Bones Flashcards
What is homeostasis?
The dynamic process of keeping a stable internal environment
Feedback vs feedforward
feedback: Responds to a change after it has happened. 2 types
- negative: returns to midline
- positive: accelerates away from midline
Feedforward: Happens when predicting a future change
3 types of Bodily fluid and their percents
- Intrastitial fluid: 67%
- Interstitial fluid: 26%
- Plasma: 7%
Types of cells
- Epithelial cells: form membranes in body
- Connective tissue: connects and supports the body (eg. tendons, bones, blood)
- neurone cells: produced and conducts electrical signals
- Muscle cells: Can contract
Types of bones
- Flat bone (skull)
- irregular bone (vertibrae)
- long bone (Humorous)
- short bone (Carpal bones)
Epithelial cell naming
Shape:
1. Cuboidal (cube)
2. Squamous (Squished)
3. columnar (long)
4. transitional (changes shape)
Layers:
1. Simple (1 layer)
2. stratified (multi layered)
3. Pheudostratified (Multi layered not uniform cells)
Types of connective tissue
- Connective tissue proper: Connects and attaches
- lymph and blood: Transport around the body
- Bones: support and structure
- Cartilage: shock absorption
Long bone anatomy
- Diaphysis: Long part of the bone
- Metaphysis: Flared part of the bone
- Epiphysis: Ends of the bone
- Epiphyseal plate/line: line between the epiphysis and the metaphysis
- Articular cartilage: around the end of the bone reduces friction and shock absorption
- medullary cavity (cavity in the middle of bone)
- Endosteum: lines the medullary cavity
- Periosteum: bilayered butter membrane of the bone
What are the two layers of periosteum?
- Outer fibrous layer: dense connective tissue
- Inner osteogenic layer: holds osteoblast and osteoclasts
What are the honey comb like structures in spongy bone called?
Trebeculae
Where is yellow/red bone marrow found and their rolls?
Yellow bone marrow: Found in the medullary cavity and stores adipose tissue (fat tissue) for energy storage
Red bone marrow: Found in spongy bone and produced red and white blood cells and platelets
Name the specific veins and arteries that supply the different areas of the bone. 4 types
- Nutrient artery and vein: Supply the diaphysis
- Epiphyseal vein and artery: Supply the epiphysis
- Metaphysical artery and vein: supply the metaphysis
- Periosteal vein and artery: supply the periosteum
Name the parts of compact bone and their uses
- Osteons: cylindrical units of compact bone
- Concentric lamellae: rings of bone that make up the osteons
- Collagen fibres: Make up the concentric lamellae, running in opposite directions as the previous ring to increase strength
- Circumferential lamellae: Bone that surrounds the diaphysis
- lacunae: gaps in between the osteons. House osteocytes
- Canaliculi: small canals that run between lacunae providing nutrient and waste removal
- Central canal: canal down the centre of the osteoblasts containing blood vessels and nerves
4 reasons for bone development
- fetal development
- Repair from a fracture
- Early life bone growth
- Bone remodelling through life
2 types of bone development and their definitions
ossification: specific process of creating new bone
osteogenesis: General term for bone development and maintenance. Ossification is a type of osteogenesis
2 types of ossification
- Endochondral ossification: Mesenchymal cells develop into cartilage model first, then bone replaces the cartilage. (most bones are made this way)
- Intramembranous ossification: Mesenchymal cells differentiate straight into bone (forms flat bones)
Intramembranous ossification in depth (layer of spongy bone between 2 layers of compact bone)
- Mesenchymal cells differentiate into osteoblasts and secrete osteoid
- Osteoid is played around the blood vessels forming trebeculae
- Minerals calcify the osteoid into bone
- Osteoblasts go to the surface off the cell and create the periosteum
- just below the periosteum, spongy bone is remodelled into compact bone
- Blood vessels in the spongy bone remodel into red bone marrow
explain the process of Endochondral ossification:
see page in binder
Post natal bone growth 2 ways
Interstitial growth: growth in length. Chondrocytes keep dividing and extending the bone then osteoblasts turn them into bone
Appositional growth: Growth in width. Osteoblasts create new layers of compact bone widening it out.
Interstitial growth: the growth plate. IMPORTANT (Ask about is calcification what makes bone)
Resting zone: Chondrocytes anchor the growth plate to the epiphysis
Prolific zone: Chondrocytes rapidly divide lengthening the bone
Hypertrophic zone: Old chondrocytes increase in size forming the lacunae between them
calcification zone: Old chondrocytes die, opening spaces for blood vessels to enter. The cartilage is calcified
Ossification zone: Osteoclasts remodel the cartilage into bone
Appositional growth in depth
- Osteoblasts on the periosteum form around the blood vessels creating new concentric lamellae, until new osteons are formed
- Osteoblasts form new circumferential lamellae
- Osteoclasts widen the medullary cavity
In adults what kind of bone growth occurs?
Only appositional growth. The growth plate is fused into the epiphyseal line, therefor no interstitial growth
What affects our peak bone mass?
- genes
- life style (diet, exersize)
What hormone is released if calcium is too low and what does it do?
Parathyroid hormone: Kidneys re-absorb more calcium. Stimulates osteoclast activity to break down bone for calcium. Synthesized more vitaminD which increases calcium absorption
What hormone is released if calcium levels are too high?
calcitonin: Osteoclast activity is inhibited (won’t put more calcium into plasma). promotes osteoblast activity. tells kidneys to reduced calcium re absorption
What is wolfs law?
Bones become thicker and stronger to resist forces and thinner and weaker if their are no faces acting on it
