Physiology - Bone and Skeletal Tissue
Few cartilages remain in adults, where are they mainly within the body?
A: In areas of articulation
What is perichondrium?
A: Dense irregular connective tissue that resists outward expansion
Skeletal cartilage doesn't contain what?
A: Contains no blood vessels or nerves
What are the 3 types of cartilage found in the body?
1. Fibrocartilage (collagen fibers)
2. Hyaline (most abundant)
3. Elastic (elastic fibers)
What are the characteristics of Fibrocartilage and where is it found?
What are the characteristics of Hyaline cartilage and where is it found?
- Most abundant and provides support, flexibility, and resilience
Articular – covers the ends of long bones
Costal – connects the ribs to the sternum
Respiratory – makes up the larynx and reinforces air passages
Nasal – supports the nose
What are the characteristics of Elastic cartilage and where is it found?
We classify bones by their shape, what are the 4 main shape classifications? Explain each one.
Long Bone: longer than they are wide
Short Bone: cube-shaped bones of the wrist and ankle
Flat Bone: thin, flattened, and a bit curved
Irregular Bone: bones with complicated shapes
List the 5 main functions of Bones.
3. Bloodcellproduction(redbonemarrow) 4. Leverage
Name the two types of bone, explain each one.
1. Compact or Cortical
Explain Diaphysis and the Epiphysis?
- Diaphysis = Tubular shaft
- Epiphysis = Expanded ends of long bones Exterior is compact bone, and the interior is spongy bone Joint surface is covered with articular (hyaline) cartilage Epiphyseal line separates the diaphysis from the epiphyses
Explain the following:
- Osteocytes – mature bone cells
- Lacunae – small cavities in bone that contain osteocytes
- Canaliculi – hairlike canals that connect lacunae to each other and the central canal
- Osteon–the structural unit of compact bone
- Lamella – column-like matrix tubes composed mainly of collagen
We know bone is metabolically active, explain the role of Osteoclasts and Osteoblasts with regards to bone maintenance.
Osteoclasts = remove old bone
Osteoblasts = makes new bone
Explain Ossification and Intramembraneous ossification.
Cartilage grows in 2 ways, list and explain each.
Appositional growth: “growth from outside”
- Cartilage-forming cells in the surrounding perichondrium secrete new matrix against the external face of the existing cartilage tissue
What is endochondral ossification?
The replacement of hyaline cartilage
(Ossification of the epiphyses; when completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages)
Bone is a calcium reservoir, what percentage of calcium is stored in bones?
99% of calcium storage in the body
Net balance of calcium is controlled by 3 hormones, what are they?
Parathyroid hormone: increases [Ca2+] in blood when [Ca2+] low
Homeostatic imbalances of bone can cause the following diseases:
Osteomalacia and Rickets: ‘soft bones’ – inadequate mineralization
- Inadequate calcium or Vit D, Rickets = kids – bow leg
What is Osteoporosis?
“ A skeletal disease characterised by low bone mass and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fracture”
List the different types of bone fractures.
Closed vs. open
Transverse fracture - break in shaft
Spiral fracture - twisting stress
Displaced fracture - abnormal alignment
Nondisplaced –normal alignment
Complete – bone is broken all the way through
Incomplete – bone is not broken all the way through
Linear – the fracture is parallel to the long axis of the bone
Greenstick - partial break of shaft (children)
Compression - crush
Explain blood cell formation.
All blood cells arise from stem cells
-located in the red bone marrow
Hemocytoblast capable of developing into a red blood cell, white blood cell or platelet.
Explain bone and it's relation to red blood cells.
Red blood cell production
What are the two membranes surrounding bone called? Explain each one.
Periosteum – glistening white double layered membrane
-Outer fibrous layer – dense connective tissue
-Inner osteogenic layer – contains osteoblasts / osteoclasts
- Nerve fibres / lymphatic vessels / blood vessels enter diaphysis via nutrient foramen
Endosteum – covers spongy bone (trabeculae) and lines canal of compact bone
- Also contains osteoblasts / osteoclasts