Chapter 13 - The Skeleton Flashcards Preview

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List the functions of the skeleton.

• Articulation
• Protection if vital organs.
• Act as storage organs for mineral salts and fat.
• Blood cell production in red marrow.


What mineral salts and fat are stored in the bones of the skeleton?

•Calcium, phosphorus, sodium and potassium are the main minerals store within bone.

• These can be distributed to other regions of the body by the circulation system when required.

Eg. Prego woman's diet does not contain enough calcium, it can be removed from her skeleton and used for the growth of bones in the developing foetus.


What does a Long Bone consist of?

• A shaft, Diaphysis - making up the main portion of the bone
• The ends, Epiphyses - enlarged ends of the bone; a thin layer of cartilage, the articular cartilage, covers each epiphysis.


Explain the structure of the Diaphysis.

•Hollow cylinder of compact bone surrounding a cavity.

•This cavity is used as a fat storage site and is often cells the Yellow Bone Marrow cavity.


Explain the structure of the Epiphyses.

They have a compact bone on the outside but their central regions contain spongy or cancellous bone.


What is a Cancellous bone?

It is more porous than a compact bone, and contains many large spaces filled with marrow. In certain bones this may be red bone marrow, where blood cell production takes place.


What is located on the outer surface if the bone?

There is a dense, white, fibrous covering, the periosteum.

There is no periosteum at the joints where the bone is covered with an articular cartilage.


What are bones classified as?

Connective tissues.


What do Connective Tissues consist of ?

Cells separated from each other by large amounts of non-cellular material called matrix.


Why are inorganic salts deposited in the matrix?

These increase it's rigidity and strength and make it the hardest of the connective tissues.


What does a compact bone consist of?

Many similar units called Osteons or Haversian systems.


Explain the structure of the Oesteons or Harversian systems.

At the centre of each Oesteon is a central canal (Haversian canal), around which are concentric layers of bony matrix called lamellae.

•Between the lamellae are small spaces in the matrix, the lacunae.

• A bone cell, or osteocyte, occupies each lacuna. Tiny canals, known as canaliculi, run between the lacunae.


How are material passed from cell to cell?

Projections from the bone cells enter the canaliculi and make contact with adjacent bone cells. In this way materials can be passed from cell to cell.


What does the central canal (located in the middles of each Osteon) contain?

At least one blood capillary. It may also contain nerves and lymph capillaries.


What gives the osteons maximum strength?

The fact that they run parallel to the long axis of the bone.


What are Spongy bone?

AKA Cancellous Bone

•Not organized into Osteons.

•It consists of an irregular arrangement of thin, bony plates called Trabeculae.

• The bone cells occupy spaces in the Trabeculae, but the lamellae are not arranged in concentric layers, and nerves and blood vessels pass through irregular spaces in the matrix.


When does bone grow?

Bone grows as an individual passes through infancy and adolescence to adulthood.

In an adult, the bones of the skeletal system are capable of repair and continue their functions if blood cell formation and storage.


What is a Cartilage?

Like bone, it is a connective tissue.

It contains numerous fibres made of a protein called collagen.


What is a Chondrin?

It is where the Collagen/ protein fibres are embedded in; It is a firm matrix of protein-carbohydrate complex.


Explain the structure of the Chondrin.

This form matrix enables cartilage to function as a structural support, while the preserve of fibres gives cartilage a certain amount of flexibility.

Because of these properties it is found on the surface if the bones at the joints and in the trachea and bronchi, and forms the nose, larynx and outer ear.


What are Chondroblasts?

•They are cartilage cells which are contained within spaces in the matrix.

•They produce matrix and gradually become surrounded by it until they are trapped in small spaces called lacunae.

->Once this has occurred, the cells are considered to be mature and are referred to as chondrocytes.


Why do Collagen fibres have to be classified?

Because the collagen fibres in the matrix range in thickness from extremely fine, so that they can just be seen with a microscope, to quite coarse.


The variation in the fibrous structure of the cartilage is used to classify it into 3 types:

1. Hyaline cartilage
2. Elastic cartilage
3. Fibrocartilage


Explain the structure of the Hyaline Cartilage.

•Contains many closely packed collagenous fibres throughout the matrix.

• These fibres are so fine that they are not distinguishable under a light microscope.

• They give the cartilage strength along with flexibility.

• Hyaline cartilage makes up the rings of the trachea and bronchi, and is also found at the ends of bones where two bones meet to form a movable joint.


Explain the structure of the Elastic Cartilage.

• Has conspicuous elastic fibres.

• It also contains collagenous fibres similar to those in hyaline cartilage, but they are not closely packed.

• Elastic cartilage provides edible elastic support in places such as the external ear.
-> Folding your ear down and letting it go shows how springy this cartilage is.,


Explain the structure of the Fibrocartilage.

• Has a coarse appearance from the parallel bundles of thick collagenous fibres that make up this tissue.

• The fibres are not compacted as much as in hyaline cartilage and therefore it is able to be compressed slightly.

•This is ideal for regions where the weight of the body is being supported or where there is a need to withstand heavy pressure.

•Fibrocartilage is found in the intervertebral discs of the spinal column, whee it provides a cushion between the vertebrae; in the articular cartilage of the knee joint; and the tissue joining the two sides of the pelvis.


Cartilage does not contain any blood vessels; list all the functions that will be affected.

• All nutrition and waste removal for the cells depends on diffusion through the matrix.

•This is a slow process and results in the chondrocytes having a slow rate of metabolism and cell division.

• Injured cartilage therefore takes quite some time to heal.


Where does the blood supply for they cartilage come from?

Blood vessels located in the inter layer of the Perichondrium. This is a fibrous membrane of connective tissue that covers the external surface of cartilage, except where the cartilage forms the articular surface of a joint.


What two sections are the bones of the skeleton divided into?

1. Axial Skeleton
2. Appendicular Skeleton


Explain the structure of the Axial Skeleton.

•It consists of the bones that lie around the central axis of the body.

•It provides the main support for erect posture, and protects the central nervous system and the organs contained within the thorax.

•The bones that form the skull, vertebral column, ribs and sternum (breastbone) make up the axial skeleton.