physiology of the skeletal system

Question 1

what are the structural roles of the skeleton ?

Answer 1

physical support for the body

attachment points for muscles

protection of internal structures

[ ribcage / skull ]

Question 2

what are some roles of the physiology of skeletal system ?

Answer 2

stores various minerals [ particularly calcium and phosphorus ]

produces blood [ bone marrow ]

Question 3

what is an osteogenic cells ?

Answer 3

precursors of osteoblasts

Question 4

what is osteoblasts ?

Answer 4

bulids bone

Question 5

what is osteocytes ?

Answer 5

osteoblasts which have become encased in bone

maintain mineral level

Question 6

what is osteoclasts ?

Answer 6

reabsorb bone

Question 7

what is the mechanism of endochondral ossification ?

Answer 7

bone develops from a precursor made of cartilage

Question 8

what is the mechanism of intramembranous ossification ?

Answer 8

bone development from general connective tissue

Question 9

which bones are made from endochondral and intramembranous ossification ?

Answer 9

most limbs = endochondral ossification
face = intramembranous ossification

Question 10

how is bone produced ?

Answer 10

the osteoid is produced by osteoblasts and maintain by osteocytes [ largely composed of collagen type 1 ]

hardened by hydroxyapatite , a form of calcium phosphate ,modified with added calcium carbonate

Question 11

what is osteoid characteristics ?

Answer 11

malleable and holds together well

Question 12

what are characteristics of minerals ?

Answer 12

hard but brittle

Question 13

what are some characteristics of bone to protect from fractures ?

Answer 13

hard but malleability to reduce risk of fracture

Question 14

what is old bone broken down by ?

Answer 14

osteoclasts

Question 15

describe the turnover of bone

Answer 15

osteoblasts produce special form of extracellular matrix

matrix becomes calcified , making bone which surrounds and encases the osteoblasts

encased osteoblasts then become osteocytes

old bone broken down by osteoclast

turnover of bone allows maintenance and reshaping

Question 16

when matrix becomes calcified what is this known as the process ?

Answer 16

mineralisation

Question 17

if less force is placed on the bone will the bones be stronger or weaker ?

Answer 17

weaker

Question 18

what is osteon in bones ?

Answer 18

rings of lamellae

Question 19

what is lacunae in bones ?

Answer 19

tiny cavities containing osteocytes

Question 20

when are phosphorous and calcium extracted from the bones ?

Answer 20

when they are low in the blood

Question 21

how much of the body stores of calcium and phosphorus stored in the bones ?

Answer 21

calcium= 99%
phosphorous = 80%

Question 22

how are minerals released into the blood stream ?

Answer 22

osteoclasts carry out the breakdown of bone matrix , releasing minerals for the blood stream

this can be triggered by parathyroid hormone [PTH]

Question 23

where is the hormone PTH released from ?

Answer 23

parathyroid glands , small structures on the back of the thyroid glands

Question 24

when is the hormone parathyroid released ?

Answer 24

released in response to low blood serum Ca 2+ ions

PTH triggers the activity of osteoclasts , which breaks down the bone matrix and therefore releases its component calcium into the blood stream

Ca2+ increases and results in less PTH being released [ negative feedback ]

Question 25

what is the name of the process to increase release of Ca2+?

Answer 25

hypercalcemia

Question 26

what is name of the process to decrease release of Ca2+?

Answer 26

hypocalcaemia

Question 27

what does the process of haematopoiesis do ?

Answer 27

produces blood cells

Question 28

where are haematopoietic stem cells [ HSCs ] found ?

Answer 28

bone marrow to produce all forms of blood cells

Question 29

where does blood cell production occur ?

Answer 29

red marrow

yellow marrow acts as a store of fat but can become red marrow when needed