A&p Ch. 5

Front 1

What is the largest organ of the human body?

Back 1

Skin

Front 2

Describe the two parts of the skin

Back 2

Epidermis - superficial layer of epithelium (external)
Dermis - deep connective tissue (deep)

Front 3

What are the functions of the skin?

Back 3

Protection, sensation, temp regulation, vit. D production, excretion

Front 4

What is the epidermis described as?

Back 4

keratinized stratified squamous epithelium

Front 5

What are merkel cells and where are they found?

Back 5

epidermis; reception of light touch

Front 6

What are langerhans cells and where are they found?

Back 6

epidermis; immune system

Front 7

What waterproofs the skin?

Back 7

keratin protien.

Front 8

What are keratinocytes?

Back 8

: comprises 90% of all of epidermal cells

Front 9

What are melanocytes?

Back 9

produces the pigment melanin. Melanocytes exist in the lower portion of the epidermis and transfer their melanin to keratinocytes by pinocytosis.

Front 10

List the five strata of the epidermis.

Back 10

Stratum:
- cornuem, lucidum, granulosum, spinosum, basale

Front 11

Describe the Stratum Corneum.

Back 11

consists of 25-30 layers of flat dead squamous cells that are completely filled with keratin. They will be continuously shed and replaced by deeper cells.

Front 12

Describe the Startaum Lucidum.

Back 12

3-5 layers of clear, flat dead cells. Found only on palms and soles of feet.

Front 13

Describe the Stratum Granulosum.

Back 13

3-5 layers of cells. Keratin begins to be formed and the nuclei of the keratinocytes begin to degenerate

Front 14

Describe the Stratum Spinosum.

Back 14

8-10 layers of cells where uptake of melanin from melanocytes to keratinocytes occurs

Front 15

Describe the Stratum Basale.

Back 15

Singles layer of stem cells that are continually going through mitosis producing new keratinocytes. Melanocytes also found in this area. The cells multiply, produce keratinocytes which push towards the surface of the skin. The nuclei will eventually degenerate because the cell is moving further away from the O2 and nutrient source, the blood. The cells die and become filled with keratin by the time they reach the stratum corneum.

Front 16

How long does it take for a cell to be pushed up from the s.basale to the top portion of the s.corneum?

Back 16

40-56 days

Front 17

What is a callus?

Back 17

skin that is under a lot of pressure or friction, the number of layers in the s. corneum increases to offer protection

Front 18

What are the three main pigments responsible for skin color?

Back 18

melanin, carotene and hemoglobin.

Front 19

Describe melanin.

Back 19

This is the most important group of pigments in skin, hair and eyes. Melanin molecules have different colors, ranging from yellow to reddish-brown to black.

Front 20

What is albinism?

Back 20

An inherited lack of melanin formation is albinism. Individual has melanocytes and tyrosine but do not produce tyrosinase and therefore are unable to produce melanin. They lack color in their hair, eyes and skin.

Front 21

How is melanin produced?

Back 21

Melanin is synthesized from an amino acid, tyrosine, in melanocytes in the presence of an enzyme called tyrosinase

Front 22

Describe carotene.

Back 22

This is a yellowish-orange pigment that accumulates in the stratum corneum and subcutaneous layer.

Front 23

Describe hemoglobin.

Back 23

This is the red pigment found in red blood cells that carries oxygen, In the skin of caucasians, where there is little melanin, the skin appears pink

Front 24

What is the dermis composed of?

Back 24

connective tissue containing collagen and elastic fibers.

Front 25

Define collagen.

Back 25

a protein that gives connective strength and pliability. The most abundant protein is connective tissue.

Front 26

Define Elastin.

Back 26

a protein that gives skin stretchability

Front 27

How is the dermis categorized?

Back 27

more superficial papillary region and the deeper reticular region; and the structures like hair follicles, glands, nails

Front 28

What are sebaceous glands?

Back 28

These are oil glands that are located in the dermis and usually connected to hair follicles. The sebum from these glands prevents the hair from becoming brittle and breaking and maintains the moisture of the skin.

Front 29

What are sudoriferous glands?

Back 29

These are sweat glands located throughout the body. There are 2 types:
1. Merocrine (eccrine) - Most abundant; the sweat from these glands is very watery and they are responsible for temperature homeostasis
2. Apocrine - mostly found in the axillary and groin areas; they become active at time of puberty. The sweat from these glands is viscous and is produced during stress or excitement. Bacteria grow rapidly on this secretion and the breakdown of the sweat by the bacteria can lead to body odor. Influenced by sex hormones.

