241 Unit 2: skeletal tissue terminology

skeletal tissue

-includes bones, cartilages, ligaments

-bones have their own blood vessels, but ligaments and cartilages have no blood vessels or nerves (avascular)

hyaline

-cartilage taht provides support, flexibility, and resillience

-most abundant type

-present in fetal skeleton, respiratory tract, articular (joint) cartilage, and costal cartilage

elastic

-similar to hyaline cartilage, but contain elastic fibers

-provides elasticity

-found in the ear and epiglottis

fibrocartilege

-contain collagen fibers (have great tensile strength)

-found in intervertebral discs, pubic symphysis, knee joint- meniscus

axial

-main group of bones by location

-includes the skull, thoracic cage, and vertebral column

appendicular

-main group of bones by location

-includes the limbs

bone functions

-support

-protection

-movement

-storage

-blood cell formation

-fat and triglycerides

support

-bone function

-for the body and soft organs

protection

-bone function

-for the brain, spinal cord, and vital organs

movement

-bone function

-levers for muscle action

storage

-bone function

-minerals (calcium, phosphorus, magnesium) and growth factors

blood cell formation (hematopoiesis)

-bone function

-takes place in marrow cavities

fat and triglycerides

-bone function

-energy

-stored in bone cavities

long bones

-classification by shape

-longer than they are wide

short bones

-classification by shape

-cube shaped bones (in wrist adn ankle) and sesamoid bones (within tendons; e.g.: patella)

flat bones

-classification by shape

-thin, flat, and slightly curved

-ex: sternum

iregular bones

-classification by shape

-complicated shapes

-ex: vertebra

compact bone

-classification by texture

-dense outer layor

spongy (cancellous) bone

-classification by texture

-honeycomb of trabeculae

-inside compact bones

tuberosity

-rounded projection

-bone marking

-site of muscle/ligament attachment

crest

-bone marking

-narrow, prominent ridge

-site of muscle/ligament attachment

trochanter

-bone marking

-large, blunt, irregular surface

-site of muscle/ligament attachment

line

-bone marking

-narrow ridge of bone

-site of muscle/ligament attachment

tubercle

-bone marking

-small, rounded projection

-site of muscle/ligament attachment

epicondyle

-bone marking

-raised area above a condyle

-site of muscle/ligament attachment

spine

-bone marking

-site of muscle/ligament attachment

-sharp, slender projection

process

-bone marking

-site of muscle/ligament attachment

-any bony prominence

head

-bone marking

-structure that helps form joints

-bony expansion carried on a narrow neck

facet

-bone marking

-structure that helps form joints

-smooth, nearly flat articular surface

condyle

-bone marking

-structure that helps form joints

-rounded articular projection

ramus

-bone marking

-structure that helps form joints

-armlike bar

meatus

-bone marking

-depression/opening

-canal like passageway

sinus

-bone marking

-depression/opening

-cavity within a bone

fossa

-bone marking

-depression/opening

-shallow, basin like depression

groove

-bone marking

-depression/opening

-furrow

-long enough for a blood vessel

fissure

-bone marking

-depression/opening

-narrow, slitlike opening

foramen

-bone marking

-depression/opening

-round or oval opening through a bone

diaphysis

-shaft of bone

-compact bone collar surrounds medullary (narrow) cavity

-medullary cavity in adults contain fat (yellow marrow), early in life it contains red marrow

epiphyses

-expanded ends

-spongy bone interior

-epiphyseal line (remnant of growth plate)

-articular (hyaline) cartilege on joint surfaces

periosteum

-outer covering of bone

-two layors: fibrous and osteogenic

-nerve fibers, nutrient blood vessels, and lymphatic vessels enter the bone via nutrient foramina

fibrous layer

-outer layer of the periosteum

-very tough

osteogenic layer

-inner layer of the periosteum

-contains lots of cells: osteoblasts, osteoclasts, and osteogenic cells

osteogenic cell

-stem cells in the periosteum and endosteum that give rise to osteoblasts

-aka osteoprogenitor

-

osteoblasts

-in the osteogenic layer

-bone forming cells (produce bone matrix)

osteoclasts

-in osteogenic layer

-bone destroying cells (destroys matrix)

endosteum

-inner layer of bones

-delicate membrane on internal surfaces of bone

-also contains osteoblasts and osteoclasts

osteocytes

-mature bone cells

adult hematopoietic tissue

-red bone marrow

-in heads of femur and humerus

-trabecular cavities of the dipoe of flat bones

newborn hematopoietic tissue

-red bone marrow

-in the medullary cavities and all spaces in spongy bone

osteon

-aka haversian system

-compact bone

-structural unit

-includes lamellae, central (haversian) canal, and canaliculi

lamellae

-in haversian system of compact bone

-weight bearing, column-like matrix tubes

central canal

-in haversian system of compact bone

-contains blood vessels and nerves

lacunae

-in haversian system of compact bones

-small cavities that contain osteocytes

-surround the central canal

canaliculi

-in haversian system of compact bones

-hair-like canals that connect lacunae to each other and the central canal

trabeculae

-spongy bone

-align along lines of stress

-no osteons

-contain irregularly arranged lamellae, osteocytes, and canaliculi

-capillaries in endostreum supply the nutrients

organic composition

-osteoid

-bone matrix secreted by osteoblasts (ground substance and collagen fibers)

