
Chapter 6
Skin and the Integumentary System

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Introduction:
A. Organs are body structures composed of two or more different tissues.
B. The skin and its accessory organs make up the integumentary system.
The skin is the largest organ by weight and accessory organs are like hair and nails.

4. Why do you think it is important for us to have skin?
It creates a barrier between ourselves and the outside.

5.  Types of Membranes (Review)
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 Types of Membranes (Review)
A. Serous membranes line body cavities that lack openings to the outside.
1. They line the thorax and abdomen and cover the organs within these cavities.
2. Serous membranes are made up of epithelium and loose connective tissue and secrete serous fluid that acts as a lubricant.

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B. Mucous membranes line the cavities and openings that lead to the outside of the body, including the oral and nasal cavities, and openings of the digestive, reproductive, respiratory, and urinary systems.
1. They consist of epithelium and connective tissue with specialized cells that secrete mucus.

7. C. Synovial membranes line the joint cavities.
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C. Synovial membranes line the joint cavities.
1. These membranes consist of only connective tissues and they secrete lubricating synovial fluid.
D. New! The cutaneous membrane consists of the skin, and is the subject of the remainder of this chapter.

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 Skin and Its Tissues
A. The skin is a large organ responsible for maintaining homeostasis through temperature regulation, protection of underlying tissues, retardation of water loss, housing sensory receptors, synthesizing certain chemicals, and excreting wastes.

9. For normal bone and teeth development!
What is vitamin D for?
For normal bone and teeth development!
How can we make it?
Diet
Cells synthesize dehydrocholestrol in the digestive system  brought to the surface of the skin via the blood  Exposed to UV light (sunlight)  Vitamin D!

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B. The skin consists of an outer epidermis and a dermis, connected to underlying tissue by the subcutaneous layer (hypodermis).
Make a table* Name and what is made of. Rows will go from the most superficial layer to the most deep layer. The skin includes two distinct layers. The outer layer is the epidermis (stratified squamous epithelium) and the inner layer is the dermis which is thicker than the epidermis and includes connective tissue and epithelial tissue. The basement layer that holds the epidermis down is what separates the two layers.
Lastly, the most deep layer is the subcutaneous layer or hypodermis made of loose connective tissue and contains a layer of adipose tissue which helps conserve body heat.

11. Fun Fact!
If the skin of a 150 pound person were spread out flat, it would cover approximately 20 square feet!

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C. Epidermis
1. The epidermis is made up of stratified squamous epithelium and lacks blood vessels.
2. The layer of reproducing cells (the stratum basale), which lies at the base of the epidermis, is well-nourished by dermal blood vessels.
Epithelial tissue lacks blood vessels and get their nutrients from their basement layer which is where they are attached. The cells closest to the basement layer aka nutrient supply grow and push older cells out of the way.

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3. Cells are pushed outward as new cells are formed, and become keratinized as they die. Four or five layers may be seen: stratum basale, stratum spinosum, stratum granulosum, and stratum corneum are always present and the stratum lucidum is found in the thicker palms and soles.
(Deep) Stratum Basale  Stratum Spinosum  Stratum Granulosum  Stratum Corneum  Stratum Lucidum (superficial)
Healthy skin is produced at the same rate cells die. However, places that are rubbed constantly cause a grow of thicker skin aka calluses on the palms and soles.

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4. The epidermis is important because it protects against water loss, mechanical injury, chemicals, and microorganisms.
5. Melanocytes, which lie deep in the epidermis and underlying dermis, produce a pigment called melanin that protects deeper cells from the sun's ultraviolet rays.
6. Melanocytes pass melanin to nearby cells through cytocrine secretion.
We already know that the epidermis protects against water loss, injury, chemicals, and bacteria, but it also protects against UV damage. Melanocytes lie deep in the epidermis to produce a pigment called melanin. Melanin is the color of your skin. The more melanin that is produced the darker the skin. This is why you tan when you are exposed to the sun. Melanin acts like a shield against UV damage to your DNA.
Melanin is passed along to other cells from the melanocytes through cytocrine secretion.

16. 4. Circulation within dermal blood vessels affects skin color.
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D. Skin Color
1. Skin color results from a combination of genetic, environmental, and physiological factors.
2. Genetic differences in skin color result from differing amounts of melanin and in the size of melanin granules.
3. Exposure to sunlight causes darkening of skin as melanin production increases.
4. Circulation within dermal blood vessels affects skin color.
We are all born with the same amount of melanocytes, but our DNA tells our melanocytes how much melanin to produce.
When the blood is well oxygenated it can make fair skinned people look pinkish while when the blood is not oxygenated well it can make fair skinned people appear bluish.

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E. Dermis
1. The dermis binds the epidermis to underlying tissues. Epidermal ridges and dermal papillae cause the border to be uneven.
2. The dermis consists of connective tissue with collagen and elastic fibers within a gel-like ground substance.
Dermal papillae can be found all over the body, but they are most abundant in the hands and feet. This is what makes up our fingerprints. Our genes tell us where these ridges form.

