C5 1-6

Question 1

Stratum Basale/germanitivum

Answer 1

1. layer of cuboidal/columnar cells - high metabolic needs and most dependent on blood supply from dermis.
2. Basal cells (which supply all new keratinocytes) dominate this stratum. Also contains Merkel cells (touch) and melanocytes.
3. Germanitivum interlocks with the underlying dermis

Question 2

Stratum Corneum

Answer 2

1. 15-30 layers of keratinized cells create a barrier (prevent water loss and pathogen/chemical entry, desmosomes also key to barrier)
2. Dead cells of corneum remain here for about two weeks before they are shed.
3. corneum is water resistant

Question 3

What factors contribute to skin color?

Answer 3

Melanin, Carotene, hemoglobin, illnesses

Question 4

How does melanin affect skin color?

Answer 4

Granules of melanin are packed into melanocytes and are transferred to surrounding keratinocytes where they act as umbrellas to protect the nucleus of cells. It is the type and amount of melanin that account for the majority of skin color variation. Eumelanin/pheomelanin - brown/black-reddish

Question 5

How does carotene affect skin color?

Answer 5

A yellow/orange pigment found in certain plants, carotene can accumulate in the stratum corneum and fatty tissue of the hypodermis.

Question 6

How does hemoglobin affect skin color?

Answer 6

In caucasians, the epidermis is nearly transparent so hemoglobin’s color can show through. (crimson)

Question 7

How does illness affect skin color?

Answer 7

Cyanosis/poorly oxygenated blood = blue, Erythema = red, Anemia/low bp/fear = pallor, Jaundice = yellow Bruise = black/blue

Question 8

3. Describe the importance and the process of keratinzation. Where does it occur?

Answer 8

In the stratum granulosum. Cells get pushed up and as they get further from their nutrient source they die. The maturing cells undergo a hardening process (keratinization) during which the cytoplasm develops strands of tough, fibrous, waterproof proteins called keratin. These dead cells form many tough, waterproof layers.

Question 9

3. Describe the importance of keratinzation.

Answer 9

The importance of keratinization is the protective property it gives skin.

Question 10

Keratinization - Where does it occur?

Answer 10

In the epidermis

Question 11

Papillary layer of dermis

Answer 11

Tissue type: areolar ct.

Structures: lots of small blood vessels, dermal papillae indenting into the epidermis, sweat and oil glands, hair follicles lymph vessels, sensory nerves

Question 12

Reticular layer of dermis

Answer 12

Tissue type: dense irregular ct.

Structures: collagen/elastin, accessory structures start here: hair, nails, glands

Question 13

6. Describe how dermal blood vessels function in temperature regulation.

Answer 13

Vasoconstriction constricts blood vessels and slows passive heat loss, vasodilation widens blood vessels increasing passive heat loss.

Question 14

Papilla

Answer 14

Small, nipple-like projection; dermal papillae are projections of dermal tissue into the epidermis

Question 15

Structure of Dermis

Answer 15

Layer of skin deep to the epidermis; STRUCTURE: papillary layer (areolar ct) and reticular layer (dense irregular, 80%) Vascular and innervated. 4mm

Question 16

Function of Dermis

Answer 16

mechanical strength (but also elastic)

reservoir for water and minerals,

supplies itself and epidermis with blood,

temperature regulation,

houses: blood vessels/sweatglands/sebaceous glands/hair follicles/nail roots

Question 17

Keratin

Answer 17

Tough, fibrous protein found in the epidermis, hair, and nails that makes those structures hard and water resistant; precursor is keratohyaline

Question 18

Melanin

Answer 18

Dark pigment formed by cells called melanocytes; imparts color to skin and hair

Question 19

integumentary system

Answer 19

Skin and its derivatives; provides the external protective covering of the body

Question 20

Epidermis

Answer 20

Superficial layer of the skin; composed of keratinized stratified squamous epithelium. Avascular but innervated.

Question 21

Cutaneous membrane

Answer 21

Epidermis and dermis, Skin. (cutaneous = pertaining to the skin)

Question 22

Subcutaneous tissue/layer structure/function

Answer 22

(tissue beneath the skin) aka hypodermis/superficial fascia. FUNCTION: Forms a connection between skin and underlying structures. STRUCTURE: Mostly loose areolar and adipose, also blood vessels and nerves.

Question 23

Fascia/deep fascia

Answer 23

General term for the fibrous ct masses in different locations in the body. Fascia binds together the structures of the body with many collagenous fibers arranged irregularly (fascia under the skin is mostly adipose)

Deep fascia: dense reg that wraps around blood vessels, muscles, organs

Question 24

What cells are associated with the epidermis?

Answer 24

Keratinocytes, melanocytes, merkel cells, langerhan’s cells

Question 25

Keratinocytes

Answer 25

- Epidermis, - function in protection, - 90% of epidermal cells filled with keratin, - keratinocytes secrete interleukin (influence t cells), first three layers of epidermis are living - keratinocytes/2 superficial layers are dead keratinocytes - FUNCTION: protection

Question 26

Melanocytes

Answer 26

5% of epidermal cells, FUNCTION: protect by absorbing UV light b4 it hits the nucleus of keratinocytes

Question 27

Merkel cells

Answer 27

Tactile cell associated with a nerve ending. FUNCTION: protect by sensing environment

Question 28

Langerhan's cells

Answer 28

Ingest foreign substances/activate immune system FUNCTION: protect by looking for foreign protein

Question 29

Discuss the evolution of skin color.

Answer 29

Darker skin at equator where more protection from sun is needed/lighter skin further from equator where less protection is needed. Melanocytes protect and give skin color, darker skin has produced and retained more melanin.