Systems Pathology 1 | Exam 1

PCC Systems Path 1, Summer 2026

the shaft, medullary cavity of a long bone is known as the _____________

diaphysis

the neck containing the open growth plate during childhood of a long bone is known as the _________

metaphysis

the end of a bone along with the articular cartilage is known as the ___________

epiphysis

what is the difference between compact and spongy (trabecular) bone

compact - densely packed, tightly organized osteons

spongy - sparsely packed, seemingly random but arranged along lines of stress

what components of bone are cellular -organic

osteoprogenitor cells

osteoblasts

osteocytes

osteoclasts

what components of bone are protein - organic

collagen

osteoid

what components of bone are mineral - inorganic

hydroxyapatite

calcium

phosphorus

what is an osteoid

the unmineralized organic components of bone

"the cells and what the cells produce"

what is the difference between woven bone and lamellar bone

woven - immature osteoid, highly cellular, disorganized

lamellar - mature, less cellular (more matrix), organized along stress lines

is woven bone or lamellar bone normal in adults

lamellar

what are osteoprogenitor cells

stem cells of bone that differentiate into osteoblasts

what are osteoblasts

bone forming cells

mature into osteocytes after surrounded by bone

what are osteocytes

mature bone cells contained in the bony matrix

what are osteoclasts

bone resorbing cells

mature from same stem cells as macrophages

normally bone remodeling is at equilibrium in adulthood until age ____________ when it begins to shift toward bone loss

30

what do osteoblasts mature from

osteoprogenitor cells

what do osteocytes mature from

osteoblasts after they are surrounded by bone

what doe osteoclasts mature from

same stem cells as macrophages

how are osteoclasts activated

RANKL (from osteoblast) binds to RANK receptor on osteoclast precursor

what is a congenital disorder

present at birth

what is dysostosis

developmental anomaly of bone or cartilage

is a dysostosis disorder congenital or acquired

congenital

is a dysostosis disorder a localized or systemic abnormality

localized

what is syndactyly

fused fingers

is syndactyly a congenital or acquired disorder?

congenital

what is polydactyly

extra finger

is polydactyly a congenital or acquired disorder

congenital

what is klippel-feil syndrome

congenital fusion of 2 or more cervical vertebra

what is the cause of klippel-feil syndrome

idiopathic

what is a sprengel's deformity

congenitally fused scapula

commonly found with klippel-feil syndrome

what type of congenital kyphosis is caused by the failed development of vertebra

type 1

what type of congenital kyphosis is caused by the failed segmentation of vertebra

type 2

what type of congenital kyphosis can possibly cause compression of the spinal cord

type 1

what is a dysplasia

mutations that interfere with the growth and remodeling of bone

is dysplasia a class of congenital or acquired disorder

congenital

what causes dysplasia congenital abnormalities

genetic mutations

are dysplasia disorders localized or systemic

systemic

affects multiple bones or the entire skeleton

a patient with a classic case of cleidocranial dysplasia would present with what abnormalities

absent/underdeveloped clavicles

dental abnormalities

delayed closure of cranial sutures

short stature

what causes cleidocranial dysplasia

RUNX2 gene mutation

what is the most common form of dwarfism and skeletal dysplasia

achondroplasia

what are the most common complications of achondroplasia

increased odds of having stenosis of the foramen magnum and spinal stenosis (stenosis of IVF)

a patient with a classic case of achondroplasia would present with what features

short stature (under 4 foot 10)

bullet vertebrae (causing hyperlordosis, kyphosis, scoliosis)

stenosis

trident hand

what is the pathogenesis (how) behind achondroplasia

inhibited endochondral growth of bone caused by decreased cartilage synthesis

what causes achondroplasia

mutated FGFR3 gene

most are spontaneous but 10% are autosomal dominant

what is the difference between thanatophoric dwarfism and achondroplasia

both are a mutation of the FGFR3 gene but thanatophoric is the most severe mutation leading to small thorax and short long bones that is fatal

_______________ is an inherited condition that results in brittle bones and weak connective tissue due to altered type 1 collagen

osteogenesis imperfecta

a type 1 osteogenesis imperfecta is associated with ________________

while type 2 is associated with ____________

normal lifespan

lethal in utero

a patient presents with a blue sclerae, what disorder could this be indicative of

osteogenesis imperfecta

should HVLA adjustments be performed on a patient with osteogenesis imperfecta

no

when reviewing an x-ray of a patient you notice zebra stripe sign on the vertebra, what disorder could this be indicative of

osteogenesis imperfecta

how is osteogenesis imperfecta caused

mutated type 1 collagen alpha 1 or 2 chains causing the premature breakdown and structural weakness of collagen

is osteogenesis imperfecta an autosomal dominant or recessive disorder

dominant

what is the difference between radiolucent and radiopaque

radiolucent - darker/black on x-ray due to lower density of structure

radiopaque - lighter /white on x-ray due to higher density of structure

what is osteopetrosis

group of genetic disorders causing skeletal sclerosis (increased density of bone) leading to bony stenosis and decreased hematopoiesis

a patient presents with a fractured femur. upon x-ray you find increased radiopaque features of the bone. the patients distal femur can also be described as having an erlenmeyer flask deformity and the fracture appears to be "chalk-stick" in nature

