Skin: Structure and Function

Question 1

Melanocyte cytoplasm contains organelles called… these contain …….
Melanosomes have ….. and are mostly …… & ………
Each melanocyte is associated with many ……, forming an epidermal …… unit

Answer 1

melanosomes, pigment melanin
dendrites, basal, suprabasal
keratinocytes, melanin

Question 2

Melanin absorbs ……
Full …… are transferred from melanocytes to keratinocytes via ……
They then form a …….. over the nucleus of the keratinocyte

Answer 2

light
melanosomes
protective cap

Question 3

Langerhans cells have ……. , they are found in the ……. ….. level of the epidermis
]the nucleus looks like a ……. ……..

Answer 3

dendrites, prickle cell

tennis racket

Question 4

Langerhans cells are though of as highly specialized …….

their function includes:

Answer 4

macrophages
Take exogenous antigen and present to T lymphocytes in skin or local nodes
Antigen presenting cells posessing surface receptors for IgG, IgE and C3b

Question 5

Merkel cells are found in the ….. layer
They do not have ….., they are …… and are transducers of ….. touch
Sparse ……. connect these cells to neighbouring keratinocytes

Answer 5

basal
dendrites, mechanoreceptors, fine
desmosomes

Question 6

What are the phases of hair growth?

Answer 6

Anagen
Catagen
Telogen

Question 7

Structure of hair?

Answer 7

(down to up)

papilla, matrix, medulla, cortex, internal and external root sheath

Question 8

Structure of pilo-sebacous unit?

Answer 8

Hair, arrector pili, sebaceous gland, hair shaft

Question 9

Components of nail?

Answer 9

Made of specialized keratins
epidermis folds over creatin gposterir nail fold and cuticle.
White curve is lunula
nailplate and nail bed

Question 10

The dermo-epidermal membrane is a …… membrane that acts as a ….. and ……
it has a key role in ……… interactions such as

Answer 10

semi permeable
barrier, filter
epithelial mesenchymal, growth, differentiation of basal cells, support, anchorage

Question 11

The EDJ is formed of a …….. ……… to which the basal layer is anchored to from above and the cells of papillary layer from below
They are anchored by …….. which hook and link layers together

Answer 11

basement membrane

proteins

Question 12

Defects in the anchoring proteins in the EDJ can result in
Bullous pemphigoid, which is when
Epidermolysis bullosa which is

Answer 12

Antibodies attack the connecting proteins in the EDJ

conegnital defect anchoring between the epidermis and dermis

Question 13

Components of dermis?

Answer 13

Ground substance (polysaccharide mix)
Fibroblasts to manufacture collagen and elastin
Abundant collagen, some elastin
Superficial aspect has blood supply to supply nutrients epidermis
Nerves
Lymphatics
Macrophages, mast cells, langerhands cells, lymphocytes

Question 14

Blood vessels form vertical plexuses to surface of skin in dermis t/f

Answer 14

F

parallel to skin!

Question 15

Smaller lymphatic vessels are …….., larger lymphatic trunks are ……
Functions?

Answer 15

non contractile, contractile
Continual draingale of excess interstitial fluid, unwanted cells, plasma proteins
Immune surveillance by circulating lymp cells and Langerhans
channel microorganisms and toxins

Question 16

Meissners Corpuscles are?

Answer 16

Sense vibration

located in papillar dermis

Question 17

Pacinian Corpuscles are?

Answer 17

sense pressure

1mm big and look like onions, frequently seen in fingers. Located deep beneath dermis

Question 18

Free nerve endings are?

Answer 18

smll and not encapsulated, associated with gllands and piloS units.
Sensitive to pain
Both demris and epidermis
Both sensory and autonomic

Question 19

sebaceous gland?

Answer 19

Commonly empty into upper region of hair follicles,
‘holocrine process’ releases cells as disintegrated matter - oily greasy product (sebum)
Mostly in UPPER THORAX AND FACE
activates at puberty
foamy looking cells

Question 20

Sebaceous gland function?

