Integument

Question 1

What is Integument?

Answer 1

Outer covering of body, such as skin and related things such as hair and nails

Question 2

What is the purpose of the integument?

Answer 2

Barrier for protection, sensation, excretion, thermoregulation, vitamin D3 synthesis

Question 3

What is the integument made up of?

Answer 3

Epidermis (ectoderm) and dermis (dermatome of the paraxial mesoderm)

Question 4

What is deep to the dermis layer and what is its function?

Answer 4

Hypoderm - loose connective tissue that binds skin to underlying tissues and corresponds to superficial fascia

Question 5

What type of epithelium is the epidermis?

Answer 5

Keratinized stratified squamous epithelium

Question 6

What is at the epidermal-dermal boundary?

Answer 6

Epidermal ridges and dermal papillae that form a zipper like structure that strengthens adhesion!

Question 7

Describe the attributes of thick skin

Answer 7

Found on palms and soles of feet, 5 layers, fingerprints, 400-1400 microM thick

Question 8

Describe the attributes of thin skin

Answer 8

Widespread over the body, 4 layers, glands and hair follicles, 75-150 microM thick

Question 9

What are the epidermal layers from deep to superficial?

Answer 9

Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (only thick skin), stratum corneum

Question 10

What are the epidermal cell types?

Answer 10

Keratinocytes, melanocytes, merkel cells and langerhans cells

Question 11

What is the most prominent cell type in the epidermis?

Answer 11

Keratinocytes

Question 12

What do keratinocytes do?

Answer 12

Produce keratins that strengthen the epidermal water barrier and will produce cornufied cells full of keratin.
Also undergo keratinization and desquamation

Question 13

What is keratinization?

Answer 13

Process of a keratinocyte maturing to the outer layer of epidermis

Question 14

What is desquamation?

Answer 14

Shedding of keratinocytes

Question 15

Stratum Basale defining features

Answer 15

Single layer of keratinocytes with stem cells interspersed; contains melanin
Bound basally by hemidesosomes and apically by desosomes - deepest layer of epidermis!

Question 16

Stratum Spinosum defining features

Answer 16

Thickest layer!

Polyhedral cells with spiny processes; keratin filaments assemble into tonofibrils here - “prickle layer”

Question 17

Stratum granulosum defining features

Answer 17

3-5 layers of flattened cells

Filled with keratohyaline granules and lamellar granules whose products create an almost impenetrable skin barrier

Question 18

What is unique about keratohyaline granules?

Answer 18

They stain intensely basophilic and the granules then undergo terminal differentiation of keratinization

Question 19

What do lamellar granules contain?

Answer 19

Lipids and glycolipids that undergo exocytosis and produce a lipid-rich layer that protects against water loss

Question 20

Stratum lucidum defining features

Answer 20

ONLY IN THICK SKIN!

Thin, translucent layer of flattened keratinocytes and cytoplasm is mostly keratin filaments

Question 21

Stratum corneum defining features

Answer 21

15-20 layers of squamous keratinized cells that are anucleate

Question 22

What are squames

Answer 22

Fully keratinized “cornified” cells that are continuously shed as desosomes break down; housed in the stratum corneum

Question 23

What do melanocytes do?

Answer 23

Produce melanin and transfer it to keratinocytes

Question 24

What is melanin and where is it derived from?

Answer 24

Pigment protein that protects nuclei from UV radiation

NCC DERIVED

Question 25

How many keratinocytes does 1 melanocyte associate with?

Answer 25

About 10

Question 26

Describe the process of melanin being formed and transferred to keratinocytes

Answer 26

Tyrosinase converts tyrosine to melanin in premelanosomes | As the melanin accumulates the premelanosome turns into a melanosome where it can now be transferred to keratinocytes

Question 27

What are langerhans cells?

Answer 27

Antigen presenting cells that phagocytose and present foreign materials to lymph node cells Found in the stratum spinosum

Question 28

What initiates epidermal cell replacement?

