BIOL 223 Exam 2 (CH 5, 6 & 7) - Minnie

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components of skeletal system: bones, cartilage, ligaments, and connective tissue that stabilize or interconnect the bones
osteology: study of bone structure and treatment of bone disorders
primary functions of skeletal system: 1. support, 2. stroage of minerals and lipids, 3. blood cell production, 4. protection, 5. leverage
support (function): muscle anchors to skeletal system
storage (function): skeletal system stores calicum and yellow bone marrow
blood cell production (function): skeletal system undergoes hematopoiesis
protection (function): skeletal bones protect organs
leverage (function): skeletal system assists in the force of motion
long bone examples: humerus, femur, tibia, fibula, metatarsals, and phalanges
flat bone examples: sternum, ribs, scapula, and cranial bones (parietal)
short bone examples: carpals, tarsals (talus), patella
irregular bone examples: pelvic bones, vertebrae, sphenoid, and ethmoid
main structures of a long bone: diaphysis and epiphysis
diaphysis: shaft of a long bone
structure of diaphysis: the wall is compact bone and the center space is a medullary cavity
medullary cavity: the central space in the shaft of bones that contains yellow bone marrow
epiphysis: the ends of long bones
structure of epiphysis: mainly spongy bone with a layer of compact/cortical bone covering it, it can also contain red or yellow bone marrow
periosteum: external sheath, covers external surfaces, except articular cartilage
endosteum: covers interior surfcaces of bone and medullary cavity
articular cartilage: covers both epiphesies, made of hyaline cartilage, once eroded rarely does it grow back (arthritis)
irreversible arthritis: eroded articular cartilage
epiphyseal growth plate: hyaline cartilage, bones are still able to grow longer, eventually becomes bone
epiphyseal line: made of bone, stops bone growth = adult height achieved
cortical bone (cortex): a layer of compact bone that covers spongy bone
structure of flat bone: resembles a sandwich of spongy bone between two layers of compact bone
diploe: within the cranium, the spongy bone sandwiched inbetween two layers of compact bone
osseous tissue: supporting connective tissue, contains specialized cells, ground substance, and extracellular protein fibers
matrix of bone: organic and inorganic matrix
organic matrix: provides flexibility and strength, collagen fibers and bone cells
collagen fibers in organic matrix: provides tensile strength, flexibility, but provides little resistance to compression forces
inorganic matrix: provides rigidity to bone and provides compression strength, also contains calcium salts and minerals
calcium salts in the inorganic matrix: calcium phosphate calcium hydroxide calcium carbonate
calcium in the inorganic matrix: comes from our diet and cannot be made in our bodies naturally
the matrix without collagen (organic): bone shatters
the matrix without minerals (inorganic): bone is extremely flexible
types of bone cells: osteocytes, osteoblasts, osteoprogenitor, osteoclasts
osteocytes: within a lacuna, mature bone cells, main cell type, amitoic
functions of osteocytes: maintain and monitor protein and mineral content of the bony matrix, and helps repair broken bone
osteoblasts: no lacunae, bone forming cells
functions of osteoblasts: make and release proteins for the organic matrix, bone deposition
osteogenesis: bone deposition (creation)
calcification: production of calcium salts in the organic matrix
mineralization: adding minerals to the bone, mainly calicum
osteoprogenitor/osteogenic cells: originate from mesencymal cells (c.t stem cells), found in the endosteum and inner cellular/osteogenic layer of the periosteum
functions of osteoprogenitor cells: repairs fractures, bone remodeling, and maintains population of osteoblast (becomes one through division)
cytoplasmic extensions: used in osteocytes to reach out to other osteocytes
canaliculi: canals that cytoplasmic extensions of osteocytes pass through to communicate with other osteocytes and diffuse nutrients
osteoclasts: giant cells with 50+ nuclei that come from stem cells that make white blood cells, ruffled edges
functions of osteoclasts: bone resorption, by secreting acids and digestive enzymes to dissolve the bony matrix, then releases stored minerals to blood
osteolysis: destroy or erode bone, performed by osteoclasts
structure of compact bone: osteon, central canal, and perforating canals
osteon/haversian system: basic unit, cylindrical, one direction (for vertical compression resistance)
central canal/haversian canal: contains blood vessels and nerves, inside the osteon, lined by endosteum
