Histology: Skin

Front 1

In the most vague terms, what is skin and what are its functions/

Back 1

Large organ with these functions: mechanical protection, moisture barrier, host defense, thermoregulation, excretion of salt, synthesis of vit D and reg of calcium absorbption, sensory organ.

Front 2

Describe 3 skin appearance concerns in clinical exams.

Back 2

Jaundice- yellow, Cyanosis- gray, Pale- anemia

Front 3

What are the 3 main layers of skin?

Back 3

Epidermis, dermis, hypodermis.

Front 4

What is another name for hypodermis?

Back 4

Superficial fascia

Front 5

What is the epidermis made of?

Back 5

Kertanizing (cornified) stratified squamous epithelials of 4 types: keratinocytes, merkel cells, melanocytes, langerhans cells.

Front 6

What are kartinocytes?

Back 6

The major cell type of epithelial layer, provides barrier function, produces vit D precursor. Forms strat squamous barrier.

Front 7

What are merkel cells?

Back 7

Special cells derived from neural crest (ectodermal derivative), harder to see, sensory receptor.

Front 8

What are melanocytes?

Back 8

Make pigment, derived from neural crest.

Front 9

What are langerhans cells?

Back 9

Come from bone marrow, potent antigen presenting cells for T-lymphocytes.

Front 10

Describe the stratification of teh keratinocytes during differentiation.

Back 10

Starts at basal layer at tips of dermal papillae, next- spinosome (spiny) held together by desmosomes which when processed look spiny, next- granulosa layer with packets of material and finally corneum layer.

Front 11

Which layer is mitotically active?

Back 11

Basal layer

Front 12

Describe the basal layer.

Back 12

Also called stratum germinativum, single layer of cells all attached to basement layer by hemidesmosomes, mitotically active of keratinocytes, 15-30 day renewal

Front 13

What is the role of desmosomes and hemidesmosomes in the basal layer?

Back 13

Desmosomes connect cell to cell, hemidesmosomes attached cell to basement membrane.

Front 14

What are lamellar bodies (Odland bodies)?

Back 14

The outer layer of cells in the spinosum layer has these bodies containing glycolipid.

Front 15

What are special features of spinosum layer?

Back 15

Many desmosomes, abundant keratin fibers, some mitosis.

Front 16

What are features of Stratum Granulosum?

Back 16

The lamellar bodies extrude glycolipid to create intercellular glue

Front 17

What are features of stratum lucidum?

Back 17

Waxy cell envelope containing keratin, doesn't stain well, found primarily in thick skin.

Front 18

What are features of stratum corneum?

Back 18

Waxy cell envelope containing keratin. Non nucleated, dead cells.

Front 19

What are features of merkel cells?

Back 19

migratory cells located in stratum basale, mechanoreceptor cells, joined to adjacent keratinocytes by desmosomes. Cyto has small dense granules.

Front 20

How do Merkel cells do their job?

Back 20

They are in contact with afferent myelinated nerve fiber coming in from dermis. Nerve fiber loses myelin sheath as it penetrates basement membrane. Forms a terminal disk at pt of contact with Merkel cell membrane.

Front 21

Describe features of melanocytes.

Back 21

Neural crest derivatives, reside in or below basal layer. No junctions with keratinocytes, they extend cellular processes b/w keratinocytes in basal and spiny layer. Make melanin.

Front 22

What is melanin?

Back 22

Pigment derived from tyrosine, produced by melanocytes, stored in melanosomes. Released into extracellular space. Protects from UV rays by locating in keratinocytes in a peri-nuclear location.

Front 23

What are langerhans cells?

Back 23

Migratory cells derived from bone marrow. No junctions with other cells in epidermis. Found in outer s. spinosum. Come and go b/w dermis and epidermis, presenting antigens to immune system, carry antigens to lymph nodes via afferent lymph. Hard to see.

Front 24

What is the 2 types dermis?

Back 24

Papillary dermis- loose CT, Reticular dermis- dense irregular CT

Front 25

What are the eccrine sweat glands?

Back 25

Responsible for thermoregulation and mineral excretion. Simple coiled gland. Derived from ectoderm.

Front 26

Describe features of eccrine gland as an excretory duct.

Back 26

stratified cuboidal epithelium, responsive to aldosterone, water and salt resorption.

Front 27

Describe features of eccrine gland as a secretory duct.

Back 27

Secrete water and electrolytes. Total mass of eccrine sweat glands is equiv to kidney.

Front 28

What causes salty kisses?

Back 28

Mutation in a Cl- ion transporter CFTR- cystic fibrosis. High salt content in sweat is diagnotic for cystic fibrosis.

Front 29

What are apocrine sweat glands?

Back 29

Incorrectly named,should be merocrine secretion. Coiled tubular gland with lumen larger than eccrine. Ducts empty into canal of hair follicle. Located in axillary and genital areas. Function unknown, bacteria action on secretion = smelly.

Front 30

What are sebaceous glands?

Back 30

Associated with hair shaft, secretes sebum by holocrine secretion.

Front 31

What is sebum?

Back 31

Secretion of sebaceous gland made of waxes, cholesterol, triglycerides. May serve as substrate for bacteria and cause acne.

Front 32

What are arrector pili muscle?

Back 32

Small muscles attached to hair follicle. When contracted, makes hair stand up (like in cat or when you are cold). Causes goosebumps.

Front 33

How is skin a sensory organ?

Back 33

Merkel cells, naked nerve endings into granular layer, nerve endings wrapped around base of hair shaft sense movement of hair, meissners corpuscles (encapsulated nerve endings) in papillary dermis for tactile sensations of pressure and vibration.

Front 34

What are Pacinian corpuscles?

Back 34

Encapsulated nerve ending deep dermis and hypodermis, tactile and pressure receptors.