Skin Histology

Question 1

Basic functions of skin

Answer 1

Physical barrier, immunologic function, temperature regulation, protection from radiation, nerve sensation, injury repair, appearance, quality of life

Question 2

Skin as a physical barrier

Answer 2

Regulates water loss and protects against mechanical, chemical and microbial insults from external environment

Question 3

Dysfunction of skin as physical barrier

Answer 3

Injury, dehydration, infection, inflammation

Question 4

Skin immunologic function

Answer 4

Barrier, senses and responds to pathogens

Question 5

Dysfunction of skin immunologic function

Answer 5

Infection, skin cancer, inflammatory skin conditions, allergy

Question 6

Skin temperature regulation

Answer 6

Helps to maintain constant body temperature with insulating properties of fat and hair and accelerating heat loss with sweat loss and a dense superficial microvasculature

Question 7

Dysfunction of skin temperature regulation

Answer 7

Hyper- or hypothermia, Raynaud phenomenon (chronic episodic attack of digital ischemia provoked by exposure to cold)

Question 8

Skin as radiation protection

Answer 8

Dark pigment melanin in epidermis protects cells from ultraviolet radiation

Question 9

Dysfunction of skin as radiation protection

Answer 9

Increased susceptibility to skin cancer

Question 10

Skin nerve sensation

Answer 10

Sensory receptors allow skin to constantly monitor environment and mechanoreceptors in skin are important for body’s interactions with physical objects

Question 11

Dysfunction of skin nerve sensation

Answer 11

Pruritus (itch), dysesthesia (abnormal sensation), insensitivity to injury

Question 12

Skin injury repair

Answer 12

Cutaneous wound repair process includes coagulation, inflammatory phase, proliferative-migratory phase (tissue formation), and remodeling phase

Question 13

Dysfunction of skin injury repair

Answer 13

Delayed wound healing

Question 14

Skin appearance and quality of life

Answer 14

Defects and aging result in considerable psychological distress and can be used as an important clinical feature of many cutaneous diseases

Question 15

Layers of skin

Answer 15

Epidermis, dermis, subcutis

Question 16

Layers of epidermis

Answer 16

Stratum corneum, stratum granulosum, stratum spinosum, stratum basale

Question 17

Stratum basale

Answer 17

Bottom layer of epidermis, source of epidermal stem cells, where cell division occurs, keratinocytes start here and move upwards

Question 18

Stratum spinosum

Answer 18

Above the stratum basale and under stratum granulosum, has a “spiny” appearance from desmosomal junctions that hold the keratinocytes together

Question 19

Stratum granulosum

Answer 19

Above the stratum spinosum and below stratum corneum, lipids produced by keratinocytes are secreted into the extracellular space between them and forms a water barrier keeping water in the skin

Question 20

Stratum corneum

Answer 20

Top layer, made up of desquamating keratinocytes, which out layer of flattened, keratinized, non-nucleated cells, barrier against trauma and infection

Question 21

Non-keratinocytic cells of the epidermis

Answer 21

Melanocytes and Langerhans cells

Question 22

Melanocyte function

Answer 22

In the basal layer, pigment-producing cells that transfer their pigment (melanin) to the keratinocytes in the same layer

Question 23

Langerhans cell function

Answer 23

Dendritic cells in the mid-epidermis (stratum spinosum), function in the afferent limb of the immune response by providing for the recognition, uptake, processing and presentation of antigens to sensitized T-cells and are important in the induction of delayed-type hypersensitivity, identified by birbeck granules

Question 24

Layers of the dermis

Answer 24

Papillary dermis and reticular dermis

Question 25

Components of the dermis

Answer 25

Blood and lymphatic vessels, nerves, sweat glands, hair follicles, fibroblasts, mast cells

Question 26

Subcutis function

Answer 26

Fat layer separating the dermis from muscle or fascia, insulates the body, energy storage, cushions and protects skin, allows for mobility over underlying structures

Question 27

Epidermal cell life cycle

Answer 27

Two weeks to get from the stratum basale to the stratum corneum, then shed two weeks later (overall 28 day cycle)

Question 28

Orthokeratosis

Answer 28

Normal basket weave of stratum corneum

Question 29

Parakeratosis

Answer 29

Presence of keratinocytic nuclei in the stratum corneum

Question 30

Hyperkeratosis

Answer 30

Thickened stratum corneum

Question 31

Acanthosis

Answer 31

Thinked spinous layer

Question 32

Acantholysis

Answer 32

Loss of attachment between keratinocytes

Question 33

Sebaceous glands

Answer 33

Everywhere except palms/sole, most numerous on face, chest, back, scalp, functionally active at puberty, sebum provides emollients to hair/skin through holocrine secretion

Question 34

Apocrine glands

Answer 34

Found primarily in axillae and groin, odorless secretion (odor comes from microorganisms), stimulated by excitement or fear, secretes milky, viscous fluid, functional at puberty, type of sweat gland

Question 35

Eccrine glands

Answer 35

Found everywhere (except mucous membranes), important in thermoregulation, type of sweat gland, secretes merocrine