anatomy exam 2 review

stratum corneum

superficial layer of the epidermis, composed of 20-30 layers of dead, flat cells

cornification

dead cells are impregnated with glycolipids and keratin to provide a tough, durable, water-proof “coat”

stratum lucidum

thin, translucent layer of dead cells, thickens the epidermic, present only in thick skin - palms, soles

stratum granulosum

composed of 3-5 layers of cells, contain lamellated granules (make epidermis water-proof) and keratohyaline granules (contain keratin that makes epidermis tough)

stratum spinosum

several layers of cells, cells connected by desmosomes, hold cells together which causes cell to appear “spiny” during histological preparation, contain tonofilaments and langerhans’ cells

stratum basale (aka stratum germinativum)

the deepest stratum, includes keratinocytes, melanocytes, merkel cells

tonofilaments

resist tension placed on the skin (in stratum spinosum)

langerhans’ cells

act as macrophages to engulf and digest pathogens (in stratum spinosum)

lamellated granules

contain glycolipids - the lipids make the epidermis water-proof (in stratum granulosum)

keratohyaline granules

contain the tough, insoluble protein keratin, makes the epidermis tough and abrasive-resistant (in stratum granulosum)

melanocytes

produces the pigment melanin contained in melanosomes

papillary layer of the dermis

composed of areolar CT, surface has dermal papillae - house blood capillaries, nerve endings, and meissner’s corpuscles which act as touch receptors

reticular layer of the dermis

composed of dense irregular CT, deeper layer of the dermis, accounts for 80% of the dermis, contains pancinian corpuscles

what are three differences between thin and thick skin?

1. thick skin has the stratum lucidum, thin skin does not

2. thin skin has hair follicles and sebaceous glands, thick skin does not

3. thick skin is thicker than thin skin in diameter

what are epidermal ridges? discuss the basis for fingerprinting

friction ridges, increase friction and enhance gripping

pattern of epidermal ridges is genetically determined and therefore unique to an individual

meissner’s corpuscles

touch receptors

pacinian corpuscles

respond to deep pressure placed on the skin - located in reticular layer of dermis

merkel discs

epidermal-dermal junctions; act as light touch receptors

sweat (sudoriferous) glands

secrete sweat for thermoregulation when body temperature rises, simple (coiled) tubular multicellular exocrine glands

eccrine sweat glands

produce watery, odorless sweat for thermoregulation (contains NaCl)

use merocrine mode of secretion

apocrine sweat glands

become active after puberty, secrete viscous yellowish fluid, secretion associated with body odor (a.k.a odoriferous glands)

use merocrine mode of secretion

sebaceous (oil) glands

simple (branched) alveolar multicellular exocrine glands, secrete sebum into hair follicles via pores to the surface of the skin

use holocrine mode of secretion

hair/hair follicles

for protection, on scalp, eyelashes, provide insulation in cold weather

nails

protects ends of the digits from trauma, for grasping and manipulating objects especially small objects, for scratching

acid mantle

the combination of acidic pH of sweat and dermcidin on the surface of the skin to retard microbial growth

what is the thermoregulatory function of the integumentary system in hot weather

sweating (perspiration)

what is the thermoregulatory function of the integumentary system in cold weather

hairs stand up due to arrector pili muscles contracting and pulling the hair follicles and hairs up

discuss how the integumentary system provides physical protection

stratum corneum contains keratinocytes that produce keratin, which creates a waterproof abrasion-resistant barrier against microbes

discuss how the integumentary system provides biological protection

langerhans’ cells act as macrophages to engulf and digest pathogens

discuss how the integumentary system provides chemical protection

melanin acts as a chemical shield to protect the nuclei of the keratinocytes from harmful effects of UV radiation in sunlight

first-degree burns

damage is confined to only the epidermis; associated with redness, swelling and pain; heal in 3 days without medical intervention (ex. sunburn)

second-degree burns

damage to the entire epidermis and the papillary layer of the dermis, associated with blisters (fluid collection at the epidermal-dermal junction), swelling, redness and pain; heal in 3-4 weeks if infection is prevented

third-degree burns

damage to the entire skin, damage to the entire epidermis and dermis including all nerve endings, hence the burn site is not painful

what are the risk factors associated with third degree burns?

