9 - Integumentary System

Question 1

Which tissue types are included in the integumentary system?

Answer 1

All of them!!!!

Question 2

What are the basic layers of the skin?

Answer 2

Epidermis
Dermis

Hypodermis (not actually a part of the skin)

Question 3

What kind of tissue is the epidermis made of?

Answer 3

Stratified squamous epithelium.

Question 4

What are the 5 strata of the epidermis? When are there only 4? Which one is missing?

Answer 4

Bad Students Get Low C's.
Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Stratum Corneum

Stratum Lucidum is only visible in thick skin.

Question 5

Describe Stratum Basale

Answer 5

 single row of cells
 2 cell types:
i. keratinocytes (90%)
 undergo mitosis
 make keratin (tough protein)
 migrate to surface as new cells produced in basale
ii. melanocytes (10%)
 produce pigment (melanin) for UV light protection
o e.g. sunburns, wrinkles (collagen damage), cancer (DNA damage).

Question 6

Why does skin colour differ between people?

Answer 6

o	we all have the same relative number of melanocytes, but cells produce different amounts/shades of melanin
o	albinos = no melanin
o	blood (hemoglobin) - in dermis can give a pinkish tinge to fair skinned people

Question 7

Describe Stratum Spinosum

Answer 7

 limited cell division

Question 8

Describe Stratum Granulosum

Answer 8

 contains dark staining granules (cells are still alive)

Question 9

Describe Stratum Lucidum

Answer 9

 flat, dead cells (too far from blood supply)

 visible ONLY in thick skin

Question 10

Describe Stratum Corneum

Answer 10

 20 - 30 layers of flat dead cells filled with keratin (tough protein), surrounded by waterproofing glycolipid (prevents water loss)
 shed and replaced from below

Question 11

Describe the Dermis

Answer 11

 contains blood vessels, nerves, glands, hair follicles
 2 sub-layers (CT – from mesoderm):
o Papillary Layer (beneath epidermis)
 areolar CT
 vascular
 has projection into epidermis = dermal papillae
o in thick skin these form dermal ridges = fingerprints (improve grip)
o Reticular Layer
 most of dermis
 dense irregular CT

Question 12

Describe the Hypodermis

Answer 12

(NOT part of skin)
 = subcutaneous layer
 = superficial fascia (these are just different names for the hypodermis)
o Fascia = CT layers that surround and support organs
 adipose CT below skin
o stores 1⁄2 of body’s adipose tissue (insulation)

Question 13

What is the difference between thick skin and thin skin? Where do you find them?

Answer 13

 refers to epidermis (not dermis)
 characteristics:
1) Thin Skin
 lucidum not apparent
 has hair follicles, sebaceous glands, arrector pili muscles
2) Thick Skin
 found on the palm of the hand and the sole of the foot
 lucidum visible
 no hair follicles, sebaceous glands, or arrector pili muscles

Question 14

What are the different epidermal derivatives?

Answer 14

Hair
Nails
Skin Exocrine Glands

Question 15

Is hair dead or alive?

Answer 15

Dead

Question 16

What are the parts of the hair?

Answer 16

a) Root = dead cells below the surface of the skin
b) Shaft = above the skin surface
c) Hair follicle – surrounds root
i. epithelial root sheath = several epidermal layers extend into the dermis
ii. bulb = expanded region at base of root
iii. matrix = single layer of cells (derived from basale cells) - site of hair growth and melanin for hair colour

Question 17

What are the structures associated with the hair follicle?

Answer 17

a) outer CT sheath ⇒ holds follicle in place (formed from the dermis)
b) hair papilla – extends upward beneath matrix
o contains blood supply for growing hair
o formed from dermis
c) root hair plexus - free nerve ending (touch)
d) sebaceous (oil) gland - opens into follicle
e) arrector pili muscle (smooth muscle) - causes “goosebumps”

Question 18

Describe Nails

Answer 18

	very heavily keratinized epidermal cells
consists of:
o	nail root (buried in skin)
o	body (visible portion)
o	free edge

Question 19

What are the 4 skin exocrine glands? What do they do?

Answer 19

a)	sebaceous glands  
	connected mainly to hair follicles
	secretes sebum (oily - mix of fats, salts, proteins)
o	softens, lubricates hair and skin, prevents drying out, antibiotic 
b)	sudoriferous glands 
	sweat glands
	secretory portions in dermis of thick and thin skin 
	ducts open onto skin surface
	act to:
o	cool the body body
o	antibiotic (acidic)
o	remove wastes (urea, etc.)
c)	ceruminous glands
	modified sweat glands
	in ear canal
	produce ear wax - prevents insects etc from entering
d)	mammary glands
	modified sweat glands
	produce milk

Question 20

What organ system are the cutaneous sense receptors a part of?

Answer 20

Nervous system, receptors are sensory neurons.

Question 21

What are the 4 main types of cutaneous sense receptors? Where are they found? What do they do?

Answer 21

1) Touch Receptors
a) free nerve endings
• in epidermis
b) Root Hair Plexuses
c) Meissner’s Corpuscles
• in dermal papillae
• corpuscle = connective tissue capsule surrounding nerve ending
2) Pressure Receptors
a) free nerve endings
• in dermis
b) Pacinian corpuscles
• deep in dermis or hypodermis
3) Thermoreceptors
• free nerve endings for temperature
4) Nociceptors
• free nerve endings for pain
• 3rd degree burns = no pain because nociceptors destroyed