perforating canals/volkmann's canals: perpendicular to central canal, carries blood vessels and nerves to bone, lined by endosteum
types of lamellae in compact bone: concentric, circumferential, interstitial
concentric lamellae: forms osteons, contains central canal (inner layer)
circumferential lamellae: found at bone surfaces contains two layers: inner and outer (outer layer)
outer (external) circumferential lamellae: covered by periostem, found at bone surfaces
inner (internal) circumferential lamellae: covered by endosteum, found at bone surfaces
interstital lamellae: space fillers between osteons, uses recycled osteons (middle layer)
structure of spongy bone: no osteons, trabeculae, light, located where bones are not heavily stressed, and not visible externally
trabeculae: bony struts/columns that support the meshwork of the bony matrix, lined by endosteum, contains no canals
spaces between the trabeculae: either filled with red or yellow bone marrow
red bone marrow: filled with blood, the site of hemopoiesis
hemopoiesis: blood cell production
yellow bone marrow: in some spongy bone, stores fat, no blood production
bone cells of the periosteum and endosteum: 1. osteoblasts 2. osteoprogenitor cells 3. osteoclasts
structure of the periosteum: made of dense collagenous c.t (c.t proper), 2 layers, and contains perforating fibers
layers of the periosteum: outer fibrous layer and inner cellular layer
inner cellular/osteogenic layer (periosteum): contains osteoblasts, osteoprogenitor cells, and osteoclasts
perforating fibers: thick bundles of collagen fibers that secure/anchors the periosteum to bone
function of the periosteum: isolates bone, a route for blood vessels and nerves, bone growth, bone repair, and remodeling and is an attachment point for ligaments and tendons
structure of the endosteum: strictly cellular (no collagen), 1 layer, and lines the internal surfaces of the medullary cavity, trabecular, and canals
layer of the endosteum: contains osteoblasts, osteoprogenitor, and osteoclasts
functions of the endosteum: bone growth, repair, and remodeling
ossification: process of replacing tissue with bone
minerlization/calcification: process of calcium salt and other mineral deposition on the organic matrix
intramembranous ossification: bone forms directly within mesenchyme, simplier, occurs in flat bones: cranium, mandible, and clavicle
endochondral ossification: bone forms within hyaline cartilage, begins at second month of development, occurs in most bones in skeleton
steps of intramembranous ossification: 1. develop ossification center 2. calcification 3. formation of trabeculae 4. develop the periosteum
steps of endochondral ossification: 1. Development of cartilage model 2. Growth of cartilage model 3. Development of primary ossification center 4. Development of medullary cavity 5. Development of secondary ossification center 6. Formation of articular cartilage & epiphyseal plate
zone of resting cartilage (resting zone): zone where there's non-dividing chondrocytes, closest to the epiphysis
zone of proliferating cartilage (proliferating zone): zone where chondrocytes actively divide and produce new cartilage
zone of hypertrophic cartilage (hypertrophic zone): zone where chondrocytes hypertrophy
hypertrophy: chondrocyte increases in size, preparing for ossification and triggering calcification
zone of calcified cartilage (calcification zone): zone where calcified cartilage form, chondrocytes die and leave an open space
zone of ossification (ossification zone): zone where osteoblasts fill in open space and being the process of osteogenesis, closest to diaphysis
appositional growth: increase in diameter and thickness of bone
effects of exercise on bone: more bone deposition than bone resorption
effects of lack of exercise on bone: more bone resorption than bone deposition
vitamin C: a vitamin required for collagen synthesis and stimualtion of osteoblast differentiation
vitamin A: a vitamin that stimulates osteoblast activity
vitamin K and B12: a vitamin that is needed for synthesis for bone proteins
calcium: most abundant mineral in body, mainly stored in bone tissue, circulates in blood
normal range for calcium: 8mg/dL - 11mg/dL
functions of calcium: 1. bone development and maintenance 2. nerve impulse transmission 3. muscle contraction 4. blood clotting
homeostasis of calcium: maintained by calcitonin and parathyroid hormone
overal function of calcitonin and PTH: control storage, absorption, and excretion of calcium
parathyroid hormone (PTH): made by parathyroid gland that increases blood calcium ion levels
increased blood calcium ion levels: stimulating osteoclasts increase absorption of blood calcium in intestines decrease calcium excretion in kidneys increases calcitriol secretion by kindeys
