part 1- layers of the skin

Question 1

what is the skin made of

Answer 1

the skin is made of tissues that work together as a single structure to perform unique and critical function

Question 2

what system does the skin belong to?

Answer 2

the skin is part of the integumentary system

Question 3

what does the skin and its accessory structures provide the body with?

Answer 3

the skin provides the body with overall protection

Question 4

how is the skin held to underlying structures

Answer 4

held to underlying structures by connective tissue

Question 5

what is the characteristic of the deepest layer of the skin?

Answer 5

the deeper layer of the skin is well vascularized (has numerous blood vessels)

Question 6

what does the skin contain for communication

Answer 6

the skin contains numerous sensory and nerve fibres ensuring communication to and from the brain

Question 7

what type of epithelium is the epidermis composed of?

Answer 7

the epidermis is composed of keratinized, stratified squamous epithelium

Question 8

is the epidermis vascular or avascular?

Answer 8

the epidermis is avascular and does not have any blood vessels within it

Question 9

what is the classification of most skin?

Answer 9

most of the skin is classified as thin skin, which has four visible layers of cells

Question 10

what are the 4 visible layers of cells in thin skin from deep to superficial?

Answer 10

1. stratum basale
2. stratum spinosum
3. stratum granulosum
4. stratum corneum

Question 11

where is the thick skin found?

Answer 11

thick skin is found only on the palms of the hands and the soles of the feet

Question 12

what is the fifth layer found in thick skin, and where is it located?

Answer 12

fifth layer is the stratum lucidum, located between the stratum corneum and the stratum granulosum

Question 13

where is the stratum basal located in the epidermis?

Answer 13

deepest epidermal layer

Question 14

what does stratum basal attach to?

Answer 14

attaches the epidermis to the basal lamina, which lies above the dermis

Question 15

what is the function of collagen fibres in the statum basale?

Answer 15

collagen fibres in the stratum basal bond the epidermis to the dermis, forming the basement membrane

Question 16

what are the dermal papillae?

Answer 16

dermal paillae are finger like projections in the dermis that increase the strength of the connection between the dermis and the epidermis

Question 17

how do dermal papillae affect the connection between dermis and epidermis?

Answer 17

greater the folding of dermal papillae, the stronger the connection between the dermis and epidermis

Question 18

what type of cells primarily make up the stratum basale?

Answer 18

primarily made up of basale cells

Question 19

function of basal cells in the stratum basale?

Answer 19

they are stem cells that give rise to the keratinocytes of the epidermis through mitosis

Question 20

what happens as new cells are formed in the stratum basale?

Answer 20

as new cells are formed, existing cells are pushed away from the stratum basale to more superficial layers

Question 21

what are the other two cell types found in the stratum basale?

Answer 21

the other two cell types are Merkel cells and melanocytes

Question 22

what is the function of Merkel cells in the stratum basale?

Answer 22

Merkel cells function as touch receptors stimulating sensory nerves that the brain perceives as touch

Question 23

where are Merkel cells especially abundant?

Answer 23

on the surfaces of the hands and feet

Question 24

function of melanocytes in the stratum basale?

Answer 24

produce the pigment melanin, which gives skin and hair color and protects against UV radiation

Question 25

when do finger prints in a fetus form?

Answer 25

the cells of the stratum basale meet the papillae of the underlying dermal layer (papillary layer), resulting in the formation of the ridges on your fingers that you recognize as fingerprints.

Question 26

what gives stratum spinosum its "spiny" appearance?

Answer 26

the protruding cell processes that join cells via desmosomes

Question 27

why does the "spiny" appearance of the stratum spinosum occur?

Answer 27

its an artifact of the staining process; unstained epidermis does't show this feature

Question 28

how many layers of the keratinocytes are found in the stratum spinosum?

Answer 28

8 to 10 layers of k

Question 29

what type of cell is found in the stratum spinosum and what is it's function?

Answer 29

langerhans cells, which act as macrophages, engulfing bacteria, foreign particles, and damaged cells

Question 30

what role do keratinocytes in the stratum spinosum play?

Answer 30

they begin synthesizing keratin and releasing a glycolipid to prevent water loss

Question 31

how are the keratinocytes of the stratum spinosum moved?

