Integumentary System

Question 1

Thick skin

Answer 1

Has thicker epidermal layer - two locations have this in the body - palms and soles of feet. Thin skin found everywhere else. No hair follicles with thick skin.

Question 2

Thin Skin

Answer 2

4 layers:

Stratum Basale
Stratum Spinosum
Stratum granulosum
Stratum corneum

Question 3

Stratum Basale

Answer 3

mitotically active layer. Stem cells give rise to new keratinocytes. As cells mature, they fill with more keratin. Adjacent to dermis. Comprised of a single layer of cuboidal cells (also stain very dark due to having a TON of ribosomes).

Question 4

Stratum Spinosum

Answer 4

Have small cytoplasmic spines that attach to macula adherins (desmosomes), and fixing the tissue causes shrinkage that creates these “spines”. Unlike stratum basale, this is extremely thick. Here intermediate filament production continues. These tonofilaments begin to be grouped into tonofibril bundles. Keratohyaline granules and lamellar body production begins in upper portion of this layer.

Question 5

Stratum granulosum

Answer 5

1-3 cell layers thick. Granulosum - because of the presence of keratohyaline granules. Intermediate filaments of keratine filaments are tono filaments, which are produced in granulosum cells. Granulosum takes these and bundles them together to form totofibrils. This process of bundling keratin filaments into totofibrils is known as cornization.

Question 6

Stratum corneum

Answer 6

no nuclei, completely dead.

Question 7

Thick skin

Answer 7

5 layers - translucent layer called the stratum lucidum - between granulosum and corneum. It is like a white line.

Question 8

Keratinocytes

Answer 8

Predominate cell type in epidermis.

Question 9

Melanocyte

Answer 9

Epidermal cells - dendritic cells (rounded cell body with dendritic processes that extend up). Hang out in stratum basale and processes extend to spinosum. Produce melanin - protects melanocyte nucleus from the sun. Look for ring of cytoplasm around nucleus.

Question 10

Langerhans cell

Answer 10

**look into how to examine this. check the slides.

Question 11

Merkel’s cell

Answer 11

Associated with acute sensory perception. Can descriminate in fine touch. Found in fingertips. Associated with sensory nerve. Combination of merkel’s cell with afferent sensory neuron = merkel’s corpuscle. Found in stratum basale. Have darkly staining secretory granules. Containing neurosecretory granules in cytoplasm.

Question 12

Dermis layers

Answer 12

2 layers:
Papillary layer
Reticular layer - has fewer cells

Question 13

Papillary layer

Answer 13

layer that is immediately adjacent to epidermis. Marked by protrusions into the epidermis known as dermal papillae. This is loose connective tissue - very cellular layer.

Question 14

Reticular layer

Answer 14

Dense irregular connective tissue.

Question 15

Hypodermis

Answer 15

Has onion-like structures - sensory receptor known as pacinian corpuscle (axon with lamina/layers of connective tissue surrounding unmyelinated portion, innermost layer is layers of schwann cell. Senses deep pressure and vibration.

Question 16

Meisner’s Corpuscle

Answer 16

Oriented perpendicular to surface of skin. Involved in deep sensory reception.

Question 17

Sebaceous gland

Answer 17

Empty into hair follicle. Secrete Sebum (lipid containing). Found in association with hair follicles. Holocrine secretion.

Question 18

Arrector pili

Answer 18

Bands of smooth muscle that extend into papillary layer of dermis on hair follicle. Receives sympathetic innervation.

Question 19

Sweat glands

Answer 19

Eccrine

Apocrine

Question 20

Eccrine

Answer 20

Involved in thermoregulation. Duct leads to skin surface, not hair follicle - duct cells are darker. Duct is small cuboidal cells - strat. cuboidal. Smaller and darker. Duct has a more narrow outside diameter and lumen than secretory portion. These are simple coiled tubular glands. Secretory portion has lighter, larger cells - double layer in dermis/hypodermis. Merocrine secretion is what these do (exocytosis of products). Widely distributed.

