Exam 2 Flashcards
what are the 2 layers of the dermis and what percentage of the dermis does each make up?
-pappilary Layer (20%)
- reticular layer (80%
What makes the subcutaneous layer ideal for drug injection?
extensive vascular network promotes rapid absorption
How does the subcutaneous layer differ among sexes?
thicker in women and accumulates in breasts, hips, thighs
thinner in men and accumulates in arms, abdomen, and back
What is the papillary layer composed of?
areolar connective tissue forms dermal papillae
what is the reticular layer composed of?
dense irregular tissue surrounding hair follicles, sebaceous glands and sweat glands, nerves, and blood vessels
what are the two most common types of exocrine glands in the skin?
sweat glands and sebaceous glands
what is another name for sweat glands?
sudoriferous glands
what are the two types of sweat glands
merocrine(eccrine) and apocrine
what part of sweat glands contract upon nervous system stimulation to release sweat?
myoepithelial cells
what type of sweat gland is most numerous?
merocrine
where are merocrine sweat glands abundant?
palms,soles, and forehead
what is a main function of merocrine glands?
thermoregulation
what to merocrine glands secrete?
sweat(99% water, salts, vit C, antibodies)
what do merocrine ducts connect to
pores of skin
where are apocrine glands located?
only axillilary and genital areas
what do apocrine glands secrete?
sweat, fatty substances, & proteins
what type of sweat gland is larger than the other?
apocrine sweat glands
what do apocrine ducts empty into?
hair follicles
when do apocrine glands begin to function?
puberty
what are the two types of modified apocrine glands?
ceruminous and mammary glands
how are most sebaceous glands formed?
most develop from hair follicles and secrete into hair follicles
what do sebaceous glands secrete?
sebum
what are the four stages of wound healing?
- cut blood vessels bleed into wound
- blood clot forms and leukocytes clean wound
- blood vessels re grew and granulation tissue forms
- epithelium regenerates and CT fibrosis occurs
what are the obstacles in healing a more severe injury?
longer time needed for wider and deeper surfaces, hair follicles, exocrine glands, and nerves may not be repaired
what indicates a first degree burn?
epidermal damage only; localized redness, swelling, and pain
what indicates a second degree burn?
epidermal and upper dermal damage; blisters appear
what indicates a third degree burn?
entire thickness of skin involved; skin can be white, bright red, or blackened, not painful or swollen, skin grafting is typically necessary
what are the treatments/concerns for burn victims?
- manage fluid loss
- relieve swelling
- manage pain
- remove dead tissue
- control infection
what are the two types of bones tissue?
compact bone and spongey bone
what is another name for compact bone?
dense/cortical bone
what percent of bone mass does compact bone make up?
80%
what is another name for spongey bone?
cancellous/trabecular bone
what percent of bone mass does spongey bone make up?
20%
where is hyaline cartilage found in bones?
- attaches ribs to sternum
- covers ends of some bones
- cartilage within growth plates
where can fibrocartilage be found in bones?
- intervertebral discs
- pubic symphysis
- cartilage pads of knees
what are some functions performed by bones?
- support and protection
- movement
- hemopoiesis
- storage of mineral and energy reserves
what is hemopoiesis?
blood cell production
where does hematopoiesis occur?
in red bone marrow CT
what key minerals are stored in bones?
calcium and phosphate
why is calcium important in the body?
essential for muscle contraction, blood clotting, and nerve impulse transmission
why is phosphate important in the body?
