Integumentary System (Ch. 5) Flashcards
What are the 4 primary types of cells found in the epidermis?
- Keratinocytes
- Melanocytes
- Tactile cells
- Dendritic cells (protective from microbes)
What are the 3 steps of keratinocyte growth and development before they get sloughed off and replaced?
- Cells divide in the basal layer and are pushed towards the surface
- Cells become keratinized as they go up
- Apoptosis (programmed cell death)
Then dead cells are sloughed off and replaced
What are the strata (developmental layers) of keratinocytes/the epidermis? 4-5 depending on thin or thick skin
Deep –> superficial
Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum (in thick skin) Stratum corneum
What does the word “integument” mean?
Covering
Is the hypodermis technically a part of the skin?
No
What are the 2 regions of the skin?
Epidermis and dermis
What kind of tissue is the dermis primarily made of? Epithelial? Connective? Muscle?
Connective
Is the dermis vascularized or avascularized?
Vascularized (it’s where the epidermis gets its nutrients and blood flow from)
What are the 2 layers of the dermis?
- Papillary layer
2. Reticular layer
Which layer (hypodermis or dermis) attaches the skin to the underlying muscle?
Hypodermis
What kind of cell junctions attach keratinocytic cells to each other?
Desmosomes
How do melanocytes make melanin? What prompts your body to produce more melanin?
an enzyme (tyrosinase) converts tyrosine to melanin. Enzyme activity increases with exposure to UV radiation.
Keratinocyte layers: Stratum basale
What level is it?
What’s deep and superficial to it?
Deepest layer
Keratinocyte synthesis
Anchored to basement membrane
Superficial to it is the stratum spinosum
Keratinocyte layers: Stratum spinosum
What level is it?
What’s deep and superficial to it?
2nd layer
Deep to it: basale
Superficial to it: granulosum
Spiny protein fibers attach to desmosomes
Keratinocyte layers: Stratum granulosum
What level is it?
What’s deep and superficial to it?
3rd layer
Cells undergoing apoptosis
Protein granules dehydrate the dying cells, and staining makes the granules dark.
Deep to it: spinosum
Superficial to it: in thick skin, stratum lucidum. In thin skin, just stratum corneum.
Keratinocyte layers: Stratum lucidum
What level is it?
What’s deep and superficial to it?
4th layer in thick skin only Deep to it: granulosum Superficial to it: corneum Clear flat dead cells Lots of keratin
Keratinocyte layers: Stratum corneum
What level is it?
What’s deep and superficial to it?
4th layer in thin skin 5th layer in thick skin Top (outermost) layer Deep to it: lucidum in thick skin, granulosum in thin skin Superficial to it: nothing Continuously shed and replaced
Papillary layer of the dermis - what kind of connective tissue is it made of?
Areolar connective tissue
Loose so that phagocytes can patrol and remove bacteria
What do dermal papillae adhere to on the epidermis?
Epidermal ridges
What do epidermal ridges adhere to on the dermus?
Dermal papillae
What part of skin causes fingerprints to exist?
Dermal papillae (and their interaction with the epidermal ridges)
Which layer of skin has the sensory innervation?
Papillary layer of the dermis
Tactile corpuscles (touch receptors)
Free nerve endings including lamellated corpuscles
What does “papillae” mean? (dermal papillae)
Nipple
What are lamellated corpuscles? Where are they found?
In the dermis.
Deep pressure receptors
What kind of connective tissue is the reticular layer of the dermis made of?
Dense irregular connective tissue
Where do stretch marks come from?
Tears in the dermis
Which layer of the dermis contains hair follicles, nerves, sebaceous glands, and sweat glands?
Reticular layer of the dermis
Which has hair and sebaceous glands, thin skin or thick skin?
Thin skin
What 3 pigments in normal skin cause skin color?
- Melanin
- Carotene
- Hemoglobin
What condition results when the blood does not have enough hemoglobin? Too much hemoglobin?
Cyanosis = too little Erythema = too much
What part of the skin color-making process is different for people with albinisim?
Melanocytes are unable to produce tyrosinase, the enzyme that makes melanin
What substance builds up in the blood to cause jaundice?
Bilirubin
What are the 3 accessory structures of the skin?
- Hair
- Skin glands
- Nails
What are the 2 regions of hair?
- Shaft
2. Root
What are the 3 layers of hair?
- Medulla (inner)
- Cortex (middle)
- Cuticle (outer)
Which layer of hair has soft keratin and pigment?
Medulla (inner)
Which layer of hair has hard keratin and pigment?
Cortex (middle)
Which layer of hair has scaly snake scales with hard keratin, and does not have pigment?
Cuticle layer of hair (outer layer)
What is the role of the hair follicle?
It produces and nourishes the growing hair
What are the 3 layers of the hair follicle?
- External root sheath (continuation of epidermis)
- Internal root sheath (produced by hair matrix)
- Glassy membrane (thick basement membrane)
What does “pili” mean?
Hair
What is the difference between vellus hair and terminal hair?
Vellus hair is what babies have - fine - also body hair of females and children
Terminal hair is coarser - pubic/axillary hair and male body hair
What are the roles of the matrix and papilla in a growing hair?
Matrix has stem cells that divide to form hair
Line inner surface of hair bulb
Papilla are in the center of the bulb - connective tissue with blood vessels to nourish the growing hair
What is the root hair plexus?
The nerve endings around the hair root
Sensitive to touch
What are the 2 broad stages of the hair growth cycle?
- Growth stage
- Resting stage
Old hair falls out when growth stage resumes
What causes hair to be different colors?
Melanocytes in the hair matrix
What elements are present in the melanin in the hair of redheads and blondes?
Iron and sulfur
What are the 3 types of skin (exocrine) glands?
- Sebaceous glands (oil)
- Sweat glands (sudoriferous glands - watery secretions)
- Ceruminous glands (cerumin = earwax)
Which type of skin (exocrine) gland produces sebum?
Sebacious (oil) glands
Which exocrine secretion is made up of triglycerides, cholesterol, proteins, and salts?
Sebum
Where do sebaceous (oil) glands empty their contents? What are the contents called?
Directly into the hair follicle
Sebum
What are the 2 types of sweat glands?
- Merocrine sweat gland
2. Apocrine sweat gland
Where do merocrine sweat glands open up? What layer of skin are they embedded in?
Surface pores (for evaporative cooling) Based in dermis
Where do apocrine sweat glands exist? Where do they open up? Where are they in relation to layers of skin?
Axillae and pubic region
Sub-cutaneous (hypodermis)
Thicker and more odorous secretions than merocrine sweat glands
Where are ceruminous glands located?
In the ear
What bodily substance is cerumen?
Earwax
What are nails made of?
Highly-keratinized epidermal cells, tightly packed
What are the 2 parts of the nail?
- Nail body
2. Nail root
What part of the nail is the nail matrix?
Stem cells of the nail
Deep to the nail root
What is the eponychium of the nail? What is it made out of?
The cuticle
Made of stratum corneum
What are the 5 main functions of the integumentary system?
- Thermoregulation
- Protection
- Cutaneous sensation
- Excretion and absorption
- Vitamin D synthesis
How is Vitamin D synthesized in the skin?
UV rays convert steroids to Vitamin D3
How does Vitamin D get converted to calcitriol? What is calcitriol necessary for?
Goes to liver and kidneys to become calcitriol, which is necessary for absorbing dietary calcium