what could the patient be diagnosed with

osteopetrosis

how is osteopetrosis caused

reduced osteoclast activity causing reduced bone resorption leading to increased density and decreased strength

who is affected by osteopetrosis

inherited

how does osteopetrosis cause a loss of hematopoietic bone marrow

reduced osteoclast activity causing growth of bony tissue overtaking medullary cavity reducing space for hematopoietic tissue

what is the etiology behind osteopetrosis

inherited

what is osteoporosis

acquired severe loss of bone density and mass

what is the difference between osteopenia and osteoporosis

osteopenia is a milder loss of bone density and mass compared to osteoporosis

in a patient with osteoporosis where would the loss of bone density/increased risk of fracture be most commonly found

vertebral bodies

femoral neck

advanced osteoporosis may affect/thin ____________-

bone cortex

Osteoporosis can be diagnosed through a T-score of _________

vs

osteopenia can be diagnosed through a T-score of _________

porosis - greater than 2.5 standard deviations below

penia - between 1-2.5 standard deviations below

what is the difference between a DEXA T-score and Z-score

T-score: DEXA compared to peak bone mineral density

Z-score: DEXA compared to age & gender match BMD

localized osteoporosis is attributed to __________

disuse

systemic (entire skeleton) osteoporosis can be categorized as primary and secondary

Primary is attributed to ____________________

Secondary is attributed to ____________

primary - senile (aging), postmenopausal

secondary - neoplasia, hyperparathyroidism, nutrient deficiencies, corticosteroids, alcohol, smoking, etc. (side effect of other diseases)

what is the pathogenesis behind senile osteoporosis

decreased synthetic activity of osteoblasts

what is the pathogenesis behind postmenopausal osteoporosis

decreased serum estrogen casues increased expression of RANK/RANKL leading to increased osteoclast activity

is senile or postmenopausal primary osteoporosis more common

postmenopausal

__% of postmenopausal women will acquire osteoporosis

50

what are the risk factors associated with osteoporosis

increased age, female, sedentary lifestyle, family history, poor diet (decreased Ca2+)

what is rickets

metabolic bone disease with decreased bone density at the growth plate causing decreased growth and bowing of the weight bearing bones and increased fracture risk

what is the pathogenesis behind rickets

vitamin D deficiency causing failed osteoid formation leading to undermineralized bone

who is most commonly effected by rickets

children

what is osteomalacia

faulty bone turnover with undermineralized bone with increased fracture risk

what is the pathogenesis behind osteomalacia

vitamin D deficiency leading to undermineralized bone

who is most commonly effected by osteomalacia

adults

what is the difference between rickets and osteomalacia

both are vitamin D deficiency diseases causing undermineralization of bone

rickets - effects children and leads to bowing and increased risk of fracture

osteomalacia - effects adults and leads to weak bones prone to fracture

what is the function of parathyroid hormone

maintain blood calcium levels

what is the difference between primary and secondary hyperparathyroidism

primary - most commonly caused by parathyroid adenoma leading int increased parathyroid hormone production and increased osteoclast activity

secondary - caused by renal failure leading to hypocalcemia leading to increased parathyroid hormone production increasing osteoclast activity

true/false:

most cases of hyperparathyroidism are asymptomatic

true

what is hyperparathyroidism

increased parathyroid hormone production leads to a decrease in bone density and increased fracture risk along with kidney stones, weakness, bone pain, peptic ulcers, depression

what unique feature of a spinal x-ray is indicative of hyperparathyroidism

rugger-jersey spine (striped appearance of the vertebral bodies)

what unique feature of a hand x-ray is indicative of hyperparathyroidism

subperiosteal resorption of the radial side of middle phalanges

who is most commonly affected by hyperparathyroidism

women 50+ (post-menopausal)

what is the pathogenesis behind primary hyperparathyroidism

parathyroid adenoma (brown "tumor") causes increased parathyroid hormone production leading to increased osteoclast activity resorbing cortical and trabecular bone and replacing it with loose connective tissue and increased Ca2+ in blood

osteitis fibrosa cystica is an x-ray feature associated with what

advanced/severe hyperparathyroidism

what causes (etiology) primary hyperparathyroidism?

secondary?

primary - idiopathic can be associated with parathyroid adenoma

secondary - kidney failure

what is another name for paget disease of bone

osteitis deformans

what is paget disease (osteitis deformans)

disordered bone remodeling leading to increased bone density that is structurally weak mostly present in the axial skeleton, pelvic girdle, and proximal femur

how is paget disease different from osteopetrosis

osteopetrosis - decreased osteoclast activity

paget - excessive osteoclast activity triggering increased haphazard osteoblast activity

when looking at a histological slide of a patients bone you notice a mosaic pattern ("jigsaw puzzle") what disease is this feature commonly associated with

paget disease

what are the three stages of paget disease

1 - regional osteoclastic activity

2- osteoblastic activity creating excessive bone

3 - sclerotic phase

who is most commonly affected by paget disease

most common in older Caucasian males

what is the eitiology behind paget disease

idiopathic

what is the difference between a complete and incomplete fracture

complete - extends through bone

incomplete (greenstick) - does not extend through thickness of bone

an incomplete (greenstick) fracture is commonly found in what population

children

when a fracture causes the overlying tissue to rupture it is known as _________

compound

when a fracture occurs leaving the overlying tissue intact is known as ________

closed