calcitonin: produced by thyroid gland and decreases blood calcium ion levels
decreased blood calcium ion levels: inhibit osteoclasts decrease absorption of blood calcium in intestines increase calcium excretion in kidneys decrease calcitriol secretion by kidneys
bone response: increase blood calcium: osteoclasts stimulated to release stored calcium ions from bone, calcium is released
intestinal response: increase blood calcium: rate of intestinal absorption increases, calcium absorbed quickly
kidney response: increase blood calcium: kidneys retain calcium, more calcitriol into intestines, and less calcium in urine
bone response: decrease blood calcium: osteoclasts inhibited while osteoblasts continue to lock calcium ions in bone matrix, calcium stored
intestinal response: decrease blood calcium: rate of intestinal absorption decreases
kidney response: decrease blood calcium: kidneys allow calcium loss, less calcitriol into intestines, more calcium in urine
4 steps to repairing a fracture: 1. fracture hematoma 2. fibrocartilaginous callus 3. bony callus 4. remodeling
fracture hematoma (step in repairing fractures): a mass of clotted blood, forming within 6-8 hrs after fracture, the blood escapes from ruptured blood vessel, forming a hematoma
fibrocartilaginous callus (step in repairing fractures): tissue repair begins, this fills the space between the ends of the broken bone for about 3 weeks
bony callus (step in repairing fractures): osteoblasts produce trabeculae of spongt bone and convert the fibrocartilaginous callus to bone joining the broken bones together, lasting about 3-4 months
remodeling (step in repairing fractures): osteoblasts bulid new compact bone reforming the bone collar, osteoclasts absorb the spongy bone creating a new medullary cavity
avulsion fracture: complete severing of a body part
colles fracture: fracture of the dital end of the lateral forearm bone, makes a "dinner fork" deformity
comminuted fracture: bone is splintered into several small pieces between the main parts
complete fracture: bone is broken into two or more pieces
compound fracture: broken ends of the bone protrude through the skin
compression fracture: bone is squashed
depressed fracture: broken part of the bone forms a concavity
displaced fracture: fractured bone parts are out of anatomic alignment
epiphyseal fracture: epiphysis is separated from the diaphysis at the epiphyseal plate
greenstick fracture: partial fracture; one side of bone breaks- the other side is bent
hairline fracture: fine crack in which sections of bone remain aligned
impacted fracture: one fragment of bone is firmly driven into the other
incomplete fracture: partial fracture extends only partway across the bone
linear fracture: fracture is parallel to the long axis of the bone
oblique fracture: diagonal fracture is at an angle
pathologic fracture: weakening of a bone caused by disease process
pott fracture: fracture is at the distal ends of the tibia and fibula
simple fracture: bone does not break through the skin
spiral fracture: fracture spirals around axis of long bone, results from twisting stress
stress fracture: thin fractures due to repeated, stressful impact such as running
transverse fracture: fracture is at right angle to the long axis of the bone
osteopenia: bones become weaker and thinner, beginning at 30-40 yrs, results in fragile limbs, reduction in height, and tooth loss
osteoporosis: severe reduction in bone mass, enough to compromise function, often at 45+ yrs old
bone mineral density (BMD): total amount of bone mass in a defined area, an indicator of overal bone strength and health, total amount of mineral content
healthy/strong BMD: higher the BMD measurement
unhealthy/weak BMD: lower the BMD measurement
dual energy x-ray absorptiometry (DEXA): techinque to determine BMD and bone loss, using 2 x-ray beams through the body, the amount of x-ray energy that passes through is measured
Fibrodysplasia Ossificans Progressiva (FOP): rare genetic disease, muscle tissue replaced by bone
gigantism: overproduction of growth hormones before closure of epiphyseal plate, bones get longer
acromegaly: overproduction of growth hormones after closure of epiphyseal plate, bone get thicker
osteitis deformans (paget's disease): chronic disorder, results in enlarged, weak, deformed bones. due to abnormal bone struction by excessive proliferation of osteoclasts and regrowth by osteoblasts
achondroplasia: genetic disorder of bone growth, cartilage being abnormally converted to bone
osteogenesis imperfecta (brittle bones disease): genetic disorder of bone, extreme fragility of the bones due to a defect in collagen deposition
