skeletal system

Question 1

Describe the difference between spongy and compact bone

Answer 1

• Spongy bone is made up of trabeculae. Trabeculae has holes and arches that contain bone marrow, allowing haematopoiesis to take place. It is found in the inner layer of flat and irregular bones, contributing to shock absorption. There are no osteons within spongy bone.
• Compact bone is the outer layer of long bones, it is dense and solid providing strength and protection. Compact bone has osteons.

Question 2

What are the main functions of the bone?

Answer 2

• Protection
• Support
• Movement
• Mineral storage
• Blood cell formation
• Hormone storage
• Hormone production
• Triglyceride (fat) storage in bone cavities

Question 3

What is haematopoiesis?

Answer 3

• Formation of blood cellular components

Question 4

What are the three sections/ layer of bone

Answer 4

• Proximal epiphysis
• Diaphysis
• Distal epiphysis

Question 5

What is the periosteum

Answer 5

• Thin layer of connective tissue that covers outer surface of bones, on all places except joints. It has a rich nerve supply.
• It has two layers: Fibrous & osteogenic
• Sharpey’s fibres connect periosteum to the bone.

Question 6

What is an endosteum?

Answer 6

• Lining of cavities and canals that pass through compact bone. Release endosteal cells

Question 7

What are endosteal cells?

Answer 7

• They are bone lining cells that communicate with osteocytes.

Question 8

What are canaliculi?

Answer 8

• Is found in compact bone, they are hairlike canals that connect lacunae to each other and central canal.

Question 9

Compact bone microstructure: How is canaliculi formed?

Answer 9

• Osteoblasts secrete bone matrix
• They maintain close contact to each other and other bone cells.
• Mature osteocytes develop as bone matrix calcifies
• Then a very fine web of canaliculi is formed.

Question 10

What are synovial joints?

Answer 10

• Freely moveable joints
• It has synovial fluid, which is produced in the synovial membrane. It is made up of hyloronich acid and lubricate. It lubricates articular cartilage.

Question 11

What are the accessory structures of synovial joints, describe them.

Answer 11

• Bursae= fluid filled sacs allowing tendon and articulating cartilage to roll against each other without creating friction.
• Fat pads= contain fat cells, act as a cushion. Have a rich blood supply.
• Ligaments= Fibrous structure attaching bone to bone. They help to maintain the integrity of a structure.
• Menisci= made of fibrocartilage. They are two wedge shaped pieces of fibrocartilage that act as a shock absorber between the tibia and femur.
• Tendon= Attach muscle to bone. Tendon sheath wraps around the tendon and are fluid filled.

Question 12

What are the main divisions of the skeleton?

Answer 12

Axial skeleton: bones of the head and trunk of a vertebrate.
Appendicular skeleton: bones of the shoulder girdle, the upper limbs, the pelvic girdle, and the lower limbs.

Question 13

What are classifications of bones by shape?

Answer 13

• Long= Bones longer than they are wide e.g., femur, humerus
• Short= Bones as wide as they are long e.g., carpal bones
• Flat= Bones like plates e.g., scapula, sternum
• Irregular= e.g., vertebrae, inner ear
• Sesamoid= Are embedded in tendon e.g., patella, psiform

Question 14

What are the types of endosteal cells/ bone lining cells?

Answer 14

Osteoblasts= Builder cells. They produce calcium binding proteins and lay down collagen fibres.
Osteoclasts= Remodelling cells. Release enzymes/ acids from ruffled edge to break down the bone.
* These both work together to remodel the bones.
Osteocytes= Sitter cells. Sit in bone and monitor the stress and strains of the bone. Help/ coordinate remodelling of bone.

Question 15

Endosteal cells (bone lining cells)=

Answer 15

Squamous cells that communicate with osteocytes.

Question 16

What is the volkmanns canal?

Answer 16

Within compact bone, creates room for blood to get in compact bone.

Question 17

What is the Haversian canal?

Answer 17

Within compact bone, takes/ brings blood supply in/ out.

Question 18

Osteon=

Answer 18

basic unit of structure of compact bone

Question 19

What are the 6 types of synovial joints?

Answer 19

• Ball and socket e.g., humeroscapular
• Hinge joint e.g., humeroulnar
• Saddle joint e.g., trapeziometacarpal
• Pivot joint e.g., radioulnar
• Gliding joint e.g., inter carpal
• Condyloid joint e.g., metacarpophalangeal

Question 20

What are the three types of muscle contraction?

Answer 20

• Isometric= This involves a muscle producing tension but staying the same length. This occurs when the body is fixed in one position e.g., plank.
• Concentric= when the total length of the muscle shortens as tension is produced e.g., upwards phase of bicep curl.
• Eccentric= involves the muscle lengthening whilst it is under tension e.g., lowering phase of a bicep curl.

Question 21

Skeleton is made of bone and…

Answer 21

Cartilage, both hyaline and fibrocartilage.
Hyaline:
- most abundant
- support + flexibility
- covers ends of bones, connects ribs to sternum, supports nose in respiratory system.
Fibrocartilage:
- strong and compressible
- In knees and discs between vertebrae and pubis.

Question 22

What is the chemical level of organisation of bone?

Answer 22

• 30% organic= bone cells, fibres. Making flexibility.
• 70% minerals= calcium phosphate, making hardness