-mineral salts

ground substance

-organic bone matrix

-proteoglycans and glycoproteins

collagen fibers

-organic bone matrix

-provide tensile strength and flexibility

mineral salts

-organic bone matrix

-65% of bone by mass

-mainly calcium phophate crystals

-responsible for hardness and resistance to compression

osteogenesis (ossification)

-bone tissue formation

-bone formation begins in the 2nd month of development

-can be intramembranous or endochondral

intramembraneous ossification

-type of osteogenesis

-bones develop from membrane

-forms flat bones, clavicle, and cranial bones

-selected centrally located mesenchymal cells cluster and differentiate into osteoblasts, forming an ossification center

endochondral ossification

-type of osteogenesis

-bones form by replacing hyaline cartilege

-forms most of the skeleton

-plates get thinner as bones grow

steps of endochondral ossification

-bone collar forms around hyaline cartilage model

-cartilage in center of diaphysis calcifies and develops cavities

-peristeal bud inavades internal cavities and spongy bone begins to form

-diaphysis elongates and a medullary cavity forms, secondary ossification centers appear in epiphyses

-epiphyses ossify, when completed hyaline cartilage remains only in epiphyseal plates and articular cartilages

nutrient artery and vein

-major set of blood vessels

-single pair of large blood vessels

-enter diaphysis through nutrient foramen

-femur has more than one pair

metaphyseal vessels

-major set of blood vessels

-supply epiphyseal cartilage

-where bone growth occurs

periosteal vessels

-major set of blood vessels

-provide blood to superficial osteons and secondary ossification centers

process of remodeling

-involves osteocytes, osteoblasts, and osteoclasts

-bone continually remodels, recycles, and replaces

-turnover rate varies (deposition>removal=stronger, removal>deposition=weaker)

growth hormone

-hormone that helps in bone growth

-regulated by pituitary hormone

thyroid hormone

-hormone that helps in bone growth and calcium homeostasis

-modulates activity of growth hormone

-calcitonin

sex hormones

-hormones that helps in bone growth

-testosterone and estrogen

-start at puberty

-promote adolescent growth

calcitonin

-a thyroid hormone that helps calcium homeostasis

-secreted by C cells/parafollicular cells

-decreases calcium levels

PTH

-helps in calcium homeostasis

-released by parathyroid glands

-increase in serum calcium concentration (by increasing vitamin D)

-activates osteoclasts, stimulates kidney tubules to reabsorb calcium from urine

-stimulates kidney tubules to produce calcitrol from calcidiol

vitamin D

-helps in calcium homeostasis

-enters body with food

-proenzyme

-synthesized within body

-helps absorption of calcium

calcitonin effects on bone

-inhibiting activity of osteoclasts, releasing calcium and phosphorus into blood

calcitonin effects on kidney

-inhibits tubular reabsorption of calcium and phosphorus, leading to increased rates of their loss in urine

calcitrol

-most active form of vitamin D

-kidney tubules produce when PTH stimulates

calcidiol

-less active form of vitamin D

-makes the active form

calcium importance

-necessary for transmission of nerve impulses, muscle contraction, blood coagulation, secretion by glands and nerve cells, and cell division

PTH control of blood calcium

-how its primarily controlled

-low levels cause parathyroid glands to release hormone which stimulates osteoclasts to degrade bone matrix and release calcium which increases blood calcium levels

opposites

-relationship between calcitonin and PTH?

9-11

-normal range of calcium concentration in blood

hypercalcemia

-too much calcium in blood (over 11 mg/100ml)

hypocalcemia

-not enough calcium in blood (under 9 mg/100ml)

calcitonin control of blood calcium

-controls concentation of calcium

-high blood levels cause parafollicular cells of thyroid to release hormone which stimulates osteoblasts to deposit calcium salts which lower blood calcium levels

fractures

-can be described in terms of location, external appearance, or nature of break

-common types: comminuted, compression, spiral, epiphyseal, depressed, and greenstick

comminuted

-common type of fracture

-bone fragments break into three or more pieces

-particularily common in the aged, whose bones are more brittle

compression

-common type of fracture

-bone is crushed

-common in porous bones (i.e: osteoporotic bones) subjected to extreme trauma (like a fall)

spiral

-common type of fracture

-ragged break occurs when excessive twisting forces are applied to a bone

-common sports fracture

epiphyseal

-common type of fracture

-epiphysis seperates from diaphysis along the epiphyseal plate

-tends to occur where cartilage cells are dying and calcification of matrix is occuring

depressed

-common type of fracture

-broken bone portion is pressed inward

-ex: skull fracture

greenstick

-common type of fracture

-incomplete break (only one side of shaft breaks, the other side bends)

-common in children (more organic matrix and are more flexible than adults)

bone healing

-hematoma forms --> fibrocarilagenous callus forms --> bony callus forms --> bone remodeling occurs

-osteoblasts bridge gap then osteoclasts remove excess (like sandpaper)

rickets

-childhood bone disease

-causes bowed legs and other bone deformities

-calcium slats not deposited

-caused by vitamin D deficiency or insufficient dietary calcium

dwarfism

-not enough growth hormone secretion

-causes super short people

gigantism

-too much growth hormone secretion

-causes super tall people

rheumatoid arthritis

-inflammation of soft tissue structure in joints

osteoporosis

-loss of bone mass-- bone resorption

-spongy bone of spine and neck of femur become most suseptible to fracture

-risk factors: lack of estrogen (after menopause), calcium or vitamin D, low levels of TSH