Panopto 27: integument

Question 1

what do melanocytes make?

Answer 1

melanin

Question 2

How numerous are melanocytes in the epidermis?

Answer 2

they are the third most numerous and make up 5% of the total cells

Question 3

what are melanocytes similar to

Answer 3

dendrites

Question 4

where do melanocytes come from?

Answer 4

the ectoderm-> neural crest

Question 5

where are melanocytes located?

Answer 5

stratum basale or the bottom of the epidermis

Question 6

are melanocytes uniform throughout the skin?

Answer 6

no we have more in our foreheads and places that have increased sun exposure. they’re a form of protection

Question 7

where is the one place in the body that has increased melanocytes even though it isn’t exposed to the sun?

Answer 7

the male scrotum and its so it looks physically more appealing

Question 8

does every human have the same number of melanocytes?

Answer 8

yes the total number of melanocytes is uniform in all humans (a black person doesn’t have more than a white person)

Question 9

do melanocytes form junctions with surrounding keratinocyte cells?

Answer 9

no

Question 10

where do melanocytes attach

Answer 10

attach and rest on the basement membrane by hemidesmosomes so they do attach just not with other cells

Question 11

where do melanocytes extend to

Answer 11

extend out of the stratum basale and into the spinosum (penetrating in between the individual cells)

Question 12

what are melanosomes?

Answer 12

membrane bound vesicles that hold melanin so they are not free in the cytoplasm

Question 13

stage 1 melanosomes

Answer 13

golgi a 250nm membrane bound vesicle that arises from the golgi apparatus (membrane bound, secretory) variety of proteins like the enzyme tyrosinase

Question 14

stage II melanocyte

Answer 14

structural protein builds a grid like structure that has a periodicity, framework for how melanin will be deposited

Question 15

what’s another word for a stage II melanosome?

Answer 15

premelanosome

Question 16

stage III melanosome

Answer 16

Over time, the stage II melanosomes take up the amino acid tyrosine. The enzyme inside is the tyrosinase, which converts the tyrosine into DOPA, which then is converted to melanin. This melanin is deposited on the surfaces of the previous frameworks. When the melanin becomes visible, we have a stage III melanosome.

Question 17

Stage IV melanosome

Answer 17

When enzyme activity disappears, and now its a mature melanosome filled with melanin. These mature melanosomes are transported into the cell processes where they are transferred to the surrounding keratinocytes (stratum spinosum). This is done through a process called cytocrine secretion: a cell to cell transfer where the melanosomes never enter the extracellular space, and the process involves the phagocytosis of this. Melanin is made by melanocytes, but our skin’s pigmentation is a result of melanin in the keratinocytes.

Question 18

whats another name for Langerhans cells

Answer 18

epidermal dendritic cells and antigen presenting cells

Question 19

How numerous are Langerhans cells?

Answer 19

least numerous in the epidermis account for 3% of the total cells

Question 20

where do you find langerhan cells?

Answer 20

in the middle or center parts of the epidermis known as the epidermal ridge or reed ridges which is epidermal tissue, surrounded by cells of the stratum spinosum

Question 21

where do langerhan cells arise from

Answer 21

blood cells in bone marrow, which come from the mesoderm that differentiates forming langerhan cells, migrate out of the bone marrow and into the epidermis at the center of a reed ridge

Question 22

what do langerhan cells belong to

Answer 22

the mononucelar phagocytic system (MPS) of cells so they are macrophages

Question 23

what is the function of langerhan cells

Answer 23

monitor the epidermis for antigens that are passing through the skin, if they encounter an antigen, it will be phagocytized, broken down into smaller fragments and be displayed on the cell surface, it will then migrate out of the epidermis to the lymph node, where it feeds the lymphocytes and will respond to the digested antigen information (antigen presenting cells: ACP)

Question 24

what immune response are langerhan cells involved in

Answer 24

involved in an immune response called the delayed type hypersensitivity reaction, it includes contact dermatitis (poison ivy)

Question 25

what is something thats unique to langerhan cells

Answer 25

Birbeck granules: In the cytoplasm we find small membranous inclusions, but we don’t know what they do

Question 26

whats another name for merkel cells

Answer 26

epidermal tactile cell

Question 27

how numerous are merkel cells

Answer 27

second most numerous in the epidermis 8%

Question 28

origin of merkel cells

Answer 28

Epithelial cell origin but not 100% sure: modified basal cells found in the stratum basale

Question 29

what are merkel cells cell processes similar to

Answer 29

dendrites on a cell body

Question 30

which epidermal cell is the only one that attaches to keratinocytes

Answer 30

Merkel cells are attached to the surrounding keratinocytes by desmosomes

Question 31

how big are merkel cells

Answer 31

small secretory vesicles less than 100nm in diameter

Question 32

what are merkel cells classified as

Answer 32

dense core neurosecretory granules and contain catecholamines: epinephrine and norepinephrine

Question 33

function of merkel cells

Answer 33

specialized for light touch, sensory neurons, and pseudo-unipolar neurons. The catecholamines function as neurotransmitters, and we have a specialized epidermal cell functioning as a sensory receptor

Question 34

what is the merkels corpusule

Answer 34

the sensory pseudounipolar neuron + merkel cell. classified as a mechanoreceptor specialized for light but we find them in our fingertips

Question 35

what are the three receptors in the skin

Answer 35

free nerve endings, pacinian corpusle, and messiners corpusle

Question 36

free nerve endings

Answer 36

penetrate into the epidermis and go as far up as the stratum granulosum. Free in this term means the endings are naked not capsulated. Free nerve endings have a broad range of senses including pain: nociceptors. Free nerve endings are the most numerous in the epidermis

Question 37

pacinian corpusle

Answer 37

encapsulated deep in the dermis, down by the hypodermis, because its so far we need additional pressure to stimulate these

Question 38

messiners corpusle

Answer 38

encapsulated, sensitive to lighter pressure because located in the tips of the dermal papilae

Question 39

what are Langerhan cells similar to

Answer 39

similar to melanocytes and dendrites