Chapter 5 - Integumentary System Flashcards
What makes up the integumentary system?
Skin, hair, nails, and cutaneous glands
What percentage of body weight does your skin make up?
7-15%
What tissue types make up the integumentary system?
All 4
What are the two primary regions of the skin? What is the region that is not part of the skin but often studied together?
- epidermis
- dermis
Not skin - hypodermis
What does the skin protect against?
Resists physical trauma and infection (keratin and desmosomes)
Bacterial invasion (sebum is acidic, dendritic cells phagocytize pathogens, outer layer is dead and dry)
UV Radiation
How does the skin regulate water loss/absorption?
Keratinized cells control water entering/leaving the body
Insensible and sensible perspiration
What is the difference between insensible and sensible perspiration?
Insensible is the release of water when not visibly sweating, sensible is visible sweat
Why is the skin important in vitamin D production?
Vitamin D production is important in bone development and requires small amounts of UV light to produce
How does the skin gather sensory information?
It’s the largest sensory organ. It senses tough, pressure, pain, and temperature and supply the CNS with information about external condictions
How does the skin regulate body temperature?
Thermoreceptors
When body temp increases, blood vessels dilate and sweat glands become active
When body temp decreased, blood vessels constrict and piloerector muscles contract
How does the skin help with communication?
Facial expression
What are the 5 layers of the epidermis?
(starting at outermost layer)
- Stratum corneum
- Stratum lucidum
- Stratum granulosum
- Status spinosum
- Stratum basale
Which of the 5 layers of the epidermis is only found in thick skin?
Stratum lucidum
What type of epithelium makes up the epidermis?
Keratinized stratified squamous epithelium
Describe the epidermis (types of cells, vascular/avascular, nerves, etc)
Outer, thin region
Dead cells
Lacks blood vessels - diffusion of nutrients comes from basement membrane/CT
Few nerve endings - touch and pain
What types of cells make up the epidermis?
- stem cells
- keratinocytes
- melanocytes
- tactile (merkel)
- dendritic cells
What are epidermal stem cells are where are they found?
Undifferentiated cells
Found int he stratum basale
What do keratinocytes do?
Synthesize keratin (most of the epidermal cells)
What do melanocytes do and where are they found?
Synthesize the pigment melanin (which shields DNA)
Found in the statue basale
What do tactical/merkel cells do and where are they found?
Touch receptor cells associated with dermal nerve fibers
Found in the stratum basale
What do dendritic cells do and where are they found?
Act as macrophages/immune cells
They originate in bone marrow
Found in the stratum spinosium and stratum granulosium
What happens in the stratum basle?
Constant cell division
What happens in the stratum spinosum
Some cell division, keratin produced
Cells flatten superficially
What happens in the stratum granulosum?
lamellar bodies release lipid contents
Cornified cellular envelope develops (CE)
What happens in the stratum lucidum?
Friction protection
Only in thick skin
What happens in the stratum corneum?
Several layers of dead, keratinized cells
Mechanical barrier
Prevents desiccation
What 3 factors determine skin color?
- pigments
- blood circulating through skin
- thickness of stratum corneum
What are the two types of skin pigments?
Melanin (determined by genetics, hormones, exposure to light) and Carotene (yellow pigment)
Where do you find melanocytes?
S. basale and S. spinosum
Do darker skinned people have more melanocytes?
No, each melanocyte just produces more melanin and the melanocytes are more spread out (basale -> corneum)
What are local concentrations of melanin called?
Freckles and moles
What are dermal papillae?
Upward, finger-like extensions of the dermis
What are epidermal ridges?
Downward waves of epidermis
resists slippage, stress, and gets nutrients to epidermis
What are lamellar corpuscles?
Allow for sensitivity to texture via vibration on friction ridges (finger prints)
What are the two layers of the dermis? Which is deeper?
Papillary layer (superficial) Reticular layer (Deeper/thicker)
What are some things found in the papillary layer?
Areolar tissue, tactile corpuscles, free nerve endings, blood vessels
What are some things found in the reticular layer?
Dense irregular CT, tick bundles of collagen, sweat glands, nail roots, hair follicles, heat receptors, lamellar corpuscles
Explain vasoconstriction/vasodilation and how it affects body temperature and blood pressure? Where are these vessels found?
Vasoconstriction - vessels narrow to reduces blood flow to skin, helps conserve heat
Vasodilation - vessels hidden to increase blood flow to skin, help release heat
Vessels are found in the dermis
What is the hypodermis and what types of tissue make it up?
Subcutaneous layer, used for protection and binding
Tissues: areolar Ct, adipose tissue
What types of cells make up the hair and nails?
Dead keratinized cells
Where is hair NOT found on the body?
Palms, soles, lips, nipples, external repro. organs
What are the functions of scalp hair?
retain heat
prevent sunburn and skin cancer
What are the functions of eyebrow hair?
Accentuate facial expressions
Reduce glare
Funnel sweat out of eyes
What are the functions of beard, pubic, and auxiliary hair?
Demonstrate maturity (puberty)
What are the functions of guard hairs (vibrissae) hair?
Block foreign particles (nostrils, ears, eyes)
What are the functions of trunk/limb hair?
Evolutionary remnants
Sensory
What are the functions of eyelashes?
Shield eyes
What determines hairiness?
Differences in texture and pigment of hair
What are the three types of hair?
- lanugo
- vellus
- terminal
Describe lanugo hair and where/when is it found?
Fine, downy, unpigmented hair
Appears on the fetus (last 3 months of development)
Describe vellus hair and where/when is it found?
Fine, pale hair that replaces lanugo by time of birth
All the hair of children except eyebrows, eye lashes, and scalp hair
Describe terminal hair and where/when is it found?
Longer, coarser, and more heavily pigmented
Eyebrows, eyelashes, and scape
At puberty, terminal hair replaces vellus hair
What are the 3 zones in the structure of the hair/follicle?
Hair bulb (swelling in dermis or hypodermis, only living hair cells) Hair root (remainder of follicle) Hair shaft (portion above skin surface)
What are the 3 layers of hair (in a cross section)?
Medulla (core, absent from thin hair)
Cortex (bulk)
Cuticle (surface)
What does the arrestor pili muscle do?
Contracts in response to stiuli
Smooth muscle attaching hair follicle to dermis, “goosebumps”
What are the 3 stages of the hair cycle?
- Anagen (growth stage, follicle grows deeper into dermis, hair cells make keratin and die)
- Catagen (degeneration stage, mitosis in hair matrix stops, base of hair keratinizes)
- telogen (resting stage, club hair falls out)
What are the 5 types of skin glands? Which are the two subtypes of sweat glands?
Sudoriferous (sweat)
- merocrine/eccrine
- apocrine
- Sebaceous
- Ceruminous
- mammary
- apocrine
Describe merocrine/eccrine sweat glands and their job
Simple, coiled tubular Secrete directly to surface via duct Activate with increased temperature Job is to sweat and cool off body (merocrine secretion method)
Describe apocrine sweat glands and their job
Simple, coiled tubular Secrete into hair follicles Activate at puberty, produce pheromones Produce body odor (merocrine secretion method)
Describe sebaceous glands and their job
Associated with hair follicles
Secrete sebum (oily substance)
(holocrine secretion method)
Describe ceruminous glands and their job
Produce cerumen (ear wax)
Job is to make eardrum more pliable, help with waterproofing, antibacterial, blocks foreign particles
Modified apocrine sweat glands
Describe mammary glands and their job
Produce milk
Develop during pregnancy and lactation
(apocrine secretion method)
