The human body gets its shape from the skeleton, which consists of bone and cartilage. Vital organs such as the lungs, heart, and brain are enclosed within the skeletal system. Enamel is the hardest substance in our body, but if we talk about which tissue is the hardest, it will be the Femoral and Temporal bone of the skull. Teeth and bone are the main substances in our body but the striking difference being teeth aren't actually bone though more than 99% of the calcium in our body is found in bones and teeth.
Our human body is made up of five sense organs- eyes, ears, nose, tongue and skin. An interesting fact is that there is a “sixth sense”, which is known as proprioception or the body's awareness of its place in space.
The skin is our body's most sensitive organ consisting of water, nutrients, lipids, and mineral deposits. The skin protects us from any kind of physical harm and, most importantly, reduces the harmful effects of UV radiation. The skin synchronises our body temperature. As most of our body is covered with skin, the most sensitive heat receptors are our elbows, nose and fingertips. The cold receptors are found on the chest, chin, nose, fingers, and upper lip. The skin covers 22 square feet of the surface area of a human body and is about 16% of total body weight.
Besides being a sensitive organ, it plays a vital role in providing immunity and protection against any kind of germs too. The skin, besides containing pain, and heat receptors, also contains hair follicles for the growth of hair. The skin, besides being the most sensitive, has varying degrees of thickness and thinness, for example, the skin below the eyes is the most sensitive, but it's thicker on the soles of feet and palms.
The human body comprises 206 bones which provide shape and form. The vital organs are also shielded by the bones, the femur being the longest, thickest and strongest, and the weakest and softest bone in our body is the clavicle which is the collar bone.
Interestingly the weak part of the body is dependent on the fact that what kind of force is operated on it, like the femur being the strongest bone, will handle impact before it cracks, but the ribs will break under much lesser impact of external force. If the impact is more than eyes, throat, knee joints, etc. will be considered weak depending on the force involved.
Cartilage is a connective tissue found all over the body. It is a vital structural component and consists of chondrocyte cells mixed with collagen, thus, making it softer than bone. It provides support and structure to the tissue and cushions the joints. There are three types of cartilage found in our body, that are, Hyaline cartilage, Elastic cartilage, and Fibrocartilage.
Hyaline is found at the ends of joints, between the ribs and inside the nose.
Elastic is found in the external ear, epiglottis and larynx.
Fibrous is the hardest cartilage in intervertebral discs, joint capsules, and ligaments.
Fibrous cartilage is the strongest because of the presence of one after another layer of hyaline cartilage, matrix and layers of collagen fibres. It has strong resistance to ductile stresses and is tough and inflexible. It is found within the knee, in the intervertebral discs and in the pubic symphysis. Being the hardest cartilage, it forms the lining of the bony grooves of the tendon.
An interesting fact is that the thigh bone (Femur) is the strongest and longest bone in the human body and takes a lot of force to break it motor vehicle accidents are the major cause of femur fractures.
1. Which is the second hardest tissue in the body?
Ans. The dentin lies beneath enamel and cementum, it's harder than bone but softer than enamel. It being the second hardest tissue and possessing a softer texture than enamel, helps absorb the pressure from chewing. Dentine is denser than bone and has a yellowish colour seen through the tooth enamel Is the second hardest tissue.
2. What is the strongest bone in the human skull?
Ans. The mandible is the largest and strongest bone forming the face, the lower part of the jaw and major part of the mouth, as it holds the lower teeth in their position, assists in chewing food and is composed of the left and right halves of the lower jaw or mandible.
The fibrocartilage is the strongest, specialised type in areas requiring tough support and strength.
Skin is the most sensitive and the largest organ of our body, the liver is the second largest.
The Mohs hardness scale is a qualitative ordinal scale. Tooth enamel ranks as hard as steel.
1. Which part of the body cannot feel pain?
The head, hair, and nails have no nerves, and the brain doesn't feel any pain because there is zero presence of nociceptors in the brain tissue. The brain does not feel pain, but the covering around the brain and the scalp all have pain receptors. Even surgery can be done on the brain, and technically, it will not feel any pain. The forearm also possesses a lot of muscle and thick skin without any nerve endings.
2. How does the skin relate to the sense of touch?
The skin is the largest organ that senses the touch, which is known as Tactioception. It detects the temperature, pain, and other external factors for protection against them. It has three layers known as Epidermis, the outer layer containing a protein called keratin. The dermis is below the epidermis and is responsible for the flexibility of the skin due to the presence of collagen, fat, and fibres. The hypodermis is the subcutaneous layer of fat which provides energy and regulates temperature.
3. What are hard tissue and soft tissue?
Hard tissue is a term referring to bones, while soft tissue means muscle, ligaments, tendons or connective tissue. The hard tissue comprises collagen, which is a form of protein and polysaccharides are the cementing medium between them. Hard tissue is also termed calcified tissue because it is mineralized and is found in bones, tooth enamel, dentin, and cementum. Soft tissue includes muscles of the heart, blood vessels and tissue surrounding bones and joints.