Lecture 5 - Skeletomuscular System Overview: Bones, Joints, Ligaments, and Tendons

Question 1

Skeletal system

Answer 1

Provides support, protects tissue, stores minerals, and forms blood cells

Ex. Axial skeleton, appendicular skeleton, teeth

Question 2

Muscular system

Answer 2

Produces movement, provides support, and generates heat

Ex. Axial muscles, appendicular muscles

Question 3

3 connective tissues that connect the skeletal and muscular systems

Answer 3

1. Cartilage - supportive connective tissue located at joint surfaces, ears, nose, and vertebral discs
2. Ligaments - dense regular connective tissue that anchor bones to other bones
3. Tendons - dense regular connective tissue that anchor bones to muscles

Question 4

Similarities and differences of cartilage and bone

Answer 4

Both are connective tissue that have a dense, solid matrix

Difference: cartilage consists of a proteoglycan matrix allowing it to be more flexible but bone tissue consists of collagen and its calcified, hydroxyapatite matrix which gives it a more rigid structure.

Question 5

3 subtypes of cartilage

Answer 5

1. Hyalin cartilage, composed of proteoglycans
2. Elastic cartilage, composed of proteoglycans and elastin fibres
3. Fibrocartilage, composed of proteoglycans and lots of collagen

They are all avascular and contain chondrocytes residing in the lacunae

Question 6

2 subtypes of bone tissue organization

Answer 6

1. Compact - dense (heavy); resists compression
2. Spongy - light and distributes force. Not as good at resisting compression and holding weight

There is a trade-off between these 2 regarding weight and weight-bearing

Question 7

Bone tissue

Answer 7

Highly vascularized and innervated. Inside bones are spaces filled with bone marrow

Question 8

True or False: bone marrow is a supportive connective tissue

Answer 8

False - it is not a type of supportive connective tissue. It creates blood cells

Question 9

4 cell types found in bone tissue and their roles

Answer 9

1. Osteogenic cells - produce other bone cells
2. Osteocytes - maintain bone matrix
3. Osteoblasts - produces bone matrix that eventually solidifies. Also secretes collagen
4. Osteoclasts - dissolves bone matrix

Question 10

2 methods of cartilage growth

Answer 10

Interstitial growth - undergoes chondrocyte proliferation; cell division. This type of growth ceases after adulthood

Appositional growth - differentiation into new chondrocytes

Question 11

2 methods of bone growth

Answer 11

Endochondral growth - occurs via ossification of cartilage. Most bone begin as hyalin cartilage. Ossification begins at the shaft and then at the epiphyses (ends). Cartilaginous epiphysial plates grow by interstitial division until they ossify at puberty

Appositional growth - adds layers to the outer surface of the bone. Osteoblasts are active at the periosteum and osteoclasts are active at the endosteum

Question 12

Exception of dermal and sesamoid bones compared to typical bone growth

Answer 12

Dermal and sesamoid bones ossify form non-cartilaginous connective tissue. Dermal bones are mostly found in the head and they ossify within the dermal tissue

Question 13

What are teeth and what are the main differences between bone and teeth?

Answer 13

They are mineralized tissue structures

Differences:
1. Hardness - the chemical composition of crystalline matrix is different
2. Growth - organization of cells compared to crystalline matrix
3. Evolutionary history

Question 14

Synovial joints

Answer 14

They connect bones in the skeleton to each other with differing tissues, such as bone and hyaline cartilage

Question 15

Bone fracture repair process

Answer 15

Bones are very vascularized - if they break they bleed. Bone repair first begins with repairing the matrix first. Bone healing involves extra proliferation of cells, which typically first differentiate into cartilage to hold the 2 broken bones together, then spongy bone, then compact bone

Question 16

Cartilage repair process

Answer 16

In general, cartilage does not repair itself well. Interstitial growth does not occur after puberty, but repair through appositional growth can occur into adulthood for fibrous and elastic cartilage

Note: articular cartilage usually cannot undergo self-repair at all as it lacks as perichondrium layer

Question 17

Osteoarthritis

Answer 17

A degenerative disorder caused by damage to the articular cartilage. Damage to the articular cartilage increases friction at the synovial joint, leading to inflammation, causing more pressure on the remaining cartilage, and more damage (ex of positive feedback loop)

Question 18

Significance of bone acting as a reservoir for minerals within the body

Answer 18

The ability of bone to be actively remodelled by cellular activity allows it to store or release minerals as they are needed

The balance between the amounts of osteoblast and osteoclast activity helps maintain calcium homeostasis (note: bones contain 99% of the body’s calcium)