ATP utilization and plasma membranes
where are lipids stored in adult bones?
in yellow bone marrow
what region of the bone is the diaphysis?
the elongated usually cylindrical shaft
what is the diaphysis composed of?
compact bones with thin spicules of spongey bone extending inward
what are the functions of the diaphysis?
provides leverage and weight support
where is the medullary cavity?
the hollow space within the diaphysis
what is found in the medullary cavity?
red bone marrow in children and yellow bone marrow in adults
where is the epiphysis?
the knobby region at each end of long bone
what is the epiphysis composed of?
composed of an outer thin layer of compact bone and an inner region of spongey bone
where is articular cartilage found?
covers the joint surface on each epiphysis
what is the function of articular cartilage in long bones?
reduces friction and absorbs shock in moveable joints
what is the metaphysis?
region of mature bone between diaphysis and epiphysis
what is another term for the growth plate?
epiphyseal plate
what is the epiphyseal plate made of?
a thin layer of hyaline cartilage
what is the epiphyseal line?
the remnant of the epiphyseal plate once growth has completed
what is the periosteum
tough sheath covering outer surface of bone
what is the outer layer of the periosteum composed of?
fibrous layer of dense irregular CT
what are the functions of the outer layer of the periosteum?
- protects bone from surrounding structures
- anchors blood vessels and nerves to bone surface
- attachment site for ligaments and tendons
what s the inner layer of the periosteum composed of?
osteoprogenitor cells, osteoblasts, and osteoclasts
what attaches the periosteum to bone?
perforating fibers
what is the endosteum
incomplete layer of cells that contains osteoprogenitor cells, osteoblasts, and osteoclasts
what is the function of the endosteum?
covers all internal surfaces of bone within medullary cavity
how does the gross anatomy of other bone types differ from long bones?
external surface composed of compact bone and interior is composed of spongey bone with no medullary cavity
What is diploe?
spongey bone in flat bones of skull
true or false, bones are avascular
false, bones are highly vascularized, ex., in regions of spongy bone
where do blood vessels enter the bone?
from the periosteum
what is the nutrient foramen?
a small opening or hole in bone where arteries can enter and veins can exit
what is the function of nerves in bone and where do they enter?
accompany blood vessels through foramen and innervate bone, periosteum, endosteum, and marrow cavity (mainly sensory nerves)
what is another name for red bone marrow?
myeloid tissue
what is a function of red bone marrow?
form blood cells (hemopoietic)
where is red bone marrow located in children?
located in spongey bone and medullary cavity of long bones
where is red bone marrow located in adults?
only in select areas of axial skeleton
what is red bone marrow composed of?
reticular CT, immature blood cells, fat
what is yellow bone marrow?
fatty substance that is a product of red bone marrow degeneration as children mature
what may cause yellow bone marrow to convert back to red bone marrow
severe anemia
what are the 4 types of cells found in bone CT?
- osteoprogenitor cells
- osteoblasts
- osteocytes
- osteoclasts
what are osteoprogenitor cells?
stem cells derived from mesenchyme that matures to become an osteoblast
where are osteoprogenitor cells found?
located in periosteum and endosteum
what is the function of osteoblasts?
synthesize and secrete osteoid
what is osteoid?
the initial semisolid form of bone matrix that is produced by osteoblasts and later calcifies
what do osteoblasts differentiate into?
osteocytes
what are osteocytes and what is their function?
mature bone cells derived from osteoblasts that maintain bone matrix, detect mechanical stress on bone, and trigger deposition of new bone matrix
what are osteclasts and what are they derived from
large, multinuclear phagocytic cells derived from fused bone marrow cells
what are the organic components of bone matrix?
osteoid contains collagen protein and semisolid ground substance, gives bone flexibility
what are the inorganic components of bone matrix?
calcium phosphate salt crystals that harden matrix and account for rigidity of bones
describe the process of bone resorption
- bone matrix is destroyed by substances released from osteoclasts
- calcium and phosphate dissolved by hydrochloric acid
- freed calcium and phosphate ions enter blood
when does bone resorption occur?
when blood calcium levels are low
what is compact bone composed of?
small cylindrical structures called osteons (haversian systems)
what is the central canal of the osteon and what is its function?
cylindrical channel at center of osteon that blood vessels and nerves extend through
what are the concentric lamellae of the osteon and what are their function?
rings of bone CT that surround central canal
what are the osteocytes of the osteon and what are their function?
mature bone cells found between concentric lamellae that maintain bone matrix
what are the canaliculi of the osteon and what are their function?
