Mitosis and Ch.5 Flashcards
What phase is the cell in most of the time?
Interphase
What cells do not replicate?
Neurons and muscle cells
What happens at the end of interphase?
DNA replication
What happens during interphase?
-Centrioles duplicate
-DNA polymerase copies DNA
-Nuclear envelope encloses nucleus
-Nucleus and Nucleolus are clearly visible
-Individual chromosomes not distinguishable
What happens during prophase?
-Nuclear envelope disappears
-Centrioles migrate
-DNA supercoils
-Mitotic Spindle forms
What happens during metaphase?
-Chromosomes attach to spindles and line up midline
What happens during anaphase?
-Sister chromatids pulled to opposite sides of cell
-Sister chromatids separate
What happens during telophase?
-Nuclear envelope reappears
-Mitotic spindle disappears
-DNA uncoils
-Cytokinesis (end of mitosis); cell divided in two
Which cells do not have the same DNA?
Sperm and egg cells
How do cells differentiate?
-Some genes are turned on and some are turned off
What do stem cells do?
-Stem cell is still dividing and changes what genes it is expressing
-Cells differentiate and become specialized cell
What are the functions of the integumentary system?
-Protection
-Sensation (touch, temp, pain)
-Thermoregulation (sweating)
-Excretion (getting rid of waste products)
-Synthesis of Vitamin D
What is another name for the skin?
Cutaneous membrane
What is the outer epidermis’s name and what tissue is it made up of?
Superficial epithelium (made up of epithelial tissues)
What is in the inner dermis and what tissue is the inner dermis made up of?
-made up of connective tissues
-contains lots of fibers
-blood vessels and cutaneous receptors
Where is the hypodermis?
Underlies the skin and is not considered part of the skin
What do epithelial tissues do?
Border cells
What do connective tissues do?
Fill spaces- fibers
What are the accessory structures of the skin and where do they originate?
-Hair, nails, multicellular exocrine glands
-originate in dermis and extend through epidermis to skin surface
What is the full name for the epidermis?
Avascular stratified squamous epithelium
How do nutrients and oxygen get to the epidermis?
They diffuse from capillaries in the dermis
What are characteristics of the epidermis?
-avascular (will not bleed)
-Multiple layers of cells (stratified)
-squamous (thin and flat)
-always sloughing (shedding)
What are the characteristics of thin skin?
-grows hair
-covers most of the body
-has 4 layers of keratinocytes
What are the characteristics of thick skin and where do you find it?
-covers palms of hands and soles of feet
-has 5 layers of keratinocytes
What are the characteristics of keratinocytes?
-change from bottom to top of epidermis
-most abundant cells in epidermis
What is the order of thin skin of the epidermis from deep to superficial?
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum corneum
What is the order of thick skin from deep to superficial?
Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Stratum Corneum
What are the characteristics of the stratum corneum?
-15 to 30 layers of cells
-water resistant
-Cells are anucleate (without a nucleus)
-Takes 40 to 50 days for cells to go from stratum basale to stratum corneum
What are the characteristics of the stratum lucidum?
-clear layer
-found only in thick skin
-covers stratum granulosum
-not visible on our histology slides
What are the characteristics of the stratum granulosum?
-grainy layer
-vesicles contain precursors to keratin; in 2 different vesicles; mixed together to make keratin
-produce keratin
-dehydrate and die, become water resistant
What are the characteristics of the stratum spinosum?
-spiny layer
-produced by division of stratum germinativum (basale layer)
-several cells thick
-cells shrinks until cytoskeleton sticks out
-further from blood supply and closer to surface air; dehydration from evaporation
-Contain dendritic (Langerhans) cells, active in immune response
What are the characteristics of the stratum basale?
-germinative layer
-one cell thick
-only cells undergoing mitosis that are stem (basale) cells and give rise to other cells in other layers
-contains Merkel cells and melanocytes
-forms strong bond between dermis and epidermis
What are Merkel cells?
-found in hairless skin
-respond to touch (trigger nervous system)
What are melanocytes?
-contain melanin
-scattered throughout stratum germinativum
What tints can melanin have?
orangish-brown
blackish-blue
Most people will have both
What do melanocytes do?
-Produces melanin in transport vesicles (melanosomes) in stratum germinativum
What happens when there is more melanin?
more protection
transferred to keratinocytes
What is carotene?
pigment contributing to skin coloration (dietary)
How does hemoglobin relate to the skin and where is it?
-in dermis and shines through epidermis
-oxygenated red blood contributes to skin color
-blood vessels dilate from heat, skin reddens
-blood flow decreases, skin pales
What is cyanosis and what causes it?
-bluish skin tint
-Caused by severe reduction in blood flow or oxygenation
What produced Vitamin D3 and what is it in the presence of in order to be produced?
-Epidermal cells
-UV radiation
-Liver and kidneys convert Vitamin D3 into calcitriol
Where does calcitriol travel to and what is its function?
Travels to small intestine as a hormone and encourages absorption of calcium and phosphorus in the gut
What happens when there is insufficient Vitamin D3?
Rickets (bones get bendy)
What are the cells in the dermis called?
Fibroblasts
What is the dermis between?