Front 30

What are ceruminous glands?

Back 30

These are modified sweat glands that are found only in the outer ear. They produce a waxy secretion called CERUMEN, which offers protection from some debris.

Front 31

What are mammary glands?

Back 31

These are modified sweat glands located in the breasts that, under the control of hormones, produce milk.

Front 32

What are nails?

Back 32

These are plates of tightly packed, hard, keratinized cells that lie over epidermis of the dorsal, distal portion of digits. Nails grow from the base and do not have a resting period, grows 1mm/week

Front 33

What is the laluna?

Back 33

a thickened area of the nail that covers the matrix, the mitotically active and is white due to thickened stratum basale

Front 34

What is the eponychium?

Back 34

the cuticle

Front 35

What is hair composed of?

Back 35

A hair is composed of columns of dead keratinized epithelial. cells

Front 36

What does the arrector pilli muscle do?

Back 36

a smooth muscle that will lift the hair when it contracts, and causing “goose bumps” in humans.

Front 37

What is lanugo?

Back 37

By the 5th month of fetal development, the fetus’ body is covered by un-pigmented hair

Front 38

What is the function of hair?

Back 38

protection, decrease in friction (in pubic region during sexual intercourse) and odor retention associated with sexual arousal.

Front 39

Describe superficial wound healing.

Back 39

An epidermal wound is like an abrasion. The central portion of the wound usually extends to the dermis whereas the edges experiences only slight injury to the epidermis. The healthy epidermal cells that are adjacent to the scrape will enlarge and migrate to the center of the wound. They will stop, due to CONTACT INHIBITION and proliferate

Front 40

How does the skin regular body temp?

Back 40

One of the functions of the skin is to help maintain the homeostasis of the body temperature at 37 C. If the environment’s temperature is high, heat receptors in the skin will send impulses to the brain.
The brain then sends impulses to the sweat glands to produce perspiration. As this fluid evaporates from the surface of the skin, the skin is cooled off and returns to normal. Also, more blood will be circulated to the skin and will release heat to the outside of the body.

Front 41

What is a burn?

Back 41

tissue damage due to heat, electricity, radioactivity or strong chemicals that denature proteins in the exposed cells. Generally, the systemic effects of a burn are greater than the local effects.

Front 42

What is a first degree burn?

Back 42

involves only the surface epidermis. Mild pain and redness, no blisters. Typical sunburn.

Front 43

What is a second degree burn?

Back 43

destroys all of the epidermis and may destroy some of the papillary region of the dermis. Redness, blisters, edema and pain. No injury to accessory skin structures.

Front 44

What is a third degree burn?

Back 44

destroys epidermis, dermis and epidermal derivatives. Skin functions are lost. Person usually dies if burn exceeds over 70% of body.

Front 45

What is a skin graft?

Back 45

If the germinal portion of the epidermis is destroyed on a large area of the body, a skin graft may be necessary. This involves the transplantation of a segment of skin from a donor to a recipient.

Front 46

What is an autograft?

Back 46

o If the donor and recipient is the same person

Front 47

What is a isograft?

Back 47

If the donor is an identical twin to the recipient,

Front 48

Whats the major cause of death in burn victims?

Back 48

infection

Front 49

Define Basal cell carcinoma.

Back 49

Accounts for 75% of all skin cancers. Tumors arise from s. basale of epidermis. Usually slow metastasis.

Front 50

Describe Squamous cell carinoma.

Back 50

Arise from s. spinosum. Usually slow metastasis

Front 51

Describe malignant melanoma.

Back 51

life threatening cancer arising from melanocytes, many times found within a preexisting mole. Metastasize rapidly. Watch areas that change in pigment, size and irregular borders.

Front 52

What is a decubitus bedsore?

Back 52

pressure sore, caused by prolonged deficiency of blood to tissues overlying a bony projection. The deficiency results in a breakdown of the skin cracking, infection and deep damage. Seen in patients that are bedridden for a long time, usually on buttocks, sacrum and heels. Turning is necessary.

Front 53

What is psoriasis?

Back 53

chronic skin condition in which the skin cells divide 7x more frequently than normal. This leads to excessive cell accumulation, seen as scaly reddened patches on skin surface

Front 54

What is vitilago?

Back 54

the development of patches of white skin due to abnormal or lack of melanocytes in that area. May be an autoimmune response.