Integumentary System - midterm 2 Flashcards
Integumentary system consists of: (6)
- skin
- hair
- nails
- glands (ex. sweat)
- sense receptors (nervous) ex. cold, hot, touch
- muscles (ex. cause hair to stand)
What are the 2 skin layers
Epidermis (upper layer) & Dermis (lower layer) …….. (below skin = hypodermis
Characteristics of Epidermis skin layer
- stratified squamous epithelium (from ectoderm….outside)
- avascular (lack of blood vessels)
- separated into 4-5 strata (sub-layers) based on cell types
What are the Epidermis strata (sub-layers): (5)
- Stratum Basale
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum
- Stratum corneum
(Bad Students Get Low C’s)
Stratum Basale
- 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. e.g.. sunburns, wrinkles (collagen damage), cancer (DNA damage)
> skin colour. 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
- thin dark line (anything above this layer is dead)
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 (through protein), surrounded by waterproofing glycolipid (prevents water loss)
- shed and replaced from below
What does the dermis contain + what are the 2 sublayers
- contains blood vessels, nerves, glands, hair follicles
- 2 sub-layers (CT - from mesoderm)
> Papillary Layer (beneath epidermis) (top layer), areolar CT, Vascular, has projection into epidermis = dermal papillae (finger prints in thick skin)
> Reticular Layer (bottom layer), most of dermis, dense irregular CT
Hypodermis
NOT part of skin, below the skin
- = subcutaneous layer
- = superficial fascia
> fascia = CT layers that surround and support organs
- Adipose CT below skin
> store 1/2 of bodys adipose tissue (insulation)
Thin skin
- lucidum not apparent
- Has hair follicles, sebaceous glands, arrector pili muscles
Thick skin
- found on the palm of the hand and sole of the foot
- lucidum visible
- no hair follicles, sebaceous glands, or arrestor pili muscles
Epidermal Derivatives includes: (3)
- ALL derived (formed) from the epidermis
1) Hair
2) Nails
3) Skin Exocrine glands
Hair
- all dead cells
parts:
a) root = dead cells below the surface of the skin
b) shaft = above the skin surface
c) hair follicle - surrounds root
Parts of hair follicle: (3)
i) epithelial root sheath = several epidermal layers extend into the dermis
ii) bulb = expanded region at base of root
iii) matrix (not the same as other matrix) = single layer of cells (derived from basale cells) - site of hair growth and melanin in hair colour
Associated with hair follicle: (5)
a) outer CT sheath
b) hair papilla - contains blood supply for growing hair
c) root hair plexus (touch)
d) sebaceous (oil) gland
e) arrector pili muscle (smooth muscle) causes goosebumps
Nails
-Very heavily keratinized epidermal cells
- consists of
nail root (buried in skin)
body (visible portion)
free edge
Skin Exocrine glands: (4)
1) sebaceous glands (causes greasy hair because of sebum)
2) sudoriferous glands (sweat glands)
3) ceruminous glands (in ear canal produce ear wax)
4) mammary glands (produce milk)
4 major types of cutaneous sense receptors
1) touch receptors
a. free nerve endings - in epidermis
b. root hair plexuses
c. meissners corpuscles- in demis papillae
2) pressure receptors
a. free nerve endings- in dermis
b. pacinian cormuscles - deep in dermis or hypodermis
3) thermoreceptors (temperature) - free
4) nociceptors (pain) - free
Cutaneous sense receptors
Specialized cell that responds to stimuli.
Receptor = sensory neuron
