integumentary system

Question 1

epidermis

Answer 1

• outermost layer of skin
• made mostly of keratinocytes
• keratinocytes start at the stratum basal and move upwards as they mature

Question 2

layers of the epidermis ( deepest to most superficial)

Answer 2

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

Question 3

stratum basale

Answer 3

• single layer of cuboidal/columnar cells
• deepest layer
• attached to the basement membrane
• most nourished cuz its closest to the blood supply
• site of cell division (mitosis)

Question 4

stratum spinosum

Answer 4

• 8 to 10 layers of spiny keratinocytes
• connected by desmosomes (tight connections that prevent tearing)
• limited cell division
• contains langherans cells (immune cells)

Question 5

stratum granulosum

Answer 5

• 2 - 5 layers of flattened cells
• cells contain keratohyalin granules (cells that make skin impermeable)
• nuclei start to breakdown (cells are dying)

Question 6

stratum lucidum

Answer 6

• only in thick skin (palms and soles)
• 2 - 5 layer of dead keratinocytes
• contains eleidin (translucent, water resistant protein)

Question 7

stratum corneum

Answer 7

• top layer
• 15 to 30 layers of dead keratin filled cells
• main function is to prevent water loss + protect the body

Question 8

epidermis cell types

Answer 8

1. keratinocytes
2. melanocytes
3. langerhans cells
4. Merkel cells

Question 9

keratinocytes

Answer 9

• most common skin cell
• make keratin which strengthens and waterproofs skin

Question 10

melanocytes

Answer 10

• make melanin
• protect against UV radiation
• stratum basale

Question 11

langerhans cells

Answer 11

• immune cells
• phagocytes

Question 12

merkel cells

Answer 12

• touch receptors
• located in stratum basale

Question 13

dermis cell types

Answer 13

1. fibroblasts
2. adipocytes
3. macrophages
4. mast cells

Question 14

fibroblasts

Answer 14

• make collagen, elastin and matrix
• main builders of the dermis

Question 15

adipocytes

Answer 15

fat cells

Question 16

macrophages

Answer 16

• immune cells that engulf pathogens

Question 17

mast cells

Answer 17

• release histamine
• inflammation response

Question 18

functions of the integumentary system

Answer 18

1. homeostasis
2. protection
3. thermoregulation

Question 19

arrector pili muscle

Answer 19

• tiny smooth muscle attached to hair follicles
• when cold - contracts - goosebumps

Question 20

hypodermis (subcutaneous layer)

Answer 20

• not part of the skin but lies under it
• made mostly of adipose tissue
• insulation, energy storage , anchors skin to underlying organs

Question 21

2 types of sweat glands

Answer 21

1. eccrine glands
2. apocrine glands

Question 22

eccrine glands

Answer 22

• found almost everywhere
• open directly to the skin surface
• cool the body thru sweat + evaporation
• controlled by hypothalamus

Question 23

apocrine glands

Answer 23

• found in armpits, groin, around nipples
• become active at puberty
• secrete thicker sweat into hair follicles
• play a role in body odor
• not for thermoregulation

Question 24

vasoconstriction

Answer 24

• when you’re cold, dermal arterioles vasoconstrict
• blood is kept deep - less heat lost

Question 25

vasodilation

Answer 25

- when you're hot, dermal arterioles vasodilate - more blood flow to skin surface - heat escapes - body cools

Question 26

nails

Answer 26

- hard keratin protects fingertips - helps with grasping objects

Question 27

calluses

Answer 27

- repeated friction - stratum basal increases cell division - thick pad of dead cells forms

Question 28

hair

Answer 28

- uv protection - traps debris ( nose, hair, eyelashes) - acts as a sensory receptor

Question 29

skin protection against abrasion and disease

Answer 29

1. stratum corneum - dead, keratin filled cells (shield against abrasion) 2. tight cell junctions + glycolipids = waterproof seal 3. sebum + sweat = acid mantle 4. low ph = stops bacterial growth 5. dendritic cells + wbc protect against pathogens