Question

1. What is the musculoskeletal system composed of and what are major functions of the system? 2. How many bones in the human body and what are the four categories they are classified by? 3. What are Bones composed of and what is it's 3 basic types? 4. What is Osteogenesis? 5. What is the process of bone remodeling and when do turnover occurs?

Answer 1

Musculoskeletal system

Human musculoskeletal system is composed of muscular system and skeletal system. Both the system are performing the main functions like movement and support and they are interconnected so commonly referred to as one name ; musculoskeletal system. It is made up of the bones, muscles, tendons, cartilages and ligaments.

Functions

* Provides form and support and shape to the body

* Allows motion or movement of the body

* storage of minerals like Calcium and phosphorus

* formation of new blood cells

* protection of vital organs

* provide the body with stability

2. An average adult human skeleton consist of 206 bones. At birth the skeletal system consist of 270 bones later some of the bones fuse together and thus decrease in the total number of bones .

Four major categories of bones

There are four major types of bones:

Long bones: longer bones are meant for support weight and to enhance movement. The long bones are longer than they are wide. They are mostly located in appendicular skeleton, include lower limb and upper limb. Examples; tibia, fibula, femur, humerous, radius and ulna.

Short bones: they are smaller bones, have tubular shaft and articular surfaces at each end . It includes metacarpels( hands), metatarsals( feet) and phalanges.

Flat bones: they are meant to protect internal organs. They are thin and have flat surface. Flat bones include skull bones, scapula , ribs , sternum etc.

Irregular bones: they are irregular in shape and structure. They are usually compact and complex in shape. Examples of irregular bones are carpel and tarsal bones, bones of vertebral column.

3. Bones are the rigid structure of musculoskeletal system. It is composed of connective tissue either soft or dense. This connective tissue is consist of specialised bone cells and calcium. Bones also contain bone marrows that helps in the production of blood cells.

Three basic types of bones based on the structure are compact bone( bone substance is bigger than bone space and are hard.)

Spongy or cancellous tissue ( bone space is more than bone sustace,honeycomb material found inside and light weight but strong.

Bone marrow ( site of the production of blood cells. It is a jelly - likw substance found in the cavities of the bone.)

4. Osteogenesis

The formation andd development of bone is called osteogenesis. This process involves osteoblasts.

5. Bone remodeling

Bone remodeling also known as bone metabolism. ' It is a continuing process of synthesis and destruction that gives bones its mature structure and maintains normal calcium levels in the body'. There are two types of cells in bones osteoblasts and osteoclasts. Osteoclasts releases Calcium into the blood stream there by resorption of bones take place. While osteoblasts absorb calcium and make new bone.

'Bone turnover refers to the total volume of bone that is both resorbed and formed over a period of time. Bone remodelling is the process and bone turnover is the effect.

6. Factors influencing bone resorption are: activity of parathyroid hormone ( increases the activity of osteoclasts leads to greater resorption of calcium), Calcitonin hormone( decreases osteoclast activity), level of Calcium( high level of Calcium causes decreased production of parathyroid hormone results in decreased bone resorption. Decreased vitamin D, stress, hormonal changes, lower protein metabolism also influences bone resorption.

7. Vitamin C : sources

Citrus fruits eg; orange, lemon, kiwi, grapes, guava

Vegetables like capsicum, brocoli, cauliflower

Vitamin D

Egg yolks

Beef liver

Fatty fish ( salmon, tuna)

Fishliver oil

Chees

Foods fortified with vitamin D

8. Calcium homeostasis: hormones

Parathyroid hormone( PTH) : stimulates osteoclasts and increases calcium resorption from bone, increases blood - Calcium level

Calcitonin: it inhibites osteoclasts activity there by decreasing bone resorption resulting in maintaining the balance of Calcium level in the blood.

9. Bone healing is a proliferative physiological process consist of three stages of inflammation, bone production and bone remodeling.

10. A fracture is a breakage in the integrity of bone. The healing of fracture consist of four stages.

Hematoma formation ( phase of inflammation : formation of clot at the injury site and broken ends are sealed by clot)

Bone generation( new capillaries grow. Dead cells cleared by phagocytes . Fibroblasts and osteoblasts enter the site and starts working)

Bony callous formation( formation of bony callous)

Bone remodeling( bone remodeled by osteoblasts and osteoclasts. This can take many months.)