Answer 28

Stem cells in the stratum basale

Question 29

What causes the number of epidermal ridges and dermal papillae to increase?

Answer 29

Sites of increased mechanical stress

Question 30

What are the layers of the dermis?

Answer 30

Papillary layer and reticular layer

Question 31

Describe the papillary layer

Answer 31

Loose CT beneath epidermis that contains vasculature and nerve endings

Question 32

Describe the reticular layer

Answer 32

Dense irregular CT that forms regular lines of tension known as the Langer's lines -- cut along them to increase healing capablities

Question 33

Subpapillary plexus

Answer 33

Capillary network between papillary and reticular layers that supplies nutrients to the epidermis

Question 34

Deep plexus

Answer 34

Capillary network near dermis-subcutaneous (hypodermis) boundary that supplies nutrients to the dermis

Question 35

What is the function of the hypodermis (subcutaneous) layer?

Answer 35

Loose CT that binds skin to subjacent organs

Question 36

What is the clinical relevance of the hypodermis?

Answer 36

It contains varying numbers of adipocytes and an extensive vasculature promotes rapid uptake of injected drugs

Question 37

What types of sensory receptors does the skin have?

Answer 37

Encapsulated and non-encapsulated

Question 38

What are merkel cells?

Answer 38

Low threshold mechanoreceptors essential for sensing gentle touch; abundant in finger tips and hair follicles

Question 39

How would you differentiate a merkel cell?

Answer 39

Lack melanosomes, contain small golgi-derived granules near the basolateral surface

Question 40

What is merkel cell carcinoma?

Answer 40

A rare, aggressive, difficult to treat cancer | 40X less common than malignant melanoma but it is 2X more deadly

Question 41

Free nerve endings

Answer 41

Located in papillary dermis and lower epidermal layers; respond to temperature, pain, itching

Question 42

Meissner's corpuscle

Answer 42

Encapsulated receptors that respond to light touch or low freq. stimuli Perpendicular to epidermis in dermal papillae; found in fingertips, palms, soles

Question 43

Lamellated (pacinian) corpuscle

Answer 43

Large encapsulated receptors that respond to coarse touch, pressure, vibrations Found deep in reticular dermis and hypodermis; also rectum wall and bladder

Question 44

Sebaceous glands

Answer 44

Abundant in face and scalp; produce a lipid mixture = sebum via holocrine secretion Lubricates skin, and discharged into hair follicle

Question 45

Eccrine sweat glands

Answer 45

Found throughout skin, stratified cuboidal duct; Myoepithelial cells facilitate expulsion Temperature regulation via cooling

Question 46

What is sweat made of?

Answer 46

H2O, salt, mucinogen, ammonia, uric acid

Question 47

Apocrine sweat glands

Answer 47

USE MEROCRINE SECRETION - odorless until mixed with bacteria Stratified cuboidal duct, myoepithelial cells facilitate expulsion, functional at puberty

Question 48

What is the terminal dilation of the hair follicle and what inserts?

Answer 48

Hair bulb and dermal papilla inserts into that hair bulb to provide nutrients

Question 49

What causes hair growth?

Answer 49

Keratinocytes dividing and differentiating

Question 50

What does the follicular bulge contain?

Answer 50

Epidermal stem cells; near the insertion of arrector pili m.

Question 51

Arrector pili m.

Answer 51

Smooth muscle that extends from midpoint of hair root to papillary layer in dermis and when contracts, hair stands up "goose bumps"

Question 52

What are nails made of?

Answer 52

Highly keratinized cells on bed of epidermis

Question 53

Nail root

Answer 53

Most proximal; covers nail matrix

Question 54

Nail matrix

Answer 54

Stem cells divide and form keratinocytes, pushed forward by continuous growth

Question 55

Cuticle

Answer 55

Extension of skin covering nail root

Question 56

What is merocrine secretion?

Answer 56

secretion delivered via membrane bound vesicles that undergo exocytosis

Question 57

What is holocrine secretion?

Answer 57

secretion delivered once secretion builds up within the cell and apoptosis releases the cell contents