Bone Tissue Flashcards
What are the structures of the long bone?
- Diaphysis
- Epiphyses
- Medullary cavity
- The metaphyses
- Periosteum
Describe Diaphysis?
The Diaphysis is the shaft of a long bone
Describe Epiphyses?
The epiphyses form the proximal & distal ends of a long bone
Describe the medullary cavity?
The Medullary Cavity contains yellow bone marrow & blood vessels
Describe the function of metaphyses?
Growth occurs at the section of the metaphysis
Describe the function of periosteum?
Connective tissue which wraps around the outside of the bone. The outer layer is fibrous and tough and the inner Layer contains osteoblasts which help the bone grown in thickness. It is rich in sensory neurone.
Briefly explain how bones grow in length?
Bones grow in length at the epiphyseal plate. The cartilage in the region of the epiphyseal plate next to the epiphysis continues to grow by mitosis.
Describe the location of the periosteum?
Wraps around the external surface of the bone
State four functions of the periosteum?
- Protects bone
- Point of attachment for ligaments & tendons
- Nourishes bone tissue
- Helps in fracture repair
Name the two types of bone tissue?
Compact bone tissue
Spongy bone tissue
Describe the location of Compact bone tissue?
-Dense, smooth outer layer of the bones
Describe the location of Spongy bone tissue?
- Always in the interior of bones
Describe the function of spongy bone tissue?
Lightweight which means it can be moved by skeletal muscle contraction. Protects bone marrow.
Describe the function of compact bone tissue?
Protection & support of spongy bone, blood vessels and nerves
Describe three structural differences of compact bone tissue?
- Is made up of osteons. This gives the long bones strength.
- Within and between the osteons is the extracellular fluid that contains osteocytes to maintain the bone tissue.
- This enables the exchange of nutrients & oxygen and the removal of waste
What are osteons?
Tiny weight-bearing pillars that have layers of collagen fibres in opposing directions. Each osteon has a central canal that contains blood vessels & a nerve. It is the osteons that give the strength and resistance to compact bone
Describe three structural differences of spongy bone tissue compared to compact bone tissue?
- Less dense than compact bone as it contains bone marrow
- No osteons but fine trabeculae ‘little beams’
- Nutrients and oxygen pass from blood vessels that surround the trabeculae
- Trabeculae are positioned along lines of stress – resist stress
What are the main types of cartilage?
- Hyalin
- Fibrocartilage
- Elastic
State the location of Hyalin cartilage?
Supports external nose (nose cartilage). Covers end of most bones at movable joints ( Articular cartilage). Connects ribs to sternum (Costal cartilage). Also in the larynx, trachea, bronchi & bronchial tubes.
State the location of Fibrocartilage?
- At sites subject to both pressure & stretch e.g Intervertebral discs, pubic symphysis, cartilage pads in knee (menisci).
State the location of elastic cartilage?
External ear, epiglottis, auditory tubes, nasal cavity
State the function of Hyalin cartilage?
Provides smooth surfaces for joint movement. Provides support and flexibility for joints
State the function of Fibrocartilage?
To support and join structures together
State the function of elastic cartilage?
Increased number of elastic fibres gives greater elasticity & resilience than other forms of cartilage
Describe the components of bone tissue?
Water – 15%
Collagen fibres - (30%) – these fibers give bone its flexibility and strength to resist being torn (like reinforced concrete)
Crystallized – 55% (most abundant is calcium phosphate). Crystallization of mineral salts with other ions (e.g. magnesium) hardens the tissue – a process called calcification
Name the describe the function of the four bone cells?
Stem cell: Develops into osteoblasts
Osteoblasts: Bone forming cells that produce bone matrix
Osteocytes: Exchange nutrients & wastes in the extracellular matrix
Osteoclasts: Release enzymes to breakdown bone- called bone resorption
Name the main type of fibre in the extracellular matrix and state the function of this fibre?
Collagen fibres - (30%) – these fibers give bone its flexibility and strength to resist being torn (like reinforced concrete)
Name the two main minerals in the ground substance and the function of these minerals?
Calcium phosphate
Magnesium
State the location, structure and function of the osteons?
Location: Arrange parallel to the diaphysis of long bones
Structure: Each osteon has a central canal that contains blood vessels & a nerve
Function: It is the osteons that give the strength & resistance to compact bone
Explain the difference between the epiphyseal plate and the epiphyseal line?
The epiphyseal growth plate becomes an “epiphyseal line”, as growing cartilage is replaced by calcified bone. The epiphyseal line is visible externally & on X-rays.
Define the terms bone deposit & bone resorption and name the bone cells involved with each?
- Bone deposit = Addition of collagen fibres & minerals to the bone by osteoblasts
- Resorption of bone = removal of collagen fibres & minerals by osteoclasts
State three factors that affect bone remodelling?
- Genetic factors
- Mechanical & gravitational forces on the skeleton
- Blood calcium levels
Name the two hormones that control bone remodelling?
Parathyroid hormone (PTH), Calcitonin
Describe the action of the parathyroid hormone?
Released from the parathyroid glands raises the blood calcium levels by stimulating the osteoclasts to break down bone. This releases calcium into the blood.
Describe the action of calcitonin?
If blood calcium levels are too high calcitonin is released from the thyroid gland to inhibit the activity of osteoclasts, preventing bone resorption. It lowers the blood calcium level.
Explain the fracture repair process?
Stage 1 – Fracture haematoma forms
Stage 2 – Soft procallus forms
Stage 3 – Bony callus forms
Stage 4 – Bone remodelling
State five factors that could delay bone healing?
- Tissue fragments between the bone ends that haven’t been removed by phagocytes
- Deficient blood supply
- Poor alignment of the bone ends
- Continued mobility of bone ends
- Illness, malnutrition, drugs, aging
Define osteoporosis?
Osteoporosis is a disease in which there is
- Significant loss of bone mass (bone density)
- The impaired structural integrity of bone.
State who is most affected osteoporosis?
Osteoporosis is most common is older women
Describe four age related changes of the skeletal system?
- Bone becomes more brittle & prone to fracture
- Articular cartilages diminish and thins
- Height is reduced
- ## Rigidity of the thoracic cage as costal cartilage ossifies
