Advanced Biology: Skeletal System

Functions of bone

structure, protection, blood cells production, store/release fat and minerals

Epiphysis

expanded portion at the end of a bone

spongy bone

in epiphysis; thin layers of compact bone with many branching plates, forms a joint, lined with hyaline cartilage

diaphysis

shaft of the bone

compact bone

in diaphysis; tightly compact tissue, no gaps, strong and resistant to bending

medullary cavity

hollow chamber in compact bone; endosteum and marrow line area

endosteum

thin layer of cells

marrow

soft connective tissue

periosteum

vascular covering of fibrous tissue, completely enclosed the bone (except for the end), helps form and repair bone tissue

osteocytes

bone cells; located in lacunae

connective tissue appears where during development

the sites of future bones

epiphyseal disk

remains between primary and secondary ossification centers, long bones continue to grow until disks are ossified

Osteoclasts

resorb bone matrix

osteoblast

replaces bone matrix

the skull protects

eyes, ears, brain

the ribcage and shoulder girdle protects

the heart and lungs

the pelvic girdle protects

lower abdominal and internal reproductive organs

levers

how bones and muscles interact

where would you find a rigid rod or bar lever

upper forearm bones

where would you find a fulcrum or pivot lever

rotating joints

hematopoiesis

blood cells formation; begins in the yolk sac early in life

red marrow

formation of erythrocytes (RBC), leukocytes (WBC), and thrombocytes (platelets)

red marrow location

spongy bone of skull, ribs, sternum, clavicles, vertebrae, and pelvis

yellow marrow

stores fat and is inactive in blood cells production

yellow marrow location

replaces red marrow with age

parathyroid hormone

stimulates the breakdown of bone tissue to release Ca when levels are low

calcitonin

from thyroid; is released to stimulate bone tissue formation when Ca is high

Axial

bony, cartilaginous parts that support and protect the organs of the head, neck, and trunk

appendicular

bones of upper and lower extremities, anchor limbs to axial skeleton

hyoid bone

in the neck between the lower jaw and larynx, movement of tongue

vertebrae seperated by

intervertebral disks

sacrum

fused vertebrae at the distal end of the spine

thoracic cage

12 pairs, most ribs attach at the sternum

pectoral girdle

connects bones of the upper limbs to the axial skeleton

coxal bones

hipbones

paranasal sinuses

air filled cavities in some bones, lined with mucous membranes, reduces skull’s weight

supraorbital foramen

eye socket

frontal sinuses

one above each eye, near the middle

foramen magnum

opening where nerve fibers pass from the brain to the spinal cord

mandibular fossae

where mandible adhears

sella turcica

where pituitary gland resides

sphenoidal sinuses

under eyes

infantile skulls are

incompletely developed

fontanels

infantile; fibrous membranes connecting cranial bones, partially compressible

how many cervical vertebrae

7

atlas

first vertebrae, supports head

axis

second vertebrae, atlas pivots on the axis

how many vertebrae in thoracic region

12

how many vertebrae in lumbar region

5

true ribs

first 7, join the sternum directly by costal cartilage

false ribs

last five, cartilage does not reach the sternum, last two or three are floating

coxal bone

ilium, lischium, pubis

ilium

flares outward to form the prominence of the hip

ischium

lower portion, L-shaped, pointing posteriorly and downward

pubis

anterior portion of the coxal bone, two join at the midline

carilaginous joints

disks of fibrocartilage or hyaline cartilage connects the bones to absorb shocks

synovial joints

most joints, allow free movement

bursae

fluid-filled sacs

ball socket joint

synovial; bone with ball-shaped head in a cup-shaped cavity

condyloid joint

synovial; oval-shaped condyle of one bone fits into an elliptical cavity, between metacarpals and phalanges

what joint has the widest range of motion

ball and socket

gliding joint

synovial; sliding/twisting motion, wrist and ankle joints

hinge joint

synovial joint; convex surface connecting to concave, elbow joint

pivot joint

synovial; cylindrical surface rotating within a ring shape of bones and ligaments, proximal end of radius and ulna

saddle joint

synovial; articulating surface has both concave and convex regions, carpal/metacarpal of thumb

3 categories of functional classifications

syntharoses, amphiarthroses, diarthroses

synarthroses

immovable

amphiarthroses

slightly moveable

diarthroases

freely moveable

fibrous joints

connected by dense connective tissues like collagen

cartiliginous joints

connected by either hyaline or fibrocartilage

synovial joints

has a joint cavity filled with synovial fluid