W2 Lecture 2 28/02

Question 1

Layers of skin

Answer 1

Epidermis, dermis, hypodermis

Question 2

Epidermis

Answer 2

Epithelium (stratified squamous), upper layers dead, filled with keratin (waxy protein), living cells replaced every 35-45 days

Question 3

Epidermis keratinocytes

Answer 3

Keratinocytes - squamous epithelial cells, Stem cells – in the basal layer, Contain keratin – protein, tough and non-polar (water insoluble), Also have lipids interspersed (also non-polar)

Question 4

Other cells in the epidermis

Answer 4

Melanocytes – epithelial cells, make melanin
Tactile (Merkel) cells – epithelial cells, detect touch, connect to a neuron
Dendritic cells – immune cells

Question 5

Protection versus UV

Answer 5

Less cells in palms/soles, skin colour depends on production rates, eumelanin is brown/black - absorbs UV

Question 6

Genetics - albinism

Answer 6

Autosomal recessive disorder
Defect in melanin production/distribution
Very pale skin
May affect eyes
Sensitive to UV damage

Question 7

Dendritic cells

Answer 7

Antigen presenting cells, Forms a near, continuous network, Detect invaders, Actually connective tissue cells

Question 8

Tactile cells

Answer 8

Formerly called Merkel cells, Epithelia adapted to detect touch, Connect to neurons (nerve cells)

Question 9

Function of keratinocytes (cell type of the epidermis)

Answer 9

Barrier to polar molecule movement and pathogen

Question 10

Function of melanocytes (cell type of the epidermis)

Answer 10

Produce melanin, protect from UV

Question 11

Function of dendritic cells (cell type of the epidermis)

Answer 11

Monitor skin bacteria, detect pathogens

Question 12

What does dermis contain??

Answer 12

Neurons, blood vessels, receptors, hair follicles, sweat glands

Question 13

What are the two layers of the dermis?

Answer 13

Papillary and reticular

Question 14

Papillary

Answer 14

20%, loose (aerolar) connective tissue, superficial
Contains blood vessels, neurons, tactile cells
Fingerprints

Question 15

Reticular

Answer 15

80%, dense connective tissue, much collagen and elastin, deeper, form stretch marks, continuous with hypodermis

Question 16

Lines of cleavage

Answer 16

Formed by collagen and elastin, in parallel bundles, important in surgery

Question 17

Hypodermis

Answer 17

Subcutaneous layer, mainly adipose tissue
insulation, infants and elderly have less

Question 18

The dermis of the skin is deep relative to..

Answer 18

Epidermis

Question 19

Which layer of the dermis is strongest and why?

Answer 19

Reticular layer - dense CT has more structural properties

Question 20

Which layer of the skin is deep relative to the dermis and is made of adipose cells?

Answer 20

Hypodermis/ hypodermic

Question 21

What do adipose cells contain and what is their function in this layer of skin?

Answer 21

Fat (lipids) for insulation

Question 22

Skin secretions

Answer 22

1. low pH retards bacterial multiplication – sweat
2. sebum oils and defensins kill bacteria

Question 23

Dendritic cells of epidermis and macrophages of dermis

Answer 23

Present foreign antigens to white blood cells

Question 24

Dilation

Answer 24

Heat loss (conduction) & prevent heat gain

Question 25

Constriction

Answer 25

Heat retention

Question 26

Sweat Glands

Answer 26

Epithelial ducts project into dermis/hypodermis. Have nerve and blood supply. Secrete onto epidermal surface. Cuboidal and columnar epithelium.

Question 27

Eccrine - skins (sweat glands cont.)

Answer 27

All over skin, secrete water

Question 28

Apocrine

Answer 28

In axillary regions. Secrete water + protein, oil

Question 29

Sebaceous glands

Answer 29

Secrete sebum (oil). Most on hair follicles

Question 30

Parts of the hair

Answer 30

Shaft, Follicle/root, Bulb, Papilla, Arrector pili, Sebaceous gland

Question 31

What type of tissue are hair follicles and sweat glands made from?

Answer 31

Epithelial tissue

Question 32

5 main modalities of cutaneous sensations

Answer 32

Pressure, touch, temperature, pain, itch

Question 33

Free nerve endings

Answer 33

Are the branching tips of sensory neurons; are unprotected & nonspecific; can respond to tactile, pain, and temperature stimuli

Question 34

Root hair plexus

Answer 34

Monitor distortions and movements across the body surface; adapt rapidly

Question 35

Tactile Discs

Answer 35

Fine touch and pressure receptors; are extremely sensitive tonic receptors with very small receptive fields.

Question 36

Merkel Cells

Answer 36

Unusually large epithelial cells in the stratum germinativum of the skin.

Question 37

Tactile discs (Merkel) (touch)

Answer 37

Epidermis

Question 38

Tactile (Meissner's) corpuscles

Answer 38

Dermis - in hairless skin

Question 39

Hair follicle receptors

Answer 39

Dermis - detect hair bending

Question 40

Lamellar (Pacinian) corpuscles (pressure)

Answer 40

Dermis - especially vibration

Question 41

Bulbous corpuscles (ruffini endings)

Answer 41

Deep dermis, hypodermis - deep continuous pressure

Question 42

Heat (temperature)

Answer 42

Nerve endings, deeper in the dermis

Question 43

Cold

Answer 43

Nerve endings, more superficial in the dermis

Question 44

Nociceptors (pain)

Answer 44

Fast pain and slow pain

Question 45

Different kinds respond to: (4)

Answer 45

Excessive heat, pinch, chemicals (acid), (itch)

Question 46

What are the four sensation modalities?

Answer 46

Touch, pressure, temperature, pain, + itch

Question 47

What are pain receptors called?

Answer 47

Nociceptors. They are modified nerve endings.

Question 48

In which layer of skin are most of these sensations detected?

Answer 48

Dermis

Question 49

What is a burn?

Answer 49

Temperature damage to skin. Classified by the level of penetration to which damage occurs.

Question 50

First degree

Answer 50

Top layer of skin or epidermis

Question 51

Second degree

Answer 51

Middle layer of skin or dermis

Question 52

Third degree

Answer 52

Deepest layer of skin or hypodermis