-epidermis and subcutaneous (hypodermic) layer
Where are the accessory structures of the skin anchored?
The dermis
What are the 2 layers of the epidermis from deep to superficial?
-reticular
-papillary
What is the structure of the papillary layer and what is its function?
-Has papilla (like little fingers)
-Made up of loose connective tissue (areolar)
-few cells; lots of fiber
-delicate layer; smaller capillaries, small sensory neurons, lymphatics
-anchors dermis to epidermis
-has dermal papillae projecting between epidermal ridges
What is the structure of the reticular layer and what is its function?
-Dense irregular connective tissue (unorganized dense fiber)
-contains larger blood vessels, lymph vessels, and nerve fibers
-contains collagen and elastin fibers
What are the characteristics of collagen fibers?
-very strong, resist stretching but bend easily
-provide flexibility and tensile strength
What are the characteristics of elastic fibers?
-Permit stretching and then recoil to original length
-limit the flexibility of collagen fibers to prevent damage to tissue
-fibers break down with age and UV radiation
What are other names for the hypodermis?
-subcutaneous layer
-tela subcutanea
-superficial fascia
What are the functions of the hypodermis?
-stabilizes skin
-allows separate movement
-site of subcutaneous injections using hypodermic needles
What is the hypodermic layer made up of?
adipose and areolar tissues
What happens during repair of the integument?
-Fibroblasts produce dermal (collagen and elastic) fibers
-overproduction can produce scar tissue
-often avascular
What can happen if there is too much collagen in scar tissue?
It can change the texture and make it less flexible
Where do accessory structures come from?
embryonic epidermis
What are the functions of the hair?
-protect and insulate
-guards openings against particles and insects
-sensitive to very light touch
What is the arrector pili muscle?
-involuntary smooth muscle
-produces goose bumps
What is the hair root composed of?
-follicle
-sheath
-bulb
-papilla
What part of the hair can you pull out?
sheath
What is special about the papilla?
It is the only portion of the hair with nuclei, because it is the only portion dividing
What is the function of the nail?
protects fingers and toes
What is the nail made up of?
-dead cells packed with keratin
What is the scientific name for the cuticle?
-Eponychium
What can change the nail structure?
Metabolic disorders
Where are apocrine sweat glands found?
armpits, groin, and around nipples
What do apocrine glands secrete?
-Water-based sweat
-secretes products into hair follicles
-Produces sticky, cloudy secretions
-break down and cause odors
-secretes more organic compounds than merocrine glands
What are apocrine glands surrounded by?
myoepithelial cells that contract like a little muscle and squeeze apocrine gland secretions onto skin surface
When are apocrine sweat glands activated?
In response to hormonal or nervous signal
What do eccrine (merocrine) glands secrete?
-secretes water, electrolytes, and some organic compounds directly onto skin
What are the functions of the merocrine glands?
-cools skin
-excretes water and electrolytes
-flushes surface of skin
What do sebaceous glands secrete and where?
-oil (sebum)
-Secretes primarily into hair follicle
-has antiseptic qualities on surface of skin
-sebum can destroy bacteria when it is secreted onto skin before bacteria invades
What is the primary function of Vitamin D?
Vitamin D is required for calcium absorption from the small intestine
What is the most numerous cell type in the epidermis?
Keratinocyte
What is the thickest layer of the epidermis?
Stratum spinosum
Which of the following cells are associated with the dermis?
-fibroblasts
-keratinocytes
-dendritic cells
-melanocytes
fibroblasts
What tissue composes the reticular layer of the dermis?
dense irregular connective tissue
Where are melanocytes located?
stratum basale of the epidermis
Extreme stretching of the reticular layer of the dermis results in _____
permanent stretch marks
Which of the following sensations is not detected by the skin?
-pain
-equilibrium
-temperature
-light touch
equilibrium
Which of the following structures is not found in thick skin?
-stratum granulosum
-hair follicles
-sweat glands
-stratum lucidum
hair follicles
Skin without keratin is more likely to…
tear upon being mechanically stressed
What is the main tissue of the epidermis?
Keratinized stratified squamous epithelium
What are the main components of the cutaneous membrane?
Epidermis and dermis
Where are blood vessels housed that nourish the epidermis?
Dermal papillae
What cells of the epidermis function as phagocytes of the immune system?
Dendritic cells
What is the primary function of melanin?
To protect the DNA of keratinocytes from mutations induced by UV radiation
The cuticle around a nail is
Eponychium
Humans often purchase antiperspirants and deodorants to suppress and mask the odors of secretion from the
apocrine glands
What type of secretion do sebaceous glands use?
Holocrine secretion
Mammary glands are specialized
sweat glands
What stimulates the secretion of sebum?
sex hormones
Melanin is produced upon exposure to
UV radiation
Eccrine glands produce
sweat containing mostly water
The nail body covers the
nail bed
The _____ is the opaque crescent-shaped area near the proximal nail fold
Lunula
Merocrine glands that secrete products into hair follicles are
apocrine glands
In which of the following locations are dead keratinized cells found?
-hair follicle
-hair root
-hair bulb
-hair shaft
hair shaft
Which of the following molecules is responsible for yellow-orange skin pigment?
carotene
