Bootcamp.com - Skeletal System

the _____ provides structure, support, rigidity, and protection to organs

skeletal system

_____ skeletons belong to organisms without bones, especially backbones

invertebrate

insects tend to have _____, which are skeletons on the outside of the organism

exoskeletons

_____ skeletons belong to organisms that have a backbone

vertebrate

vertebrates have _____, which are skeletons on the inside of the organism

endoskeletons

what are the two parts of human endoskeletons?

axial; appendicular skeletons

which bones are included in the axial skeleton?

bones at the core of the endoskeleton like the skull, vertebral column, and rib cage

which bones are included in the appendicular skeleton?

bones of the appendages as well as the pectoral and pelvic girdle

what are the types of bones?

long; short; flat; sesamoid; irregular

of which bone types are long bones composed?

cortical and cancellous

what are some examples of long bones?

femur; radius; ulna

what are some of the predominant structural features of long bones?

epiphyses; diaphysis; a medullary cavity; metaphyses; epiphyseal growth plates

_____ are the bumpy parts at the ends of long bones

epiphyses

_____ covers epiphyseal compact bone in synovial joints

articular cartilage

articular cartilage covers epiphyseal compact bone in _____ joints

synovial

what type of joint is formed between long bones?

synovial joints

_____ bone marrow is located in spongy trabecular bone of adults

red

hematopoiesis occurs in the _____ bone marrow of _____ bone

red; spongy trabecular

the _____ of a long bone is the shaft between the ends

diaphysis

the _____ is the "hollow" part of the diaphysis, which contains _____ bone marrow in adulthood

medullary cavity; yellow

_____ are found between the medullary cavity and epiphyseal plates of a long bone

metaphyses

metaphyses have a similar structure to the _____ of a long bone

epiphyses

(structure is spongy trabecular bone)

which type of cartilage are epiphyseal plates composed of during adolescence?

hyaline cartilage

during puberty, epiphyseal plates form an epiphyseal line via _____

ossification

epiphyseal plates grow before ossification to promote _____

bone lengthening

epiphyseal plates grow toward the _____ to lengthen the _____ of a long bone

metaphyses; diaphysis

epiphyseal lines are found between long bone _____ and _____ in adults

epiphyses; metaphyses

(same holds true for epiphyseal plates in adolescents)

cartilage is _____, which makes it difficult to heal

avascular

breaking a bone at the epiphyseal plate can stunt growth because epiphyseal plates are made of _____, which is avascular and difficult to heal

hyaline cartilage

_____ bones are cuboidal and provide support with little movement

short

short bones are primarily _____ bone covered by a thin layer of _____ bone

cancellous (spongy trabecular); cortical (dense)

what are some examples of short bones?

carpals of the wrist or tarsals of the ankle

_____ bones are thin, with outer layers of cortical bone surrounding spongy, cancellous interiors

flat

what are some examples of flat bones?

sternum and the bones forming the skull

sesamoid bones are found in _____, and they act to increase muscle power - what is an example of a sesamoid bone?

tendons; patella

irregular bones have _____ layers surrounding _____ interiors; however, their shapes do not fit any other bone class

dense, cortical; spongy, cancellous

what are some examples of irregular bones?

vertebrae; sacrum; pelvis

_____ bone is the outer layer of bones

cortical

what allows bones to support weight?

cortical bone density

what are the microstructures in cortical bone?

osteons; Haversian canals; lamella; lacunae; canaliculi; Volkmann's canals

_____ are the functional unit of cortical bone, and they appear as multi-layer cylinders

osteons

what direction do osteons travel within cortical bone?

parallel to the bone's long axis

the layers that make-up an osteon are called _____

lamellae

_____ contain cortical bone and collagen fibers

lamellae

_____ are the central canals of an osteon

Haversian canals

Haversian canals contain blood vessels to supply nutrients to the _____ of an osteon

osteocytes

(Haversian canals connect to osteocytes through canaliculi)

_____ are small spaces between lamellae that house bone cells

lacunae

canaliculi connect _____ and _____ of a single osteon

lacunae (housing osteocytes); Haversian canals

_____ connect adjacent Haversian systems as well as peripheral osteons to the periosteum

Volkmann's canals

_____ bone is soft and flexible, and it is made of _____ that soak up bone marrow like a sponge

cancellous; trabeculae

(trabecular/cancellous bone = spongy bone)

_____ are precursors to osteoblasts

osteoprogenitors

osteoblasts contain _____ nucleus

1

what is the main function of osteoblasts?

to build bone (secrete collagen + proteins that make osteoid)

