that skin lecture

Question 1

4 functions of skin

Answer 1

protective - acting as a barrier against microbes and other things
biochemical synthesis function as it makes vit D with help of UV influence
homeostatic function of controlling body temp
sensory function

Question 2

what are the non keratinocyte cells in the epidermis and whats their function

Answer 2

langerhans cells which provide immune function to the skin
merkel cells which are the sensory nerve endings of the epifermis - light touch
melanocytes which produce melanin which protects from UV

Question 3

what are the dermal papillae

Answer 3

this is the part of the dermis which projects up between the epidermal peg. this is where we fidn the keratinocyte stem cells - the epidermal pegs

Question 4

what are the two components of the basal lamina

Answer 4

the lamina lucida and the lamina densa

Question 5

what part of the basal lamina are the hemidesmosomes connected to

Answer 5

the lamina lucida

Question 6

stratum spinosum cells synthesise what

Answer 6

cytoplasmic intermediate filaments called cytokeratin

Question 7

what does cytokeratin do

Answer 7

gets bundled up to make the tonofibrils, combining with the granules in keratinisation releasing keratin to the stratum corneum.

Question 8

what are the granules of the granular layer called

Answer 8

keratohyalin granules

Question 9

function of the granules

Answer 9

these granules synthesise hydrophobic glycophospholipids.

Question 10

what do the hydrophobic glycophospholipids of the granules do

Answer 10

release into the space between stratum granulosa and the stratum corneum, forming a water barrier

Question 11

what type of collagen are the two parts of the dermis made of

Answer 11

papillary layer is made of type 3 collagen. the reticular layer is made of type 2 collagen.

Question 12

cells of the secretory part of a sweat gland are different pigment under microscope to the duct cells - whys that

Answer 12

because the duct cells have more mitochondria. this is because they need energy to change the composition of the sweat produced

Question 13

on the outer part if the secretory component of the sweat galnds are myoepithelial cells, what do they do

Answer 13

these squeeze the secretory acini and direct the secretions towards the ducts of the sweat gland.

Question 14

whats the more superficial part of the basal lamina

Answer 14

the lamina lucida - the part the hemidesmosome links to

Question 15

name of the cells in the sebaceous glands

Answer 15

sebocytes

Question 16

describe the free nerve endings

Answer 16

Free nerve endings: these are the most common receptor in skin.
These are unmyelinated small diameter fibres.
Usually small swellings at distal ends = sensory terminals. Sensory terminals have receptors that can respond to various painful, thermal and chemical stimuli. The free nerve endings mainly respond to temperature, pain some movement and pressure, some itch in response to histamine.
Some of these nerve endings wrap around hair follicles acting as touch receptors for hair displacement.

Question 17

describe the merkel discs

Answer 17

Free nerve endings within the deepest layer of the epidermis. These are tactile discs as they are associated with large disc shaped (merkel) cells.
These have small receptive fields so are involved in fine two point touch discrimination.
They are sensitive to fine touch and light pressure, and can respond to texture shape and edges of objects.

Question 18

describe meisseners corpuscles

Answer 18

Located in the dermal papillae. Are especially common in hairless skin.
Branch sensory termional which is associated with adapted schwan cells, which is then ensheathed in a capsule. Shwann cell doesn’t make myelin when wrapped around.
They are encapsulated by schwann cells and then a thin oval of fibrous connective tissue.
they are rapidly adapting mechanoreceptors which are sensitive to touch

Question 19

describe the Pacinian corpuscles

Answer 19

These are deep in the dermis and hypodermis.
They are made by a single dendrite being surrounded by concentric layers of collagen. Between this collagen is gelatenous interstitial fluid. The collagen is made by fibroblasts.
These respond mainly to deep pressure, when defromed the opening of Na+ channels makes an AP.
Rapidly adapt, so they dectect deep pressure and vibration quickly and only for short time. Helpful for running fingers over things to feel surface material.
When outer layer is deformed pressure wave goes through the fluid and to the dendrite causing AP
responsive to pressure and vibration

Question 20

describe the ruffinis ending

Answer 20

Located in the dermis and subcutaneous tissues. They are made by nerve endings which are intertwined with collagen of the dermis.
Capsule surrounds the structure.
As it continues with dermal collagen it is sensitive to deep pressure and stretching or distortion of the skin. These can be proprioceptors as the degree of signal from them dictates stretch of joint or skin.