tiny, interconnecting channels within bone CT that allow for exchange of nutrients, minerals, and other substances between blood vessels and osteocytes
what are perforating canals?
canals that blood vessels and nerves travel through that run perpendicular to central canals
what are circumferential lamellae
rings of bone
what are insterstitial lamellae?
components of compact bone between osteons that are incomplete
what are trabeculae and what are their function?
open lattice of narrow rods and plates of bone that resists stress found in spongey bone
describe the steps of interstitial growth in cartilage
1.) chondrocytes within lacuna are stimulated to divide
2.) two chondroblasts cells occupy a single lacuna
3.)chondroblasts secrete new material and become separate chondrocytes
4.)cartilage continues to grow internally
describe the steps of appositional growth in cartilage
1.) stem cells at edge of perichondrium begin to divide
2.) new undifferentiated stem cells and chondroblasts are formed
3.)chondroblasts push apart and become chondrocytes
how does cartilage growth occur during early embryonic development?
interstitial and appositional growth occur simultaneously
how is cartilage growth affected as carilage matures?
interstitial growth declines rapidly and cartilage becomes semi rigid
how is cartilage growth affected after cartilage is fully mature?
new cartilage growth stops and only occurs after injury
what are the 2 types of ossification?
intramembranous and endochondral ossification
what is intramembranous ossification and what does it produce?
bone growth within a membrane, produces flat bones of skull, some facial bones, and mandable
describe the steps of intramembranous ossification
1.) ossification centers form within thickened regions of mesenchyme
2.) osteoid undergoes calcification
3.)woven bone and surrounding periosteum form
4.) lamellar bone replaces woven bone
what bones are produced via endochondral ossification?
almost all bones inferior to skull
when does endochondral ossification occur and how so?
begins late in 2nd month of development using hyaline cartilage models
describe the steps of endochondral ossification
1.) begins at primary ossification center in center of shaft
2.) bone collar forms around diaphysis of cartilage model
3.) central cartilage in diaphysis calcifies
4.)periosteal bud invades cavities and forms spongey bone
5.) diaphysis elongates and medullary cavity forms
what are the two types of postnatal bone growth?
interstitial and appositional growth
define interstitial growth in bones
increase in length of long bones
define appositional growth in bones
increase in bone thickness
what is required for interstitial growth?
presence of epiphyseal cartilage
how does the epiphyseal plate close and when does this typically happen?
bone lengthening ceases as the none and epiphysis and an diaphysis fuse, occurs at about 18 for females and 21 for males
how does appositional growth occur?
osteoblasts beneath periosteum secrete bone matrix on external bone and osteoclasts remove bone on endosteal surface (occurs throughout life)
how is the growth hormone important for bone growth?
most important in stimulating epiphyseal plate activity in infancy and childhood
how is the thyroid hormone important for bone growth?
regulates activity of growth hormone and ensures proper proportions
how are testosterone and estrogen important for bone growth?
promote adolescent growth spurts and end growth by inducing epiphyseal plate closure
what percent of bone mass is recycled each week
5-7%
how often does bone get replaced?
spongey bone - every 3-4 years
compact bone - every 10 years
what does bone remodeling consist of?
bone deposit and bone resorption
why is calcium important in the body?
functions in:
- nerve impulse transmission
- muscle contraction
- blood coagulation
- cell division
how much calcium do we have in our bodies?
1200-1400 grams (99% as bone)
what hormone regulates blood calcium levles
parathyroid hormone (PTH),
calcitonin may also be involved
describe the 3 fracture classifications
1.)position of bone ends after fracture
- nondisplaced: ends retain normal position
-displaced: ends out of normal alignment
2.)completeness of break
- complete: broken all the way through
- incomplete: not broken all the way through
3.) whether skin is penetrated
- open (compound)
- closed (simple)
what are the two types of reduction used to treat fractures?
closed reduction: physically manipulated to correct position
open reduction: surgical pins pr wires secure ends
what are the stages of bone repair
1.) hematoma forms
2.)fibrocartilaginous callus forms
3.)bony callus forms
4.)bone remodeling occurs