osteosacroma (osteogenic sacroma): a type of cancer, starts in bone, typically in tibia and fibula in males 10-25 yrs old
rickets: a disease in children and adolescents, failure of osteoid to calcify- resulting in soft and weak bones from prolonged vitamin D deficiency
osteomalacia: in adults, failure of osteoid to calcify- results in soft and weak bones from a vitamin D deficiency
osteomyelitis: bone infection from S. auerus, can begin from an open fracture or after surgery where an area is infected and spread to bone
integument: made of keratinized stratified squamous epithelium, covering, body's first line of defense, most exposed
what are the two major components of the inegumentary system?: cutaneous membrane and it's accessory structures
cutaneous membrane: epidermis + dermis = skin
epidermis: superifical epithelium, avasular
dermis: underlying connective tissue, vascular
acessory structures of the integumentary system: hair, nails, exocrine glands, located in the dermis, and projects through the skin's surface
keratinocytes: 90% of epithelial cells in epidermis that make keratin and lamellar granules
keratin: fibrous protein, rope-like structure
lamellar granules/bodies: specialized organelles, flat layers of lipids inside cytoplasm of keratinocytes
hard keratin: thick; hair and nails
soft keratin: loose; skin
basale (germinative) cells: stem cells, a layer of stratum basale that contains dividing cells
stratum basale (germinativum): deepest layer, 1 layer of living keratinocytes, and within them are scattered keratin intermediate filaments, anchored to basement membrane via hemidesmosomes
epidermolysis bullosa (EB): inability of stratum basale to effectively anchor to basement membrane which results in painful blisters anywhere were epithelium is located
horizontal division (mitosis) occurs at?: at the dermal papilla
vertical division (mitosis) occurs at?: at the valley
specialized cells of the stratum basale: merkel cells and melanocytes
eumelanin: brown-black
pheomelanin: yellow-brown
melanocytes: 10-25% of stratum basale cells, produces and protects pigment melanin, has "arms" that reach out to keratinocytes
stratum spinosum: 8-10 layers of living cells, spiny layer due to keratinocytes making coarser bundles of keratin intermediates, provides strength and flexibility to skin, lamellar bodies accumulate
specialized cells of stratum spinosum: dendritic (langerhans) cells aka intraepidermal marcophages
dendrictic (langerhans) cells: in epidermis, cells that are part of our immunity, phagocytes pathogens
stratum granulosum: 3-5 layers of keratinocyutes beginning apoptosis, keratohylain granules bind thick bundles of keratin and plasma membrane collects proteins to make a tough cell envelope
keratohyalin granules: dense granules that cross-link keratin fibers with kertain intermediates
stratum lucidum: 4-6 layers of dead cells found only in thick skin, cells are clear flattened, dead, and densely pack with no organelles
stratum corneum: 50+ layers of dead cells found on the exposed surface of skin that are cornifed and are resistant to abrasion, waterproofs skin, reduces water loss, and protects from microbes
lamella ichtyosis: autosomal recessive disorder, either from birth or later in life from inablity to form a cell envelope for intercellular lipid layers to adhere, creating a defective barrier and scale-like skin (in stratum granulosum)
which strata contains dead cells: stratum lucidum and stratum corenum
keratinization (cornification): formation of a layer of dead, protective cells filled with keratin, occurs on all surfaces except the eyes
skin life cycle: 4-6 weeks, moving a cell from stratum basale to stratum corneum and then sheds
thin skin: majority of superficial epithelium, causes hairy skin (except for lips and external genitalia)
thin skin contains:: sebaceous glands, merocrine (eccrine) sweat glands, and apocrine sweat glands
structure of thin skin: thicker dermis, composed of 4 epidermal strata, papillae are less pronounce, and few sensory receptors
thick skin: hairless, covers palms, soles of feet, fingertips
thick skin contains:: merocrine (eccrine) sweat glands
structure of thick skin: thinner dermis, 5 epidermial strata, dermal papiliae are more pronounce (gives more surface area for fingerprints, grip and sensitivity) and contains no hair follices or associated structures
compontents to skin coloration: epidermal pigmentation and dermal circulation
two pigments associated with epidermal pigmentation: carotene and melanin
carotene: orange-yellow pigment from epidermal cells and fatty tissue, that converts to vitamin A
melanin: brown, yellow-brown, or black pigment that protects skin from UV radiation, but it's synthesis is slow
