Anatomy M02: Bone Tissue + The Skeletal System

osteology

the study of bone

functions of the skeleton

support, protection, movement, electrolyte balance, acid-base balance, blood formation

support

limbs and vertebrae support the body

protection

prevent the brain, spinal cord, heart, and lungs from damage

movement

limb movements, breathing, etc.

electrolyte balance

calcium and phosphate levels

acid-base balance

buffers blood against large pH changes by altering phosphate and carbonate salt levels

blood formation

red bone marrow → main producer of RBCs

bone is made up of connective tissue with the matrix hardened by

calcium phosphate and other minerals (calcification)

calcification

the hardening of bone

flat bones have

thin curved plates and protect soft organs

long bones are

longer than wide and are crucial for movement

short bones are equal in

length and width, glide against each other in multiple directions

irregular bones have

elaborate shapes that don’ fit other categories

epiphysis

rounded ends/tips of a long bone

long bones are

compact and spongy, include articular cartilage, periosteum, ad marrow cavity

articular cartilage

covers the ends of the bones

flat bones are

“sandwich like”

flat bones have two layers of

compact bones sandwiching a layer of spongy bone

diploe

spongy middle layer

osteogenic cells

stem cells found in endosteum and inner layer of periosteum

osteoblasts

bone-forming cells

osteocytes

former osteoblasts that have become trapped in the matrix they deposited

osteocytes act as

“strain sensors” and regulate bone remodeling (shape and density)

osteoclasts

bone dissolving cells found on bone surface

osteoclasts develop from

the same bone marrow stem cells that give rise to RBCs

dissolving bone is apart of

bone remodeling

bone marrow

soft tissue occupying marrow cavities of long bones and spall spaces of spongy bone

red marrow (myeloid tissue)

contains hemopoietic tissue that forms blood cells

red marrow is found in

every bone in kids and in adults skull, vertebrae, ribs, sternum, pelvis, proximal heads of humerus + femur

yellow marrow is

fatty marrow that does not produce blood

yellow marrow can transform to red in the case of

chronic anemia

ossification/osteogenesis

formation of bone

intramembranous ossification

creation of bone from embryonic tissue without a model

endochondral ossification

bone is created by replacing cartilage

disturbance of calcium homeostasis can impact

nervous and muscular systems

mineralization

the process where calcium, phosphate, and other ions are taken from blood and deposited bone

mineral reabsorption

process of dissolving bone and releasing minerals into blood

orthodontic appliances reposition teeth by

reabsorption and deposit

hypocalcemia

deficient calcium in blood

hypocalcemia is caused by

vitamin D deficiency, diarrhea, thyroid tumors, underactive parathyroid glands, pregnancy and lactation

hypercalcemia

excessive calcium levels

hypercalcemia makes

ion channels less responsive and nerves/muscles are less excitable

calcium homeostasis is regulated by

calcitrol, calcitonin, and parathyroid hormone

calcitriol is the

most active form of vitamin D and produced by the skin, liver, and kidneys

calcitriol is the hormone that

rasies blood calcium level and provides calcium/phosphate for bone deposition

rickets

abnormal softness in bones cause by lack of calcitriol in children

osteomalacia

abnormal softness in bones cause by lack of calcitriol in adults

parathyroid hormone secreted by glands on

posterior surface of thyroid

PTH raises

calcium levels when low

PTH lowers

lowers phosphate levels by promoting urinary excretion

ossification prominent in puberty bc there are surges of

growth hormone, estrogen, and testosterone

axial skeleton

form central body: skull, vertebrae, sternum, ribs, sacrum, and hyoid

appendicular skeleton

forms outer skeleton: pectoral girdle, upper extremity, pelvic girdle, lower extremity

how many bones in adults

206

how many bones at birth

270

how many bones in the skull

22

foramina

holes that allow passage for nerves and blood vessels

paranasal sinuses (frontal, sphenoid, ethmoid, maxillary)

air-filled, lined by mucous membrane, chambers that add resonance to the voice

anterior cranial fossa holds the

frontal lobe of the brain

middle cranial fossa holds the

temporal lobes of the brain

posterior cranial fossa holds the

cerebellum

perpendicular plate forms

superior two-thirds of nasal septum

cribriform plate forms

roof of nasal cavity

how many bones in the face

14

fontanels

spaces between unfused cranial bones

how many vertebrae

33

how many vertebrae in the C spine

7

how many vertebrae in the T spine

12

how many vertebrae in the L spine

5

how many vertebrae in the Sacral spine

5

how many vertebrae in the Coccygeal spine

4

herniated disc

ruptured/slipped disc puts painful pressure on the spinal nerve/cord

nucleus pulposus

inner gelatinous mass

anulus fibrosus

outer ring of fibrocartilage

how many pairs of ribs

12

layer of connective tissue lining the inside of bones is

endosteum

layer of connective tissue lining the outside of bones i s

periosteum

where do you find osteogenic cells

endosteum and periosteum

lacunae

small cavities osteocytes reside

osteocytes are former

osteoblasts

purpose of canaliculi

to provide a passageway between lacunae

hydroxyapatite is

inorganic, and is a calcium-phosphate salt that mineralizes bone tissue

protein and carb portion of the bone matrix forms

organic matter

part of the organic matter that makes up the matrix of a bone

collagen

lamellae

layers of bony matrix in compact bone tissue

osteons are

cylinders

channels that extend longitudinally through the center of an osteon

haversion canal and central canal

most of the matrix bone is made up of

inorganic matter

perforating canals

diagonal passages that join central canals

trabeculae

structure in spongy bone that lines up with the bone’s line of stress

metaphysis

transitional areas at the end of marrow cavities

hyaline cartilage

tissue replaced with bone during endochondral ossification

zone of epiphyseal plate farthest from marrow cavity

zone fo reserve cartilage

secondary ossification typically occurs in

epiphyses

which type of bone forms within a tendon as a result to stress

sesamoid

condyle

a rounded knob that articulates w/ another bone

facet

a smooth, flat, slightly concave surface

head

the prominent end of a bone, sometimes rounded

alveolus

a pit or socket