Week 7 - Integumentary System

Question 1

skin

Answer 1

one of the largest organs of the body

Question 2

protection

Answer 2

-mechanical protection -> keratin in the outermost layer
-prevents dehydration -> lipid secretions from cells and glands
-UV radiation protection -> melanin in melanocytes and keratinocytes absorb UV radiation
-antimicrobrial effect

Question 3

body temperature regulation

Answer 3

helps in regulating body temperature; sudoriferous glands produce sweat to reduce heat

Question 4

sensation

Answer 4

contains various receptors which detect stimuli: mechanoreceptors, thermoreceptors, nociceptors

Question 5

excretion

Answer 5

removes waste products (eg. salts, urea, ammonia, CO2) from the body; sweating removes a variety of chemical wastes, in small amounts

Question 6

synthesis of vitamin D

Answer 6

UV radiation from sun stimulates the skin to convert an inactive form of vitamin D to an active form; vitamin D is needed to absorb calcium

Question 7

epidermis

Answer 7

-keratinocytes (~90%): produce keratin, which protects and keeps the skin waterproof
-melanocytes (~8%): produce melanin, one of the major pigments responsible for skin colour, also protects the skin from UV rays

Question 8

layers of the epidermis

Answer 8

stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale

Question 9

stratum corneum

Answer 9

flat, closely packed, dead keratinocytes (20-30 layers of cells), keratin instead of cytoplasm, glycolipids in extracellular space; the layer that is shed during abrasion

Question 10

stratum lucidum

Answer 10

only in areas where the skin is thick (palms, soles, fingers); clear, flat, dead keratinocytes that contain eleidin which will eventually transform into keratin

Question 11

stratum granulosum

Answer 11

three to five rows of flattened, dying keratinocytes, losing nuclei and organelles; contains granules of keratohyalin

Question 12

stratum spinosum

Answer 12

eight to ten rows of live keratinocytes and melanocytes packed tightly together containing pre-keratin; surfaces of cells appear to look spiny

Question 13

stratum basale

Answer 13

rapidly dividing keratinocytes and melanocytes to replenish the cells above it; single row of cuboidal or columnar cells

Question 14

dermis

Answer 14

deep to the epidermis;
-papillary region: loose areolar connective tissue; contains blood vessels and sensory receptors
-reticular region: dense irregular connective tissue with bundles of collagen and elastic fibers; gives the skin its strength, flexibility, and elasticity

Question 15

hypodermis

Answer 15

deep to the dermis; contains adipose tissue and blood vessels; not considered part of the skin

Question 16

sebaceous glands

Answer 16

produces oil to keep hair from drying out; keeps skin waterproof, soft and pliable

Question 17

sudoriferous glands

Answer 17

produces sweat to control body temperature and to excrete chemical wastes