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.
The bone is the major skeletal material present in the skeleton of vertebrates. A fully formed bone is composed of living cells called osteocytes (The osteocytes are arganic in nature). These bone cells (osteocytes) are fortified or made strong by minerals (which are inorganic), especially hydroxyapatite (formed from calcium phosphate) and calcium carbonate. Collagen fibres are also present as a component of bones.The mineral component of the bone cells are non living and they account for about two third (2/3) of the mass of the bone. This is why a bone is much stronger and rigid than a cartilage (as a result of their high mineral content).
Note: Calcification of bones will only occur when collagen fibres are present.
Calcification is the process whereby mineral salts (hydroxyapatite) are deposited on the collagen fiber. This process crystallizes and hardens the bone tissue.
1. Osteoblasts: These bone cells are responsible for bone formation. They secrete both the organic and inorganic components of the bone.
2. Osteocytes: These are matured bone cells and do not undergo division. They maintain the bone’s structure by recycling the mineral component of bone matrix. They are the living tissues in bone and make up about one third (1/3) of the mass of a matured bone.
3. Osteoclasts: They are large bone cells that function to dissolve (remove) the bone structure. They release lysosomal enzymes and acids on the bone matrix to bring about their dissolution effect. Through this process, calcium and phosphate minerals are released into the blood and body fluids in order to increase their concentrations. This process is important in certain physiological conditions.
4. Osteoprogenitor cells: They are responsible for the formation of osteoblasts which makes them important for the repair of broken bones (fracture).
Ossification is the natural process that leads to the formation of bone by osteoblasts. Another term for ossification is osteogenesis.
Adult human beings have a total of 206 bones while a newly born child has even more. Knowledge of all the bones in the human body will help you better understand the human skeleton.
Bones can be classified based on a number of criteria. We will consider 4 of these:
We have 7 types of bones with regards to their shape. These are:
Image Credit: Owlcation
These bones appear long in appearance because they typically have an elongated shaft called diaphysis and two expanded ends on either side of the diaphysis. The expanded ends are referred to as the epiphysis. The epiphysis is covered with an articular cartilage because joints are formed around them. Within the shaft of long bones is a space or cavity called the medullary cavity.
The medullary cavity contains the bone marrow
Note: All blood cells are produced in the bone marrow. Blood cells include:
We have three categories of long bones. These are:
They are short is appearance and are often named according to their respective shapes. The bones comprising the wrist and ankle (carpal and tarsal bones) are short bones.
Wrist bones (also known as the carpal bone) includes:
The ankle bones (also known as tarsal bone) are:
These bones look like the sesame seed and are embedded inside of joint capsules. They will usually develop inside a tendon, thus are usually present within joints. They will ossify only after birth. A typical example of a sesamoid bone is the patella found in the kneecap/knee joint.
They are thin and broad in appearance with two main surfaces. Their surfaces aid in the attachment of various muscles. The scapula, the bone that make up the roof of the skull, sternum (breast bone) and ribs are flat bones.
These bones have a variety of shape, hence the name “irregular bone”. They could be flat, short or notched in shape depending on their location. They are found in the pelvis, vertebrae and the base of the skull.
Although these bones are irregular in shape, they are also very light because of the presence of large air cavities or spaces within them. Examples are the maxilla, sphenoid and ethmoid bones which contribute to the lightness of the skull.
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: