BIO 160: Chapter 6: The integumentary system

Question 1

Define: Integument

Answer 1

Integument= coverings. It is also known as the skin.

Question 2

What does the Integumentary system consist of?

Answer 2

It consists of the skin and its accessory organs- the hair, nails, and cutaneous glands.

Question 3

What is the scientific study and medical treatment of the integumentary system called?

Answer 3

It is called Dermatology.

Question 4

Break down Dermatology.

Answer 4

Dermat= skin; logy= study of

Question 5

Is the skin the body’s largest and heaviest organ?

Answer 5

Yes, it accounts for about 15% of the body weight.

Question 6

What are the 2 layers of the skin called?

Answer 6

A stratified squamous epithelium called the Epidermis and a deeper connective tissue layer called the Dermis.

Question 7

What layer is below the dermis? Is it part of the skin? Why.

Answer 7

Below the dermis is another connective tissue layer, the Hypodermis, which is NOT part of the skin but is customarily studied in conjunction with it.

Question 8

The skin can be classified as Thick skin or Thin skin, Where can you find both?

Answer 8

Thick skin covers the palms, soles, and corresponding surfaces of the fingers and toes. Thick skin has sweat glands but no hair follicles or sebaceous (oil) glands.The rest of the body is covered with thin skin. Thin skin possesses hair follicles, sebaceous glands, and sweat glands.

Question 9

What are the 6 functions of the skin?

Answer 9

1) Resistance to trauma and infection
2) Other barrier functions
3) Vitamin D synthesis
4) Sensation
5) Thermoregulation
6) Nonverbal communication

Question 10

Describe how skin is resistant to trauma and infection.

Answer 10

The skin suffers the most physical injuries to the body, but it resists and recovers from trauma better than other organs do. The epidermal cells are packed with the tough protein Keratin and linked by strong desmosomes that give this epithelium its durability. Few infectious organisms can penetrate the intact skin. Bacteria and fungi colonize the surface, but their numbers are kept in check by its relative dryness, its slight acidity (pH 4-6), and certain defensive antimicrobial peptides called dermcidin and defensins.

Question 11

What other barrier functions does skin have?

Answer 11

The skin is important as a barrier to water. It prevents the body from absorbing excess water when you are swimming or bathing, but even more importantly, it prevents the body from losing excess water. The epidermis is also a barrier to ultraviolet rays, blocking much of the radiation from reaching deeper tissue layers.

Question 12

What is vitamin D needed for?

Answer 12

Vitamin D is needed for bone development and maintenance. The skin carries out the first step, the liver and kidneys complete the process.

Question 13

Describe thermoregulation of the skin.

Answer 13

Cutaneous nerve endings called thermoreceptors monitor the body surface temperature. In response to chilling, the body retains heat by constricting blood vessels of the dermis, keeping warm blood deeper in the body. In response to overheating, it loses excess heat by dilating those vessels allowing more blood to flow close to the surface and lose heat through the skin.

Question 14

Describe nonverbal communication of the skin.

Answer 14

Complex skeletal muscles insert on dermal collagen fibers and pull on the skin to create subtle and varied facial expressions. The general appearance of the skin, hair and nails is also important to social acceptance and to a person’s self-image and emotional state.

Question 15

Define: Epidermis

Answer 15

The epidermis is a keratinized stratified squamous epithelium. That is, its surface consists of dead cells packed with the tough protein keratin. Like other epithelia, the epidermis lacks blood vessels and depends on the diffusion of nutrients from the underlying connective tissue. It has sparse nerve endings for touch and pain, but most sensations of the skin are due to nerve endings in the dermis.

Question 16

Break down Epiderm

Answer 16

Epi= above, derm= skin

Question 17

What cells can be found in the epidermis?

Answer 17

1) Stem Cells
2) Keratinocytes Cells
3) Melanocytes Cells
4) Tactile Cells
5) Dendritic Cells

Question 18

Describe Stem Cells

Answer 18

Stem cells are undifferentiated cells that divide and give rise to the Keratinocytes. They are found ONLY in the deepest layer of the epidermis called the stratum basale.

Question 19

Describe Keratinocytes

Answer 19

Keratinocytes are the great majority of the epidermal cells. They are named for their role in synthesizing keratin. In ordinary histological specimens, nearly all the visible epidermal cells are keratinocytes.

Question 20

Describe Melanocytes

Answer 20

Melanocytes also occur only in the stratum basale, amid the stem cells and the deepest keratinocytes. They synthesize the brown to black pigment Melanin. They have branching processes that spread among the keratinocytes and continually shed melanin-containing fragments from their tips.

Question 21

Describe Tactile cells

Answer 21

Tactile cells, relatively few in numbers, are receptors for touch. They, too, are found in the basal layer of the epidermis and are associated with an underlying dermal nerve finer.

Question 22

Describe the Dendritic cells

Answer 22

The Dendritic cells are found in two laters of the epidermis called the stratum spinosum and stratum granulosum. They are immune cells that originate in the bone marrow but migrate to the epidermis and epithelia of the oral cavity, esophagus, and vagina. They stand guard against toxins, microbes, and other pathogens that penetrate into the skin. When they detect such invaders, they alert the immune system so the body can defend itself.

Question 23

What are the 5 layers of the epidermis?

Answer 23

1) Stratum basale
2) Stratum spinosum
3) Stratum granulosum
4) Stratum lucidum
5) Stratum corneum

Question 24

Describe Stratum Basale.

Answer 24

The stratum basal consists mainly of a single layer of cuboidal to low columnar stem cells and keratinocytes resting on the basement membrane. Scattered among these are the melanocytes, tactile cells, and stem cells. As the stem cells divide, they give rise to keratinocytes that migrate toward the skin surface and replace lost epidermal cells.

Question 25

Describe Stratum Spinosum

Answer 25

The stratum spinosum consists of several layers of keratinocytes. In most skin, this is the thickest stratum, but in thick skin it is usually exceeded by the stratum corneum. The deepest cells of the stratum spinosum remain capable of mitosis, but as they are pushed farther upward they cease dividing. Instead, they produce more and more keratin filaments, which cause the cells to flatten. Dendritic cells are also found throughout the stratum spinosum. Epidermal keratinocytes are also bound to each other by tight junctions, which make an essential contribution to water retention by the skin.

Question 26

Describe Stratum Granulosum

Answer 26

Stratum Granulosum consists of 3-5 layers of FLAT keratinocytes. More in thick skin than in thin skin.

Question 27

Describe Stratum Lucidum

Answer 27

Stratum Lucidum is a thin zone superficial to the stratum granulosum, seen only in thick skin. Here, the keratinocytes are densely packed with a clear protein named ELEIDIN. The cells have no nuclei or other organelles.

Question 28

Describe Statum Corneum

Answer 28

Stratum Corneum consists of up to 30 layers of dead, scaly, keratinized cells that form a durable surface layer. It is especially resistant to abrasion, penetration, and water loss.

Question 29

Where do Keratinocytes begin?

Answer 29

Keratinocytes are produced deep in the epidermis by the mitosis of stem cells in the stratum basale. Mitosis requires an abundant supply of oxygen and nutrients, which these deep cells can acquire from the blood vessel in the nearby dermis. Once the epidermal cells migrate more than 2 or 3 cells away from the dermis, their mitosis ceases.

Question 30

Why does skin wrinkle after a bath/shower?

Answer 30

The keratin of the stratum corneum absorbs water and swells, but the deeper layers of the skin do not. The thickening of the stratum corneum forces it to wrinkle. Because the fingers and toes have such a thick stratum corneum and they lack the sebaceous glands that produce water-resistant oil elsewhere on the body.

Question 31

Describe the Dermis.

Answer 31

Beneath the epidermis is a connective tissue layer, the dermis. It is composed mainly of collagen, but also contains elastic and reticular fibers, fibroblasts, and the other cells typical of fibrous connective tissue. It is well supplied with blood vessels, cutaneous glands and nerve endings. Hair follicles and nail roots are embedded in the dermis.