18. You remember how identical twins have the same DNA?
Fun Fact!
You remember how identical twins have the same DNA?
Well their fingerprints are still different because when the fetus is developing, it presses its hands against the uterus which alters these ridges. This is why even identical twins have unique prints.

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3. Dermal blood vessels carry nutrients to upper layers of skin and help to regulate temperature.
4. The dermis also contains nerve fibers, sensory fibers, hair follicles, sebaceous glands, and sweat glands.
Because dermal blood vessels supply nutrients to the epidermis, if something were to obstruct the blood flow in the dermal layer, for example laying in one position for a long time then you would have death of the epidermal layer aka necrosis and a pressure sore may appear.

20. Fun Fact!
The reason tattoos are permanent is because an ultrafine needle injects ink into the dermal layer. The dermal layer does not shed; therefore, the ink does not shed. Before lasers, tattoos used to be removed by scraping, freezing, or cutting away. Ouch!

21. 3. No sharp boundary exists between the dermis and subcutaneous layer.
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F. Subcutaneous Layer
1. The subcutaneous layer (hypodermis) is composed of loose connective tissue and insulating adipose tissue.
2. It binds the skin to underlying organs and contains the blood vessels that supply the skin.
3. No sharp boundary exists between the dermis and subcutaneous layer.

22. Review! List the general functions of the skin
Name the tissue in the outer layer of the skin
Name the tissues in the inner layer of skin
Name the tissues in the subcutaneous layer beneath the skin
What are functions of the subcutaneous layer?
What are the layers of the epidermis?
What is the function of melanin?
What factors influence skin color?

23.  Accessory Organs of the Skin
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 Accessory Organs of the Skin
A. Nails
1. Nails are protective coverings over the ends of fingers and toes.
2. Nails consist of stratified squamous epithelial cells overlying the nail bed, with the lunula as the most actively growing region of the nail root.
3. As new cells are produced, older ones are pushed outward and become keratinized.

25. 1. Hair can be found in nearly all regions of the skin.
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B. Hair Follicles
1. Hair can be found in nearly all regions of the skin.
2. Individual hairs develop from cells at the base of the hair follicle, an invagination of the lower epidermis that dips down into the dermis.
3. As new cells are formed, old cells are pushed outward and become keratinized, and die forming the hair shaft.

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4. A bundle of smooth muscle cells, called the arrector pili muscle, attaches to each hair follicle. These muscles cause goose bumps when cold or frightened.
5. Hair color is determined by genetics; melanin from melanocytes is responsible for most hair colors. Dark hair has eumelanin while blonde and red hair have pheomelanin.

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C. Sebaceous Glands
1. Sebaceous glands (holocrine glands) are associated with hair follicles and secrete sebum that waterproofs and moisturizes the hair shafts.

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D. Sweat Glands
1. Sweat glands (sudoriferous glands) are either eccrine, which respond to body temperature, or apocrine, stress, and sexual arousal.
2. Modified sweat glands, called ceruminous glands, secrete wax in the ear canal.
3. Mammary glands, another modified type of sweat glands, secrete milk.

30.  Regulation of Body Temperature
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 Regulation of Body Temperature
A. Proper temperature regulation is vital to maintaining metabolic reactions.
What could happen if we get too warm?
B. The skin plays a major role in temperature regulation with the hypothalamus controlling it.
How does the skin control our body temperature?
C. Active cells, such as those of the heart and skeletal muscle, produce heat.
How do our cells produce heat?

31. Can you think of a process that allows this?
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D. Heat may be lost to the surroundings from the skin through radiation.
Can you think of a process that allows this?
E. The body responds to excessive heat by dilation of dermal blood vessels and sweating.
How would dilation be helpful?
F. The body responds to excessive cooling by constricting dermal blood vessels, inactivating sweat glands, and shivering.
How would this keep us warmer?
Did you know that 80% of your body heat escapes through your head?

32.  Healing of Wounds and Burns
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 Healing of Wounds and Burns
A. Inflammation, in which blood vessels dilate and become more permeable, causing tissues to become red and swollen, is the body's normal response to injury. (Redness, swelling, heat, and pain).
B. Superficial cuts are filled in by reproducing epithelial cells.

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C. Deeper cuts are closed off by clots, covered by scabs, and eventually filled in by fibroblasts, making connective tissue. Blood vessels extend into the area, injured tissues are replaced, and the scab falls off.
D. Large wounds leave scars and healing may be accompanied by the formation of granulations.

34. Granulation of the Skin

35. Granulation of Nail

36. Common Skin Disorders

37. Acne

38. Alopecia

39. Boil

40. Cyst

41. Birthmark

42. Dermatitis

43. Eczema

44. Herpes

45. Keloid

46. Psoriasis

47. Scabies

48. Ulcer

49. Vitiligo

50. Seborrhea

51. Review! Describe the structure of the nail bed? Explain how hair forms
What is the function of sebaceous glands?
Distinguish between the eccrine and apocrine gland
Why is regulation of body temperature so important?
How does the body lose excess heat?

52. Review Continued Which actions help conserve body heat?
What are the four cardinal signs of inflammation?
What is granulation?