subjected to infections and fluid loss

basal cell carcinoma

involves proliferation of keratinocytes in stratum basale. Least malignant and most common type of skin cancer – GROWS SLOWLY

squamous cell carcinoma

involves the cells in the stratum spinosum. Second most common type of skin cancer – GROWS RAPIDLY

melanoma

proliferation of the melanocytes; most aggressive type of skin cancer, highly metastatic and resistant to chemotherapy; least common

why are albino people more susceptible to developing skin cancer?

they lack melanin, which naturally provides natural protection against UV radiation

compact bone tissue

composed of osteon (structural units of compact bone), form the hard outer layer of all bones and diaphysis (shaft), provides high-density support

spongy bone

like a honeycomb - composed of needle-like structures called trabeculae (structural unit of spongy bones), found in the interior of bones and epiphyses of long bones, balances strength with weight reduction

long bone

consist of a shaft (diaphysis) and two ends of (epiphyses), primarily compact bone with spongy interior (ex. humerus)

short bone

rougly cube-shaped, providing stability, support, and limited motion (ex. carpals in wrist)

flat bone

thin, flattened, these bones provide extensive surface area for muscle attachment and protect underlying soft tissues (ex. sternum)

irregular bones

complex, specialized shapes that do not fit into other categories (ex. vertebra)

medullary cavity

contains red bone marrow in childhood and yellow bone marrow in adulthood

periosteum

composed of the outer fibrous layer (composed of dense irregular connective) and the inner osteogenic layer (contains osteoblasts and osteoclasts, covers outer layer of bones

endosteum

covers the internal surfaces of bone such as the canals, contains osteoblasts and osteoclasts

sharpey’s fibers

peforating fibers, attaches periosteum to compact bone

epiphyseal line

remnant of the epiphyseal plate (growth plate) that appears in long bones after longitudinal growth finishes

osteoid

organic matrix of bone tissue

osteon

structural units of compact bone

canaliculi

tiny canals that connect lacunae to each other and to central heversian canals

lamellae

concentric tubes composed of collagen fibers and form concentric rings around haversian canals

what are the types of prenatal ossification?

intramembranous ossification & endochondral ossification

what are the types of postnatal ossification?

longitudinal bone growth & appositional bone growth

intramembranous ossification

develops from fibrous connective tissue membrane (derived from mesencyme) and results in the formation of membrane bones (cranial bones and clavicles)

what type of bone are most membrane bones?

flat bones

endochondral ossification

derived from hyaline cartilage produced by chondroblasts, bones formed from this are called endochondral or cartilage bones (all other bones in the body except cranial bones and clavicles)

what are chondroblasts and fibrod connective tissue membrane derived from?

mesenchyme

after endochondral ossification, where does hyaline cartilage persist?

in two areas of the long bones as articular cartilage and epiphyseal plates

longitudinal bone growth

linear bone growth, increases the length of long bones (height)

involves epiphyseal plates

new hyaline cartilage is added on to the epiphyseal faces of the epiphyseal plates

new bone tissue is added on at the diaphyseal faces of the epiphyseal plates

*amount of new hyaline cartilage = the amount of bone tissue so thickness of epiphyseal plates does not change

appositional bone growth

increases the width/diameter of all bones

more new bone tissue is added on to the external surface and old bone tissue is slightly reabsorbed from the internal surface, resulting in thicker but lighter bone

the growth promoting effect of growth hormone on longitudinal bone is considered indirect - explain this statement

the effect of growth hormone on longtidinal bone is considered indirect because it is primarly mediated by insulin-like growth factor. Growth hormone stimulates hepatocytes to produce insulin-like growth factors (IGFs). IGFs then stimulate chondroblasts to proliferate and produce hyaline cartilage on epiphyseal facts of epiphyseal plates

what are three different ways an individual may have short stature?

