Biology Option B

What are the 3 types of cartilage

Hyaline cartilage, white fibrous cartilage, yellow elastic cartilage

What is hyaline cartilage

It has a high proportion of collagen but is the weakest type of cartilage. It becomes bone in the foetus (I.e it ossifies). If it is damaged it is replaced by fibrocartilage scar tissue. A fibrous coat of connective tissue called the perichondrium, surround the hyaline cartilage

Where would you find hyaline cartilage

It is retained as adults from the foetus at the ends of bones e.g. joining ribs to sternum, nose, trachea, larynx, bronchi.

What is white fibrous cartilage

It is the strongest type of cartilage. It is collagen organised in dense fibres so it has greater tensile strength than other types of cartilage. The fibres are arranged in the direction of stress.

Where would you find white fibrous cartilage

Intervertebral discs and ligaments

What is yellow elastic cartilage

It is intermediate in strength. In addition to collagen its chondrocytes are surrounded by a network of fibres made of elastin. This makes it elastic but maintains its shape.

Where would you find yellow elastic cartilage

In the ear pinna and the epiglottis

What are the functions of bone in the body

Structural support in the skeleton, movement because bones are attachment sites for muscles, physical protection of organs e.g. brain, blood cell production, mineral regulation e.g. storage of calcium and phosphorus, trapping some minerals that would cause harm elsewhere in the body e.g. lead, regulation of calcium conc in blood

What are the two types of bone in the body

Spongy/cancellous bone and compact bone

What is spongy/cancellous bone

It has a network of spaces containing bone marrow, the flexible in which blood cells are made

Where is spongy/cancellous found

At the end of long bones and in vertebrae

What is compact bone

Represents 75% of bone in the body. Haversian and volkmann canals run through the bone allowing blood vessels to penetrate. Compact bone surround most bones, and gives them their white and shiny appearance. It is strong and rigid. Cells called osteoblasts continually build it up and cells called osteoclasts continually degrade it. These cells are held in a matrix secreted by osteoblasts which is 30% organic - mainly collagen fibres so it resists fractures and 70% inorganic hydroxy-appetite rich in calcium and phosphate ions which is very hard and resists compression

What is an osteon/Haversian systems

They are about 1mm wide and a few mm long running longitudinally through the bone. Volkmann canals carry blood vessels from the bone surface through to the Haversian canal in the centre.

What do haversian canals contain

An arteriole, a venue, lymph vessels and nerve fibres

What is the structure of the osteon/haversian systems

It is build in concentric rings or lamellae around the Haversian canal. Osteoblasts are the bone cells that secrete hydroxy-apatite that makes the lamellae. They sit in spaces called lacunae. Canaliculi are channels that radiate out of the lacunae into the bone lamellae. They contain the processes from the osteoblasts, which are bathed in fluid derived from the blood vessels in the Haversian canals and volkmann canals

What are the methods that osteoblasts get their nutrients and remove their waste

The matrix of the lamellae is slightly permeable, so food and oxygen brought by the blood can diffuse through the bone to the cells.

These fluid and the processes from the osteoblasts in the canaliculi exchange materials. The canaliculi run through the bone matrix and those of neighbouring lacunae make contact in a three-dimensional network.

How are Haversian systems/osteons separated

By interstitial bone

How are cartilage bones formed

These bones include the bones of the limbs, vertebrae and the ribs. They are derived from hyaline cartilage in the embryo, in a process called ossification cartilage cells flatten and calcium salts are deposited around them. Osteoblasts secrete layers of bone matrix around the cartilage while osteoclasts break cartilage down. Blood vessels invade.

How are cartilage bones formed in the long bones of the limbs

Ossification begins at the caps at the ends (epiphyses) and in the middle (diaphysis). The cartilage that remains allows for growth but eventually that ossifies too.

What is periosteum and where does it derive from

It is dense, fibrous connective tissue surrounding bones. It develops from the perichondrium, the connective tissue surrounding the cartilage