Lecture 15 Integumentary

Question 1

What are the two layers of skin

Answer 1

1. Epidermis
2. Dermis

Hypodermis is not apart of the two layers

Question 2

Epidermis is

Answer 2

Stratified squamous keratinized epithelium
Avascular
Renewed by mitosis (2 – 4 wk cycle)
Epidermal (rete) ridge – helps keep epidermis attached to dermis

Question 3

Dermis is

Answer 3

Fibrous connective tissue
Vascularized – nourishes epidermis
Dermal papilla – helps epidermal ridges to bind epidermis & dermis

Question 4

Clinical correlation: excessive rubbing can tear the epidermis from the dermis.

Answer 4

The space fills with fluid to create a friction blister.

Question 5

Dermis is fibrous – mostly TYPE _______ COLLAGEN; some elastic fibers

Answer 5

type I collagen

Question 6

Two layers of Dermis

Answer 6

1. Papillary Layer: Loose connective tissue – Thin fibers Nourish, support & defend epidermis
2. Reticular Layer: Dense irregular CT – Thick fibers Gives strength and elasticity to skin

Question 7

4 Cells of the epidermis

Answer 7

1. keratinocyte — Forms a barrier
2. melanocyte — Forms pigment
3. Langerhans cell — Antigen-presentation
4. Merkel cell — Sensory perception

Question 8

Main cell Type of Epidermis

Answer 8

Keratinocyte
Under LM, generally recognized by:
-Euchromatic nucleus
-Prominent nucleoli
-Acidophilic cytoplasm (reflects accumulated keratin)

Helps to form a water barrier

Question 9

Life-cycle of keratinocytes

Answer 9

4. Exfoliation when desmosomes loosen
5. Eventually keratinocytes fill with keratin, lose nucleus, & die (process of keratinization)
6. Layers based on distinct maturational events
7. Continuous cell mitosis at base pushes up maturing keratinocytes

Question 10

What Layer of Epidermis is this?

Answer 10

Stratum basale
Single layer of stem cells on basement membrane

Basal (stem) cells continuously divide to renew the epidermis

Contain many free ribosomes for production of the protein keratin

Question 11

basal cell carcinoma

Answer 11

is the most common but least dangerous form of skin cancer. It arises from mutations in the basal cells.

Comes from Stratum Basale

Question 12

What Layer of Epidermis is this

Answer 12

Stratum spinosum

Characterized by “spiny-looking” keratinocytes

Keratins are assembled into tonofibrils (intermediate filament), which anchor into desmosomes

Desmosomes keep adjacent cells connected in life & after slide prep

Question 13

squamous cell carcinoma originates where

Answer 13

Stratum spinosum
keratinocytes

Question 14

What layer is this

Answer 14

Stratum granulosum

Keratinocytes contain many basophilic keratohyaline granules that link tonofibrils together
Lamellar bodies (LB) – secreted to make water-resistant lipid envelope around cells

Question 15

What layer of Epidermis is this?

Answer 15

Stratum corneum

Water resistant Dead cells packed with keratin – acidophilic

Question 16

What are 1-4

Answer 16

1. Melanocyte
2. Keritonocytes
3. Stratum Spinosum
4. Strautm Basale

Question 17

Characteristics of Melanocytes

Answer 17

Melanocytes are found among cells of the stratum basale, produce melanin
Round cells with clear cytoplasm (no keratin) under LM

Question 18

What cell type and its fxn

Answer 18

Langerhans cell

Specialized macrophage – connective tissue cell (comes from precursor cell in bone marrow)

Functions as an antigen-presenting cell

Question 19

What cell type is this and its distinguishable characteristics

Answer 19

Langerhans cell

Birbeck granule – helps breakdown some viruses

Question 20

What cell type are these

Answer 20

Merkel cells (M) are mechanoreceptors specialized for sensing gentle touch

Notice the Nerve ending!

And lots of granules for NT release

Question 21

Where are merkel cells found

Answer 21

stratum basale

Question 22

Cell + nerve ending = sensory receptor –

Answer 22

Merkel (tactile) disk

Question 23

Innervation of skin
1. Merkel disk
2. Pacinian corpuscle
3. Free nerve ending
4. Meissner’s corpuscle

Answer 23

1. Fine touch
2. Sustained pressure, vibrations
   Found in deep dermis
3. Pain, temperature
4. Light touch
   Found in dermal papilla
   Concentrated on fingertips, lips

Question 24

What is this

Answer 24

Pacinian corpuscle
Sustained pressure, vibrations
Found in deep dermis

Question 25

What is this?

Answer 25

Meissner’s corpuscle Light touch Found in dermal papilla Concentrated on fingertips, lips

Question 26

What are 1-3

Answer 26

1. Root Sheath: downward continuation of basale and spinosum layers 2.Hair bulb – terminal dilation 3. Within the hair bulb, keratinocytes divide rapidly, grow, and receive pigment

Question 27

What is the dashed lines what is the blue dot

Answer 27

Arrector pili muscle – smooth muscle; pulls hair erect making “goose bumps” Follicular bulge – region of outer root sheath where reserve stem cells & melanocytes reside

Question 28

What is the outlined Where is it found and not found

Answer 28

Sebaceous glands secrete sebum, a mix of lipids and cellular debris that maintains skin and hair texture

Question 29

Sebaceous gland

Answer 29

Located between follicle & arrector pili muscle – compression squeezes the gland, duct empties into hair follicle Holocrine secretion – cell dies and contributes to secretory product (sebum)

Question 30

Two types of sweat glands

Answer 30

Eccrine sweat glands Water-rich sweat Temperature regulation Widespread in skin Apocrine sweat glands Protein-rich sweat Functions relating to scent Secretion begins at puberty Restricted to axillary & perineal skin Associated with hair follicle

Question 31

What cell type is this

Answer 31

Eccrine Sweat gland Psuedostrstified epithelium

Question 32

What Cell type is this

Answer 32

Apocrine sweat gland

Question 33

Where is this found

Answer 33

In areas of high friction (palms & soles) Hairless (no hair follicles) No sebaceous or apocrine glands

Question 34

Where is this found

Answer 34

Entire body except thick skin areas Mostly hairy (except lips) Has all types of glands