Answer 20

Sebum
serves to soften and waterproof skin
controls moisture loss
protects from fungal infections

Question 21

sebaceous glands, appocrine and endocrine glands all release sweat t/f

Answer 21

F ]APP and END only

Question 22

Apocrine glands?

Answer 22

found in axillae and perineum

Produce milky odorless fluid that produces distinctive odor after bacterial decomposition

Question 23

Eccrine glands?

Answer 23

Empty directly on skin surface
Whole skin surface but palms soles and axillae in particular
sympathetic and cholinergic nerve supply (mental thermal and gustatory stimulation)
Secretes water, sodium and potassium ions (sweat)

Question 24

Function eccrine?

Answer 24

cool by evaporation
soles aid grip
moisturizes palms

Question 25

Sweat secreted by eccrine glands is less tan 10L per day

Answer 25

F | >10L per day

Question 26

Where does the epidermis come from?

Answer 26

Ectoderm cells form a single layer of periderm, these layers gradually increase and then the periderm cells are cast off ( Vernix caseosa, also known as vernix, is the waxy or cheese-like white substance found coating the skin of newborn human babies, protective function)

Question 27

Where does the dermis come from?

Answer 27

Mesoderm (below ectoderm)

Question 28

Where do mlanocytes come from?

Answer 28

Neural crest (derived from folding of the ectoderm into the mesoderm)

Question 29

keratin layer, granular layer, prickle cell layer, basal layer, dermis are all developed by 16 weeks t/f

Answer 29

T

Question 30

Blaschko's lines is the developmental pattern of skin, it follows nerves t/f

Answer 30

Developmental path of skin, doesn't follow vessels skin or lymph F B lines visible in disease

Question 31

it takes 48hrs for keratinocytes to move from bottom to top of epidermis t/f

Answer 31

F!! 28 days

Question 32

Differentiation occurs via?

Answer 32

Daughter cells from basement membrane migrating upwards

Question 33

Basal layer is usually ..... cell thick, it is small ......, has lots of ....... and is ...... metabolically active

Answer 33

one, cuboidal, keratin, highly

Question 34

Prickle cell later has larger ...... cells with lots of ...... that connect to ........

Answer 34

polyhedral, desmosomes, intermediate filaments (keratin)

Question 35

Granular layer is made of ...... layers of ...... cells, the granules within them contains ......... , there is a high ...... content and the nuclei is .......

Answer 35

2-3, flatter, proteins (structural filaggrin and incolucirin help water barrier), lipid, lost

Question 36

The prickle cell layer is lost in eczema t/f?

Answer 36

F | granular lost

Question 37

Keratin layer is made of ....... and functions as a ......

Answer 37

corneocytes (overlappin non nucleated cell remnants) tight water proof barrier

Question 38

What is the function of skin?

Answer 38

Strong barrier to antigens and organisms Thermoregulation-BV and sweat glands Fluid and electrolyte balance-sweat glands Endocrine function-UV stimulation of Vitamin D Protection from UV rays-melanin pigment Immune function-Langerhans cells Sensory function-touch, temperature, pressure

Question 39

How is the itch sensation transmitted?

Answer 39

Unmyelinated C fibres

Question 40

What are the different causes of itch? (4)

Answer 40

Pruritoceptive: something (usually associated with inflammation or dryness) in skin that triggers itch Neuropathic: damage of any sort to central or peripheral nerves causing itch Neurogenic: no evident damage in CNS, but itch caused by, e.g., opiate effects on CNS receptors Psychogenic: psychological causes with no (currently detectable) CNS damage, e.g. itch in delusions of infestation

Question 41

What systemic diseases are associated with itch?

Answer 41

Haematological, Paraneoplastic, Liver and bile duct, Psychogenic, Kidney disease, Thyroid disease