Question 21

Apocrine

Answer 21

Associated with hair follicles. Not functional at birth, become functional during puberty. Only located with arm and pubic hair. Products of these is protein rich. Odor is only the result of bacterial breakdown of these proteins. Coiled tubular. Develop from same epidermal downgrowths that form hair follicles.

Secretory portion- at apical surface you see cytoplasmic protusions. Merocrine glands** Usually in hypodermis or dermis. Simple cuboidal epithelium with eosinophilic cytoplasm.

Question 22

Sweat glands - another name

Answer 22

Sudoriferous glands

Question 23

Skin functions

Answer 23

Protective, immunologic (contains antigen affector cells), homeostasis, sensory, endocrine/exocrine.

Question 24

Epidermis

Answer 24

Avascular - receives nourishment from dermis.

Question 25

Dermis

Answer 25

Derived from mesoderm.

Question 26

Hypodermis

Answer 26

Subcutaneous layer/fascia

Question 27

“Thickest” skin

Answer 27

Skin on upper level of back - dermis and epidermis**

Question 28

Langerhan’s Cells

Answer 28

Antigen presenting cell of the immune system.

Question 29

Merkels cell

Answer 29

mechanoreceptor cells associated with sensory nerve endings.

Question 30

Percentages

Answer 30

Keratinocytes: 85%
Melanocytes: 5%
Langerhan’s Cells: 2-5%
Merkels cells: 6-10%

Question 31

Keratins form

Answer 31

Keratin filaments - classified as intermediate filaments, referred to as tonofilaments. Comprise 85% of a fully differentiated keratinocyte. Participates in forming epidermal water barrier - do this by producing tubular/ovoid shape organelles lamelar bodies (lipid containing).

Question 32

lamelar bodies

Answer 32

Secreted in intercellular space between stratum granulosum and stratum corneum.

Question 33

Stratum Lucidum

Answer 33

between stratum corneum and granulosum. Essentially a transition between the two layers - where nuclei are lost, but cells are not quite full.

Question 34

Melanosomes

Answer 34

Produce in melanocytes - travel to ends of dendritic processes, where they accumulate and transfer to adjacent cells.

Question 35

Melanin collects over

Answer 35

keratinocyte nuclei to shield DNA from UV.

Question 36

Langerhans cells

Answer 36

From bone marrow - migrate into epidermis from blood. Travel from epidermis to regional lymph node. H and E staining doesn’t show these, immunostaining is a must.

Question 37

Skin cancer

Answer 37

Basal cell carcinoma, squamous cell c., malignant melanoma

Question 38

Basal cell carcinoma

Answer 38

Slow growing tumor that does not mestastisize - most common and least aggressive. Representes cells of basale- surgical treatment is removal of lesion

Question 39

Squamous cell carcinoma

Answer 39

More aggressive - more prone to mestastisize. Characterized by atypical cells in varying levels with varying patterns.

Question 40

Malignant melanoma

Answer 40

Originates from melanocytes - looks like an irregularly pigmented multicolor rough lesion. Surgery with chemo is needed.

Question 41

Pacinian corpuscles

Answer 41

Encapsulated nerve endings (in connective tissue capsules) to detect pressure changes and vibrations across skin surface. ovoid in dermis and hypodermis

Myelinated nerve ending with concentric lamellae surrounding it. Inner core is a series of schwann cells tightly packed around unmyelinated axon.

Question 42

Meisners Corpusles

Answer 42

Detect light touch. Tapered and cylindrical - in skin and lips. Perpendicular to skin surface. Unmyelinated nerve endings follow spiral path covered by unmyelinated schwann cells.

Question 43

Epidermal skin appendages

Answer 43

Form from downgrowths of epidermis.

Hair follicles, apocrine, eccrine, sepaceous glands

Question 44

Nails

Answer 44

Plates of keratinized cells that rest on nail beds. Difficult to sustain in histological sections.