Structure and function of skin

Question 1

what are the three layers of the skin

Answer 1

epidermis, dermis (looser, connective tissue), subcutis

Question 2

how do the three layers of the skin stain?

Answer 2

epidermis - intense stain because cells close together
dermis - cells further apart so stains less intensely
subcutis - fat which doesn’t stain at all

Question 3

what are the layers of the epidermis (top to bottom)

Answer 3

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

Question 4

what makes the cells in stratum spinosum appear spiny? (3)

Answer 4

desmosomes - holding cytoskeleton of cells together - strong cellular adhesion.

Question 5

what is a friction blister?

Answer 5

when top layer of skin rubs against basal layer and spiny cells burst, releasing their fluid which is full of protein and so osmotic pressure increases and water gets pulled In via osmosis as a transudate.

Question 6

what are the two things in granule cells in the stratum granulosum

Answer 6

1. keratohyaline granules (precursor to keratin)

2. lamellar bodies

Question 7

what is the stratum corneum made from (brick and mortar)

Answer 7

brick - (dead - anucleated) keratin from keratohyalin bodies
mortar - lipids from lamellar bodies

Question 8

does the epidermis have blood supply?

Answer 8

no.

Question 9

what allows the epidermis to access nutrients from blood vessels? (2)

Answer 9

dermal papillae 
rete ridges (goes into dermis)

Question 10

whats the extra layer in thick skin?

Answer 10

stratum lucideum (clear - contains immature keratin)

Question 11

what two layers is the stratum lucideum in-between in the epidermis in thick skin?

Answer 11

stratum corneum and stratum granulosum.

Question 12

what are the other important cells in the epidermis? (3)

Answer 12

1. melanocytes
2. lymphocytes
3. Merkel cells

Question 13

what determines the colour of you skin?

Answer 13

the rate at which melanin that is released from melanocytes is processed by surrounding cells

Question 14

what is vitiligo?

Answer 14

loss of melanocytes causing change in pigmentation

Question 15

what are langerhan cells?

Answer 15

immune cells that act as APCs.

Question 16

what are Merkel cells?

Answer 16

sensory cells associated with nerve endings

Question 17

what are appendages?

Answer 17

something attached to something larger

Question 18

what are the three main appendages of the skin?

Answer 18

1. hair follicles
2. sweat glands
3. sebaceous glands

Question 19

what muscle controls the angle of the hair in hair follicles?

Answer 19

arrestor pilli

Question 20

what are the two types of sweat glands?

Answer 20

1. apocrine (smelly - armpit and groin)

2. eccrine (all over body)

Question 21

what types of glands are sebeceous glands?

Answer 21

holocrine glands

Question 22

how do merocrine glands secrete something?

Answer 22

via exocytosis (eccrine glands)

Question 23

how do apocrine glands secrete something?

Answer 23

pinch bits off, give bits away

Question 24

how do holocrine glands secrete something?

Answer 24

blow up

Question 25

what other example is there of an appendage?

Answer 25

nail - hard keratin

Question 26

describe the blood supply of skin

Answer 26

blood supply arises from the subcutaneous tissue
theres a deep plexus that communicates with a superficial plexus
lots of arteriovenous anastomoses (connects arteries to veins)
held tight by nerves.

Question 27

what is lack of vitamin D in children called?

Answer 27

Rickets

Question 28

what is lack of vitamin D in adults called?

Answer 28

Osteomalacia