Integumentary System

Question 1

Integumentary system

Answer 1

Interface between the body and its external environment

Skin proper and its derivatives

Question 2

Skin proper

Answer 2

2 main layers of the skin

Epidermis and dermis

Question 3

Skin derivatives or appendages

Answer 3

Hair and nails

Sweat, sebaceous, and mammary glands

Question 4

Epidermis

Answer 4

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

Question 5

Dermis

Answer 5

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

Question 6

Hypodermis

Answer 6

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

Question 7

What are the layers of the epidermis?

Answer 7

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

Question 8

Stratum basale/germinativum

Answer 8

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

Question 9

Stratum spinosum

Answer 9

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

Question 10

Stratum granulosum

Answer 10

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

Question 11

Stratum lucidum

Answer 11

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

Question 12

Stratum corneum

Answer 12

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

Question 13

Keratohyaline granules

Answer 13

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

Question 14

Melanocytes

Answer 14

Melanin-producing cells found in the epidermis

Derived from neural crest cells that broke off the neural tube and migrated to the skin

Question 15

Melanin

Answer 15

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

Question 16

Eumelanin

Answer 16

Form of melanin
Brown
Most common form

Question 17

Pheomelanin

Answer 17

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

Question 18

Melanosome

Answer 18

Membrane-bound vesicle containing melanin

Found in melanocytes

Question 19

How is melanin transferred to keratinocytes?

Answer 19

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

Question 20

Langerhans cell

Answer 20

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

Question 21

Merkel’s cells

Answer 21

Cells found in the epidermis

Function is debated; may have something to do with mechanoreception

Question 22

Dermatoglyphics

Answer 22

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

Question 23

Papillary layer of the dermis

Answer 23

Upper layer, underneath the stratum basal of epidermis

Contains Meissners corpuscles

Question 24

Reticular layer of the dermis

Answer 24

Lower layer of dermis, above the hypodermis

Contains Pacinian corpuscles

Question 25

Meissners corpuscles

Answer 25

Encapsulated touch receptors found in dermal papillae

Question 26

Pacinian corpuscles

Answer 26

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

Question 27

Encapsulated receptors

Answer 27

Receptors covered with CT or epithelial tissue

Loose function without capsule

Question 28

Dermal sensory fibers

Answer 28

Free nerve endings that detect heat and cold

Question 29

Dermal motor fibers

Answer 29

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

Question 30

Anogen

Answer 30

Quick, active growth of a hair

Question 31

Catogen

Answer 31

Brief period of cessation of hair growth

Question 32

Telogen

Answer 32

Hair stops growing

Follicle atrophies and hair is lost

Question 33

DHT

Answer 33

Dihydrotestosterone

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

Question 34

Arrector pili

Answer 34

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

Question 35

Sebacceous gland

Answer 35

Secrete oil via holocrine secretion

Functions as a lubricant

Question 36

Pilo-sebacceous apparatus

Answer 36

Hair follicle and sebaceous gland

Question 37

Apocrine sweat gland

Answer 37

Apocrine secretion of pheromones and sweat

Thermoregulates in mammals but NOT in humans

Question 38

Pheromones

Answer 38

Attraction hormones that affect the behavior of other organisms

Question 39

Eccrine sweat glands

Answer 39

Thermoregulation

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

Question 40

Nails

Answer 40

Accessory organ of the skin

Epithelial cells

Question 41

Tyrosine

Answer 41

Essential amino acid that is the precursor to melanin

Question 42

Lanula

Answer 42

Crescent-shaped structure of the nail

Capillaries are deeper so there is decreased blood flow and it appears lighter