Topics in BiologySkeleton 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 _____.
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.
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.
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:
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.
The structure of spongy bone is such that empty spaces or cavities are more when compared to the bony tissue (osteocytes, hydroxyapatite 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
They are found only in fetus and are composed mainly of fibres.
We the 3 types of bones with regard to how they are developed; they are:
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
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.
Examples are collar bone (clavicle), occipital bone and the mandible.
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:
The axial skeleton in humans is found along the midline of their body. They include the following bones:
Image Credit: Bikramjenn
The ribs, sternum and the thoracic vertebra form the rib cage or thoracic cage.
The appendicular skeleton is located lateral (away) from the body. They include the:
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
NOTABLE POINTS IN Biology
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: