Biology 3.11

Question 1

Integument System

Answer 1

Network or organs that protect internal environment of the body. Includes skin, hair in humans. Includes exoskeletons, shells in other organisms

Question 2

Functions of the skin

Answer 2

Thermoregulation, protection, environmental sensory input, excretion, immunity, blood reservoir, vitamin D synthesis

Question 3

Thermoregulation as a function of skin

Answer 3

provides surface for heat dissipation, regulates body temperature, sweating cools body down, contraction of hair follicles trap in heat

Question 4

Protection as a function of skin

Answer 4

Physical barrier to abrasion, bacteria, dehydration, chemicals, UV radiation

Question 5

Environmental sensory input as a function of skin

Answer 5

Senses temperature, pain, touch, pressure

Question 6

Excretion as a function of skin

Answer 6

Water, slats, ammonia secreted as sweat

Question 7

Immunity as a function of skin

Answer 7

Specialized cells of epidermis are in immune system

Question 8

Blood reservoir as a function of skin

Answer 8

Vessels in dermis hold up to 10% of the blood in resting adult

Question 9

Vitamin D synthesis as a function of skin

Answer 9

UV radiation activates a skin molecule that is precursor to vitamin D

Question 10

Main layers of skin structure

Answer 10

Epidermis, dermis, hypodermis (subcutaneous)

Question 11

Epidermis

Answer 11

Outermost layer composed of avascular epithelial tissue, dependent on dermis for oxygen and nutrients.

Question 12

Type of cells in epidermis

Answer 12

Keratinocytes, melanocytes, Langerhan cells, Merkel cells

Question 13

Keratinocytes

Answer 13

Produce keratin to waterproof the skin

Question 14

Melanocytes

Answer 14

Make and distribute melanin to keratinocytes

Question 15

Langerhan cells

Answer 15

Dendritic cells of skin, interact with helper T-cells of immune system

Question 16

Merkel cells

Answer 16

Mechanoreceptors that attach to sensory neurons, allow for detection of touch and pressure

Question 17

Layers of epidermis from outermost to innermost

Answer 17

Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale (germination)

Question 18

Stratum corneum

Answer 18

Outermost layer of epidermis, 25 to 30 layers of dead keratinocytes, cells filled with keratin and secrete lipids containing lamellar granules to allow this layer to be water repellent

Question 19

Stratum lucidum

Answer 19

Second outermost layer of epidermis, additional protection for plasma, soles of feet, fingertips, 3 to 5 layers of dead keratinocytes

Question 20

Stratum granulosum

Answer 20

Third outermost layer of epidermis, 3 to 5 layers of dying keratinocytes, cells secrete lamellar bodies/ granules that release hydrophobic lipids into extracellular matrix

Question 21

Stratum spinosum

Answer 21

Fourth outermost layer of epidermis, strength, flexibility, 8 to 10 keratinocyte layers held together by desmosomes-keratin interactions involving adhesion proteins

Question 22

Stratum basale (germination)

Answer 22

Innermost layer of epidermis, has Merkel cells and skin stem cells that divide to make keratinocytes, attached to basement membrane that separates epidermis from dermis

Question 23

Life cycle of skin cell/keratinocyte

Answer 23

Begins at stratum basale/germinativum where stem cells divide and make new keratinocytes. Old keratinocytes rise up epidermal layers while making keratin and lamellar bodies/granules. As keratinocytes become increasingly filled with keratin, they secrete lamellar granules and eventually die from being filled with keratin. At stratum corneum, dead skin cells are sloughed off spontaneously or by contact with other surfaces. Turnover rate of skin cells is 30 days

Question 24

Dermis

Answer 24

Second main layer of skin, comprised of connective tissue, colllagen and elastic fibre. Contains hair follicles, glands, nerves, and blood/ lymph vessels. Consists of papillary region and reticular region

Question 25

Papillary region

Answer 25

Outermost region of dermis, loose connective tissue, has phagocytes, lymphatic capillaries, nerve fibres, small blood vessels, interdigitates with the stratum basale

Question 26

Reticular region

Answer 26

Inner region of dermis, dense connective tissue with tight meshwork of collagen and elastic fibres, has oil glands, sweat gland ducts, fat, hair follicles, provides strength and elasticity

Question 27

Hypodermis (Subcutaneous)

Answer 27

Underneath skin, composed of areolar and adipose tissue. For fat storage, pressure sensing nerve endings, passage for blood vessels. Consists of skin glands including sebaceous (oil) glands, sudoriferous (sweat) glands, ceruminous (wax) glands, mammary (milk) glands

Question 28

Sebaceous (oil) glands

Answer 28

A skin gland part of hypodermis (Subcutaneous). Connected to hair follicles, not in palms and soles, secretions are at an unfavourable pH of 3 to 5

Question 29

Sudoriferous (sweat) glands

Answer 29

A skin gland part of hypodermis (Subcutaneous). - Eccrine is in majority, regulates temperature through perspiration - Apocrine is in armpits, pubic region, nipples and secretions more viscous

Question 30

Ceruminous (wax) glands

Answer 30

A skin gland part of hypodermis (Subcutaneous). In ear canal, barrier to entrance

Question 31

Mammary (milk) glands

Answer 31

A skin gland part of hypodermis (Subcutaneous). Makes lactic secretion after pregnancy, stimulated by suckling