1. hyposecretion of growth hormone = growth hormone deficiency

2. absence of growth hormone receptors on hepatocytes, then IGFs are not produced

3. absence of IGF receptors on chondroblasts in the epiphyseal plates - decrease in chondroblast proliferation

what do osteoblasts do in bone remodeling?

formation of new bone

what do steoclasts do in bone remodeling?

resorption of old bone

epiphyseal plate closure

complete ossification of the epiphyseal plates

how does epiphyseal plate occur?

sex steroid hormones stimulate ossification of the epiphyseal plates from the diaphyseal face

what is the consequence of epiphyseal plate closure?

excessive increase in appositional bone growth (acromegaly), longitudinal bone growth ceases

acromegaly

excessive increase in appositional bone growth

what is a stimulus for the release of parathyroid hormone (PTH) in bone remodeling?

hypocalcemic conditions - PTH released to stimulate osteoclasts to cause bone reabsorption to release calcium from bone into blood

what is a stimulus for the release of 1,25 dihydroxyvitamin D3 in bone remodeling?

hypocalcemic conditions with PTH present - stimulates bone resorption, calcium absorption from the small intestine

hypercalcemic conditions when PTH is absent - activates osteoblasts to stimulate bone formation and restore blood calcium levels to normal

functions of bone remodeling

to maintain calcium homeostasis

allow for bone repair after fracture

what is a stimulus for the release of calcitonin in bone modeling?

hypercalcemic conditions - released to stimulate osteoblasts to produce bone tissue and stimulate mineralization - uses calcium from blood

state wolff’s law

bones remodel/grow in response to mechanical stress placed on them

what are three examples where wolff’s law is applicable?

1. bone attachment sites for active skeletal muscles appear thicker

2. long bones are thicker in the middle region of diaphyses where bending stresses are greatest

3. bones in the right arm of a right-handed individual are thicker than bones in their left arm and vice versa

what are 2 main factors that control bone remodeling?

hormonal control & mechanical stress

what are the 3 functional classes of joints

synarthortic joints (immovable joints)

amphiarthortic joints (slightly movable joints)

diarthrotic joints (freely moveable joints)

what are the 3 structural classes of joints?

1. fibrous joints

2. cartilaginous joints

3. synovial joints

what are the 3 types of fibrous joints?

sutures, gomphoses, syndesmoses

which are the immovable joints?

synarthortic joints

which are slightly movable joints?

amphiarthrotic joints

which are freely moveable joints?

diarthrotic joints

sutures

located only in the skull

functional class in baby - amphiarthortic joints

functional class in adult - synarthrotic joints

gomphoses

located only between teeth and bony alveolar sockets

syndesmoses

bones connected by ligaments or bones connected by interosseous membranes

name the type of fibrous joint that is only found in the skull

sutures

name the type of fibrous joint that is located between teeth and the alveolar sockets

gomphoses

name the type of fibrous joint formed by interosseous membrane

syndesmoses

name the type of fibrous joints that are considered amphiarthrotic joints

syndesmoses

name the type of fibrous joints that are considered synarthrotic joints

sutures and gomphoses

what are the 2 structural types of cartilaginous joints?

synchondroses & symphyses

synchondroses

hyaline cartilage connects bones

symphyses

fibrocartilage connects bones

what is the functional class of synchonroses

synarthrotic joints

what is the functional class of symphyses

amphiarthrotic joints

the epiphyseal plate is an example of which type of cartilaginous joint?

synchondroses

what type of cartilaginous joint is an intervertebral disc?

symphyses

plane joints

articulating surfaces are flat

pivot joints

one articular surface is round

one articular surface is a sleeve or round