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Flashcards in Bone and Connective Tissue Deck (67):

What is bone tissue?

A supporting connective tissue.


What makes up bone tissue?

Collagen and calcium phosphate crystals


What makes up 2/3 the weight of the bone?

Calcium phosphate crystals


What makes up 1/3 the weight of the bone?

Collagen fibres


What adds flexibility to the bone?

Collagen fibres


What adds strength and weight-baring capabilities?

Calcium phosphate crystals called hydroxyapatite


What types of cells comprise osseous tissue?



What are Osteocytes?

Mature bone cells
Found in small packets called lacunae
Sandwiched between layers of calcium matrix known as lamella.


What are Osteoblasts?

Responsible for the production of new bone, a process called osteogenesis.


What is osteogenesis?

The production of new bone.


What are osteoclasts?

Giant cells with 50 or more nuclei.
Dissolves the bony matrix and releases the stored minerals of calcium phosphate.


What is osteolysis?

The process of osteoclasts dissolving the bony matrix.


What is the relationship between Osteoblasts and Osteoclasts?

Osteoblasts produce new bone. Osteoclasts dissolve bone tissue.


What are osteoprogenitor cells?

These cells produce daughter cells that can differentiate into osteoblasts. Play a role in fracture repair.


What are the two types of bone tissue?

Cortical or compact
Cancellous or spongy


Describe cortical bone.

Forms the hard outer layer and is found in the shafts of long bones.


What is the hard outer layer of bone that consists of a number of cylindrical structures called?

Osteons or haversian systems


What makes up a haversion system?

Central aversion canal - contains blood, lymphatic vessels and nerves
Lamellae - rings of bone around the haversian system
Lacunae - spaces between the lamellae, which contain osteocytes (mature bone cells)
Canaliculi - channels carrying nutrient fluid which connect the lacunae and communicate with the aversion canal
Interstitial lamellae - fill the spaces between adjacent aversion systems
Volkmann's canals - join the various haversion canals


Describe cancellous bone.

Found in the part of the bones where lightness, strength and area are needed.
Present at the ends of long bones
These regions are the heads or epiphyses


What are the ends of long bones called?



What is the name of the membrane that surrounds the outer layer of the bone?

The periosteum


What is the function of the periosteum?

To isolate the bone from the surrounding tissues
To provide a route for circulatory and nervous supply
To actively participate in bone growth and repair

Near joints the fibrous layer of the periosteum blends with the connective tissues and bind the bones together.

At a joint the periosteum is continuous with the joint capsule.


When does the bony skeleton begin to form in the fetus?

6 weeks after fertilization. Before this time the skeletal elements are cartilaginous.


When does bone growth stop?

Early 20s.


What is the process of replacing other tissues with bone?



What term describes the deposition of calcium salts within a tissue?



What are the two major forms of ossification?

Intramembranous and endochondral


Describe Intramembranous ossification

Also known as dermal ossification
Begins when osteoblasts are produced within a fibrous connective tissue
Occur in the deep layers of the dermis


What are the steps in intramembranous ossification?

1. Osteoblasts cluster together and secrete collagen fibres and osteoid. These then become mineralized through the crystallization of calcium salts.

2. The developing bone grows out from the ossification centre in small branches called spicules.

3. Initially, the bone assumes the structure of spongy or cancellous bone. With subsequent remodeling compact bone can be produced.


Describe endochondral ossification.

Process by which bone formation takes place in the long bones or limb bones. They start as hyaline cartilage and ossify into bone.

1. Cartilage cells begin to disintegrate.

2. Osteoblasts form

3. Blood vessels penetrate the region and grow towards the epiphyses. Fibroblasts become osteoblasts and begin producing spongy or cancellous bone.

4. Remodeling occurs creating a marrow cavity. Bone becomes thicker. Cartilage near epiphysis is replaced with bone.


Describe appositional bone growth.

Blood vessels and collagen fibres of the periosteum become incorporated into the bony structure.


What are the steps to increase the length of a bone?

1. Capillaries and osteoblasts migrate into epiphyses creating a secondary ossification centre.
2. In the epiphyseal plate, chondrocytes closest to the epiphysis divide and thicken the plate forcing the epiphyses further from the shaft.
3. Osteoblasts and capillaries invade the lacunae and replace the dead cartilage with living bone creating secondary ossification centres.


What has to keep pace with the rate of osteoblast invasion in order for bones to maintain or grow?