Answer 31

they are pushed into the stratum granulosum as new keratinocytes are formed in the stratum basale

Question 32

what gives the graunlosum its "grainy" appearance?

Answer 32

the accumulation of keratin and keratohyalin proteins within the cells

Question 33

how many layers of cells are in the stratum granulosum?

Answer 33

three to five layers of cells

Question 34

what changes occur to the keratinocytes in the stratum granulosum?

Answer 34

cells become flatter, cell membrane thicken, and they generate large amounts of keratin and keratohyalin

Question 35

what happens to the nuclei and cell organelles in the stratum granulosum?

Answer 35

they disintegrate as the cells die, leaving behind keratin, keratohyalin and cell membranes

Question 36

what do the remnants of the cells in the stratum granulosum form?

Answer 36

the stratum lucidum, stratum corneum and accessory strucutes like hair and nails

Question 37

where is stratum lucidum found?

Answer 37

thick skin such as palms, soles and digits (finger or toe)

Question 38

what is the appearance of the stratum lucidum?

Answer 38

it is a smooth, translucent layer

Question 39

what type of cells make up the stratum lucidum?

Answer 39

dead, flattened keratinocytes

Question 40

what protein do the cells of stratum lucidum contain, and what function?

Answer 40

eleiden, a clear protein driven from keratohylain, which gives the cells their transparent appearance and acts as a water barrier.

Question 41

what is the stratum corneum?

Answer 41

most superficial layer of the epidermis, exposed to outside environment

Question 42

why is the stratum corneum named as such?

Answer 42

due to increased keratinization (cornification) of the cells

Question 43

how many layers of cells are typically in the stratum corneum?

Answer 43

15 to 30 layers of cells

Question 44

how to remember layers of epidermis dermis and hypodermis

Answer 44

epi= over hypo= under/below

Question 45

dermis

Answer 45

It contains blood and lymph vessels, nerves, and other structures, such as hair follicles and sweat glands. The dermis is made of two layers of connective tissue that compose an interconnected mesh of elastin and collagenous fibres, produced by fibroblasts

Question 46

what type of connective tissue makes up the papillary layer?

Answer 46

loose, areolar connective tissue

Question 47

what structure forms in the papillary layer and projects into the stratum basale?

Answer 47

dermal papillae (finger like projections)

Question 48

what cells are found within the papillary layer?

Answer 48

fibroblasts, adipocytes (fat cells) and phagocytes

Question 49

what is the role of phagocytes in the papillary layer?

Answer 49

help fight bacteria and infections that breach the skin

Question 50

what additional strucutes are found in the papillary layer?

Answer 50

small blood vessels, lymphatic capillaries, nerve fibres and tactile corpuscles (touch receptors)

Question 51

what type of connective tissue makes up the reticular layer?

Answer 51

dense, irregular connective tissue

Question 52

what fibres make up the reticular layer and what do they provide?

Answer 52

elastin fibres (for elasticity) and collagen fibres (for the structure, tensile strength and hydration)

Question 53

how does collagen in the reticular layer help the skin?

Answer 53

it provides tensile strength, structure and binds water to keep the skin hydrated

Question 54

how does the reticular layer appear under a microscope?

Answer 54

it appears reticulated (net like) due to the tight meshwork of fibres

Question 55

what is the main function of the hypodermis?

Answer 55

it connects the skin to the underlying fascia of bones and muscles

Question 56

what tissues make up the hypodermis?

Answer 56

loose, areolar connective tissue and adipose tissue

Question 57

what are the functions of adipose tissue in the hypodermis?

Answer 57

fat storage, insulation and cushioning for the integument

Question 58

what pigments influence skin colour?

Answer 58

melanin, carotene and hemoglobin

Question 59

what is melanin produced?

Answer 59

my melanocytes in the stratum basale of the epidermis

Question 60

how is melanin transferred to keratinocytes?

Answer 60

through melanosomes, cellular vesicles that carry melanin

Question 61

how does sun exposure affect melanin production ?

Answer 61

UV rays stimulate keratinocytes to secrete chemicals that activates melanocytes, increasing to melanin production and resulting in a tan

Question 62

what is the role of melanin in protecting the skin?

Answer 62

it helps protect the DNA of epidermal cells from UV damage

Question 63

what is the downside of excessive melanin production?

Answer 63

too much melanin can interfere with vitamin D production, affecting calcium absorption