melanosomes: packages and carries melanin from melanocyte to keratinocyte
where in the body does the number of melanocytes heavily accumate among the keratinocytes?: nipples, scrotum (males), and labia (females)
what does skin pigmentation rely on?: depends on melanin production not the number of melanocytes
nevus: mole, harmless overgrowth of melanocytes
freckles: yellowish-brown spots, localized areas of increased melanocyte activity, depends on sun exposure and heredity
albinism: inherited autosomal recessive condition, melanin production non-functional, melanocytes can't produce melanin
vitiligo: autoimmune disorder, a loss of color and melanocytes
erythema: excessive redness of the skin by blood vessels dialting and increasing blood flow
what can cause erythema?: inflammation, infection, excessive heat, allergic reaction
pallor: paleness from blood vessels constricting and decreasing blood flow
what can cause pallor?: shock, excessive cold, and anemia
cyanosis: skin turns blue-purple from severe reductti
what can cause cyanosis?: exposure to extreme cold, lack of oxygen to the tissue from heart failure, or severe asthma
jaundice: bulidup of bile pigment, bilirubin, made from the liver. Gives yellow colorization to the skin and whites of eyes
addison's disease: autoimmune disease, causes the destruction of the adrenal gland causing skin darkening or bronzing to occur
basal cell carcinoma: common, least dangerous, seldom metastasizes (no spreading), in stratum basale
characteristics and location of a basal cell carcinoma: small, shiny elevation, develops into central depression with a pearly edge. Often seen on the face
squamous cell carcinoma: may metastasize, in stratum spinosum's keratinocytes, and treated with early detection and surgical removal
characteristics and location of squamous cell carcinoma: early= raised, red, and scaly. late= concave ulcers with elevated ridges. Often found on scalp, ears, and lower lip
malignant melanoma: most deadly, agressive growth and metastasis, commonly from a pre-existing mole, requires early detection and advanced therapies to treat
ABCDE rule: usual signs of melanoma, asymmetry, border, color, diameter, evolving
What are the two layers of the dermis?: papillary layer and reticular layer
papillary layer: superificial layer of dermis, areolar tissue, contains smaller capillaries, lymphatics, sensory neurons, and dermal papillae
dermatitis: inflammation of the skin, mainly papillary layer, itchy and painful, caused by infection, radiation, mechanical irritation or chemicals (poison ivy)
reticular layer: deeper layer of dermis, dense irregular collagenous connective tissue (collagen and elastic fibers) contains blood vessels, lymphatic vessels, nerve fibers, hair follicles, sebaceous and sudoriferous glands
collagen fibers: very strong, resists stretching
elastic fibers: permits stretching and recoil, provides extensibility and elasticity to skin
skin turgor: Measure of hydration, which tests how quickly the skin returns to its normal position after being pinched
sagging and wrinkles: reduced skin elasticity
what causes wrinkles and sagging?: dehydration, aging, horomal changes, and uv exposure
stretch marks: striae, thickened scar tissue resulting from excessive stretching to the reticular layer of the dermis
what causes stretch marks?: pregnancy, weight gain and weight loss
lines of cleavage (tension lines): collagen and elastic fibers in the dermis arranged in parallel bundles that resist force in specific directions
a parallel cut with tension lines: remains shut, heals well
a right angled or perpendicular cut with tension lines: pulls open and scars, delayed healing
contusion: damage to blood vessels resulting bruising
forms of innervations of skin: nerve fibers (neurons) and sensory receptors (nerve endings)
nerve fibers (neurons): controls blood flow and gland secretions
sensory receptors: provides cutaneous sensations
merkel (tactile epithelial) cells: in epidermis, light touch, and superficial pressure
tactile (meissner) corpuscle: in dermal papillae, light rubbing and light touch
bulbous (ruffini) corpuscle: in dermis, steady pressure and stretching
root hair plexus: free nerve endings in hair, light touch, and movement of hair shaft
free nerve endings: in epidermis, temperature, and pain
lamellated (pacinian) corpuscle: in reticular layer and subcutaneous, deep pressure and vibration
thermoregulation: function of skin, body temp regulation, makes sweat at the surface and adjust blood flow to the dermis
blood reservoir: function of skin, holds volumes of blood, dermis has plexus of blood vessels that carry blood flow
