Bones and Type of Bone part 2

Olawunmi Omosanya - Tue, 02nd July, 2019 @ 17:20: PM

Topics in Biology

Skeleton and Type of Skeletal Materials Bones and Types of Bone Bones and Type of Bone part 2 Red Blood Cells and Hemoglobin Tropical Rainforest and Savanna with their characteristics Desert and Swamp Forest with their characteristics Autotrophic mode of Nutrition Amazing facts in Biology Characteristics of Protists Characteristics of Reptiles

Academic Questions in Biology

Chemical digestion of carbohydrate (cooked starch) begins in the _____.

  1. mouth
  2. oesophagus
  3. stomach
  4. small Intestine
  5. large Intestine

ANSWER is Mouth

The digestion of carbohydrate (cooked starch) begins in the mouth through an enzyme called salivary amylase (formerly called ptyalin) found in the saliva. This enzyme breaks down the starch present in carbohydrates into maltose. Maltose is a disaccharide. Please read on sugars and disaccharide here.

Note: With regards to digestion, chemical digestion is emphasized. We also have mechanical digestion which involves the grinding action of the teeth.


Types of Bones:

Recall that bones are composed of living cells called osteocytes and non-living cells (minerals salts and collagen fibres). In a previous article, we explained the classification of bones based on shape. In case you missed our explanation on bones and the above classification; Please read on it here.

In this article, we will continue to explain the various types of bone based on their classifications.


  • Classification of bone based on Structure

We already know that all bones are composed of the same materials, that is, osteocytes or bone cells, hydroxyapatite (Calcium phosphate), Calcium carbonate, protein and collagen fibres. Based on how the contents of the bone is structured, we may classify them into the followings:

1. Compact Bone

A compact bone has more of bone cells together with minerals (hydroxyapatite); and as a result, only little space or cavity is present within it. They form the hard external layer of all bones and will typically surround the medullary cavity (which houses the bone marrow). The compact bone function to strengthen and protect the inner matrix of the bone. Compact bone contains osteons. The haversian systems are present within the compact bone.

Note: Osteons are composed of osteocytes and minerals (hydroxyapatite) connected by a canaliculi which transports blood.

A compact bone is sometimes called cortical bone.


2. Spongy bone

The structure of spongy bone is such that empty spaces or cavities are more when compared to the bony tissue (osteocyteshydroxyapatite and fibres). They form the internal layers of bones; unlike compact bone which forms the external layers. Spongy bone tissue does not contain osteons that constitute compact bone tissue, rather they are made of trabeculae. When we examine the head of long bones (epiphysis), we will observe that within it are spongy bones. Here, they function to reduce the density of the epiphysis, thus allowing for compression when such bone is stretched.

 Note: A spongy bone can be easily broken and chewed to extract its fluid. In Nigeria, it's fondly referred to as “biscuit bone”.

Another name for spongy bone is Cancellous bone

3. Fibrous bone

They are found only in fetus and are composed mainly of fibres.

4. Lamellar bone


  • Classification of bone based on Development

We the 3 types of bones with regard to how they are developed; they are:

1. Cartilaginous bones

Ossification of cartilaginous bone begins from the cartilage. The bones of the upper limbs, lower limbs and rib cage are all cartilaginous bone.

The upper limb is the region from the arm through the fingers

The lower limb is the region from the thigh through the toes

2. Membranous Bones or Dermal Bones

These bones are very likely to in a fetus (when the baby is still inside the mother’s womb. The process through which they ossify is termed intra-membranous ossification. The skull and face bones are membranous bones.

3. Membrocartilaginous bones

Examples are collar bone (clavicle), occipital bone and the mandible.


  • Classification of bone based on bodily region

These bones are classified base on whether they are medial (towards the midline) of the body or lateral (away from the midline of the body). We can categorize them into 2:

1. Bones of the axial skeleton

The axial skeleton in humans is found along the midline of their body. They include the following bones:

  1. Skull
  2. Vertebral column
  3. Sternum
  4. Ribs

Image Credit: Bikramjenn

The ribs, sternum and the thoracic vertebra form the rib cage or thoracic cage.

2. Bones of the appendicular skeleton

The appendicular skeleton is located lateral (away) from the body. They include the:

  1. Bones of the upper limbs: The upper limb in humans consists of the region of the arm through the fingers. The bones of the upper limbs include the humerus, ulna, radius, wrist bones (carpal bones), metacarpals and phalanges.

  3. Bones of the lower limb: The lower limb in humans consists of the region from the thigh through the toe nails. The bones of the lower limb include the femur, tibia, fibula, ankle bones (tarsal bones), metatarsals and phalanges

Amazing facts in Biology

An adult human being is composed of about 60% water. In fact, a newly born baby is composed of about 80% of water. This will drop to 65% after a year and finally to about 60% as the child ages

Without saliva, food can never be enjoyed. Food becomes tasteless since saliva is needed to dissolve the chemicals present in food onto the tongue’s taste buds.

Saliva also contains an enzyme called salivary amylase or "ptyalin" which helps to digest cooked starch to maltose. Maltose is a double sugar or disaccharide. Please read on sugars here


The gas used in the manufacture of food by plants is Carbon dioxide or Carbon(IV)oxide or CO2. 

Plants manufacture food through a process called photosynthesis. Please read on photosynthesis here

Note: Plants are the only orgnisms that take away CO2 from the atmosphere

In the Biological organization of life, it is said that cells form tissues, tissues form organs and organs form systems. There are 12 systems in the human body; these are:

  1. Cardiovascular System
  2. Digestive System
  3. Endocrine System
  4. Immune System
  5. Integumentary System
  6. Lymphatic System
  7. Muscular System
  8. Nervous System
  9. Reproductive system
  10. Respiratory System
  11. Skeletal System
  12. Urinary or Renal System

Please read on the amazing facts in Biology here

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