Cartilage growth


What are the steps in repairing a fracture?

1. Bleeding into the area creates a fracture haematoma acting as a bridge along which new cells grow.
2. Ostoblasts form a fracture callus creating both an internal and external callus of cartilage
3. The cartilage of the external callus is replaced by bone
4. A swellin marks the location of the fracture. Over time this region will be remodeled by the combined action of osteoblasts and osteclasts leaving little evidence of the break.


Is the bone stronger after a break in that same area?



What does the matrix contain?

It's a firm gel that contains proteoglycans called chondroitin sulphates.


What are the only types of cartilage cells to be fond within the matrix?






What are the 3 types of cartilage found in the body?

Hyaline Cartilage
Elastic Cartilage


Describe hyaline cartilage.

Most common
Contains closely packed collagen fibres
Somewhat flexible
Located between the tips of the ribs and the bones of the sternum, bone surfaces of synovial joint
Supporting the larynx, trachea and bronchi, nasal septum
Function by providing stiff but somewhat flexible support
Reduces friction between bony surfaces


Describe elastic cartilage.

Extremely resilient and flexible
Located on the Pinna of the external ear, tip of the nose, the epiglottis


Describe fibrocartilage.

The matrix is made up of densely interwoven collagen fibres making it tough and durable
Located in the discs separating the vertebrae, the menisci of the knee joint, between the pubic bones of the pelvis
It functions by resisting compression, prevents bone-to-bone contact, limits relative movement.


Describe non-elastic ligaments

Bands of strong fibrous connective tissue that bind together the articular ends of bones and cartilage at the joints to facilitate or limit motion.
Can tolerate a limited amount of stretching
Provides additional support in the knee, elbow and wrist


Describe elastic ligaments.

Resemble tough rubber bands and can tolerate more stretching than non-elastic ligaments. Found along the spinal column and stabilize the vertebrae.


What are the 3 layers of muscle tissue?

Epimyseum - outer
Perimysium - center
Endomysium - inner


Describe the epimysium muscle layer of connective tissue.

Dense fibrous connective tissue layer that surrounds the entire skeletal muscle. Separates muscle from surrounding tissue.


Describe the perimysium layer of muscle connective tissue.

Divides the muscle into a series of internal compartments.


Define fascicle.

bundle of muscle fibers


Describe endomysium.

Surrounds each skeletal muscle fibre and binds them together.


What is a tendon?

At the end of each muscle, the collagen fibres of the epimysium converge to form a thick fibrous extension known as a tendon.
Attache skeletal muscles to bone


What are aponeuroses?

Collagenous sheets or ribbons that resemble flat, broad tendons.


What are the functions of the nervous system?

Providing information about the internal and external environments.
Integrating sensory information
Co-ordinating voluntary and involuntary motor activities
Controlling and regulating other tissues and systems


What are the two divisions of the nervous system?

The central nervous system (CNS) and the peripheral nervous system.


What does the central nervous system consist of?

CNS consists of the brain and spinal cord and is responsible for integrating, processing and co-ordinating sensory data and motor commands.
It is also the seat of higher functions such as intelligence, memory, learning and emotion.


What does the peripheral nervous system (PNS) include?

The PNS includes all the neural tissue outside the CNS and carries motor commands to the peripheral tissues and systems.


What are the cells called that are responsible for the transfer and processing of information in the nervous system?



What are the longest cells in the body?

Neurons. Many reaching a meter in length.


What can't a neuron do?

Divide or repair itself after injury


What is another name for the neuron's cell body?

Soma and it contains a large nucleus


What are the branching processes extending from the cell body called?

Dendrites and a single axon


Describe the messaging capabilities of the dendrites and axon.

Dendrites receive incoming messages.
Axons conduct outgoing messges.


What makes a neuron long?

They length of its axon.


What are sensory nerves?

Nerves that transmit afferent impulses from teh periphery of the body to the spinal cord and then to the brain where they are interpreted and perceived as sensations.


What are motor nerves?

Convey efferent impulses from the brain and spinal cord to other parts of the body, stimulating the contraction of all muscles and glandular secretion.


What happens when a sensory nerve is damaged?

That area it supplies is deprived of all sensory perception.


What happens when a motor nerve is damaged?

Paralysis of those muscles supplied by that nerve


What happens to damaged nerves in the extremities?

Often times both the motor and sensory are damaged thus there is a loss of movement and sensation.