Skeletal System 7.3

im crashing out

Functions of the bone

shape, support, protect body structures
aid body movements
house tissue that produces blood cells
store inorganic salts

hematopoiesis

process of blood cell formation

begins in yolk sac, which lies outside human embryo

later, blood cells manufactured in liver and spleen

still later in the bone marrow

red marrow

formation of erythrocytes, leukocytes, and blood platelets

color comes from oxygen-carrying pigment hemoglobin in RBCs

in an infant, red marrow occupies cavities of most bones

yellow marrow

as a person ages, this replaces much of the red marrow

stores fat

not active in blood cell production

in adults, found in spongy bone of the skull, ribs, sternum, clavicles, vertebrae, and hip bones

if blood cell supply deficient, some yellow marrow may become red marrow

blood is low in calcium

parathyroid hormone stimulates osteoclasts to break down bone tissue —> releases calcium salts from EM to blood

high blood calcium levels

inhibits osteoclast

stimulates calcitonin (from thyroid gland) stimulates osteoblast to form bone tissue —> storing excess calcium in EM

what two bones contain significant amounts of red bone marrow in an adult?

sternum, hip bones