_____ are mature bone cells that develop from osteoblasts

osteocytes

how do osteoblasts become osteocytes?

osteoblasts get trapped in the osteoid they secrete

osteoclasts contain _____ nuclei, and they are found in _____

multiple; Howship's lacunae

what cell type gives rise to osteoclasts?

monocytes

what is the main function of osteoclasts?

to resorb ("chew") bone

what are Howship's lacunae?

pits created by osteoclasts

what is bone remodeling?

the back and forth between resorption (osteoclasts) and ossification (osteoblasts)

what are the primary factors that affect bone remodeling?

parathyroid hormone, vitamin D, calcitonin

parathyroid hormone (PTH) is secreted from the parathyroid gland, and it _____ (increases/decreases) blood Ca2+

increases

PTH stimulates _____ (bone cell) and depresses _____ (bone cell)

osteoclasts; osteoblasts

vitamin D is activated by _____ to _____ (increase/decrease) blood Ca2+

PTH; increase

through which type of feedback does activated vitamin D affect PTH secretion?

negative feedback

vitamin D stimulates Ca2+ _____ in the intestines, and increases the number of _____ for resorption

absorption; osteoclasts

calcitonin is secreted by the _____, and it opposes PTH to _____ (increase/decrease) blood Ca2+

thyroid gland; decrease

calcitonin decreases the activity of _____, so _____ have less competition

osteoclasts; osteoblasts

_____ is made of proteins and type 1 collagen fibers, to provide bones with tensile strength

osteoid

_____ provides bone density, and it is made of inorganic crystals of Ca2+, phosphate, & H2O

hydroxyapatite

what are the two types of embryonic ossification?

intramembranous and endochondral

what is the most common type of embryonic ossification?

endochondral ossification

_____ ossification occurs when bone is created directly within a fibrous membrane

intramembranous

list the steps of intramembranous ossification

1. osteoblasts secrete osteoid

2. osteocytes in the hardened bone matrix create trabeculae

3. the trabeculae gets wrapped in blood vessels and forms the periosteum

4. cortical bone grows between the periosteum and trabeculae

what types of bones are usually made by intramembranous ossification?

flat bones

_____ ossification occurs when bones are created indirectly, from a cartilage model

endochondral

list the steps of endochondral ossification

1. hyaline cartilaginous matrix hardens into the cartilage model

2. the cartilage model's center calcifies

3. capillaries and osteoblasts invade the calcified center and establish the primary ossification center

4. secondary ossification sites are made at epiphyses

5. osteoclasts resorb the inside of the diaphysis, which creates the medullary cavity

what are the three main types of connective tissue?

fibrous; cartilage; joints

what bones are made through endochondral ossification?

long bones

fibrous connective tissue includes which three things?

tendons; ligaments; periosteum/endosteum

_____ connect bones to muscle

tendons

_____ connect bones to other bones

ligaments

the _____ is a protective fibrous membrane that covers cortical bone

periosteum

what are the two sublayers of the periosteum?

outer fibrous layer; inner/cambium layer

(cellular layer = inner/cambium layer)

the outer fibrous layer of the periosteum is _____

vascularized

the _____ layer of the periosteum contains collagen and osteoprogenitor cells

inner/cambium

the _____ is a single layer membrane between cortical and cancellous bone

endosteum

what processes are both the periosteum and endosteum involved in?

bone growth, repair, and remodeling with respect to bone thickness

cartilage is _____ and not _____

avascular; innervated

how do cells living in cartilage get nutrition/immune support?

from the surrounding fluid

cartilage building cells are called _____

chondroblasts

(analogous to osteoblasts)

chondrocytes are mature _____

chondroblasts

(analogous to osteoblasts --> osteocytes)

how do chondroblasts give rise to chondrocytes?

chondroblasts get trapped by the matrix they secrete

(analogous to osteoblasts --> osteocytes)

what is the primary function of chondrocytes?

maintaining cartilage

(similar to osteocytes, which maintain bone)

where are chondrocytes found?

cartilaginous lacunae

(similar to osteocytes inhabiting lacunae of an osteon)

chondroblasts secrete a cartilaginous matrix containing:

collagen and elastin

how can you change the type of cartilage?

change the amounts of collagen and elastin

what is the most common protein in mammals?

collagen

what are the three types of cartilage?

hyaline; fibrous; elastic

_____ cartilage has a glassy appearance, and it absorbs shock by supporting the ends of long bones at synovial joints

hyaline

(the articular cartilage found at synovial joints is hyaline cartilage)