Bone Structure and Function Flashcards
What is the skeletal system made up of?
Bones along with their cartilages.
How many bones are you born with? Then later what happens?
You are born with 300 bones, which later fuse together into the 206 bones of an adult.
What is a function of the skeletal system in red bone marrow?
Blood cell production.
What is the function of the skeletal system in yellow bone marrow?
Triglyceride storage.
What does the skeletal system protect?
Internal organs.
The skeletal system has muscle attachments, what does this aid with?
Movement.
The skeletal system stores minerals in a process called what?
Mineral homeostasis.
What does the skeletal system do structurally?
Support the framework of the body.
What are the 5 types of bones?
Long, short, flat, sesamoid, irregular.
Where are long bones found?
In the arms and legs.
And collarbones (clavicle).
Give some examples of long bones in the arms and hands. (5)
Humerus (upper arm).
Radius (lower arm).
Ulna (lower arm).
Metacarpals (hand).
Phalanges (fingers).
Give some examples of long bones in the legs and feet. (5)
Femur (upper leg).
Tibia (lower leg)
Fibula (lower leg).
Metatarsals (feet).
Phalanges (toes).
Where are short bones found?
(hint: where you sprain)
In the wrist and ankle.
(carpals and tarsals)
Where are flat bones found?
Rib cage, skull, shoulder blade, breastbone
What are two examples of sesamoid bones?
Pisiform (carpal)
Patella (kneecap_
Give some examples of irregular bones. (4)
Think of capital i shape.
Skull, ears, spine, hips.
With the macroscopic anatomy of a long bone, draw and label the different parts.
Name them starting from the top.
Articular Cartilage
Proximal Epiphysis
Metaphysis
Diaphysis
Metaphysis
Distal Epiphysis
Articular Cartilage
What is the diaphysis?
Shaft of the bone.
Where is the epiphysis?
Located at the distal and proximal ends of the bone.
Where is the metaphysis?
Located between the diaphysis and epiphysis.
What is articular cartilage?
Hyaline cartilage (connective tissue) covering the epiphysis where bone articulates with another bone.
Where is the periosteum and what are its 2 layers?
It surrounds the external bone surface.
Outer surface = fibrous layer
Inner surface = cellular layer
What is the endosteum?
A thin membrane that lines the surface of the medullary cavity.
How does a paediatric (child) long bone differ from an adult long bone?
A child’s long bone has a growth plate (physis) which is a thin layer of hyaline cartilage responsible for the growth and development of long bones in children and adolescents.
What are the two types of bone tissue?
Compact and cancellous.
What is the function of compact bone tissue?
- To protect and support the bone.
- To resist stresses of weight and movement.
What are the structural units in compact bones that are shaped as microscopic cylinders?
Osteons.
What is on the inner and outer surface of compact bone? What does it act as a boundary to?
Outer surface = periosteum.
Inner surface = endosteum which acts as a boundary between compact and cancellous bone tissue.
In an osteon, what is the central canal called and what does it contain?
- Haversian canal
- Contains the arterial blood supply (blood vessels), venous drainages, lymphatic vessels and nerves.
What run parallel to the long bone axis?
What do they do?
Volkmann’s canals are at right angles to the central canal.
They join the various haversian canals.
They allow blood vessels to enter the bone and haversian canal from the periosteum.
(connect periosteum + haversian canal)
What are the rings in an osteon called?
What do they contain?
Lamellae.
Contains extracellular matrix.
What do the collagen fibres and mineral salts do?
They are in the bone matrix and run in opposite directions to give great torsion strength. (resists twisting force.)
What do the canaliculi do?
Connect lacunae for nutrient delivery and waste removal.
What are lacunae and what do they contain?
They are ‘small lakes’ that house osteocytes.
Where is the extracellular matrix and what do they consist of?
- They are located in the lamellae between the osteocytes.
- They consist of organic and inorganic components and water.
What is the organic component of the extracellular matrix and what does it give?
- Osteoid - protein and collagen.
- Gives bone its tensile strength.
What is the inorganic component of the extracellular matrix and what does it give?
- Hydroxyapatite (calcium phosphate + calcium hydroxide)
- Mineral portion of bone
- Gives bone strength and density
What is the function of cancellous bone tissue?
- To reduce the overall weight of the bone.
- To support and protect red bone marrow.
What is cancellous bone also referred to? Why?
What does cancellous bone not contain as opposed to compact bone?
- Spongy bone (due to appearance, not its texture)
- Does not contain osteons or a haversian canal.
What does cancellous bone consist of?
What do the spaces between them help with?
- They consist of an irregular lattice of thin columns called trabeculae.
- Spaces between trabeculae help make bones lighter and sometimes contain red bone marrow.
What are the openings on the surface of cancellous bones, what do they do?
- Canaliculi
- Connect to adjacent cavities instead of a haversian canal for a blood supply.
Where is bone marrow found and what is it?
- Found in cancellous bone.
- Nutrient-dense, spongy tissue.
- Produces white and red blood cells and platelets.
- Contains stem cells.
In contrast to compact bone, is cancellous bone:
1) Stronger or weaker?
2) More or less dense?
3) More or less flexible?
1) Weaker.
2) Less dense.
3) More flexible.
What are the four types of cells found in bone? (cells of bone formation)
Osteoprogenitor cells, osteoblasts, osteocytes, osteoclasts.
What are osteoprogenitor cells?
Where are they located?
- Unspecialised stem cells, precursors to osteoblasts.
- Located in inner layer of periosteum, the endosteum and epiphyseal plates of growing bone.
What are osteoblasts?
Where are they located?
What can happen to osteoblasts?
[CONSTRUCTION WORKERS]
- Osteoblasts make new bone, and synthesise osteoid and the enzyme required to form hydroxyapatite. Also regulate calcification.
- They thicken the bone by depositing osteoid.
- Located on all bone surfaces
- As they deposit new bone and become trapped in bone matrix, they can become/differentiate into osteocytes and supply nutrition to the bone.
What are osteocytes?
What do they do?
Where are they located?
[MAINTENANCE GUYS]
- Mature osteoblasts.
- They maintain daily metabolism and nutrient exchange. (regulate existing bone).
- They have long cytoplasmic extensions which help supply nutrients to existing bone.
- Located in the lacunae of cancellous and compact bone within the bone matrix.
What are osteoclasts?
What do they do?
Where are they located?
[PHAGOCYTIC CELLS]
- They are formed from white blood cells.
- They release enzymes and acids to digest components of the matrix. (bone degradation, erodes and recycles existing bone by breaking down tissue).
- Work with osteoblasts to maintain calcium homeostasis and respond to mechanical stress.
- Located on all bone surfaces and particularly concentrated in the endosteum.
What are the identifying features of osteoblasts, osteocytes and osteoclasts?
- Osteoblasts - single nucleus, sits on surface of bone.
- Osteocytes - have cytoplasmic projections and a single nucleus.
- Osteoclasts - large and multinuclear.
