Topic 9: Integumentary System Flashcards
What does the system consist of?
consists of: o skin o hair, nails, glands o sense receptors (nervous) o muscles
List the layers of the skin
2 layers
- epidermis
- dermis
epidermis
upper layer
dermis
lower layer
hypodermis
below skin
Is the hypodermis part of the skin?
NO
below the skin
List the characteristics of the Epidermis
stratified squamous epithelium (from ectoderm)
avascular
separated into 4-5 strata (sub-layers) based on cell types:
List the sub- layers of the epidermis:
o Stratum Basale o Stratum Spinosum o Stratum Granulosum o Stratum Lucidum o Stratum corneum
Stratum Basale
single row of cells
2 cell types
i. keratinocytes (90%)
ii. melanocytes (10%)
keratinocytes
undergo mitosis
make keratin (tough protein)
migrate to surface as new cells produced in basale
melanocytes
10%)
produce pigment (melanin) for UV light protection
o e.g. sunburns, wrinkles (collagen damage),
cancer (DNA damage)
skin colour
o we all have the same relative number of
melanocytes, but cells produce different
amounts/shades of melanin
albinos
no melanin
blood (hemoglobin
in dermis can give a
pinkish tinge to fair skinned people
Stratum Spinosum
limited cell division
Stratum Granulosum
contains dark staining granules
Stratum Lucidum
flat, dead cells (too far from blood supply)
visible ONLY in thick skin
Stratum corneum
20 - 30 layers of flat dead cells filled with keratin (tough protein),
surrounded by waterproofing glycolipid (prevents water loss)
shed and replaced from below
Describe the characteristics of the dermis
contains blood vessels, nerves, glands, hair follicles
2 sub-layers (CT – from mesoderm):
o Papillary Layer
o Reticular Layer
Papillary Layer
(beneath epidermis)
areolar CT
vascular
has projection into epidermis = dermal papillae
o in thick skin these form epidermal ridges = fingerprints
(improve grip
Reticular Layer
most of dermis
dense irregular CT
dermal papillae
has projection into epidermis
Describe the Hypodermis
(NOT part of skin)
subcutaneous layer; under
superficial fascia; not deep so above
adipose CT below skin
o stores 1⁄2 of body’s adipose tissue (insulation
Fascia
CT layers that surround and support organs
What does thick vs thin skin refer to?
refers to epidermis (not dermis)
Thin Skin
lucidum not apparent
has hair follicles, sebaceous glands, arrector pili muscles
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
Epidermal Derivatives
ALL derived (formed) from the epidermis
List the epidermal derivatives:
- hair
- nails
- skin exocrine glands
Hair
all dead cells
List the parts of hair
a) root
b) shaft
c) hair follicle
Root
dead cells below the surface of the skin
Shaft
above the skin surface
Hair follicle
surrounds the root
- epithelial root sheath
- bulb
- matrix
epithelial root sheath
several epidermal layers extend into the dermis
bulb
expanded region at base of root
matrix
single layer of cells (derived from basale cells) - site of hair
growth and melanin for hair colour
List what is associated with each hair follicle
a) outer CT sheath
b) hair papilla
c) root hair plexus
d) sebaceous (oil) gland
e) arrector pili muscle (smooth muscle)
outer CT sheath
holds follicle in place (formed from the dermis)
hair papilla
extends upward beneath matrix
o contains blood supply for growing hair
o formed from dermi
root hair plexus
- free nerve ending (touch)
sebaceous (oil) gland
- opens into follicle
arrector pili muscle (smooth muscle)
- causes “goosebumps”
Nails
very heavily keratinized epidermal cells consists of: o nail root (buried in skin) o body (visible portion) o free edge
List the skin exocrine glands
a) sebaceous glands
b) sudoriferous glands
c) ceruminous glands
d) mammary glands
sebaceous glands
connected mainly to hair follicles
secretes sebum (oily - mix of fats, salts, proteins)
o softens, lubricates hair and skin, prevents drying out, antibioti
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.)
ceruminous glands
modified sweat glands
in ear canal
produce ear wax - prevents insects etc from entering
mammary glands
modified sweat glands
produce milk
receptor
sensory neuron (part of NS
Cutaneous Sense Receptors
specialized cell that responds to stimuli (touch, temp., pain)
List the 4 major types of cutaneous sense receptors
1) Touch Receptors
2) Pressure Receptors
3) Thermoreceptors
4) Nociceptors
Touch Receptors
a) free nerve endings • in epidermis b) Root Hair Plexuses c) Meissner’s Corpuscles • in dermal papillae • corpuscle
corpuscle
= connective tissue capsule surrounding nerve ending
Pressure Receptors
a) free nerve endings
• in dermis
b) Pacinian corpuscles
• deep in dermis or hypodermis
3) Thermoreceptors
• free nerve endings for temperature
Nociceptors
- free nerve endings for pain
* 3rd degree burns = no pain because nociceptors destroyed
Describe which layers get damaged in a first second and third degree burn
1st= epidermis 2= dermis 3= hypodermis
When we get a cut which layer of the skin have we reached?
dermis- bc vacular