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Flashcards in Integument Deck (54):
1

What are the 6 essential functions of skin?

Barrier, immunological (antigen processing),homeostatic (body temperature and water loss), endocrine (secrete hormones, growth factors and hormones), excretion (sweat), and conveys sensory information about the external environment to the nervous system (temperature, surface texture)

2

what are the layers of skin?

Epidermis, dermis, and hypodermics (layer of subcutaneous tissue)

3

What two epidermal derivative are not found in thick skin?

Hair follicles/hair and sebaceous glands

4

What determines if skin is thin or thick?

The thickness of the epidermal layer

5

What are the layers of the epidermis?

Corneum (dead, keratinized cells), lucidium (can only be seen in thick skin), granulosum (cells that about to die), spinosum (maturing and slowly dying cells), basale (can differentiate).

MNEMONIC: Come, let's get sun burnt

6

Keratinocytes

Most abundant cell type. Attached to each other via desmosomes and attached to the basal lamina by hemis.

7

Apoptosis of keratinocytes

They are proteolytically cleaved on the desmosomes, which allows them to move through the layers until they reach the corneum where they are sloughed off

8

Keratins

Strengthen the keratinocyte, makes up about 85% of it.

9

Lamellar Bodies

water barrier in keratinocytes

10

Melanocytes

Derived in the neural crest(dendritic cells with long cytoplasmic extensions). Can replicate throughout life

11

How do melanocytes appear on an EM?

Clear with a large elongated nucleus and cytoplasm a cytoplasmic extensions.

12

What is the function of melanocytes cytocrine secretion?

UV protection through the release of melanin

13

How is melanin produced?

oxidation of tyrosine to DOPA and DOPA gets transformed into melanin

14

Langerhans Cells

Originate from a common lymphoid progenitor. Present antigens to the T cells in lymph nodes. No desmosomal junctions. Involved in delayed-type hypersensitivity reactions (type of allergic reaction)

15

How do langerhans look on EM?

Dendritic processed, clear cytoplasm and dark nucleus, nucleus is indented, possess birbeck granules which look like tennis rackets

16

Merkel's Cells

Least numerous. Dendritic cells. Detect touch sensations, found where sensory perception is acute (fingertips). Contain desmosomes and keratin. Antigenic markers of both epidermal and neural type cells.

17

How do Merkels cells look on EM?

Lobed nucleus, neurosecretory granules in the cytoplasm

18

Merkels Corpuscle

Area that is closely associated with the expanded terminal bulb of afferent myelinated nerve fivers

19

Stratum Basale

Bottom layer. Single layer of cuboidal cells. Contains keratinocyte stem cells, melanocytes, and Merkel cells. Provides for epidermal cell renewal. Attached to basal lamina by hemidesmosomes, and extensively attached to other cells by desmosomes .

20

How does the stratum basale look?

Closely packed nuclei with little cytoplasm. Intensely basophilic (dark)m with many melanin granules.

21

Stratum Germinativum

Keratinocyte stem cells

22

Stratum Spinosum

Several layers. Large cells compared to the basale. Cells change appearance as they move to surface. Numerous cytoplasmic spines (prickle layer due to shrinkage). Cells are attached to each other by desmosomes.

23

Node of Bizzozero

Slight thickening of desmosomes that can be seen between cells

24

How do cells change as they mature in the stratum Spinosum?

Cells move to the surface and increase in size as they mature, they also become flattened in a plane parallel to the surface. Nuclei become elongated instead of ovoid.

25

Stratum Granulosum

Most superficial of the non keratinized layers. Anywhere from 1-3 layers. Contains conscious granules which give them a granulated appearance. Contain lamellar bodies to act as a water barrier.

26

Keratohylan

Granules found in the granulosum which are irregularly shaped, vary in size, rich in cysteine and histidine, and a precursor for fillagrin. Responsible for aggregating the keratin filaments within cornified cells.

27

Stratum Lucidium

Thick skin only, considered a subdivision of the corneum. Contain cells that are in the process of being keratinized.

28

What does the stratum lucidium look like?

Appears under LM as a highly refractile eosionphilic band

29

Stratum Corneum

Several layers of dead keratinocytes. No organelles or nuclei. Deep level contains the water barrier. Filled with keratin filaments that are aggregated into toon fibrils.

30

Tonofibrils

Aggregated keratin filaments

31

Keratinization

Cells lose their organelles, cytoplasm, and nuclei. To filets are formed and arranged into fibrils by fillagrin. When the tonofilaments reach the upper layers of the stratum corneum the desmosomes are broken apart and the cells are sloughed off. Type of apoptosis.

32

Rete Ridges

Epidermal ridges that are infoldings that act to reduce stress.

33

What two layers make up the dermis?

The papillary (loose CT) and the reticular (DICT)

34

What kind of tissue makes up the dermis?

Connective tissue

35

What are some functions of the dermis?

Gives strength and elasticity to skin, contains the smooth muscles that move hair, puckering or skin especially in erectile organs

36

Papillary Layer

Superficial layer. Loose connective tissue (more cells than fibers). Vascular. Type I and type III fibers. Irregular network of elastic fibers that form an irregular network. Contains meissner corpuscles.

37

Reticular Layer

Thicker and deep to the papillary layer. Made of DICT (less cells). Characterized by thick irregular bundles of type I collagen

38

Hypodermis

Layer of adipose tissue, varies in thickness. Serves as a major energy storage and insulation

39

Epithelial Appendages

Outgrowths of the epidermis that extend into the dermis. Hair follicles, hair, nails, glands (eccrine, sebaceous, apocrine)

40

Hair Follicle

Invagination of the epithelium that extends into the hypodermis. Not found in thick skin. Bulb contains matrix cells for hair formation.

41

What are the three parts of the hair follicle?

Infundibulum (opens on the surface), isthmus (narrowing of follicle), and inferior segment (hair bulb)

42

Phlebo Sebaceous Gland

Hair+hair follicle+smooth muscle+sebaceous gland

43

What are the three parts of hair?

Medulla-central part that contains large vaculated cells cell and only present in thick hairs
Cortex-peripherally to the medulla and contains cuboidal cells undergoing differentiation into keratin filled cells
Cuticle-squamous cells that form the outmost layer

44

Nails

Hard plates made of epidermal keratinized cells. Help with grip and give protection.

45

Hyponysium

Loose CT that is found under the nail bed and contains the nerve endings

46

Sebaceous Gland

Simple branched acinar. Opens into the hair follicle, Holocene secretion of sebum. Helps to keep hair from being brittle. Secretory portion is located in the deeper dermis.

47

Sweat Glands

Found in all kinds of skin. Simple coiled tubular glands. Found in the deep dermis.

48

What are the three types of cells that sweat glands contain?

Clear cells-abundant glycogen (PAS stain)
Dark Cells-lots of rER and secretory granules
Myoepithelial Cell-basal aspect of the secretory segment.

49

What kind of epithelium makes up the sweat glands?

Stratified cuboidal epithelium

50

Apocrine Glands

Found in armpit and perineum. Coiled tubular glands. Secretes hormones. Merocrine excretion. Opens into the hair follicle.

51

Pacinian Corpuscles

Pressure changes and vibrations. Found deep in the dermis Large and surrounded by Schwann cells.

52

Meissner's Corpuscles

Light touch-located close to the epidermis. Looks like a q-tip

53

Ruffini's Corpuscles

Stretch and torque

54

Where do free nerve endings terminate?

The stratum granulosum