Module 6 - Bones

Question 1

Bone Function

Answer 1

Functions
Support – attachment site for muscles – structural framework – support for soft tissue
Protection – internal organs have bony coverings
Movement – assist muscles
Mineral Homeostasis – store and release minerals – calcium and phosphorus
Production of blood cells – red marrow of bones – hemopoiesis
Triglyceride storage – yellow marrow

Question 2

Bone Classification

Answer 2

Classification
Long bones – shaft with two ends - femur
Short – cube-like – ankle bones (tarsals)
Flat – thin and curved – skull bones
Irregular

Question 3

Long Bone - Parts

Answer 3

Long Bones
Diaphysis
Epiphyses
Metaphysis
Hyaline cartilage
Periosteum
Medullary cavity
Endosteum
Red marrow
Yellow marrow

Question 4

Diaphysis

Answer 4

Diaphysis – shaft

Question 5

Epiphyses

Answer 5

Epiphyses – ends

Question 6

Metaphysis

Answer 6

Metaphysis – area b/w diaphysis and epiphyses – epiphyseal plate

Question 7

Hyaline cartilage

Answer 7

Hyaline cartilage – ends of bones – reduces friction and absorbs shock

Question 8

Periosteum

Answer 8

Periosteum – connective tissue – covering surface – osteogenic cells – protect bones – assist in fracture repair – nourish bone tissue – attachment point for ligaments and tendons

Question 9

Medullary cavity

Answer 9

Medullary cavity – in shaft – yellow marrow

Question 10

Endosteum

Answer 10

Endosteum – lines inner medullar cavity

Question 11

Red marrow

Answer 11

Red marrow – blood cell production

Question 12

Yellow Marrow

Answer 12

Yellow marrow – fat storage

Question 13

Bone Cells

Answer 13

Osteoprogenitor
Osteoblasts
Osteocytes
Osteoclasts – break down bone – reabsorption

Question 14

Osteoprogenitor

Answer 14

Osteoprogenitor – stem cells

Question 15

Osteoblasts

Answer 15

Osteoblasts – bone building cells

Question 16

Osteocytes

Answer 16

Osteocytes – mature bone – maintain bone – principle cells

Question 17

Osteoclasts

Answer 17

Osteoclasts – break down bone – reabsorption

Question 18

Matrix

Answer 18

Matrix
inorganic salts – hydroxyapatite, calcium carbonate, and collagen fibres
salts deposited into framework of collagen fibres – calcification or mineralization
mineral salts = hardness
collagen = tensile strength

Question 19

Compact Bone

Answer 19

Compact Bone
arranged in Osteons or Haversian Systems
Osteons
blood vessels, lymphatic vessels, nerves, and osteocytes
aligned in same direction – along stress lines
hollow passage
Calcified matrix

Question 20

Spongy Bone

Answer 20

Spongy Bone
No osteons
Trabeculae
Canaliculi
Endosteum
Lamellae
Lacuna
Red marrow
Most structure of short, flat, and irregular bones
Epiphysis of long bones
Light
Supports and protects red marrow

Question 21

Canaliculi

Answer 21

Canaliculi – light openings on surface – pores
Spongy bone

Question 22

Trabeculae

Answer 22

Trabeculae – columns or beams of bone
spongy bone

Question 23

Endosteum - Spongy Bone

Answer 23

Endosteum – lining outside
spongy bone - inside

Question 24

Lamellae - spongy bone

Answer 24

Lamellae – concentric rings – like tree rings - spongy bone

Question 25

Lacuna

Answer 25

Lacuna – spaces b/w rings – osteocytes and fluid - spongy bone

Question 26

Ossification

Answer 26

Ossification – bone formation Mesenchymal cells give template 2 types Intramembranous Endochondral

Question 27

Intramembranous Ossification

Answer 27

Intramembranous Ossification from or w/in fibrous connective tissue membranes flat bones of skull and mandible

Question 28

Intramembranous Ossification - Steps

Answer 28

4 Steps Osteoblast cluster at centre of ossification – mesenchymal cells group Osteoblasts secrete matrix – osteoid traps blasts – become osteocytes Trabeculae lay down to form spongy bone – blood vessels come in – periosteum form, outer surface covering Compact bone develops superficial – blood vessels condense to red marrow

Question 29

Endochondral Ossification

Answer 29

Endochondral Ossification Hyaline cartilage template Early fetal development Growth in length and thickness

Question 30

Endochondral Ossification - Steps

Answer 30

5 steps Cartilage model – mesenchymal cells differentiate into chondroblasts – form model – cells organize into columns – mature to chondrocytes Calcification – chondrocytes at center hypertrophy – secrete matrix of collagen and glycoprotein – calcification of tissue Primary Ossification center – model becomes vascular – chondrocytes die – bone marrow formed at center – osteoprogenitor cells come and differentiate into osteoblasts – in diaphysis Secondary Ossification center – epiphysis – ossification continues in the diaphysis – new site in ends of bones – ends become vascular – ossification begins at ends Epiphyseal plate formation – joint surface as articular cartilage

Question 31

Remodeling

Answer 31

Remodeling Constantly breaking down and reform

Question 32

Remodeling Phases

Answer 32

Phases: Activation – pre-osteoclasts are attracted to area – fuse into multinucleated osteoclasts Resporption – osteoclasts dig out resorption pit or tunnel – calcium released into blood – osteoclasts disappear Reversal – stem cells appear and differentiate into osteoblasts Formation – release osteoid = new matrix – matrix is mineralized with calcium and phosphorous Quiescense – dormant lining cells

Question 33

Minerals

Answer 33

Minerals needed Calcium Phosphorus Magnesium

Question 34

Vitamins

Answer 34

Vitamins A B12 C D K

Question 35

Hormones

Answer 35

Hormones Thyroid hormones Insulin calcitonin Human growth hormone: Estrogen Testosterone

Question 36

Calcium Homeostasis

Answer 36

Calcium Homeostasis Blood level calcium ions (Ca2+) Normal: 10mg/dL Regulated for physiology of: Cardiac Nerve Enzyme Blood

Question 37

Parathyroid hormones (PTH)

Answer 37

Parathyroid hormones (PTH) – below normal -10mg/dL Regulated Ca2+ of bones and blood Increases blood calcium levels Parathyroid gland Osteoclasts release Ca2+ from bones Calcium is reabsorbed from urine by the kidneys Calcium absorption in the small intestine increases via vitamin D synthesis

Question 38

Calcitonin (CT)

Answer 38

Calcitonin (CT) – above normal +10mg/dL Thyroid gland Decreases blood Ca2+ Thyroid gland releases calcitonin Osteoclast activity is inhibited Ca2+ reabsorption in kidneys decreases