5 functions of bones
Framework Protection Attachment Movement Haemopoeisis Mineral reservoir
How many bones in the body
206
What is the formation/development of blood cells called
Haemopieisis
2 types bone tissue
Spongy
Compact
3 types bone cells
Osteoblasts
Osteoclasts
Osteocyte
What is an osteoblast
Bone building cell
What is osteo last
Bone dissolving cells
Which bone cells are multi-nucleated
Osteoclasts
What is the name of the process in which Osteoclasts dissolve the bone cells
Bone resorption
What is an osteocyte
Mature bone cell in lacunae
4 parts of Osteon
Lamella
Lacunae
Canaliculi
Central canal
Basic unit of compact bone is?
osteon
Describe lamellar
Extracellular matrix
Contains minerals/collagen fibres
Tubular
Describe lacunae
‘Lagoons’
Spaces between lamellae
Contain osteocytes
Describe canaliculi
Network of canals
So osteocytes can receive nutrients/remove waste
What does central canal of compact bone contain
Blood vessels and nerves
What doesn’t spongy bone have that compact does
Osteons
Describe structure of spongy bone
Columns of bone -trabeculae
In irregular lattice
What do trabeculae contain as well as osteons
Lamellae
Osteocytes
Lacunae
Canaliculi
What are spaces between trabeculae filled with
Bone marrow
What does bone marrow do
Make blood cells
Outer covering of compact bone
Periosteum
Larger 2 types canals in compact bone
Volkmans (L-R)
Haversian up down
Long shaft of bone
Diaphysis
Ends of bone
Epiphyses
Describe long bone
Cylindrical
Curve 2 planes greater strength
What is epiphyseal growth plate
Hyaline cartilage ‘disc’ bordering epiphyses, around which growth occurs.
Structure of epiphysis
Thin outer compact bone covered by hyaline cartilage capsule
Inner spongy bone with red marrow/myeloid tissue
Epiphyseal growth plate
What covers outside of diaphysis
Periosteum
Myeloid tissue
red bone marrow
What is periosteum
Vascular, connective tissue membrane covers outer diaphysis
What lines central medullary canal in diaphysis
Endosteum
All bone marrow starts off as -
Red bone marrow
In severe blood loss what can happen to the marrow
Yellow can convert to red
Structure of diaphysis
Outer compact bone covered by periosteum
Central medullary canal contains red marrow/myeloid tissue/yellow blood cells lined with endosteum.
2 layers of periosteum
Outer - tough, fibrous,protects
Inner - CAMBIUM - contains osteoblasts & osteoclasts important for growth/repair.
What replaces periosteum on joint surfaces
Hyaline cartilage
5 jobs of periosteum
Protect bone Bone growth/repair Attachment for ligaments/tendons Provides blood supply Has nociceptors-nerve endings sense pain
5 bone shapes in body
long short irregular flat sesamoid
Example of long bone
femur
ex of short bone
carpals/tarsals
ex flat bone
skull/hip
ex irregular bone
vertabrae
ex sesamoid bone
patella
structure of all bones apart from long -
peroisteum enclosing
compact bone outer
spongy inside, containing bone marrow
What does red bone marrow do
creates red blood cells,
platelets,
white blood cells
what does yellow bone marrow do?
stores fat
creates some white blood cells
Why is exercise particularly important in older women?
To help strengthen their bones after menopause
prevent Osteoporosis
Bone formation known as
ossification/osteogenisis
3 times ossification/genesis occurs
during growth
continuous bone renewal
repair
2 types ossification
Intramembraneous ossification
Endochondral ossification
What are cartilage cells known as?
Chodrocytes
Describe intramembraneous ossification
Bones form directly within the mesenchyme
Describe Endochondrial Ossification
Bones form within hyaline cartilage at epiphyseal plate
what is mesenchyme
cell soup
By which process are bone cells produced around the epiphyseal growth plate during endochondrial ossification?
Mitosis
Which cells ossify the matrix to form bone during endochondrial ossification?
Osteoblasts
At what age doe endochondrial ossification cease?
early 20’s boys
late teens girls
What are our bones left with after completely ossifying
epiphyseal line
what is the growth in bone thickness known as
appositional growth
inner layer of periosteum called?
cambium
Describe how diameter of bone increases during appositional growth
Osteoblasts in cambium form compact bone
Osteoclasts in medullary cavity carve out bone
Main hormones affecting bone growth in children
Growth hormone
thyroid hormone
Main hormones affecting bone growth in adults
testosterone & oestrogen
calcitonin
parathyroid hormone
What to take for restless legs
magnesium glycinate
Which mineral do bones store large amounts of?
Bone is an important calcium reservoir
Blood calcium levels have to be tightly controlled to ensure proper
blood clotting
nerve & muscle function
If blood calcium levels are low what happens in body to restore homeostasis
Osteoclasts break down/release calcium into blood
If blood calcium levels are high what happens to restore homeostasis
Calcium in absorbed back into the bone via Osteoblasts
Which two glands regulate calcium exchange
Parathyroid
thyroid
Describe negative feedback system that increases blood calcium
RECEPTORS - parathyroid gland detect lower calcium
CONTROL CENTRE - switches on PTH gene
PTH stimulates the EFFECTORS - Osteoclasts (bone resorption)/Kidneys keep the calcium in blood
Describe negative feedback system that decreases blood calcium
come back
What helps bones get stronger
weight bearing exercise
Which type of exercise doesn’t help bone strength
swimming
What rate of bone mass loss a week can astronauts/the bedridden expect?
Up to 1% per week
Exercise leads to increased —- and — in bones
increased mineral deposition and increased production of muscle fibres
What helps to ensure bone formation occurs more quickly than bone resorption
exercise
what is the bioactive form of vit D?
calcitrol
what is calcitonin?
hormone that promotes bone growth & decreases blood calcium when too high
