Bone Tissue

Question 1

What are the structures of the long bone?

Answer 1

• Diaphysis
• Epiphyses
• Medullary cavity
• The metaphyses
• Periosteum

Question 2

Describe Diaphysis?

Answer 2

The Diaphysis is the shaft of a long bone

Question 3

Describe Epiphyses?

Answer 3

The epiphyses form the proximal & distal ends of a long bone

Question 4

Describe the medullary cavity?

Answer 4

The Medullary Cavity contains yellow bone marrow & blood vessels

Question 5

Describe the function of metaphyses?

Answer 5

Growth occurs at the section of the metaphysis

Question 6

Describe the function of periosteum?

Answer 6

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.

Question 7

Briefly explain how bones grow in length?

Answer 7

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.

Question 8

Describe the location of the periosteum?

Answer 8

Wraps around the external surface of the bone

Question 9

State four functions of the periosteum?

Answer 9

• Protects bone
• Point of attachment for ligaments & tendons
• Nourishes bone tissue
• Helps in fracture repair

Question 10

Name the two types of bone tissue?

Answer 10

Compact bone tissue

Spongy bone tissue

Question 11

Describe the location of Compact bone tissue?

Answer 11

-Dense, smooth outer layer of the bones

Question 12

Describe the location of Spongy bone tissue?

Answer 12

• Always in the interior of bones

Question 13

Describe the function of spongy bone tissue?

Answer 13

Lightweight which means it can be moved by skeletal muscle contraction. Protects bone marrow.

Question 14

Describe the function of compact bone tissue?

Answer 14

Protection & support of spongy bone, blood vessels and nerves

Question 15

Describe three structural differences of compact bone tissue?

Answer 15

• 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

Question 16

What are osteons?

Answer 16

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

Question 17

Describe three structural differences of spongy bone tissue compared to compact bone tissue?

Answer 17

• 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

Question 18

What are the main types of cartilage?

Answer 18

• Hyalin
• Fibrocartilage
• Elastic

Question 19

State the location of Hyalin cartilage?

Answer 19

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.

Question 20

State the location of Fibrocartilage?

Answer 20

• At sites subject to both pressure & stretch e.g Intervertebral discs, pubic symphysis, cartilage pads in knee (menisci).

Question 21

State the location of elastic cartilage?

Answer 21

External ear, epiglottis, auditory tubes, nasal cavity

Question 22

State the function of Hyalin cartilage?

Answer 22

Provides smooth surfaces for joint movement. Provides support and flexibility for joints

Question 23

State the function of Fibrocartilage?

Answer 23

To support and join structures together

Question 24

State the function of elastic cartilage?

Answer 24

Increased number of elastic fibres gives greater elasticity & resilience than other forms of cartilage

Question 25

Describe the components of bone tissue?

Answer 25

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

Question 26

Name the describe the function of the four bone cells?

Answer 26

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

Question 27

Name the main type of fibre in the extracellular matrix and state the function of this fibre?

Answer 27

Collagen fibres - (30%) – these fibers give bone its flexibility and strength to resist being torn (like reinforced concrete)

Question 28

Name the two main minerals in the ground substance and the function of these minerals?

Answer 28

Calcium phosphate | Magnesium

Question 29

State the location, structure and function of the osteons?

Answer 29

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

Question 30

Explain the difference between the epiphyseal plate and the epiphyseal line?

Answer 30

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.

Question 31

Define the terms bone deposit & bone resorption and name the bone cells involved with each?

Answer 31

- Bone deposit = Addition of collagen fibres & minerals to the bone by osteoblasts - Resorption of bone = removal of collagen fibres & minerals by osteoclasts

Question 32

State three factors that affect bone remodelling?

Answer 32

- Genetic factors - Mechanical & gravitational forces on the skeleton - Blood calcium levels

Question 33

Name the two hormones that control bone remodelling?

Answer 33

Parathyroid hormone (PTH), Calcitonin

Question 34

Describe the action of the parathyroid hormone?

Answer 34

Released from the parathyroid glands raises the blood calcium levels by stimulating the osteoclasts to break down bone. This releases calcium into the blood.

Question 35

Describe the action of calcitonin?

Answer 35

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.

Question 36

Explain the fracture repair process?

Answer 36

Stage 1 – Fracture haematoma forms Stage 2 – Soft procallus forms Stage 3 – Bony callus forms Stage 4 – Bone remodelling

Question 37

State five factors that could delay bone healing?

Answer 37

- 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

Question 38

Define osteoporosis?

Answer 38

Osteoporosis is a disease in which there is - Significant loss of bone mass (bone density) - The impaired structural integrity of bone.

Question 39

State who is most affected osteoporosis?

Answer 39

Osteoporosis is most common is older women

Question 40

Describe four age related changes of the skeletal system?

Answer 40

- Bone becomes more brittle & prone to fracture - Articular cartilages diminish and thins - Height is reduced - Rigidity of the thoracic cage as costal cartilage ossifies -