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Flashcards in Integumentary System Deck (42):
1

Integumentary system

Interface between the body and its external environment
Skin proper and its derivatives

2

Skin proper

2 main layers of the skin
Epidermis and dermis

3

Skin derivatives or appendages

Hair and nails
Sweat, sebaceous, and mammary glands

4

Epidermis

Upper layer of skin
Visible
Renewable population of keratinized stratified squamous cells
Made up of layers

5

Dermis

Lower layer of the skin
Dense regular and irregular fibrous CT containing sensory and motor nerve fibers
Consists of a papillary layer and a reticular layer

6

Hypodermis

Layer of white adipose and CT fibers underneath the dermis
Separates the skin proper from underlying muscle
NOT part of the skin

7

What are the layers of the epidermis?

1. Stratum basale/germinativum
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucidum
5. Stratum corneum

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Stratum basale/germinativum

Basal layer of epidermis
Gives rise to new cells at a constant rate
Some cells contain melanin
New cells move up as they differentiate

9

Stratum spinosum

Layer of epidermis above stratum basale
Cells have "spines" that come in contact with spines of other cells to form desmosomes called node of Bizzozero
Cells are keratinocytes
Cells and nuclei flatten as they move up from below

10

Stratum granulosum

Thin layer of epidermis above stratum spinosum
Cells are further differentiated
Cells have large granules called keratohyaline granules

11

Stratum lucidum

Thin layer of epidermis above stratum granulosum
Only found in thick skin
Cells are filled with aggregated keratin (clear appearance of cells)
Nuclei and organelles are broken down
Slowly dying cells due to lack of blood supply from the dermis

12

Stratum corneum

Uppermost layer of epidermis
Sloughs away
Renewed by cells coming up from the bottom layer

13

Keratohyaline granules

Large granules filled with the protein flaggrin that induces clumping of keratin
Increases waterproofing
Allowed evolution of aquatic to terrestrial animals
Found in keratinocytes of stratum granulosum

14

Melanocytes

Melanin-producing cells found in the epidermis
Derived from neural crest cells that broke off the neural tube and migrated to the skin

15

Melanin

Antioxidant with protective function
Protects against extreme temperature and chemical exposure; UV light radiation in the skin
2 types: eumelanin and pheomelanin

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Eumelanin

Form of melanin
Brown
Most common form

17

Pheomelanin

Form of melanin
Red
Produced by some red-haired people
Not as common

18

Melanosome

Membrane-bound vesicle containing melanin
Found in melanocytes

19

How is melanin transferred to keratinocytes?

Keratinocytes phagocytize part of the melanocyte containing melanosomes, called cytokrine secretion
Melanocyte does not die

20

Langerhans cell

Stellate, APC found in the epidermis
Very active when skin is infected/exposed to infectious agents
Immunologically involved

21

Merkel's cells

Cells found in the epidermis
Function is debated; may have something to do with mechanoreception

22

Dermatoglyphics

Genetically controlled pattern of the skin consisting of epidermal and dermal papillae
Unique to each person
Fingerprints

23

Papillary layer of the dermis

Upper layer, underneath the stratum basal of epidermis
Contains Meissners corpuscles

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Reticular layer of the dermis

Lower layer of dermis, above the hypodermis
Contains Pacinian corpuscles

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Meissners corpuscles

Encapsulated touch receptors found in dermal papillae

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Pacinian corpuscles

Encapsulated pressure receptors found in the dermal reticulum
Also found in the pancreas and spleen
Consists of layers of concentric CT around a sensory nerve fiber

27

Encapsulated receptors

Receptors covered with CT or epithelial tissue
Loose function without capsule

28

Dermal sensory fibers

Free nerve endings that detect heat and cold

29

Dermal motor fibers

Autonomic innervation of dermis of skin, bv, swear glands, and arrector pili muscles

30

Anogen

Quick, active growth of a hair

31

Catogen

Brief period of cessation of hair growth

32

Telogen

Hair stops growing
Follicle atrophies and hair is lost

33

DHT

Dihydrotestosterone
Responsible for loss of vascularization of hair follicles, leading to hair death (telogen)

34

Arrector pili

Muscle that pulls on hair follicle to make it stand up
Vestigial in humans
Found in hairy mammals
Functions as a sympathetic response to make them look bigger in times of stress, and as an insulation against heat loss

35

Sebacceous gland

Secrete oil via holocrine secretion
Functions as a lubricant

36

Pilo-sebacceous apparatus

Hair follicle and sebaceous gland

37

Apocrine sweat gland

Apocrine secretion of pheromones and sweat
Thermoregulates in mammals but NOT in humans

38

Pheromones

Attraction hormones that affect the behavior of other organisms

39

Eccrine sweat glands

Thermoregulation
Development of this gland coincides with decreased hair in humans --> allowed us to be hairless

40

Nails

Accessory organ of the skin
Epithelial cells

41

Tyrosine

Essential amino acid that is the precursor to melanin

42

Lanula

Crescent-shaped structure of the nail
Capillaries are deeper so there is decreased blood flow and it appears lighter