how does keratin provide protection?: protects underlying tissues from microbes, abrasion, heat, and chemicals
how does lipids provide protection?: inhibit evaporation
how does sebum provide protection?: keeps hair and nails from drying out and contains bacterial-killing chemicals
how does melanin provide protection?: UV protection
intraepidermal macrophages: phagocytizes microbes
how does acid pH provide protection?: stunts growth of some microbes with the acidic mantle of skin
cutaneous sensation: function of skin, detects touch, pressure, vibration, and pain
excretion and absorption: function of skin, excretes salts, water, and organic wastes
synthesis of vitamin D: function of skin
decubitus ulcers: bedsores, results from dermal circulation being restricted affecting both the epidermis and dermis
functions of hair: protects, insulates, guards openings, and is sensitive to light touch
the human body is covered with hair, except:: palms, sides of fingers, toes, soles of feet, lips and portions of external genitalia
hair follicle: deep in dermis, makes nonliving hairs, consists of dermal root sheath and epithelial root sheath
dermal root sheath: dense fibrous connective tissue, outer most layer
epithelial root sheath: epithelial tissue, consists of external (middle) and internal (inner) layers
hair: consists medulla, cortex, cuticle, hair root, and hair shaft
medulla: central core of hair
cortex: middle layer of hair
cuticle: surface layer of hair
hair root: deeper/lower part of hair thats attached to integument, contains hair bulb
hair bulb: the base of the hair root that contains hair papilla and matrix
hair shaft: superficial/upper part of hair that is not attached to the integument
arrector pili muscle: involuntary smooth muscle that causes hair to stand up, producing "goose bumps"
hair production: occurs at the hair bulb
hair papilla: mound-shape structure that projects into the hair bulb and contains capillaries
hair matrix: a layer of dividing basal cells that produces hair structure, pushes hair up and out of skin
growing hair: firmly attached to hair matrix
club hair: hair is not growing and attached to an inactive follicle
new hair growth cycle: follicle becomes active, produces new hair, club hair is shed or pushed out by growing hair
vellus hair: soft and fine hair that covers the body surface
terminal hair: heavy and pigmented hair, that covers the head, eyebrows, eyelashes and other parts of the body after puberty
hair color: produced by melanocytes at the hair matrix and determined by genes
anagen: growing phase, 6-8 years, stratum basale is actively divding hair, papillae will descend
catagen: degrenterative phase, 2-3 weeks, transition to inactive
tetogen: resting phase, 1-3 months, club hair falls out
hypertrichosis: inherited or genetic or spontaneous mutation, overgrowth of hair, werewolf syndrome
ingrown hair: when a shaved or tweezed hair grows back into the skin, causing inflammation, pain, and bumps. Common in very curly hair
sebaceous glands: exocrine gland, holocrine secretion, makes sebum, lubricates hair and skin and controls bacteria
sebum: oil that inhibits growth of bacteria, lubricates and protects the keratin of the hair shaft, made by sebaceous glands
acne: plugged sebaceous duct and hair follicle from increased activity of sebaceous gland secretions
two types of sudoriferous glands: apocrine and merocrine sweat glands
mammary glands: exocrine gland, specialized sweat gland that produces milk, compound alveolar/acinar glands
ceruminous glands: exocrine gland, produces cerumen, protects the eardrum
cerumen: earwax
nails: made of dead keratinocytes packed with keratin, protects fingers and toes
nail body: visible portion of the nail
nail bed: keratinized stratified squamous epithelia, underneath the nail body
nail root: the portion of a nail that is buried in a fold of skin
free edge: distal to the nail root
lunula: pale crescent at the base of the nail
hyponchium: beneath the distal free edge of the nail
eponychium: cuticle, where the visible nail emerges
nail matrix: contains dividing cells that produce new nail cells
ingrown toenails: common, painful condition where the lateral nail fold grows over the edges of the nail or the nail grows into the skin
psoriasis: an autoimmune disorder, causing a high rate of mitotic division of keratinocytes that result in abnormal accumulation of dead cells
furuncle: a skin infecftion, a boil
impetigo: infection of skin surface, caused by staph
onycholysis: nail lifting, separation of nail body from the free edge of the nail bed
carbuncle: skin infection where a group of hair follicles clusters into a boil and is pus filled
cutaneous horn: hard keratin on skin
ringworm: highly contangious fungal skin infection