Unit 9 - Integumentary System Flashcards
Main function of the integumentary system
Protection
What does the integumentary consist of
- skin
- hair
- nails
- glands
- muscles (goosebumps)
- sense receptors (nervous)
- hypodermis
Hypodermis
- layer below the skin
- not a layer of the skin
Layers of the skin
- Epidermis - outermost layer (superficial)
- Dermis - deep layer
Epidermis tissue
Stratified squamous epithelium
Is the epidermis vascular or avascular
Avascular
Epidermis sub-layers
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
What are the epidermis sub-layers based on
Cell types
Stratum basale of epidermis
- single row of cells (one layer)
- deepest layer
- consists of
1. Keratinocytes (90% of skin)
2. Melanocytes (10 % of skin)
Keratinocytes
- actively undergo mitosis (shedding skin)
- makes keratin
- pushed towards the surface as new cells are produced in basale
Keratin
- tough protein
- give skin protective feature
Melanocytes
- produce pigment (melanin) for UV light protection
- skin colour
What do melanocytes protect us from
- sunburns
- wrinkles (collagen damage)
- cancer (DNA damage)
How do people have different skin colours
- we all have the same relative number of melanocytes, but some cells produce different amounts and/or shades of melanin
What can blood (hemoglobin) in the dermis do
Give a pinkish tinge to fair skinned people
Skin colour in relation to sunlight
- people exposed to lots of sun will usually be darker in skin colour
- this is because of evolution over time, darker skin helps to protect those who live near the equator from getting skin damage
Stratum spinosum
- low levels of mitosis
Does the stratum granulosum consist of living or dead cells
- last layer of living cells
- no mitosis occurs
Granules in Stratum granulosum
- help produce keratin (strength)
- start to produce waterproofing glycolipids (prevents water loss)
Does the Stratum lucidum consist of dead or living cells
- first layer of dead cells
- no mitosis
Where is the stratum lucidum found
ONLY IN THICK SKIN
Why are the cells in the stratum lucidum dead
They are too far from the blood supply
Stratum corneum cells
- many layers of flat, dead cells filled with keratin
- shed and replaced from below
What makes the stratum corneum waterproof
- glycolipids between cells
- this prevents water loss
What does the dermis contain
- blood vessels
- nerves
- glands
- hair follicles
- arrest or pili muscles (smooth muscle)
Layers of the dermis
- Papillary layer
- Reticular layer
What is the Papillary layer of dermis connected to
The epidermis
What kind of tissue is the papillary layer of the dermis made of
Areolar connective tissue
Is the papillary layer of dermis vascular or avascular
Vascular
Dermal papillae
- projection into epidermis from papillary layer
- made of Areolar connective tissue
- in thick skin these form epidermal ridges (fingerprints - improve grip)
Where is the reticular layer of dermis
Between papillary layer of dermis and hypodermis
What forms most of the dermis
Reticular layer
What kind of tissue is the reticular layer of the dermis made of
Dense irregular connective tissue
What causes the look of stretch marks
- tears in collagen in reticular layer
What does the thickness of skin refer to
The epidermis (not the dermis)
Characteristics of thin skin
- covers most of body
- no stratum lucidum
What does thin skin consist of
- hair follicles
- sebaceous glands
- arrector pili muscles
Where is thick skin found
- on the palm of the hand and the sole of the foot
What does thick skin have that thin skin doesn’t have
A stratum lucidum
What does thick skin consist of
NO!!!!!
- hair follicles
- sebaceous glands
- arrector pili muscles
What things are derived (formed) from the epidermis
- Hair
- Nails
- Skin exocrine glands
Are hair cells living or dead
All dead
What is the hair root
The part of the hair that is embedded in the skin
What is the hair shaft
The visible part of the hair that is above the surface of the skin
What is the hair follicle
Surrounds the root of the hair
1. Epithelial tooth sheath- several epidermal layers extended into the dermis
2. Bulb- expanded region at base of root
3. Matrix- single layer of cells
What is the matrix of the hair follicle the site of
Hair growth and melanin for hair colour
Outer CT sheath of hair follicle
Holds follicle in place
- formed from the dermis
Hair papilla
Extends upward beneath matrix
- contains blood supply for growing hair
- formed from dermis
Hair root plexus
Free nerve ending (touch)
Sebaceous (oil) gland
Opens into follicle
Arrector pili muscle
- smooth muscle
- causes goosebumps
What are nails
Very heavily keratinized epidermal cells
What do nails consist of
- Nail root (buried in skin)
- Body (visible portion)
- Free edge
Types of skin exocrine glands
- Sebaceous glands
- Sudoriferous glands
- Ceruminous glands
- Mammary glands
Where are sebaceous glands mainly connected to
Hair follicles
What do sebaceous glands secrete
Sebum (oil)
- mix of fats, salts and proteins
- softens, lubricates hair and skin
- prevents drying out
- antibiotic
What do Sudoriferous glands secrete
Sweat
Where are Sudoriferous glands located
Secretory portions in dermis of thick and thin skin
Where do Sudoriferous glands ducts open to
The skin surface
Functions of Sudoriferous glands
- temperature regulation (cool the body)
- antibiotic action (due to sweat being acidic)
- waste removal (ex. Urea)
What are ceruminous glands
Modified sweat glands
Where are ceruminous glands found
In ear Canal
What do ceruminous glands produce
Ear wax
- prevents insects etc from entering
What are mammary glands
Modified sweat glands
What do mammary glands produce
Milk
What are sensory receptors
- sensory neuron (part of the nervous system)
- specialized cell that responds to stimuli (touch, temp, pain)
Types of sense receptors
- Touch receptors
- Pressure receptors
- Thermoreceptors
- Nociceptors
Touch receptors
- most major type
- consist of:
1. Free nerve endings (in epidermis)
2. Root hair plexuses (nerve ending at end of hair follicles)
3. Tactile (Meissner’s) corpuscles - found under dermis
- in dermal papillae
- corpuscle is a CT capsule surrounding a nerve end
Pressure receptors
Consist of:
1. Free nerve endings (in dermis)
2. Lamellar (Pacinian) corpuscles
- looks like onion through microscope
- deep in dermis or hypodermis
Thermoreceptors
free nerve endings for temperature
Nociceptors
Free nerve endings for pain
Burns
- 1st and second degree burns hurt more because Nociceptors are still intact
- 3rd degree burns destroy Nociceptors, causing lack of pain sensation in affected areas
Hypodermis
NOT a part of the skin
- layer under the skin
Another name for hypodermis
Superficial fascia
- fascia= CT layers that surround and support organs
What kind of tissue is the hypodermis made of
Adipose CT below skin that stores half of the body’s adipose tissue (insulation, fat)
Albinism
Lack of melanin production my melanocytes
Psoriasis
- autoimmune disorder that causes accelerated mitosis of keratinocytes in the stratum basale
- accelerated cell cycle delays maturation and differentiation of keratinocytes
- immature keratinocytes accumulate in the epidermis and the stratum corneum fails to shed, resulting in a thick scaly area on the surface of the skin
